Virology Flashcards
The main advantage of using virus isolation over the molecular based diagnostic assays such as PCR is that:
Unlike PCR, virus isolation demonstrates the presence of live virus in the sample
Describe the characteristic features typical to all herpesviruses.
- Enveloped, icosahedral virions 120-200nm in diameter.
- Linear double-stranded DNA genome.
- Replicates in nucleus, acquires envelop by budding through nuclear membrane.
- Fragile in environment.
- Produces latent infections.
Explain viral latency
Latency refers to a state in which the viral genome is present in an animal’s body but only a few (if any) genes are transcribed and there is no production of infectious virus.
provide examples of viral latency clinical significance
Latency is categorised as a form of persistent infection, along with chronic infection and infections that spread slowly so the virus can be periodically reactivated and shed from latently infected animals
Reactivation (recrudescence) can occur even in the presence of circulating
antibodies.
Recurrent episodes are usually milder and may be sub-clinical.
TRUE OR FALSE The virus cannot be confirmed clincally while it is latent.
TRUE
True or false: The immune system cannot detect latent viruses
true
Describe briefly the range of clinical presentations that herpesviruses can cause.
Respiratory disease as seen in equine herpesvirus 1, equine herpesvirus 4, bovine herpes
virus 1, and feline herpesvirus.
• Fetal death/abortion by crossing the placenta as seen in equine herpesvirus 1, and
bovine herpesvirus 1.
• Lymphoproliferative changes as seen in malignant catarrhal fever.
• Ulcerative skin lesions as seen in bovine herpesvirus 1 and 2, malignant catarrhal fever,
and many others.
• Cerntral and peripheral nervous system changes (in an abnormal host) as seen in suid
herpesvirus 1.
List the veterinary herpesviral diseases common in New Zealand.
- Equine herpesvirus 1 and 4 (3 is uncommon).
- feline herpes virus 1
- bovine herpes virus 1
- infectious bovine rhinotracheitis
- malignant catarrhal fever virus (MCF) seen in NZ deer
- bovine mammallitis: BoHV-2
- Marek’s disease - galled herpes virus 2
- Gallid herpes virus 1
Describe what control measures may be helpful in minimizing the risk of herpesviral abortion
on a stud farm.
Isolate clinically affected animals (those that have aborted, have neurological problems,
or respiratory disease).
Separate groups likely to shed EHV-1 such as young, stressed horses from pregnant mares
quarantine new horses
Properly dispose aborted foetuses and placentas.
Clean and disinfect regularly.
Minimize stress as it can cause recrudescence.
• Vaccination (2 killed whole virus vaccines and 1 subunit vaccine is available in New
Zealand)
Main clinical signs of Bovine herpes virus
- subclinical/mild/severe
- nasal discharge
- fever
- depression
- inappetence
- ulcers on nasal mucosa
Main clinical signs of Respiratory disease often called infectious bovine rhinotracheitis (IBR)
- affects young cattle and deer
- droplet tranmission
- in NZ but our are at the less virulent end of the scale
Main clinical signs of Feline herpes virus 1 or feline rhinotracheitis
- very common in kittens
- discharge from nose, eyes
Main clinical signs of bovine mammillitis (BoHV-2)
teats and udder affected in NZ
Main clinical signs of Aujeszkys disease in pigs
- only on north island
- eradicated by 1997
- reproductive, respiratory and CNS signs
Main clinical signs of gallid herpesvirus 1 (ILT) in birds
- coughing
- sneezing
- ocular discharge
- dyspnea
- gasping
