DISTRIBUTION OF EQUID HERPESVIRUS-1 (EHV-1) IN THE RESPIRATORY-TRACT OF PONIES - IMPLICATIONS FOR VACCINATION STRATEGIES

Twelve adult ponies and 2 conventional foals were exposed to 10(6.6) T CID50 of Equid herpesvirus-1 (EHV-1), strain Ab4 and samples of respir atory tract tissues were recovered. Infectious virus in tissue homogen ates was detected using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochem istry of paraffin sections. The results illustrated the rapid dissemin ation of EHV-1 throughout the respiratory tract, with early replicatio n in the lungs one day after exposure. Endothelial cell infection was prominent in all areas of the nasopharynx by Day 4 emphasising the rol e of endotheliotropism and viraemia in dissemination of this virus to sites of secondary replication. Clinical disease in the adult ponies w as mild.