Derivation and characterisation of a live equid herpes virus-1 (EHV-1) vaccine to protect against abortion and respiratory disease due to EHV-1.
A German abortion isolate of EHV-1 (strain M8) was grown in equine dermal (ED) cells at a low multiplicity of infection in presence of 5-bromo-2-deoxy uridine. The resulting stock was dialysed, titrated and cloned by terminal dilution in ED cells grown in 96-well microtitration plates. Of 192 clones each originating from a single focus, clone 147 (C147) was found to be restricted for growth at and above temperatures of 38.5 degrees C. It was also restricted for growth at 37 degrees C in rabbit kidney (RK-13) cells which are widely used for the isolation and titration of EHV-1; hence clone 147 was EHV-4-like. Clone 147 showed a remarkable efficacy as a vaccine in protecting conventional pregnant Welsh Mountain pony mares against abortions due to EHV-1. A single intranasal (IN) vaccination protected five out of six (83.3%), and four out of five (80%) of mares upon challenge 4 and 5-6 months, respectively, after the immunisation, whereas all six unvaccinated mares aborted between 9 and 19 days after IN EHV-1 challenge. With the exception of the day 9 abortion, foetuses of the remaining five mares were EHV-1 infected. Placenta from the early aborting mare was, however, EHV-1 positive. Both groups of vaccinated mares were also significantly protected against clinical reaction (notably pyrexia), nasal shedding and viraemia following challenge infection.
Patel
J R
JR
Intervet UK Ltd., The Elms, Thicket Road, Houghton, Huntingdon, Cambridgeshire PE28 2BQ, UK. jay.patel@intervet.com
Bateman
H
H
Williams
J
J
Didlick
S
S
D000034:Abortion, Veterinary / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D003001:Cloning, Molecular / Q000379:methods; D005260:Female; D006566:Herpesviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D004861:Herpesvirus 1, Equid / Q000254:growth & development / Q000276:immunology*; D006734:Horse Diseases / Q000276:immunology / Q000517:prevention & control / Q000821:virology*; D006736:Horses; D009500:Neutralization Tests / Q000662:veterinary; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D014611:Vaccination / Q000662:veterinary*; D014613:Vaccines, Attenuated / Q000276:immunology / Q000592:standards; D014765:Viral Vaccines / Q000276:immunology*; D014766:Viremia / Q000662:veterinary; D017201:Virus Shedding
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines