3.4 DNA viruses 2 Flashcards
are herpesviridae enveloped? What is their genome structure?
- Large, enveloped viruses with dsDNA genome
what do herpes viruses require for transmission?
Herpesvirus virions are fragile outside the body- transmission requires close contact- particularly mucosal contact
recovery from a primary acute herpes infection can result in what?
Latency is a unifying aspect of herpesvirus pathogenesis. Recovery from a primary acute infection can result in latent infection
what is the general mechanism of herpesviridae latency? When do we most likely see reactivation?
- Virus genome persists latently in neurons of ganglia or in lymphoid cells with Intermittent reactivation of latent virus
- Often in times of stress
- Winter
do all types of herpes viruses establish latency in the body in the same way/place?
A major difference between the 3 groups of herpesviruses is WHERE they establish latency in the body
what species do herpesviridae effect?
mammals, birds, reptiles
what are the three groups of herpesviridae?
alpha-, beta-, gamma- herpesvirinae
what disease does bovine herpesvirus 1 cause?
Infectious bovine rhinotracheitis
what disease does Equid herpesvirus 1 cause?
Equine abortion
what disease does Felid herpesvirus 1 cause?
Feline rhinotracheitis
what disease does Gallid herpesvirus 2 cause?
Marek’s disease
what disease does Ovine Herpesvirus 2 cause?
Malignant Catarrhal Fever
what is the one reportable herpes virus and what disease does it cause?
Suid herpesvirus 1, causes pseudorabies
Characteristics of Alphaherpesviruses
- Rapid lytic cycle
- Rapid growth and spreading in cultured cells
- Infection of epithelial cells (vesicular lesions)
- Latent infections in sensory ganglia
Characteristics of Betaherpesviruses
- Long reproductive cycle
- Slow infection in culture
- Latent infections in secretory glands, lymphoreticular tissues (lymph nodes and spleen), kidneys
- Restricted host range
Characteristics of Gammaherpesviruses
- Lymphotropic and establish latency in lymphocytes (lymphoid tissue)
- Acute and lymphoproliferative diseases
two common Alphaherpesvirinae
Bovine herpesvirus 1
Feline herpesvirus 1
what disease does Feline herpesvirus 1 (FHV-1) cause? what are the symptoms? Is it more common in a certain age group or setting?
- Feline rhinotracheitis
- Acute upper respiratory disease
- Sneezing, coughing, nasal + ocular discharge
- Conjunctivitis and keratitis
- Anorexia, fever, tongue ulcers
- Common (in kittens <1 year) and widespread
- Common in shelters, households with several cats
what disease is clinically very similar to Feline herpesvirus 1 (FHV-1)?
Clinically very similar to Feline calicivirus
how can we detect Feline herpesvirus 1 (FHV-1)? How can we prevent or treat it?
- PCR panels: feline respiratory diseases
- Vaccination (standard core vaccines)
- Antivirals: Inhibitors of viral DNA synthesis
- Cidofovir, Idoxuridine
what diseases does Bovine herpesvirus-1 (BoVH-1) cause? Can it be deadly?
- Variety of diseases in cattle
- Rhinotracheitis, vulvovaginitis, balanoposthitis, conjunctivitis, abortion, enteritis, and a generalized disease of newborn calves
- Can cause substantial mortality in feedlots and dairy farms
How long does Bovine herpesvirus-1 (BoVH-1) last in the body?
- Life-long latent infection
how do we diagnose Bovine herpesvirus-1 (BoVH-1)? How can we prevent it?
- Diagnosis: PCR on vesicular fluid or scrapings, serology
- Vaccines are available - EU countries have eradicated the disease, Canada and USA have a control program
what is the most important viral cause of abortion in horses?
Equine herpesvirus-1 (EHV-1)
what list is Bovine herpesvirus-1 (BoVH-1) on?
OIE list 2020
what diseases does Equine herpesvirus-1 (EHV-1) cause? what is its global range?
- Most important viral cause of abortion in horses
- Also, respiratory disease and encephalomyelitis
- Equine herpesvirus-1 is enzootic in horse populations world-wide
how do we diagnose Equine herpesvirus-1 (EHV-1)?
Diagnosis relies on history of abortion and characteristic intranuclear inclusion bodies in affected tissue- confirmed by immunohistochemical staining + PCR
what can we characteristically see upon post mortem in cases of Equine herpesvirus-1 (EHV-1)?
Characteristic foci of necrosis in fetal liver
what virus is associated with Marek’s disease?
- Gallid herpesvirus 2 (GaHV-2)
where is Marek’s disease found? what type of animals does it infect?
- Common and widespread (highly contagious), ubiquitous in the environment
- Young chicken (2-5 months)
- Quails and rarely turkeys can also be infected
what cells does Marek’s disease infect? How can we prevent it?
- Infects lymphocytes (T-cells): T cell lymphoma
- Vaccination at hatching or in ovo
what is the pathological process of Marek’s disease? what forms are there and what are their characteristics?
- Aerosol > respiratory epithelium > lymphoid tissue
> viremia > T lymphoblastoid cell proliferation > neoplasia (lymphoma) > infiltrates different organs/tissues: - If infiltrate around nerves (usually sciatic nerve) > classical form
- Form nodules/tumours in organs and nerves > acute form
- Invade iris > ocular (rare)
- Feather follicles > cutaneous form
what will be enlarged in the classical form of Marek’s disease, leading to paralysis?
Enlarged sciatic nerves
what will we see in the acute form of Marek’s disease upon post mortem?
Nodules in the liver, spleen, gonads, heart, lung, kidney, muscle, and proventriculus
what will we see in the Follicular/cutaneous form of Marek`s disease?
Infiltration of lymphocytes in the feather follicles
what would we see histologically in the case of a betaherpesvirus infection?
Mucous gland epithelial cells are enlarged (cytomegaly)
what is an important betaherpesvirus in pugs?
- Inclusion body rhinitis (Suid herpesvirus 2)
what are the symptoms and characteristics of infection with inclusion body rhinitis
- Inclusion body rhinitis (Suid herpesvirus 2)
- Causes mucopurulent rhinitis in 1–5- week-old pigs
- Older pigs generally mount an immune response without becoming ill
- Variable mortality
- Infection of naïve, pregnant sows –> fetal mummification, still births, neonatal deaths, failure of piglets to thrive
what type of virus causes Malignant catarrhal fever?
Gammaherpesvirus
what animals does Malignant catarrhal fever infect?
- Invariability fatal disease of cattle, deer, antelope, giraffe and swine.
what type of tissue does Malignant catarrhal fever effect?
- Generalized lymphoproliferative disease
- Affects lymphoid tissue, respiratory, gastrointestinal tracts and
central nervous system of susceptible hosts
what animals are reservoirs for malignant catarrhal fever viruses showing only persistent subclinical infection? what virus strains cause this disease?
- Wildebeest and sheep are reservoirs
- Africa: Alcelaphine herpesvirus 1 (wildebeest)
- Outside Africa: Ovine herpesvirus 2 - Canada (no signs in sheep)
what is a risk factor for malignant catarrhal fever?
- Risk factor: sheep and cattle raising in proximity (control!)
what vaccine is available for Malignant catarrhal fever?
no vaccine available
symptoms of Malignant catarrhal fever that we may see
-Fever, depression, leukopenia, generalized lymphadenopathy, CNS signs
-Mucopurulent nasal discharge
-Corneal opacity (edema)
-The surface of the muzzle can sloughed
-Congestion of the mucosa in colon
Which of the following is NOT CORRECT about Herpesviruses?
a. Herpesviruses affect many species of animals
b. Alphaherpesviruses establish latent infection of the ganglion
c. Only Alphaherpesviruses establish latent infections
d. Gammaherpesviruses cause lymphoproliferative diseases
c. Only Alphaherpesviruses establish latent infections
General characteristics of poxviruses. How do they persist in the environment? what is their virion structure? what is their genome structure and where do they replicate?
- Large enveloped viruses
> But it persists in the environment in scabs - Complex virion structure
- dsDNA genome but replicates in the cytoplasm; encode all enzymes required for replication
where are lesions related to poxviridae often found?
- Epitheliotropic and lesions are often found in skin and mucosa
what cytoplasmic sign do we see with poxviridae infections?
cytoplasmic inclusion bodies
what are three reportable poxviruses in Canada? which of these have never been found in Canada? are they similar?
Lumpy skin disease virus - Lumpy skin disease
Sheeppox virus - Sheep pox
Goatpox virus - Goat pox
- Sheep and goat pox and lumpy skin disease have never been found in Canada.
- Sheep pox, goat pox and lumpy skin disease viruses are genetically similar- serology cannot differentiate these viruses
what are the most economically important pox viruses? why?
Sheep pox, goat pox and lumpy skin disease
* The most economically important pox viruses of livestock- can cause significant meat and milk production loss (as well as mortality) and limit export and cause significant economic loss
can Sheep pox, goat pox and lumpy skin disease infect humans?
- No conclusive evidence of human infection
how can we gain immunity to sheep pox, goat pox and lumpy skin disease?
Vaccination as well as recovery from infection generate lifelong immunity
clinical signs of Capripoxvirus (Sheep &goat poxvirus,
lumpy skin disease virus)
- lesions on skin and mucous membranes
- fever
- lymphadenitis
- viral pneumonia
what might we see post mortem in a uterus of an animal infected with Capripoxvirus? In the lung?
-ruminant, uterus. The endometrium contains several tan papules (pox) among the caruncles
-ruminant, lung. There are numerous raised pale nodules (multifocal pneumonia)
which pox virus infects birds? which birds, and how is it passed on? what forms are there and what types of lesions do they cause? what are common, serious symptoms?
Fowlpox virus (Avipoxvirus)
* Chicken and turkeys
* infection via mosquito bite > cutaneous form > skin lesions (dry pox)
* Infection via droplets > diphtheric form > wet pox with exudate on mucosa of larynx and mouth
– Can cause dyspnea and death, high mortality
how can we protect against fowlpox virus? has it been found in canada?
- Vaccine available
- Reported in Canada
where geographically can we find Bovine papular stomatitis virus? is it serious?
- Little clinical importance but occurs worldwide
what are the symptoms of bovine papular stomatitis virus?
- Papular and erosive lesions on muzzle, lips, mouth and teats of cattle, may extend into esophagus
what zoonotic poxvirus can infect humans and cows? what are the symptoms in humans?
Bovine papular stomatitis virus
(Parapoxvirus)
* Zoonotic – painful red papules, ulcers, scabby proliferative lesions
this poxvirus is a differential diagnosis of foot and mouth disease
Bovine papular stomatitis virus
(Parapoxvirus)
which poxviruses are zoonotic and what diseases do they cause?
Bovine popular stomatitis virus - Bovine popular stomatitis
Contagious ecthyma (Orf) virus - Orf; contagious ecthyma
Pseudocowpox virus - Milker’s nodule
what species does orf commonly infect?
- Species of animals affected: Goats, sheep, llamas, alpacas, and camels
what lesions does orf cause?
mucocutaneous junction of lips, buccal mucosa, feet/coronary bands, dams of infected animals may have teat lesions
symptoms of orf in peolpe
papules that may become ulcerative, mild fever, lymphadenitis, painful but spontaneously resolve
Which of the following is CORRECT about Poxviridae:
a. Infection with poxviruses induce lifelong immunity
b. Poxviruses encode all the enzymes necessary for replication
c. Poxviruses are epitheliotropic
d. None of the above
e. All of the above
f. All except C
e. All of the above
has African Swine Fever virus (ASFV) ever been found in canada? is it reportable?
OIE list 2020 and Reportable in Canada
Never reported in Canada
what is the structure of African Swine Fever virus (ASFV)? how does replication take place?
- Asfarviridae (Asfar-African swine fever and related viruses): Asfivirus
– Large and enveloped virus with dsDNA genome
– DNA replication takes place in the nucleus
what species does African Swine Fever virus (ASFV) infect? what cells are infected?
- Species affected: Domestic and wild pigs
- Host cells infected: monocytes and macrophages
how is african swine fever virus transmitted and what is unique about it is this regard? does it survive well in the environment?
- Transmission: Ticks are biological vectors: viral multiplication (arbovirus)- the only known DNA arbovirus
-ASFV is thermolabile and sensitive to lipid solvents but survives for many years in refrigerated meat
is African Swine Fever virus economically significant?
very
how have recent outbreaks of african swine fever virus arisen?
-Undercooked pork products fed to pigs
-Raw pork at airport or shipping ports
-Movement of infected wild boars
is African Swine Fever virus zoonotic?
no, humans are not susceptible
acute disease from African Swine Fever virus has what symptoms?
Acute disease is characterized by severe hemorrhagic disease and high mortality (up to 100%)
what are the two cycles of african swine fever virus transmission? what is involved in each?
Domestic cycle: epizootic and enzootic cycles in domestic swine Sylvatic cycle: warthogs and ticks in Africa and
Note: Epizootic is as an outbreak of disease involving unusually large number of cases, whereas an enzootic refers to a low level of disease that is constantly present in a population
what is the structure of adenoviridae? what is type of genome do they have and where do they replicate? what does their unique structure do?
- Non-enveloped virus with dsDNA genome
- Replication in the nucleus
- The fiber on their shell can hemagglutinate red blood cells
what type of infection do adeniviridae usually cause?
subclinical in most species
what diseases occur as a result of adenoviridae?
- Infectious canine hepatitis
- Fowl adenovirus infections
- Mammalian adenoviruses
what is another name for Canine adenovirus 1?
(Infectious canine hepatitis virus)
what are the symptoms of canine adenovirus 1? and 2?
- Causes hepatitis in dogs
- Possible mild respiratory disease, corneal opacity
>“blue eye” => corneal edema - Canine adenovirus 2 causes mild respiratory disease
what has helped mitigate canaine adenovirus in many countries?
- Widespread vaccination eradicated the disease in many countries
- Part of CORE vaccines: DAPP (canine distemper virus, adenovirus type 1 and 2, canine parainfluenza virus, and canine parvovirus)
- CAV-2 vaccine provided cross-protection against CAV-1
what has helped mitigate canaine adenovirus in many countries?
- Widespread vaccination eradicated the disease in many countries
- Part of CORE vaccines: DAPP (canine distemper virus, adenovirus type 1 and 2, canine parainfluenza virus, and canine parvovirus)
- CAV-2 vaccine provided cross-protection against CAV-1
Which of the following is NOT CORRECT about adenoviruses:
a. Adenoviruses can agglutinate red blood cells
b. Canine adenovirus 1 causes hepatitis and corneal opacity
c. Most adenoviruses usually cause subclinical infections
d. Canine adenovirus 2 is associated with respiratory disease
e. None of the above
e. None of the above
=> all are correct
