Characterisation of CTL and IFN-gamma synthesis in ponies following vaccination with a NYVAC-based construct coding for EHV-1 immediate early gene, followed by challenge infection.
Equine herpesvirus-1 (EHV-1) is a ubiquitous pathogen of horses, which continues to cause respiratory and neurological disease and abortion, despite the widespread use of vaccines. Cell mediated immunity (CMI) is thought to play a major role in protection against infection with EHV-1. The aim of this study was to characterise the virus-specific CMI response in ponies vaccinated with vP1014, a vaccinia-based construct (NYVAC) coding for the immediate early gene (gene 64) of EHV-1. This gene product is a CTL target protein for an equine MHC class I allele expressed on the A3 haplotype. EHV-primed yearling ponies expressing this haplotype were vaccinated once (n = 1), three (n = 1), or four times (n = 2), and one pony was kept as an unvaccinated control. Cytotoxic T lymphocyte (CTL) activity and interferon gamma (IFN-gamma) synthesis were measured before and after vaccination and challenge infection with EHV-1. Multiple immunisations with vP1014 resulted in increased CTL activity and IFN-gamma synthesis specific for EHV-1 compared with unvaccinated or singly vaccinated ponies. The phenotype of EHV-1 specific T-cells synthesising IFN-gamma was also modified by immunisation. In the unvaccinated pony, the predominant population synthesising IFN-gamma after EHV-1 stimulation was CD8alpha+. In contrast, multiply vaccinated ponies demonstrated an increased proportion of CD8alpha- T-cells synthesising IFN-gamma. The results demonstrated that vaccination with a NYVAC-based construct coding for gene 64 stimulated CMI. This immune response alone did not protect against challenge infection. However, the study does illustrate that vaccinia-based vaccines can stimulate CMI in the horse and may therefore contribute to protection against disease caused by EHV-1.
Paillot
R
R
Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Newmarket, Suffolk CB8 7UU, UK. romain.paillot@aht.org.uk
Ellis
S A
SA
Daly
J M
JM
Audonnet
J C
JC
Minke
J M
JM
Davis-Poynter
N
N
Hannant
D
D
Kydd
J H
JH
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D005260:Female; D017781:Genes, Immediate-Early; D006566:Herpesviridae Infections / Q000517:prevention & control / Q000662:veterinary*; D004861:Herpesvirus 1, Equid / Q000276:immunology*; D022283:Herpesvirus Vaccines / Q000276:immunology*; D006734:Horse Diseases / Q000517:prevention & control*; D006736:Horses; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis*; D008297:Male; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*
D000914:Antibodies, Viral; D022283:Herpesvirus Vaccines; D019444:Vaccines, DNA; D007371:Interferon-gamma