Herpesviridae - Alphaherpesvirinae - Equine Herpesvirus 1 Flashcards
Where is EHV-1 located?
Worldwide.
THE MOST VIRULENT EQUINE HERPESVIRUS.
How is EHV-1 transmitted?
Inhalation of infected aerosols
Direct or indirect contact with nasal discharge
Placenta or placental fluid
What allows the virus to survive and spread within the equine population?
The latency of it
Where does the latent form of the disease reside?
CNS (neuron cell bodies of the trigeminal ganglia) and lymph system (lymphocytes) without causing any clinical symptoms.
When is the virus reactivated?
When the host is immunosuppressed.
Shedding begins
What protects EHV-1 from the immune system?
Cell-associated viremia
What does cell-assocaited viremia allow EHV-1 to do?
Spread to endothelial lining of the blood vessels in the CNS and pregnant uterus
What is the central lesion caused by EHV-1?
Infection of endothelial cells that leads to vascular necrosis, thrombus formation and death of the tissues revoked by these blood vessels due to ischemia.
What is the main virulence factor that allows EHV-1 to persist?
A protein that inhibits that TAP protein inhibiting the delivery of the antigen to MHC I molecules.
What are the clinical signs of the respiratory form?
Affects younger horses
Rhinopneumonitis
Fever, bilateral nose discharge, coughing, inappetence, depression
Secondary bacterial infections
What are the clinical signs of Encephalomyelopathy?
Affects any horse breed or age.
Immune mediated vasculitis leading to infarction and hemorrhage within the brain and spinal cord.
Slight hind limb incoordination to quadriplegia and recumbency leading to death
What are the clinical signs of the reproductive form?
Majority of abortions occur in 8-10 months of gestation
Reproductive efficacy is not compromised
Abortion storms can occur
How long does natural immunity to EHV-1 last?
2-3 years
This is why abortion storms tend to display in 3 year cycles