Onset and duration of immunity to equine influenza virus resulting from canarypox-vectored (ALVAC) vaccination.
Equine influenza virus remains an important problem in horses despite extensive use of vaccination. Efficacy of equine influenza vaccination depends on the onset and duration of protective immunity, and appropriate strain specificity of the immune response. This study was designed to test the protective immunity resulting from vaccination with the North American commercial ALVAC equine influenza vaccine (RECOMBITEK Influenza, Merial, USA)(1) against challenge with American lineage influenza viruses. In experiment 1, 12 ponies were vaccinated twice, at a 35 day interval, using the ALVAC-influenza vaccine expressing the HA genes of influenza A/eq/Newmarket/2/93 and A/eq/Kentucky/94 (H3N8), and 11 ponies served as unvaccinated controls. Six months after the second vaccination, all ponies were challenged with A/eq/Kentucky/91. In experiment 2, 10 ponies received one dose of the ALVAC-influenza vaccine, 10 ponies served as unvaccinated controls, and all ponies were challenge infected with A/equine/Ohio/03, 14 days after vaccination. Parameters studied included serological responses, and clinical disease and nasal viral shedding following challenge infection. In experiment 1, following the two-dose regimen, vaccinated ponies generated high titered anti-influenza virus IgGa and IgGb antibody responses to vaccination and demonstrated statistically significant clinical and virological protection to challenge infection compared to controls. Infection with A/eq/Kentucky/91 produced unusually severe signs in ponies in the control group, requiring therapy with NSAID's and antibiotics, and leading to the euthanasia of one pony. In experiment 2 following the one-dose regimen, vaccinates generated IgGa responses pre-challenge, and anamnestic IgGa and IgGb responses after challenge. Vaccinates demonstrated statistically significant clinical and virological protection to challenge infection compared to controls. The results of this study clearly demonstrate the early onset, and 6-month duration of protective immunity resulting from ALVAC-influenza vaccination against challenge with American lineage equine influenza viruses.
Soboll
Gisela
G
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523, USA.
Hussey
Stephen B
SB
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523, USA.
Minke
Jules M
JM
Merial S.A.S., 254 rue Marcel Merieux, 69007 Lyon, France.
Landolt
Gabriele A
GA
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523, USA.
Hunter
James S
JS
Merial Limited, 6498 Jade Road, Fulton, MO 65251, USA.
Jagannatha
Shyla
S
School of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
Lunn
David P
DP
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523, USA. Electronic address: lunnp@mail.colostate.edu.
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation / Q000276:immunology; D028121:Canarypox virus; D006734:Horse Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D006736:Horses / Q000276:immunology; D053123:Influenza A Virus, H3N8 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology / Q000627:therapeutic use*; D008297:Male; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D014614:Vaccines, Synthetic / Q000276:immunology / Q000627:therapeutic use; D017201:Virus Shedding / Q000276:immunology
D000914:Antibodies, Viral; D007252:Influenza Vaccines; D014614:Vaccines, Synthetic