Viral Diseases Exam 2

What viruses cause equine encephalitis?

-WEE

-EEE

-VEE

-West nile virus

-Japanese encephalitis virus

What kind of viruses are WEE/EEE/VEE?

togaviridae

What kind of viruses are WNV and JEV?

flaviviridae

Togaviruses and flaviviruses are:

-positive sense

-single stranded

-enveloped

-RNA

T or F: vaccinations for viral equine encephalitis are very effective

True

How are equine encephalitis viruses transmitted?

mosquito vector that has been infected by a bird

What is the enzootic cycle of EEE?

stays in the wetlands circulating between mosquitoes and birds

What is a epizootic cycle with EEE?

virus escapes and is transmitted to external animals by mosquito

What animals are dead end hosts regarding WNV?

-humans

-horses

What is a dead end host?

A host from which infectious agents are not transmitted to other susceptible hosts

What kind of virus is a herpes virus?

-double stranded

-enveloped

-DNA

T or F: herpes viruses are not host specific

False

What are common overlapping signs with encephalitis viruses in horses?

-fever

-alteration to mentation

-cranial nerve deficits

-spinal ataxia

What are specific clinical signs to WNV?

-muzzle and muscle fasciculations

-may progress to recumbency

-improve with NSAIDs

What are the clinical signs of EEE?

-high fever

-rapid progression

-recumbency

-death

T or F: WEE and VEE typically have mild signs

True

What clinical signs are associated with feline HV1?

-conjunctivitis

-respiratory signs

What does it mean for a herpes infection to be lytic?

virus attaches to host membrane -> membrane fusion and penetration -> viral DNA translocates to nucleus -> viral DNA replicates -> viral protein synthesis -> capsid assembly -> egress from nucleus -> egress lyses

What does it mean for a herpes infection to be latent?

-viral DNA translocates but there is no translation

-virus makes copies in circular episomal form in nucleus

What cells hold latent virus?

-CD8+ T lymphocytes

-neuronal cells

What can trigger reactivation of latent virus?

stress

What are the signs of equine herpes myeloencephalitis?

-fever precedes neurologic signs

-nasal and ocular discharge

-altered mentation

-ataxia

-urine dribbling

-loss of tail tone

What are the pathophysiological signs of EHM?

-vasculitis

-thrombi

-ischemia of uterus and CNS

-caudal thoracic spinal cord showing lymphocytic perivascular cuffing

-CSF with xanthochromia

When should pregnant mares be vaccinated for EHM?

5, 7, and 9 months of pregnancy

Which herpes virus causes reproductive signs?

EHV-3

How to test for WNV?

IgM capture ELISA

How does CSF appear with EEE?

neutrophilic pleocytosis with increased protein

How does CSF appear with WNV?

normal or mononuclear pleocytosis with increased protein

What is "non-bite" exposure to rabies?

contamination of wound or mucous membrane with saliva or infective tissue