Herpesviruses

Question 1

Transmission ?

Answer 1

shedding of the virus in nasal, oral or genital secretions

Question 2

Structure

Answer 2

dsDNA
large genome
30 proteins
enveloped

Question 3

Replication cycle ?

Answer 3

glycoprotein attachment
fusion of viral and cell membranes
nucleocapsid enters cytoplasm
DNA/protein complex enters nucleus
protein synthesis
genome replication
viral DNA is encapsidated and enveloped at membrane of nucleus
virions are located to the ER
virions released by exocytosis

Question 4

Describe the latency process seen

Answer 4

viral genome can exist as an episome in the cell nucleus - it is not reproducing until reactivation
how reactivation occurs is unclear, but it is understood to be immune regulated

Question 5

Name the most important herpes viruses

Answer 5

infectious bovine rhinotracheitis (IBR)
[ BoHV1 ]
equine rhinopneumonitis
[ EHV-1/4 ]
malignant catarrhal fever complex (MCF)
[ AIHV-1 & OvHV-2 ]
Marek’s disease virus 1 and 2
[GaHV-2 & GaHV-3 ]
feline rhinotracheitis virus
[ FeHV-1]
elephant endotheliotropic herpesvirus

Question 6

IBR transmission

Answer 6

aerosol, direct contact

Question 7

IBR pathogenesis

Answer 7

replication in MMs of URT
local spread and systemic spread
weak viremia

Question 8

IBR clinical signs

Answer 8

coughing with heavy breathing
conjunctivitis and ocular discharge
fever
milk drop
nose discharge
vesicles on the muzzles and nares (pustules)
abortion common

Question 9

herpes virus diagnostic samples

Answer 9

nasal swabs
serum
tissue
aborted foetus

Question 10

herpes virus diagnosis ?

Answer 10

PCR for active infection
antibodies in serum can be identified, works for latent infection
virus isolation possible

Question 11

IBR control

Answer 11

eradicated in the UK due to detection and slaughter method
vaccines are available (modified live, inert and attenuated)

Question 12

EHV1/4 transmission

Answer 12

inhalation

Question 13

EHV1/4 clinical signs

Answer 13

fever
anorexia
sporadic cough
nasal exudate
conjunctivitis
neuro signs
LN swelling
abortion or weak foals

Question 14

MCF complex clinical signs

Answer 14

highly variable
no CS common with depression and rapid death
high fever, corneal opacity and catarrhal discharges from the eye and nares seen in chronic disease

Question 15

MCF complex pathology (histo)

Answer 15

lymphoid cell accumulation in non-lymph organs
vasculitis
lymphocyte hyperplasia in lymph organs
lymphoproliferation
hyperplasia and necrosis of lymph organs
epithelial necrosis

Question 16

Marek’s disease clinical signs

Answer 16

lymphoproliferative syndrome
- lymphoma
- paralysis of legs or wings
- wing dropping
- dilation of crop
ocular syndrome
- rare
- greying of iris w/ irregular pupils
cutaneous syndrome (red leg, nodular lesions) and immunosuppression also possible

Question 17

Marek’s disease transmission

Answer 17

inhalation of contaminated dust and dander
–> lymphoid cell and macrophage infection leading to immunosuppression

Question 18

FeHV-1 clinical signs

Answer 18

acute disease of the URT
sneezing and coughing (sudden)
frothy salivation
dyspnoea
anorexia
weight loss
fever
tongue ulcers
keratitis
similar to feline calciviruses !!