Viruses Flashcards
What are the general characteristics of Rickettsia virus
Gram -ve - small pleomorphic - Ribosomes for protein synthesis - Replicates intracellularly - Produces toxins- (Fission of double membrane with daughter cells with infectivity of parent cell)
What are the natural hosts/transmitters of Rickettsia virus
Hosts = Vertebrates (rodents/Reservoir host/Asymptomatic) Transmitters = Biting/sucking arthropods (Fleas, ticks , mites)
What are the 2 main family’s of Rickettsia
Rickettsiaceae = infects endothellia cells (Lukecysites) Causing Lymphoreticular/Vascular damage) Anaplasmataceae = Infects RBCs causing RBC damage/anaemia + Haemoglobinuria
What is Lymphoreticular
Leaking of blood cells/Vascular cells
What are the general characteristics of Chlamydia
Gram -ve - Replication in cytoplasm - Infectious elementary body infects cell -> Forms large reticulate body (Non infectious) -> Fission division -> Re-organised into Progeny elementary bodies - Dependent on host for ATP
How is Chlamydia transmitted
Fluids/direct transmission (No arthropods)
What virus causes cattle tick fever
Anaplasma Marginale
What are the clinical signs/Distribution of Anaplasma marginale (Cattle tick fever)
Mild fever - Jaundice - Anaemia Boophilus microplus (Cattle tick) - or mechanically via veterinary procedures
What are the 5 main Chlamydia species endemic to Australia
C. trachomatis - C. pneumoniae - C. psittaci - C. felis - C. pecorum/Koala one
What are the general features of Chlamydia trachomatis
Host specific to humans - expressed as Trachoma (Infection in eye causing corneal scaring) or Urogenital (STD - infertility in women)
What are the general features of Chlamydia pneumoniae
Isolated from koalas - common respiratory disease in humans via rhinitis/coughing/sneezing/serous nasal discharge
What is Rhinitis
Inflamation of the mucous membrane
What are the general features of Chlamydia psittaci
Zoonotic - Symptoms dependant of host species - transmitted via direct contact/Aerosols (Dried feacal/nasal excrement)
What are the general features of Chlamydia felis
Cats - 3 to 10 day incubation period - Conjunctivitits / nasal discharge / Sneezing - Transmitted via direct contact
What are the general features of Chlamydia pecorum in live stock
signs = polyarthritis - Fever - Inappetence - depression - Death (Vague) - Sporadic outbreaks of ovine abortions
What is Polyarthiritis
Systemic infection localisation (Stiff joints) of organisms in serous membranes
What are the general features of Chlamydia pecorum in koalas
Keretoconjunctivitis (Eye infection) - Urogenital tract infection - transmitted via sexually / fighting (males/mothers + offspring)
What is a virus
A piece of nucleric acid (DNA/RNA) that replicates within a host cell, using the cells synthetic machinery (Ribosomes,transcription,translation) to synthetise specialized elements (Infectious bodies) to transfer the viral genome to another host cell
How do virus differ from other micro-organisms
Viruses need host cell for replication - Viruses are particulate (small single particule) - Viruses are relatively simple
Describe the components of a virus
Nucleric acid genome (DNA or RNA) - Enclosed within a capsid(capsomers = subunits) - does or does not have an envelope modified from the host cells membrane
What are helical viruses
Viruses that are enveloped RNA that nearly all have a negative sense (3’ to 5’) (coiled RNA in a protein subunit)
What are the current classification schemes of viruses based on
A combination of phenotypic and genotypic characteristics
How can viruses be classified
Genome characteristic - Morphology of the virion - Replication - Characteristic enzymes
How can viruses be classified using Genome characteristics
DNA or RNA - Size - Single or double stranded - Circular or linear - Number of molecules within the virion - Nucleotide sequence/presence of characteristics open reading frames
How can viruses be classified using Morphology of the virion
Shape and size - Number of capsomers - Presence or absence of an envelope
How can viruses be classified using possession of characteristic enzymes
Presence or absence of reverse transcriptase - Neuraminidase (Cleave) ECT
How are virus taxa chosen
Initialisms/Acronyms - Geographical locations - Clinical signs of the disease they’re associated - Microscopic lesions they induce in host cell - Microscopic morphology features of virus
What are the 10 steps in the replication of DNA based viruses
Attachment/Absorption -> Penetration -> Uncoating/Transport to replication site -> early Transcription + Translation -> DNA synthesis -> Late Transcription + Translation -> Assembly -> Release
What are the similarities/differences of RNA based viruses replication
1,2,3 steps similar to DNA - 4 + sense Start transcription then flip for the mirror image/ - sense need intravirion polmerase - Steps 9,10 are the same
How are Retroviruses transcribed in replication
+ sense RNA + reverse transcriptase -> ssDNA + reverse transcriptase -> dsDNA -> Hydrolysis of host DNA -> new virus dsDNA inserted
What is Proviral DNA
Virus DNA inside the cell DNA
What are some important generalisations of Enveloped viruses
Enveloped typically are more fragile to environment Non-enveloped are typically more resistant to environment
What are some important generalisations of Physical inactivation
Heat = Denatures proteins Desiccation (Drying of virus) = Long periods of inactive state Radiation = Breaks nucleotides chain
What are some important chemical inactivation
Detergents - Alcoholes - Halogens - Oxidising agents - Acid/bases - Alkylating agents
What are some methods of viruses detection
Cell cultures - Embryonated eggs - Electron microscopy - Tissue sections - Serology - Molecular - Computet next gen sequencing - Syncytia - Presence of antibodies
What are the 3 types of cell cultures
Primary cell culture (Chick embryo firoblasts) Secondary cell culture (Cell strains ie Calf kidneys) Continuous cell culture (Cell lines ie Veros = Lineages of cells)
What are the 4 main places viruses are incubated in an Embryonated egg/How to recognise the presence of a virus
Chorio-allantoic membrane (Sticks to the shell) - Allantoic cavity (Whites) - Amniotic (Fetus’s sac) Yolk sac Death of embryo/Pocks or plaques on membrane/Haemaglutination
What is Serology
The detection of antigens from the viral protein
What is Molecular virus detection
PCR sequencing
What is Computet Next Gen Sequencing
Sequencing of genomes
What is Syncytia
Detecting large cells
What is a virus neutralisation test
the dilution of a serum to 64 times to remove all antibodies to allow the virus to grow again to test - Paired serum samples can see if there is virus growth or not
What are the general characteristics of Poxviridae
Enveloped - Replication in cytoplasm (Does not need nuclues) - Target epithelial cells (Skin/respiratory) - Transmission via respiratory route/Arthropods (Mechanically) - Causing large intr-cytoplasmic inclusion bodies
What are the major poxviral disease of vet significance
Orf virus (Scabby mouth) (Zoonosis) - Avipoxvirus - Leporipoxvirus
What is Avipoxvirus/signs/forms
Depression - Reduced appetite - Poor growth/Egg production Cutaneous (dry) / Diptheritic (Wet) Transmitted via mosquito bites (Blood to blood)
What are the species of Avipoxvirus
Canarypox - Fowlpox - Pigeonpox - Quailpox - Turkeypox
What is Leporipoxvirus/signs/transmission
Myxoma virus -> Myxomatosis - signs Blepharo (inflamation in eyelids) / Conjunctivits Transmission via Arthropods Vaccine RHD effective on RHDV1 K5
What are the general characteristics of papillomaviruses
Not enveloped - Replication intranuclear - Target epithelial cells - Hosts Amniotes - transmission direct contact (cut) - infection site Keratinocytes (Under skin basel epithelial cells) - Stops E6 protein causing Sarcoids
What are Sarcoids
Cancer like growth on the lower limbs
What are the general characteristics of Polyomavirvuses
Not enveloped - Replication intranuclear - Target numerous cell types - Host birds/mammals - Stops E6 protein
What does Budgerigar fledgling polyomavirus cause
Effects fledgling birds causing Lethargy - Crop stasis = death in 24-48 hours
What are the general characteristics of Parvoviruses
Not enveloped - Replication intranuclear (Autonomous virus) - Target Enterocytes (Rapidly dividing cells) - Host Arthropods/Mammals - Highly infectious
What are Autonomous viruses
Viruses dependant on S-phase (Replication) as they only occur in dividing cells
What are the general characteristics of Circoviruses
Not Enveloped - Replication intranuclear - Target epithelia/bone marrow derived cells - Host Birds/Mammals
What are associated diseases of Parvoviruses
Feline panleukepenia virus (FePLV) Canine parvovirus 2 (CPV2)
What is the origin of Canine parvovirus type 2
FePLV -> Mutation -> Mink/racoon/fox-parvovirus -> Mutation of species -> Canine parvovirus type 2 -> Mutation -> CPV2 a, b, c (These can infect cats)
What are clinical signs of CPV2
Neonatal pups = general disease syndrome Nursing pups = Myocarditis (Cardiomyopathy if they survive) Weaned pups = Protacted vomiting - anorexia - Lethargy - Diarrhoea - Dehydration - Blood stained feaces - Haemorrhagic Dogs = similar to weaned pups
What is Myocarditis
Inflammation of heart muscles
What is Cardiomyopathy
Damaged heart muscle = harder to pump blood
What can occur if a pregnant sow is infected with Porcine parvovirus
SMEDI - Can be prevented with vaccines
What is SMEDI
Still birth - Mummification - Embryonic - Death - Infertility
What are the general features of Chicken anaemia virus (CAV)
Replicates in Hemocyblasts within the bone marrow, Thymus, and Spleen - Transmitted via feacel matter/maternally antibodies - Clinical signs = 12-17 days after hatching/infection - Anorectic/Lethargic/Depressed/Pale Haemoatology = Anaemia/Leukopenia/Pancytopenia
What are the general features of Beak - Feather disease virus (PBFDV)
Clinical signs = Feathering abnormalities/Immune suppression - Transmission via Aerosols/Direct-Indirect contact - Histopathology = Inflammatory cells in feather pulp/Bursa (Basophilic intracytoplasmic inclusion bodies)
Why is it difficult to eradicate Parvoviruses
What are the general characteristics of Herpesviruses
What is the life cycle/envelope acquisition of Herpesviruses
What are the classification and subfamily properties of Herpesviruses
What does Cercopithecine herpesirvus B (Monkey herpes) / Herpesvirus simplex virus 1 (HSV1) cause
What does Human Herpesvirus 3 (Viricella and Zoster) cause
What does Gallid Herpesvirus 1 cause in chickens/pheasants
What does Gallid Herpesvirus 2 cause/what cells it infects
What does Canid Herpesvirus 1 cause