Virology Flashcards

Question

What is the host immune reaction to a POX virus ?

Answer 1

Immune reaction to a POX virus ? * progressive multifactoral * early on interferons, inflammatory cells and natural killer cells may contribute to slowing the spread of infection *** most important is cell mediated cytotoxic T lymphocytes and delayed hypersensitivity for recovery** *B cell humoral has yet to be demonstrated in recovery, however is very important in preventing reinfection *

Answer 2

How POX viruses evade the immune system ? * produce many gene products homologous to host genes * these products damage the host immune response * Epidermal growth factor and vascular growth factor which act to modulate the growth of genes * complement proteins cytokines, interferon gamma proteins which enhance the viral environment for replication

Answer 3

POX virus sampling and diagnosis Sampling * clinical signs overt and typical * if viremic - blood VI, PCR, EM * scabs EM and VI * serum, SNT and ELISA * immunohistochemistry - immunoperoxidase

Answer 4

Fowlpox Occurance is worldwide Two forms Cutaneous form = nodular lesions of the wattle, comb and eyelids + other non feathered areas * cutaneous form most common Diphtheroid form = nodules on the mucosal membranes of pharynx, trachea and oesophagus Special histological changes = cytoplasmic inclusion bodies*

Answer 5

Diag / control Avipoxvirus Fowlpox * skin lesions are relatively pathognomonic * tracheal lesions (must be differentiated from larntracheitis infection) * histopathology - lesions, proliferation, intracytoplasmic inclusion bodies * PCR for specific sequencing of the genome Control * cell culture propagated vaccine for chicks one day old * embryo origin vaccine chicks 8-10 weeks of age * traditional vaccination via wing stab

Answer 6

Capripoxvirus Sheeppox virus, goat pox and lumpy skin disease Transmision = oral, mechanical and respiratory Occurance = Africa and Asia * most important of mammalian poxvirus infections * transboundary * huge economic importance * sheeppox and goatpox are distinct viruses, however recombination may occur between them * may remain infectious for upto six months in sheep pens, or 3 months on wool and hair * most isolates only infect sheep or goats, but some isolates may cause serious disease to both species

Answer 7

Clinical signs capripoxvirus sheep * stable in the environment * skin nodules - circumscribed firm * lesions may develop in lungs and respiratory tract * infections are generally acute with no strong evidence for latent or persistant infections * occasionally fatal disease * fever * lymphadenopathy * severe economic loss

Answer 8

LSD lumpy skin disease cattle (capripoxvirus) * highly variable disease between indivduals - some are asymptomatic * sudden onset of fever * salivation * occular and nasal discharge * nodules on skin and internal organs * pneumonia and death * mortality 1% (upto 75% in outbreaks); this range is due to many factors including breed, virus isolate, prior animal health, type of insect vector, secondary infections

Answer 9

Capripoxvirus LSD Transmission - cattle water buffalo worldwide not Australia and NZ * direct contact * biting flies * ticks *semen Diagnosis * clinical signs - fever, enlarged lymph nodes, characteristic skin nodules * note many animals are asymptomatic *occasionally fatal disease * lab test EM, PCR, Histopathology and ELISA * requires a differential diagnosis * vaccination is recomended in endemic countries

Answer 10

Myxoma * Virus host coevolution - benign fibromas in American host but severe generalised disease in European rabbit * most rabbits die 12 days * surviving rabbits have subcutaneous swellings which appear all over the body (myxomatosis) * when introduced to European rabbits in Australia mortality of 99% * dvelopment of of resistance by the emergence of attentuated virus strains

Answer 11

Clinical signs parapoxvirus - bovine papular stomatitis virus and Orf virus Sheep and cattle * contagious localised lesions in a range of animals * scab formation around the mouth, nostrils and eyes * lesions mammary gland vulva, infected lactating ewes may abandon lambs * common in the commisure of the mouth * capable of surviving for years in the environment * common in sheep and goats / usually young animals General characteristics * easily distinguished from other pox viruses as as it is more narrow and oval shaped

Answer 12

Parapoxvirus * prevention by vaccination + disinfect equipment between animals * live attenuated vaccine * skin of inner thigh is scarified and a lesion will develop * immunity achieved within two weeks * vac pregnant ewes behind the elbow to prevent infection of the udder

Answer 13

Adenoviridae Large dsDNA - replicate in the nucleus * associated with infection respiratory tract, eye and GIT * many infections with adenovirus are subclinical * heavily dependant on the cell for transcription * resist heat and many chemicals

Answer 14

Canine adenovirus Cav-1 * once an important disease of dogs * majority of infections are asymptomatic * fever, hepatic necrosis, widespread haemmorrhage and vascular injury * systemic paracute - pup found dead * systemic acute - fatal, fever, loss of apetite, vomiting haemorrhages of the gums * systemic mild - partial immunity Cav-2 * respiratory disease (integral part of kennel cough complex)

Answer 15

Fowl adenovirus some causative agents of inclusion body hepatitis transmission horizontal and vertical Clinical signs * hepatitis * high mortality rate in young broilers * hepatocyte viral inclusion bodies * liver - pale, friable, swollen with focal to extensive necrosis

Answer 16

Fowl Adenovirus * control is via vaccination of breeding birds - broilers are protected by maternal antibody * live attentuated vaccine for Australian outbreaks * there is litle cross protection between different strains - which prevented the development of effective inactivated vaccines * biosecurity to prevent horizontal spread

Answer 17

many mosquito borne viruses ss + sense RNA enveloped

Answer 18

Orthomyxoviridae * negative stranded, segmented RNA viruses * enveloped viruses between 80-120nm

Answer 19

Influenza A * most common fastest mutating influenza virus * birds, humans, pigs, horses and dogs * currently circulating H3N2 and H1N1pdm9 Influenza B * less common * humans, seals Influenza C * humans, pigs Influenza D * cows, pigs

Answer 20

Natural host influenza A viruses * wild water birds Order Anseriformes (ducks, geese and swans) * detected in 1-60% of migratory water birds depending upon season * infected wild birds usually present asymptomatically * replicate mainly in epithelial cells of the GIT (lesser extent respiratory) in wild birds * large amount of virus excreted in faeces

Answer 21

Two mechanisms for the rapid evolution for AIV evolution ? Reassortment (antigenic shift) * occurs when two influenza viruses concurrently infect the same person or host * may result in a progeny virus with the genetic material from both parent viruses * segmented virus Mutation / adaptation (antigenic drift) * occurs when an influenza virus accumulates mutations that enable more efficient infection and spreed within a new host

Answer 22

Influenza host affects symptoms Influenza HA binds to salylated glycans on cell surface Human * bind to alpha2-6 sialic acid receptors * epithelial cells upper respiratory tract * usually a mild disease Avian * bind alpha2-3 sialic acid * GIT and lower respiratory tract of birds * severe pulmonary disease * alpha2-3 sialic receptor are located deeper in the lungs causing a more severe disease 2-3 affinity will be less transmissable but causes deep lung disease

Answer 23

What determines HPAI and LPAI ? * where HPAI = high pathogenic avian influenza, and LPAI low pathogenic avian influenza * In both LPAI and HPAI the hemagglutinin precursor molecule (HAO) must be cleaved by host proteases for HAI and HA2 to mediate fusion between the virus and host cells. LPAI = The HAO from LP viruses can only be cleaved in the lungs and the GIT - resulting in mild localised infections HPAI = The addition of multiple basic amino acids at the cleavage site results in HAO being cleaved by ubiquitos proteases in a wide range of organs - resulting in a lethal systemic infection.

Answer 24

The HAO from LP viruses can only be cleaved by proteases found within the intestinal and respiratory tract * results in a mild localised infection * respiratory and intestinal * mild or asymptomatic * sneezing, coughing, occular and nasal discharge / inflammation of the trachea and lungs * may have reduced egg production or fertility * morbidity / mortality are low

Answer 25

High pathogenic avian influenza (HPAI) The addition of multiple basic amino acids at the cleavage site results in HAO being cleaved by ubiquitous proteases in a wide range of organs. * results in a lethal systemic infection * high mortality * in paracute cases death may occur before the onset of clinical signs * cyanosis of the head wattle and cone * petechial hemorrhages on visceral organs and muscles * blood tinged oral and nasal discharge * greenish diarrhoea

Answer 26

Similar symptoms

Answer 27

Avian influenza of all subtypes is a notifiable disease Diagnose * oropharyngeal and cloacal swabs * RT-PCR conserved regions of the matrix M gene * Virus isolation best suited in mammalian viruses * virus may also be isolated in the allantoic / amnitotic cavity of embryonated chicken eggs

Answer 28

Control of AIV * stamping out programs culling * poultry vaccination * destocking, cleaning and rest in live bird markets * out right ban on live bird markets Vaccination * vaccination is now being used in some countries, however the live attentuated vaccine negatively affects export * in addition the vaccine only acts to suppress symptoms it is still able to spread the virus * costly to administer * mostly used in Asia

Answer 29

Swine influenza A number of genetically diverse genotypes are circulating in pigs worldwide - H1N1, H1N2 and H3N2 Clinical signs * characterised by a largenumber of pigs being infected but low numbers dying as a result * going off feed * high fever * discharge from eyes + nose sneezing * breathing difficulties barking cough * huddling and inactivity

Answer 30

Influenza and the mixing vessel swine *Several elements of pigs are important in the genesis of a pandemic virus 1. pigs can become naturally infected with both avian and mammalian viruses 2. tracheal epithelium in pigs contain both alpha 2-3 and alpha 2-6 receptors 3. avian virus replication in pigs gives rise to variants recognising human like receptors 4. reasortment in pigs resulted in the emergence of the 2009 H1N1 pandemic

Answer 31

Avian influenza of all subtypes is a notifiable disease Diagnose * oropharyngeal and cloacal swabs * RT-PCR conserved regions of the matrix M gene * Virus isolation best suited in mammalian viruses * virus may also be isolated in the allantoic / amnitotic cavity of embryonated chicken eggs

Answer 32

Paramyxoviridae * negative stranded * sphereical filamentous * non-segmentaed * pleomorhic Genus Respirovirus * Bovine influenza, Canine influenza, Menangle virus Genus Morbillivirus * Measles, Rinderpest, Peste-des-petits and canine distemper

Answer 33

Canine parainfluenza 5 infectious cofactor in canine respiratory disease (kennel cough, cird etc). Frequently causes infections of the upper respiratory tract, along with Bordetella bronchiseptica Epidemiology * occurs world wide * incubation 5-9 days after virus exposure * usually restricted to the upper respiratory tract - occasionally recovered from the lungs * most fequently seen in kennels * more prevalent in younger dogs

Answer 34

Canine parainfluenza virus * 3-14 days * mucous nasal dischrage * dry, harsh, hacking cough * pharyngitis * pyrexia (temp) * tonsillitis * commonly involves multiple pathogens making it difficult to atribute symptoms to CPIV alone * studies of viral pathogenesis often asymptomatic

Answer 35

Canine parainfluenza virus * virus genome RT-PCR * virus will replicate in cell cultures forming a characteristic syncytia * available in a vaccine usually in combination (reduces severeity) * CPIV is a non core vaccine AVA

Answer 36

Menangle virus (MenV) An outbreak of severe reproductive failure and congenital defects was observed in a large piggery in Menangle NSW * first recognised 1997 (isolated to main piggery and 2 contract farms) * zoonotic Reservoir = native Australian fruit bats Transmission - bat / pig = fecal oral human = limited bat contact, however very close contact to contaminated pigs

Answer 37

Menangle virus (MenV) * reduced farrowing rate (82-38%) * reduced liter size * delivery at term of a large number of mummified and still born piglets * foetuses severe skeletal + craniofacial defects + arthrogyposis (joint deformities) * no disease in adult or young pigs * not highly contagoius slow spread * poor survival in the environment * brachygnathia (recession of the jaw * domed cranium * MenV was consistently isolated from the brain and myocardium

Answer 38

PPRV Principally a disease of goats and sheep (Rinderpest of small ruminants) * PPR global eradication program * very similar antigenically - antibodies are cross protective * genetically distinct * cattle and pigs seroconvert but do not develop or transmit disease * wild ungulates may be affected

Answer 39

PPRV Epidemiology * more than one billion sheep and goats are vulnerable worldwide * PRR recently observed in South and North Africa * Lineages 1 and 2 found mainly in West Africa * lineages 3 found East Africa * Also present in Asia and Europe Transmission * is via close contact confinemant favours outbreaks * inhalation * can be shed during the incubation period, and has been found in nasal, ocular secretions, saliva, urine and faeces

Answer 40

Clinical signs PRR * morbidity and mortality may reach 100% in anaive herd * young animals most susceptable * peracute cases when first introduced to a naive herd - fever, severe depression, death Acute cases * sudden fever, inappetence, depression and somnolence * nasal and occular discharge (serous non purulent) * painful lesions on gums, lips, palate, cheeks anf tongue * profuse diarrhea, dehydration and emaciation * pneumonia

Answer 41

Canine distemper virus Canine distemper virus is a highly contagoius, systemic viral disease of dogs seen worldwide (including sporadic cases in Australia) * historically common infection of dogs * in developed countries nearly eliminated through the use of vaccines * epidemiology is complicated due to the wide number of species it affects * Reservoir = domestic dogs (including feral dogs)

Answer 42

Clinical signs * infection may be mild or inapparent to severe disease * transient fever observed 3-6 days after infection (leukopenia) * fever will subside followed by a second fever which may be accompanied by nasal discharge, lethargy and anorexia * gastrointestinal and respiratory disease * typically accompanied by secondary infections * encephlomelitis may occur (swelling of the brain and spinal cord)

Answer 43

Canine distemper Neurological signs * A longer course of illness is associated with neurological signs * localised involuntary muscle twitching 9myoclonus, chorea, flexor spasm, hyperkinesia) * convulsions * increased salivation * chewing movements of the jaw (chewing gum fits) * this disease should be considered in the diagnosis of any febrile conditions in dogs with multisystemic infestations Post mortem * ncrosis of lymphatic tissues * interstitual pneumonia * cytoplasmic and intranuclear bodies * thymic atrophy * lesions within the CNS

Answer 44

Hendra virus * Respiratory and neurological disease in horses * 62 equine out breaks, 7 human infections - zoonotic Hendra virus reservoir = Australian fruit bats through QLD and NSW - found world wide * there is no evidence of human bat transmission * infection of horses through contact with bat urine, placenta and uterine fluids * between horses not highly contagious * the clinical response and pathological findings are similar in cats to horses

Answer 45

Clinical signs of hendra * incubation 8-16 days * can be asymptomatic during incubation, but will still shed the virus * depression * pyrexia (fever) * dyspnea * initial nasal discharge * infected mucous membranes * dependant odema * head pressing ataxia * sudden death 1-3 days after onset

Answer 46

Nipah virus * zoonotic * disease in pigs * highly contagoius - incubation period 7-14 days * may be asymptomatic * severe respiratory disease * acute fever (>40) * characteristic harsh barking cough * mortality 1-5% adults and 40% of piglets Neurological signs = trembling, twitching, muscle spasms, rear leg weakness, possible lameness or spastic paresis

Answer 47

New Castle disease * synonymous with avian paramyxovirus 1 (APMV-1) * mortality rates are highly variable depending upon the viral strain * Transmission = gastrointestinal or respiratory

Answer 48

NCD grading Velogenic (90% mortality) Viscerotropic velogenic = characterised by acute lethal infections, usually with haemorrhagic lesions in the intestine of dead birds Neurotropic velogenic = characterised by high mortality following respiratory disease and neurological disease, but where gut lesions are usually absent Mesogenic (10% mortality) - respiratory disease and neurological signs but low mortality Lentogenic (negligible mortality) - respiratory infections and or asymptomatic viruses - frequently used as vaccine viruses

Answer 49

Clinical signs New Castle disease * sudden drop in egg production * eggs that are produced are abnormal (no shell, misshappen, soft) * loss of apetite, fever, weakness * swelling and cyanosis of the comb and wattles * distinctive bright green diarrhoea * up RR, respiratory distress and coughing * high pitched sneeze Post mortem = brain lesions, thrombosis and oedema Nervous signs = loss of balance, circling, twisting of head and neck or complete paralysis

Answer 50

Viruses - smallest infectious agent size 20-300nm diameter - filterable agents when compared to bacteria - only have one type of nuceic acid either RNA or DNA - surrounded by protective protein shell = capsid - the capsid can not be hydrolysed by enzymes - in some viruses the capsid is enclosed within an envelope = which contains both protein and lipid

Answer 51

Viral envelope - viruses may mature by budding through a membrane and acquiring a lipid envelope of host origin - viral glycoproteins which are embedded in the envelope are important in virus/ host interactions - large viral envelope glycoproteins may be referred to as spikes or peplomers (Coronaviridae - the envelope is usually nessary for infectivity

Answer 52

Viral proteins can be structural or non structural - structural proteins are incorporated into the virions (eg capsid protect viral genome) - most of the non-structural proteins are enzymes - envelope proteins are frequently glycoproteins

Answer 53

Family Rhabdoviridae * bullet shape * single molecule of -ve sense RNA

Answer 54

Maintenance host * the species sustains the virus life cycle * successful control of rabies virus in the maintenance host will lead to its eradication * dog, fox, mongoose etc Spillover host * species which do not normally maintain the virus biotype * no epidemiological significance in sustaining epidemics * usually dead end hosts * may transmit the virus but such events are relatively rare * human, horse, cattle, sheep and pigs etc

Answer 55

Clinical signs of rabies - furious and paralytic rabies Dogs are the most important host for rabies virus (cats second most important) Furious rabies 20% Paralytic rabies 80% * cause acute encephalitis (flu) in almost all species eventually leading to death * first signs are non specific lethargy, fever, vomiting and anorexia * progresses through to cranial nerve dysfunction ataxia, paralysis, seisures, difficulty breathing, difficulty swallowing and excessive salivation * abnormal behaviour aggresion and self mutilation * following first clinical signs death within four days

Answer 56

Rabies genus lyssavirus * in humans 100% lethal * preventable through the use of vaccine * 60,000 rabies deaths occur each year mostly in Asia (India) * present with hydrophobia, abdominal discomfort and convulsions * most lethal virus known to science

Answer 57

Ephemerovirus in cattle * vector is mosquitos and biting midgees * widespread through the tropical and subtropical world * unusual out breaks have occured in Asia in the middle East with high mortality. * endemic NA and epidemic QLD and further Soiuth

Answer 58

One single point of entry

Answer 59

Affects cattle

Answer 60

Diagnose * First via clinical signs muscle lamenes, muscular stiffness, pain, short fever and rapid spread through out the herd * PCR test - most successful when samples are collected in the first few days of clinical disease * alternatively two blood samples the first taken during the fever stage and the second 14 days later. This is used to detect the pressencer of antibodies to the virus Control * modified live vaccine * good levels of protection and long lasting * first vaccine 1-2, vaccinate before spring when insect populations emerge * annual booster

Answer 61

Vesicular Stomatitis virus Host = cattle, horses and swine Classified as two serotypes New Jersey VSNJV and Indiana VSNJ * sporadic activity has benn reported in Northern Mexico and Western United States * sporadic activity is not clearly understood * VS produces severe economic losses especially in West America where the outbreaks display a pettern of epidemics once every ten years * New Jersey causes the majority of out breaks 80% * infection of horses is particularly significant in the United States * primarily domesticated horses, cattle and swine * infection is generally short lived and self limiting *

Answer 62

Vesicular stomatitis virus * horses, cattle and swine * first manisfestation of disease is usually excessive salivation * blanded raised and broken vesicles of various sizes in the mouth * foot lesions observed in horses, cattle and pigs * pigs may go lame * teat lesions may occur in dairy cattle * may be confused with blue toungue or swine vesicular disease

Answer 63

Transmission of Vesicular stomatitis During outbreaks VSV spreads quickly with animal herds Direct contact * infected animals salivate excessively, and their saliva contains high titres of virus Fomites * virus laden saliva and vesicular exudates easily spread within the environment - allowing a efficient animal to animal transmission Vectors * mechanical and biological vectors biting flies and non biting flies

Answer 64

Diagnose * vesicular fluid swabs of recently raptured vesicles * mouth and feet * PCR and ELISA Control * vaccination - may difficult in areas where disease is sporadic * can be zoological humans present with influenza like disease for a few days rarely present with vesicles

Answer 65

Caliciviridae virus * +ve sense * not segmented * single stranded RNA virus * generally a gastrointestinal disease * faecal oral route * direct contact * can not be grown in culture

Answer 66

Rabbit haemorrhagic disease virus (RHDV) Released in Australia and NZ for the purposes of rabbit biol-control Transmission = direct, mechanical (flies) * extremely contagious and fatal viral hepatitis of adult domesticated and wild rabbits * young rabbits (less than 8 weeks are sub-clinically infected) * incubation period of 1-5 days * symptoms fever, anorexia, apathy and prostration (lying stretched out on the ground) * neurological = convulsion, ataxia, paralysis * Respiratory = dyspnoea, frothy and bloody discharge * cyanosis of mucous membranes * death observed 12-36 hours after the onset of fever * 80-90% mortality

Answer 67

Rabbit haemorrhagic disease (RHDV) Due to the rapid progress of disease animals are often found in good condition after death - liver necrosis - splenomegaly - triggers a disseminated intravascular coagulation and death

Answer 68

Detection * vesicular fluid * RT PCR and ELISA Control * test and slaughter * stop swill feeding * classified as exotic in 1959 efforts were effective

Answer 69

Reservoir = fish offal Transmission = swill feeding Pathology Known for causing a highly infectious vesicular disease in febrile swine Clinical signs - vesicles in the mouth, tongue, lips, snout and feet - lesions can occur on the coronary band and between the digits - encephalitis - myocarditis - fever - abortion - diarrhea - hepatitis - pneumonia and haemorrhage - failure of recovered animals to thrive

Answer 70

Feline calicivirus * highly contagoius and distributed worldwide * Transmission = virus is shed in nasal, oral secretions, and faeces (oral faecal route) * infection through the oral, nasal or conjunctival routes * many animals will recover but continue shedding the virus (>30days) * there are many serological strains of calicivirus with different disease presentations

Answer 71

Feline Calcivirus Pathology and clinical signs Transient viremia occurs 3-4 days after infection and there is necrosis of epithelial tissue * oral ulceration is consistent * pulmonary involvement is rare but may progress to pneumonia Transient lameness * lesions in joints * observed a few days or weeks post acute oral or respiratory signs * acute synovitis - thickening of the synovial membrane and an increase in synovial fluid production * viral antigens found within the macrophages of the synovial joint Feline stomatitis Feline lymphocyte-plasmocytic gingivitis and stomatitis * serious condition but uncommon * cats present with increasingly worse inflamation of the oral mucosa VERY DIFFICULT TO TREAT REQUIRES PARTIAL REMOVAL OF THE JAW

Answer 72

VS FCV * high mortality 70% of infected cats * pathogenesis not well understood * widespread lesions * subcutaneous ulcerations - particularly on the nose, ears and paw pads * ulceration of the mouth * bronchointerstitial pneumonia * necrosis of the liver, spleen and pancreas Mutations in the genome may be responsible for this highly virulent strain, however each out break has been distinct genetically prolonged pharyngeal carrier state - survives a long time in the environment

Answer 73

Diagnose * conjunctival, oral swabs * readily propagated in culture * RT-PCR Vaccination is a core vaccine by AVC The continuing mutation of the virus and large variations between countries makes this difficult

Answer 74

Astroviridae * small * single stranded RNA * +ve sense * can not be grown in a lab easily * contain the genus Mamastroviruses (gastrointestinal) and Avastroviruses (chickens and humans)

Answer 75

Avian nephritis virus Distribution = widely spread world wide Transmission = direct or indirect transmission Host = young chicks <7days, will develop immunity at a month * virus is consistently detected in faeces for up-to ten days * RT PCR No effective treatment general hygienic precautions

Answer 76

Avian Nephritis virus * diarrhoea * growth retardation * kidney damage * gout * moderate mortality 10% * young chicks are most susceptible but develop immunity by about 1 month of age * histological changes can be seen in the kidney

Answer 77

RSS runting stunting syndrome WCS white chick syndrome

Answer 78

small non enveloped ss RNA virus genome is linear Two genera Orthohepevirus Piscihepevirus

Answer 79

Hepatitis E virus HEV the most common cause of enteric hepatitis infection (20mil a year in people) * in humans most cases are from contaminated pork liver pate * worldwide distribution * zoonotic

Answer 80

Hepatitius in pigs (HEV) * ubiquitous most pigs are seropositive * infections are usually subclinical * some may present with mild multifocal hepatic lesions * Transmission in pigs is by direct contact with faeces or contaminated water

Answer 81

Avian hepatitus Is distinct from mammalian hepatitis * big liver and spleen * hepatitus splenomegaly HSS syndrome in chickens

Answer 82

Coronavirus * enveloped * single stranded * RNA - largest RNA identified

Answer 83

CORONAVIRUS Canine coronavirus worldwide, including Australia Transmission = faecal oral route, with some evidence of aerosols Susceptibility - most susceptible puppies < 12 weeks of age - A common infection of dogs, particularly those housed in large groups eg kennels, shelters and breeding facilities - Two genotypes CCoV1 and CCoV2, closely related but have markedly different spike proteins. - CCoV1 co-circulates extensively, CCoV2 often occurs as a co infection Alphacoronavirus and Betacoronavirus - geographical distribution highly dependant on bat populations

Answer 84

Canine Coronavirus Pathology * replicates in the epithelial cells of the intestines * changes in intestinal morphology translate into a loss of normal absorptive and digestive properties resulting in diarrhea and dehydration in affected animals * can be fatal in young dogs, particularly when coinfected with parvovirus Clinical signs * most susceptible animals pups <12 weeks of age * mild gastro intestinal clinical signs * diarrhoea * vomiting * dehydration *can become fatal with secondary infections such as parvovirus

Answer 85

Feline coronavirus Clinical signs * infection often subclinical * transient mild gastrointestinal illness in kittens * diarrhoea, occasionally vomiting * death is uncommon Epidemiology * prevalent worldwide * prolonged shedding * transmitted by inhalation or ingestion of virus containing faeces or through contact with fomites Treatment is usually symptomatic

Answer 86

Positive sense RNA = is the same orientation as messenger RNA A positive sence RNA may act as messenger RNA. * produce a polymerase * a full length negative strand is produced * and then two mRNAs are produced

Answer 87

The five steps in viral replication 1. Attachment 2. Penetration 3. Uncoating 4. Eclipse phase - replication of viral proteins and nucleic acid 5. Assembly of the viral proteins and packaging of the nucleic acids (addition of envelope in some cases) 6. release of virions (budding, or lysis)

Answer 88

* Eclipse phase - replication of nucleic acids * Latent phase - from start of infection to first appearance of extracellular virus * exponential phase

Answer 89

Viruses attachment * Ligands, receptors on the surface of virions bind to receptors on the cell surface * receptors immunoglobulin family * bond may initially be reversable (electrostatic) or irreversable (temperature dependant) * initial binding is by electrostatic forces (depends upon electrolyte balance) * Attachment occurs at specific sites/ receptors distributed over the cell surface, corresponding to points of attachment by peplomers * interaction of receptor and antireceptor depends on temperature, PH and ions Tropism - is determined by the preseence or absence of sites which determines pathogenesis or which organ is affected

Answer 90

Virus penetration Endocytosis = the virus may enter the cell by receptor mediated endocytosis. The viruses are enclosed in vessicles within the cytoplasm. Fusion - Enveloped viruses may fuse with the cell membrane, and the viral nucleocapsid enters the cytoplasm

Answer 91

Viral uncoating * different viruses uncoat in different ways * this process is brought about by lysosomes by the host * the protein coats if more than one is present are systematically removed * some viruses may have their own uncoating enzymes * nucleic acid is then set free in the cytoplasm This is the begining of the eclipse phase

Answer 92

Negative sense * paramyxoviridae, Filoviridae, Rhabdoviridae * viral transcriptase is used to produce viral mRNAs * a full length + strand is transcribed as a template for viral RNA * assembly takes place via budding

Answer 93

JeV and pigs Pigs act as an amplifying host * two viral amplification cycles in pigs * 1= when pigs initially become infected by biting mosquitos leading to around a 20% infection rate * the second round involves infection of mosquitos infected by viraemic pigs * these mosquitos then infect other pigs leading to a 100% seroconversion amongst the pig population * dense pig herds may increase transmission * also can transfer virus by direct transfer through the oronasal route Removal of pigs from areas of high human population have been shown to reduce JEV burden

Answer 94

Family Flaviviridae ss (+ve sense) RNA enveloped mosquitos Genus Flavivirus * JEV Japanese encephalitis, Yellow fever virus, Dengue virus, Marry Valley encephalitis Genus Pestivirus * Classical swine fever virus, bovine diarrhea virus Genus Hepacvirus * Hep C virus in humans

Answer 95

Japanese encephalitis Reservoir mosquito, pig and wading birds Humans * humans are a dead end host * primarily affects children < 14 years of age * most humans have asymptomatic symptoms or flu like symptoms * in rare cases encephalitis (inflammation of the brain) * haemorrhagic lesions may develop in the brain * those that recover may have lifelong mental impairment and physical ailments such as difficulty speaking and moving Pigs * generally asymptomatic or causes mild disease - making it difficult to detect * may have reduced fertility in boars * increase the rate of abortion and still birth in naive sows * encephalitis has been observed in piglets following experimental infection

Answer 96

Japanese encephalitis JEV circulates in a natural circle envovling a range of species including Culex mosquitos, wild wading birds and pigs * Located throughout Asia and North QLD * reservoir wading birds, but pigs often play an important role as a amplifying host * often clinical signs present in children <14 years of age - most people have no symptoms Problem * many countries in Asia do not have surveilance * may also lack the capabilities to diagnose JEV

Answer 97

Dead end host = develop low viraemia and incapable of transmitting the disease back to the reservoir eg mosquitos in JEV

Answer 98

Treatment * safe and effective vaccines available (live attentuated) * remove pig populations from urban environments * vacc pig populations difficult due to culling at 6 months of age Diagnosis * serological test paired serum samples 2-4 weeks apart (compared to related circulating Flaviviruses.) * seroconversion between paired serum samples * RT-PCR * immunohistochemistry * antibody in cell cultures

Answer 99

West Nile virus Kunjin * able to infect horses, humans and frogs * emerging virus first discovered in US 19999 * endemic to parts of Australia + notifiable disease

Answer 100

Humans * dead end host * usually asymptomatic or mild symptoms * in rare cases develop into a life threatening illness involving inflammation of the brain and spinal cord

Answer 101

Diagnose Treatment * able to vaccinate horses, not people * vector control eg mosquitos

Answer 102

Genus Pestivirus

Answer 103

Bovine viral diarrhoea * 2 genotypes BVDV-1 and BVDV-2 (not present in Australia more pathogenic) * Two biotypes cytopathic CP and non cytopathic NCP * NCP is the most common biotype, but recombination may result in the more pathogenic BVDV CP * important component of the shipping fever complex Transfer * may cross the placenta - infecting the foetus or placenta * horizontel spread

Answer 104

Pestivirus bovine viral diarrhoea Foetus * may cross placenta (infect foetus or placenta), outcome depends upon stage of placental development * NCP BVDV depends upon stage of foetus * virues which do not kill the foetus may present in T and B cells during development Clinical affects * <40 days abortion, congenital abnormalities and mummification * 40-150 daysfoetus fails to recognise the virus as foreign persistant infection develops * 120-180 days birth defects, retinal degeneration, cerebellar atrophy or hypoplasia) * 180+ days normal calves with antibodies * BVDV may cause abortions throughout gestation If there is tolerance to viral antigens the offspring may be born persistently infected

Answer 105

Bovine viral diarrhoea virus - mucosal disease This occurs to animals in utero affected with non cytopathic BVDV - or with superinfection with cytopathic BVDV * these animals become carriers * carrier animal dose not recognise the virus as foreign and hence does not mount an immune reaction * it develops the foetal condition known as mucosal disease * the onset of mucosal disease occurs when the calf is between 6 months and two years of age but can be later * death occurs quickly after the onset of symptoms Clinical signs * profuse watery diarrhea, unresponsive to drenching * chronic weight loss * erosions (ulcers) gums, dental pad and muzzle (sometimes covered in scabs) * excessive salivation and nasal discharge * ulcers may occur on the coronent and between the claws of the hoof causing lameness * death quickly after onset of symptoms

Answer 106

Diagnose * blood samples are usually taken from suspected animals * cows who have aborted * proportion of the herd * blood is tested for antibodies to the virus * RT-PCR ear notch or blood Managment * identified carriers are culled * manage the herd to maximise infection of young heifers will before giving birth * regular vaccination against Pesti virus

Answer 107

Classical swine fever virus * lesions which cause damage to blood vessels * subsequent necrosis and haemorrhage * haemorrhages may be observed in multiple organs on autopsy The virus is able to cross the placenta and cause infection of the foetus - could result in a persistent infection or carrier

Answer 108

Pestivirus classical swine fever Endemic to most countries with significant economic harm * last time it was observed in Australia 1962 This virus is able to cross the placenta causing infection of the foetus * this can result in a persistent infection - which may continue to excrete the virus throughout their life

Answer 109

Pestivirus Classical swine fever * endemic to most countries - treatment with a attentuated live vaccine * In epidemic countries (Australia and Europe) treatment is by detection and culling * it is vital all carriers are detected and culled Diagnosis * persistently infected animals do not mount an immune response - persistent viraemia may not cause a cytopathic effect detect through the use of immunostaining * RT-PCR

Answer 110

Bunyaviruses * 3 segemnt large virus * large, medium, small segments * some +ve, some -ve sements * RFVF - zoonotic haemorrhagic fever viruses * large group of viruses > 100 Includes Phlebovirus Rift Valley virus, Orthobunyavirus Akubane and Schmallenberg

Answer 111

Rift Valley disease Affects cattle, sheep and goats usually * can infect wild life = maintenance host * outbreaks in Kenya, Egypt Transmission to humans * mosquito transmitted * can also be spread through direct contact with tissues fluids of infected animals * aerosol * may also infect humans and wild life Transmission to animals * mosquito transmitted

Answer 112

Rift valley disease Mostly infects cattle, sheep and goats, but may also infect humans and wild life Vector = mosquito Cattle (water buffalo, camels) * high abortion rates * death of young animals Humans * flu like symptoms and death * inflammation of the brain and a bleeding disorder Not specific - consistent symptoms between species * anorexia, nasal discharge, fever * lethargy, abortion and variable mortality rates * young animals especially susceptible

Answer 113

Akabane virus Spread by mosquitos (Culicoides biting midgees) down the coast during warmer months (favourable environmental conditions) Endemic in Northern Australia * immunity by sexual maturity * seroprevalance 80% Epidemics in Southern states * naive susceptable animals

Answer 114

Arkabane virus adult sheep and cattle asymptomatic pregnant ruminants = abortion and still birth * premature births * dystocia * congenital defects - hydrocephalus, hypoplasia or spinal cord ageness, microencephally, hypoplastic skeletal muscles and lungs, fibrinous polyarticular synovitus The clinical signs varie with the stage of gestation * early behavioural = dummy calves / behavioural abnormality and skull deformity * second trimester severe muscle atrophy, Arthrogyrosis - rigidly flexed joints, severe muscle atrophy, scoliosis (sideways spine curvature), kyphosis last trimester bright and alert unable to stand ataxia, paralysed limbs, muscle atrophy

Answer 115

Clinical signs of Schmallenberg virus Adult sheep and goats = generally asymptomatic Adult cattle = reduced milk yield, fever, inappetence, loss of body condition and diarrhoea The problem is the virus crosses the placenta to affect the growing foetus * the most susceptible stages 60-180 days cattle, and 15-28 sheep * damages foetal nerve tissue and results in brain and spinal cord abnormalities, with secondary problems in the muscle and skeleton caused by nerve damage * at term may be born alive or dead * abortion may occur following infection of the dam * bent limbs, fixed joints * brain deformities (hydraencephaly), and damage to the spinal cord

Answer 116

Porcine respiratory and reproductive syndrome virus PRRS Host = pigs Vector = Culicoides midges and crosses the placenta to affect the foetus * Currently a common disease in the USA, Asia and Europe * In America 60% to 80% of pigs may be infected * exotic to NZ and Australia Out breaks of disease have lasted between 2-3 weeks, with individual affected animals only being afflicted for a few days.

Answer 117

PRRS * associated with acute out breaks of reproductive failure in sows Fertility * anorexia, abortions, early farrowing's *increased frequency of still borns * mummies * delayed return to oestrous *weak born piglets Respiratory * respiratory distress, fever, pneumonia * skin lesions and blue ears * increased pre-weaning mortality in pigs Problem may be exacerbated with secondary infections of Salmonella, Streptococcus and Haemophilus

Answer 118

PRRS Persistance is a critical component of PRRSV pathogenesis Subversion of innate and humoral immune response Evasion of humoral response is through * glycan shielding * genetic variation Can block the early induction of type one interferons

Answer 119

Equine arteritis virus EVA Acute contagious vial disease Host = horses predominately in standardbreds (other breeds usually seronegative) * has been identified in Australia since 1975 * endemic in standardbred stallions and mares in Australia and NZ Economic loss Direct - abortion, pneumonia, febrile (fever) disease in performance horses Indirect loss - losses are associated with National and International trade

Answer 120

Picornaviridae foot and mouth disease Highly contagious disease of even toed ungulates - cattle, sheep, goats and pigs Transmission * inhalation, fomites, contact with abraded skin * highly contagious * animal products meat, milk, offal, semen and embryos Listed disease of major International importance - speed of spread and severe losses of production in infected animals There are seven serotypes and infection with one dose not counter immunity against another * Quasispecies strains are recognised in each serotype * Africa and Asia

Answer 121

Picornaviridae - foot and mouth disease Characterised by fever and the formation of vessicles * fever loss of appetite * reduced milk production * potential abortion due to fever * profuse salivation as vessicles appear in the mouth and rapidly rapture leaving painful ulcer * vessicles also appear on the coronary band and interdigital cleft - leading to weight shifting and lameness * vessicle may appear on the teats of lactating cows * calf deaths may occur due to myocarditis In pigs the hoof lesions may be more pronounced leading to sloughing Disease in sheep and goats is generally milder The virus dose not cross the placenta

Answer 122

Control Non-endemic country - detect and cull (burn carcasses and use acid) * the virus is susceptible to low PH * Premises are cleaned and treated with an acid solution to inactivate the virus Endemic country * vaccination * must be of appropriate serotype and subtype * immune response does not last longer than 12 months * disease is intolerant to modern high production systems * trade implications

Answer 123

Equine Rhinitus A virus The virus produces a systemic infection with respiratory signs Rhinitus * foals most susceptable to rhinitis * worldwide distribution * recently attributed to abortions in camels * transfer via aerosol and nasal secretions * Diagnosis = RT-PCR or ELISA Equine rhinitus B virus Upper and lower respiratory tract infections in young horses * spread nasal secretions and aerosol * Diagnosis RT-PCR and serology * nasal and pharyngeal swabs collected during outbreaks

Answer 124

Clinical signs of FIPV The mortality is extremely high once clinical signs are present * some cats may survive months to years after displaying clinical signs * most common in young cats within a crowded environment The signs * abdominal distension with ascites * dyspnoea with pleural effusion * jaundice * disernable masses on the kidneys or mysenteric lymph nodes * eye inflammation * neurological signs due to brain or spinal cord involvement

Answer 125

Epidemiology of Schmallenberg Virus Host = sheep (most common), cattle and goats Transmission = culicoides midges and crosses the placenta New virus discovered in Germany spread from the middle East - Germany, the Neverlands - Orthobunyavirus common in Asia, Africa and Australia, but not previously in Europe

Answer 126

Picornaviridae * Linear ss (+) sense RNA viruses * non enveloped * spherical * large family of viruses Includes * Apthovirus - Foot and mouth disease FMD and Equine rhinitus virus * Enterovirus

Answer 127

FMD Pathology Host = even toed ungulates cattle, sheep, goats, pigs and buffalo etc Transmission * direct contact * inhalation * ingestion, insemination, inoculation or contact with abraded skin * animal products meat, offal, milk, semen and embryos Spread * incubation 2-8 days *Viral replication occurs in the pharynx, followed by spread through the blood stream to predilected areas - mouth, muzzle, feet and teats. Cause of clinical signs * vesicle formation results from swelling and rapture of infected keratinocytes, in the stratified squamous epithelium * profuse salivation due to vesicles in mouth * vesicle on hoof = lameness * vesicle teat udder * abortion = fever * calf mortality = myocarditis

Answer 128

FMD Immunity There are seven serotypes and immunity against one dose not confer immunity against another Quasispecies - strains are recognised in each strain *Pigs - feet lesions are more pronounced and the hooves may slough * sheep, and ruminants = disease is generally milder presenting as a rapidly spreading lameness accompanied by fever Humans = fever, vesicles on the skin and mucous membranes Important the virus can persist after recovery in the Pharyngeal region of animals that have recovered * persistence, three years cattle, several months sheep, unknown in pigs * transmission from a carrier to susceptible animal has only been demonstrated in wild buffalo

Answer 129

Swine Vesicular disease Epidemiology Host = pigs Transmission = direct contact, not spread by aerosol * resistant to PH change difficult to clean, and remove from faecal matter Same symptoms as FMD * produces vesicles around the feet and mouth * many cases are subclinical may take a long time to identify * damage to hooves observed progressing down the hoof

Answer 130

Papillomaviridae Circular DS DNA Icosahedral replicates in the nucleus of cells * genome frequently remains episomal and is not integrated into host chromosomses * not enveloped * difficult to culture * all mRNAs are transcribed from only one DNA strand * highly stable genomes - infect nearly all animals

Answer 131

Epidemiology Papilloma virus Distribution - worldwide most species - highly species specific Infection = occur where there is micro-injury to stratified squamous epithelium, allowing the virus to replicated in the basement membrane Transmission = fomites, contact with infected surfaces, halters, nose leads * venereal transmission/ sexual transmission in cattle is common * papilloma virus is present in normal bovine skin

Answer 132

Papillomavirus replication Papillomavirus can only multiple in differentiating stratified squamous epithelium * only 8 active genes in the virus - so heavily rely upon the host for replication * as the cell matures the virus shiftsgear from maintaining its genome to full blown productive function Persistance * because basal stem cells are self renewing, infecting them allows HPV to establish a long term reservoir of infection * HPV does not kill its target cells and most HPV infections are inapparent Basal cells divide it own DNA, but HPV is "stay" or "go" within the daughter cell ... eventually gone (approximately 6 months to regress.

Answer 133

Expression of genes by papilloma viruses Effect * inhibit apoptosis * inhibit immune cell signalling * increase cellular proliferation (formation of warts) Viruses are shed from the body through desquamation - skin shedding. E6, E7 and E2 and expressed by papilloma viruses E6 - binds and inhibits p53 (host tumour suppression protein). P53 acts to suppress the cell cycle if DNA is damaged leading to apoptosis. - also activates telomerase that allows cells to replicate continuously E7 - bind pRB (tumor suppression gene) that is involved in DNA replication and cell division - break on proliferation E2 - normally would act to supress the expression of E6 and E7 - the integrated viral genome fails to code for a functional E2 protein - excessive expression of E6 and E7

Answer 134

Expression of genes by papilloma viruses Effect * inhibit apoptosis * inhibit immune cell signalling * increase cellular proliferation (formation of warts) Viruses are shed from the body through desquamation - skin shedding. E6, E7 and E2 and expressed by papilloma viruses E6 - binds and inhibits p53 (host tumour suppression protein). P53 acts to suppress the cell cycle if DNA is damaged leading to apoptosis. - also activates telomerase that allows cells to replicate continuously E7 - bind pRB (tumor suppression gene) that is involved in DNA replication and cell division - break on proliferation E2 - normally would act to supress the expression of E6 and E7 - the integrated viral genome fails to code for a functional E2 protein - excessive expression of E6 and E7

Answer 135

Papilloma virus Pathology The virus enters through an abrasion of the skin or reactivation of already present infection of epithelial cells. * causes hyperplasia * subsequent degeneration * hyperkeratinisation Papilloma's persist between 1-6 months before spontaneously regressing * multiple warts regress spontaneously Clinical signs multiple papilloma - wart Bovine - mucocutaneous papilloma's that develop on haired skin, tongue, teats and penis - upper ailamentary papillomas (oral cavity, oesophagus, rumen). -usually confined to the neck and shoulders

Answer 136

Bovine papillomavirus infection of another species - sarcoid Sarcoid Persistent and progressive skin lumps that occur mainly around the head, in the axilla and the groin region, as well as developing from wounds - locally invasive tumor (fibrosarcoma), but do not spread to other organs - frequently recur after surgery - not malignant do not metastasize PCR and immunohistochemistry - responsible for at least 85% of skin tumours in horses - common in horses 1-3 years of age - natural infection of horses with BPV exposure eg cattle, fomites

Answer 137

Papillomavirus Diagnosis * Clinical signs benign lesions are characteristic * PCR - not high risk as BPV is widespread, DNA may be detected in individuals not infected Immunohistochemical staining - using appropriate antiserum useful in confirming the presence of a specific virus Treatment * warts will eventually disappear without treatment - self limiting * vaccine but no protection between strains - too many virus isolates * Bovine interferon alpha * IMIQUIMED topical treatment not frequently used.

Answer 138

Epidemiology of Parvovirus Distribution = worldwide Susceptible = young animals neonates and foetuses Transmission = - highly contagious both feline and canine parvoviruses have a common ancestor - highly resistant to desiccation in the environment - prefer active dividing cells within the S phase - thus cause an age dependant susceptibility - more severe in foetuses and neonates - considerable cell division may result in widespread infection and tissue damage that causes developmental defects - tropism for rapidly dividing haemopoietic precursors and lymphocytes, and progenitor cells of the intestinal linning - replication of these viruses is usually limited in older animals with already differentiated organs Many parvoviruses cause acute immune infections where as others persist for long periods in the face of a robust host immune response - not well understood

Answer 139

ss DNA virus small replicate in the nucleus intranuclear inclusion bodies - histopathology virus extremely stable in the environment replication is completed rolling, hair pin

Answer 140

Epidemiology Distribution = worldwide Transmission = saliva, mucous, cough Susceptible = pups 6weeks to 6 months -Two variants CPV-2 and CPV2a -CPV-2 was rapidly spread worldwide, then quickly replaced by CPV-2a - CPV-2 does not infect felids, where as CPV-2a can infect cats making them asymptomatic carriers - a highly contagious cause of acute gastrointestinal disease in young dogs

Answer 141

Pathogenesis canine parvovirus Transmission = oropharyngeal entry of virus Require cycling cells for virus replication - infects newborn - Pathogenesis in dogs is distinguished by the absence of cerebellar hypoplasia/atrophy and the occurrence of myocarditis in pups Myocarditis - due to rapid proliferation of myocytes first week after birth - myocardial necrosis and inflammation - results in pulmonary oedema/ or hepatic congestion from acute heart failure Intestinal lesions - infection and destruction of enterocytes populating the intestinal crypts - subsequent mucosal collapse, maldigestion, and malabsorption diarrhoea - haemorrhages may also occur in other organs Lymphoid tissue - can become infected with subsequent destruction of lymphocytes - results in immune suppression

Answer 142

Clinical signs canine parvovirus Parvovirus is characterised by a rapid onset of diarrhoea, vomiting, anorexia, fever, depression, lymphopenia and dehydration - foul smelling bloody diarrhoea in young dogs - high pup mortality - infection of pregnant bitches can result in intrauterine infection and myocarditis in new born pups

Answer 143

Immunity after infection is life long - maternal antibody is transferred in colostrum - titre is variable - protection can be form a few weeks to 16 weeks Prevention and control - live attenuated vaccine - cleaning of contaminated environments is crucial - problems frequently occur in crowded spaces, kennels, shelters and colonies

Answer 144

Panleukopenia virus Host = all felids Distribution = worldwide Transmission = shed in faeces, vomitus, urine, saliva and is very stable within the environment - highly contagious The virus is most common in kittens around the time of weaning when maternal antibodies wane - cats of all ages are susceptible Clinical signs - cerebellar hypoplasia / atrophy frothy at mouth or vomiting - diarrhoea - fever - lethargy, anorexia

Answer 145

Pathogenesis In foetuses infected in the last two weeks, or first two weeks of life, dramatic lesions are present in the external layer of granular layer of the cerebellum. Virus enters oropharynx and initial replication occurs in the pharyngeal lymphoid tissue - from there a cell associated viremia via blood to other organs - incubation 5 days - leukopenia involves all white blood cell elements including lymphocytes, neutrophils, monocytes and platelets are destroyed.

Answer 146

Epidemiology Porcine parvovirus Occurs worldwide Transmission = direct contact / can cross the placenta Infection disease of reproductive failure in swine - losses are most extreme if the virus is introduced into a seronegative herd at a time when most sows are pregnant - in most herd a large proportion of the gilts will be infected naturally before they conceive and are hence immune - passive acquired antibodies persist for 6 months / interfare with vaccination - there is reduced immunity during parturition which may lead to a decline in antibodies to unprotective levels - this makes the pregnancy high risk

Answer 147

Porcine parvovirus Pathology The outcome of disease is dependant upon the stage of gestation < 30 days = after conception early embryonic death 30-70 days = after conception can result in the death of the foetus and sometimes mummification - no development of immune response > 70 days = after conception the foetus mounts an immune response, clears the virus and is healthy upon birth. - not all foetuses are infected at the same time - and death at different stages of pregnancy is typical - some foetuses survive and are born alive but are consistently infected, thus persistent shedding Clinical signs = SMEDI still birth, mummification, embryonic death and infertility

Answer 148

Porcine Parvovirus Diagnosis frozen section of aborted foetus immunofluoresence Haemagglutination PCR Serolgy - antibodies Treatment Vaccination of gilts - inactivated and attenuated vaccines

Answer 149

Circoviridae small circular DNA virus non enveloped icosahedral replication in nucleus Beak and feather disease Porcine Circovirus 1 and 2

Answer 150

Beak and feather disease Circiviridae Host = parrots, principally cockatoos Transmission = horizontal and vertical Pathogenesis - virus replicates in the basal epithelial layer of hair follicles, beak and claw - intracytoplasmic inclusion bodies follicular epithelium, bursa, macrophage - lymphoid depletion - death - the disease is progressive - infection result in persistent immunosuppression Clinical signs - permanent loss of feathers - develop beak and claw deformities - lesions - around the feathers or beak - leukopenia - non regenerative anemia Diagnosis - intracytoplasmic inclusion bodies - histological examination of hair follicles - PCR Treatment - test and cull - no vaccination - strict hygiene / quarantines in breeding colonies

Answer 151

Porcine circovirus Transmission = direct contact, fomites, respiratory secretions and urine PCV1 = not common considered apathogenic PCV2 = antigenically distinct - isolated in most regions of the world - porcine circovirus associated disease - occurs commonly in piglets 7-15 weeks of age - post weaning multisystemic wasting syndrome - characterised by inflammation in lymphoid tissue, lungs, kidney and heart - porcine dermatitis - nephropathy syndrome - infarctive skin lesions particularly on the rear legs and kidney Clinical signs - post weaning multisystemic disease - porcine dermatitis hind legs - nephropathy syndrome - granulomatous enteritis - exudate epidermitis (greesy pig disease)

Answer 152

Diagnosis RT-PCR viral load immunohistochemistry Good nutrition and hygiene, disinfection transmission inactivated and recombinant vaccines

Answer 153

Canine coronavirus Diagnose * A definitive diagnosis is difficult to achieve - rarely done * PCR * genomes have a highly variable nature * serological test * can only confirm exposure , and can not distinguish between infecting CCoV serotypes or genotypes Treatment * There is alive attenuated vaccine, however this is not available in Australia * no available antiviral drugs * care is usually supportive eg fluids and electrolytes

Answer 154

Pantropic CCoV - Pantropic canine coronavirus Increasing reports of lethal CCoV infections in dogs Epidemiology Increase in severity and the emergence of novel genes CCoVs can be attributed to the high level of recombination in the spike protein * This can occur during infection by more than one CCoV type within the host Pathology and clinical signs *fatal systemic disease * high fever * haemorrhagic gastroenteritis, neurological signs and leukopenia

Answer 155

Canine respiratory coronavirus CRCoV Distribution = UK, Canada, USA - not in Australia Transmission = inhalation, or contact with contaminated droplets on surfaces - highly contagious - beleieved to have originated from bovine coronaviruses CRCoV occurs in dogs of all ages - causes mild respiratory disease often with coinfections - may be involved in the canine respiratory disease complex

Answer 156

Feline enteric coronavirus Epidemiology Distribution = worldwide, highly prevalent Transmission = ingestion or inhalation of virus containing faeces, or through contact with contaminated fomites * two genotypes exist type one is unique to cats, type two recombinant with canine coronavirus. Faecal shedding begins within a week of infection and continues at high levels for up to two months. However lower shedding may continue for months or unto two years. Clinical signs Infection is often a subclinical or characterised by transient, mild gastrointestinal illness of kittens. * diarrhoea * occasionally vomiting may become acute or severe * death is uncommon Usually treated through symptoms eg fluid, electrolytes

Answer 157

FIPV - Infectious peritonitis virus cats There is a general consensus that FIPV arise by internal mutation from FECoVs * the causative mutation occurs independently within each cat * there are three mutations involved * initially the mutations cause a switch from enterocyte to macrophage tropism * this ultimately leads to infection, replication and survival in peritoneal macrophages * only 1-5% of FECoV infected animals develop FIP, mainly kittens Susceptability = Although cats of any age can become infected it is more prevalent in kittens 4-16 months of age - animals loaded in crowded places eg catteries, shelters and vets

Answer 158

Clinical signs FIPV The mortality is extremely high once clinical signs appear - although some cats survive for weeks, months or years Clinical signs * undulating antibiotic resistant fever * abdominal distension with ascites (fluid build up) * dyspnoea and pleural effusion * disernable masses on the kidneys * eye inflammation * neurological signs due to brain and spinal involvement Wet effusive FIP = Accumulation of fluid within the abdomen or chest, which can result in breathing difficulties Dry non effusive FIP = similar clinical signs with out the accumulation of fluid * cats with dry FIP are more likely to show ocular or neurological signs Variable time to death - shorter young cats - shorter in cats with effusive disease

Answer 159

Diagnose * common in faeces from diarrhoeic or healthy shelter cats * low intrinsic disease potential * cats with FIP often shed FECoV, it is inconsistent and the virus is shed at lower levels than in healthy cats * virus is usually of the enteric and not the FIP biotype Treatment Currently there is no effective treatment no efficious vaccines for FECoV or FIPV

Answer 160

Porcine transmissible gastroenteritis virus (TGE) Transmissible gastroenteritis virus (TGE) is a common viral disease of the small intestine that causes vomiting and profuse diarrhoea in pigs of all ages. Distribution = most pig producing countries but not Australia Transmission = easily spread during an epidemic, by animal contact and fomites (more prominent in water) - appears to have originated from Canine coronavirus

Answer 161

TGE Pathology * TGEV infects and destroys the villous epithelium cells of the jejunum, and ileum * severe villous atrophy, malabsorption, osmotic diarrhoea and dehydration * more prominent in winter Clinical signs * vomiting is the initial sign, followed by profuse watery diarrhoea * dehydration and excessive thirst * faeces of piglets often contain curds of undigested milk * small intestine dilated with gas, thin walled * mortality of piglets <1week old 100% usually through dehydration

Answer 162

Treatment * There is no specific treatment * supportive care to prevent dehydration and heat loss Vaccinate * avoid vaccinating herds free of TGEV

Answer 163

Retroviridae The only viruses which are diploid - two single stranded RNA molecules are converted into a double stranded DNA molecule (reverse transcriptase) - lacks the usual prrofreading of DNA, hence they mutate often The DNA copy of the genome (provirus) is inserted into the DNA of the host cell that it invades - thus changing the genome of that cell. This integration underlies the ability of retroviruses to cause persistent infections

Answer 164

Exogenous retrovirus = Are transmitted horizontally among the host animals - not common Endogenous retrovirus = Are inherited vertically in the genomes of the host - replication of a provirus in a host germ cell, the provirus may be inherited by the host's progeny and down the generations as a ERV -5-8% of human genome - all vertebrate genomes examined so far contain ERV

Answer 165

Feline immunodeficiency virus FIV decreases the function of the immune system of domestic and wild cats Distribution = worldwide including Australia Transmission = spread from cat to cat through saliva, primarily by biting Susceptible animals = - cats which roam outside - once cats become infected they are infected for life, and most eventually have a deterioration of immune function and increased risk of other infections

Answer 166

Feline immunodeficiency virus (FIV) All animals become persistently infected - a transient disease coincides with initial viremia thereafter, animals remain extensively healthy for many years - increased viremia in later stages of disease is associated with opportunistic infections - decrease CD4 + cells Clinical signs - increased likely-hood of acquiring other secondary infections - increased risk of developing certain types of blood cancers: Lymphoma and leukamia

Answer 167

There is no effective treatment Prevention - provide supportive care - prompt treatment of secondary infections - balanced diet, control parasites and removing tumours The best preventative measure is to spay/ neuter cats and keep them indoors to prevent exposure A vaccination is available - but not all cats will be protected so it is better to prevent exposure (non-core)

Answer 168

FELV epidemiology Distribution = worldwide including Australia Transmission = oronasal contact * infections with saliva, urine represents the most likely mode of horizontal transmission * the virus replicates in the oropharyngeal lymphoid tissue * from there carried in the blood by mononuclear cells to the spleen, lymph nodes, epithelial cells of the intestine and bladder. There are four FeLV subgroups of clinical importance Almost all naturally affected cats are originally infected by FELV-A Once a cat is infected with FeLV - A, a mutation of the virus can lead to new FeLV subgroups - FeLV - B = increase neoplastic diseases FeLV - C = erythroid hypoplasia and extreme anemia FeLV - T = infect and destroy lymphocytes / immunodeficiency (rare)

Answer 169

Pathology and clinical signs Immunosuppression is the single biggest cause of clinical signs in FeLV cats * chronic and recurrent disease * progressive deterioration over time * extremely diverse clinical signs * fever, lethargy, weight loss, persistent respiratory problems, skin and intestinal problems * anaemia, neoplasia, reproductive problems, enteritis * neurological dysfunction and stomatitis

Answer 170

Prevention * virus is unstable and susceptable to disinfection * kittens most at risk Treatment * vaccination (non - core) * avoid stress provide good husbandry * some cats survive for years without serious complications (average 2.4 years) Diagnosis * PCR, rapid immunoassays and ELISA * FeLV subtypes must be distinguished by sequence analysis