Efficacy of a canarypox-vectored recombinant vaccine expressing the hemagglutinin gene of equine influenza H3N8 virus in the protection of ponies from viral challenge.
OBJECTIVE
To determine onset and duration of immunity provided by a 2- or 3-dose series of a new canarypox-vectored recombinant vaccine for equine influenza virus (rCP-EIV vaccine) expressing the hemagglutinin genes of influenza H3N8 virus strains A/eq/Kentucky/94 and A/eq/Newmarket/2/93 in ponies.


METHODS
Forty-nine 1- to 3-year-old male Welsh Mountain Ponies that were seronegative for equine influenza virus.


METHODS
Vaccinated and control ponies were challenged with aerosolized influenza virus A/eq/Sussex/89 (H3N8), representative of the Eurasian lineage of circulating influenza viruses. In trial 1, control ponies and ponies that received rCP-EIV vaccine were challenged 2 weeks after completion of the 2-dose primary vaccination program. In trial 2, ponies were challenged 5 months after 2 doses of rCP-EIV vaccine or 1 year after the first boosting dose of rCP-EIV vaccine, administered 5 months after completion of the primary vaccination program. After challenge, ponies were observed daily for clinical signs of influenza and nasal swab specimens were taken to monitor virus excretion.


RESULTS
The challenge reliably produced severe clinical signs consistent with influenza infection in the control ponies, and virus was shed for up to 7 days. The vaccination protocol provided clinical and virologic protection to vaccinates at 2 weeks and 5 months after completion of the primary vaccination program and at 12 months after the first booster.


CONCLUSIONS
The rCP-EIV vaccine provided protection of ponies to viral challenge. Of particular importance was the protection at 5 months after the second dose, indicating that this vaccine closes an immunity gap between the second and third vaccination.
Minke
Jules M
JM
Merial SAS, 254 rue Marcel Mérieux, Lyon, 69007, France.
Toulemonde
Caroline Edlund
CE
Coupier
Hervé
H
Guigal
Pierre-Michel
PM
Dinic
Sonia
S
Sindle
Tracey
T
Jessett
David
D
Black
Linda
L
Bublot
Michel
M
Pardo
Maria C
MC
Audonnet
Jean-Christophe
JC
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D028121:Canarypox virus / Q000235:genetics*; D015967:Gene Expression Regulation, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics* / Q000276:immunology*; D006734:Horse Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology*; D006736:Horses; D053123:Influenza A Virus, H3N8 Subtype / Q000276:immunology* / Q000502:physiology; D008297:Male; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology
D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D014614:Vaccines, Synthetic