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A new modified live equine influenza virus vaccine: phenotypic stability, restricted spread and efficacy against heterologous virus challenge
Author(s) -
CHAMBERS T. M.,
HOLLAND R. E.,
TUDOR L. R.,
TOWNSEND H. G. G.,
COOK A.,
BOGDAN J.,
LUNN D. P.,
HUSSEY S.,
WHITAKERDOWLING P.,
YOUNGNER J. S.,
SEBRING R. W.,
PENNER S. J.,
STIEGLER G. L.
Publication year - 2001
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.2746/042516401776249291
Subject(s) - virology , heterologous , virus , equine influenza , horse , influenza vaccine , biology , influenza a virus , nasal administration , live attenuated influenza vaccine , vaccine efficacy , medicine , vaccination , immunology , paleontology , biochemistry , gene
Summary Flu Avert IN vaccine is a new, live attenuated virus vaccine for equine influenza. We tested this vaccine in vivo to ascertain 1) its safety and stability when subjected to serial horse to horse passage, 2) whether it spread spontaneously from horse to horse and 3) its ability to protect against heterologous equine influenza challenge viruses of epidemiological relevance. For the stability study, the vaccine was administered to 5 ponies. Nasal swabs were collected and pooled fluids administered directly to 4 successive groups of naïve ponies by intranasal inoculation. Viruses isolated from the last group retained the vaccine's full attenuation phenotype, with no reversion to the wild‐type virus phenotype or production of clinical influenza disease. The vaccine virus spread spontaneously to only 1 of 13 nonvaccinated horses/ponies when these were comingled with 39 vaccinates in the same field. For the heterologous protection study, a challenge model system was utilised in which vaccinated or naïve control horses and ponies were exposed to the challenge virus by inhalation of virus‐containing aerosols. Challenge viruses included influenza A/equine‐2/Kentucky/98, a recent representative of the ‘American’ lineage of equine‐2 influenza viruses; and A/equine‐2/Saskatoon/90, representative of the ‘Eurasian’ lineage. Clinical signs among challenged animals were recorded daily using a standardised scoring protocol. With both challenge viruses, control animals reliably contracted clinical signs of influenza, whereas vaccinated animals were reliably protected from clinical disease. These results demonstrate that Flu Avert IN vaccine is safe and phenotypically stable, has low spontaneous transmissibility and is effective in protecting horses against challenge viruses representative of those in circulation worldwide.