Equine herpesvirus-1-specific interferon gamma (IFNgamma) synthesis by peripheral blood mononuclear cells in thoroughbred horses.
BACKGROUND
An assay has been developed that measures EHV-1 specific interferon gamma synthesis (IFNgamma), a cytokine produced following the activation of memory T lymphocytes and therefore a measure of cell mediated immunity. The method requires validation in the field.


OBJECTIVE
To measure the frequency of EHV-1 specific, IFNgamma synthesising peripheral blood mononuclear cells (PBMC) in a population of Thoroughbred horses, and examine its relationship with age, gender, premises and history of vaccination or field infection with EHV-1.


METHODS
Lymphocytes from 200 Thoroughbred horses were stimulated with EHV-1 in vitro, and IFNgamma detected using a monoclonal antibody and indirect immunofluorescence. Percent positive cells were enumerated by flow cytometric analysis and the results described and compared statistically between groups.


RESULTS
The frequency of IFNgamma+ PBMC was significantly higher in animals age >5 years compared with 2-4 years, in females vs. males, on stud farms vs. training yards and following vaccination of 2-year-olds with inactivated virus compared with nonvaccinates. Age strongly confounded all these associations and care must therefore be taken interpreting these results. Mares exposed to a field infection with EHV-1 also had higher frequencies of IFNgamma+ PBMC than other vaccinated horses.


CONCLUSIONS
The frequency of EHV-1 specific, IFNgama+ PBMC among the sample Thoroughbred population was diverse but lowest in young, unvaccinated horses-in-training.


CONCLUSIONS
The frequency of EHV-1 specific lymphocytes synthesising IFNgamma in this population may be associated with its susceptibility to infection with this virus. This easy technique may be applied to monitor the antigenicity of vaccines and their effectiveness at stimulating cellular immunity.
Luce
R
R
Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK.
Shepherd
M
M
Paillot
R
R
Blacklawst
B
B
Wood
J L N
JL
Kydd
J H
JH
D000367:Age Factors; D000818:Animals; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D006566:Herpesviridae Infections / Q000097:blood / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D004861:Herpesvirus 1, Equid / Q000276:immunology*; D022283:Herpesvirus Vaccines / Q000276:immunology*; D006734:Horse Diseases / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D006736:Horses; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000096:biosynthesis*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D012737:Sex Factors
D022283:Herpesvirus Vaccines; D007371:Interferon-gamma