Canarypox-vectored equine influenza virus (EIV) vaccines expressing hemagglutinins of A/equine/Kentucky/94 (vCP1529) and A2/equine/Ohio /03 (vCP2242) were evaluated for induction of antibody responses against canine influenza virus (CIV) in dogs.

Dogs (35) were randomly allocated into 4 groups; group 1 (n = 8) and group 2 (9) were inoculated SC on days 0 and 28 with 1.0 mL (approx 105.7 TCID50) of vCP1529 and vCP2242, respectively. Dogs in group 3 (n = 9) were inoculated twice with 0.25 mL (approx 105.7 TCID50) of vCP2242 via the transdermal route. The 9 dogs of group 4 were control animals. All dogs were examined for adverse reactions. Sera, collected on days -1, 7, 13, 21, 28, 35, and 42, were tested by hemagglutination inhibition (HI) and virus neutralization (VN) assays for antibodies against CIV antigens A/Canine/FL/43/04-PR and A/Canine/NY/115809/05, respectively.

Inoculations were tolerated well. The HI and VN antibodies were detected by 7 days after primary inoculation. Most dogs of groups 1 and 2 and all dogs of group 3 had detectable antibodies by 14 days after initial inoculation. The second inoculation induced an anamnestic response, yielding geometric mean HI titers of 139, 276, and 1,505 and VN titers of 335, 937, and 3,288 by day 42 (14 d after booster inoculation) in groups 1, 2, and 3, respectively.

Conclusions and Clinical Relevance Canarypox-vectored EIV vaccines induce biologically important antibodies and may substantially impact CIV transmission within a community and be of great value in protecting dogs against CIV-induced disease.

Reference: Karaca et al. AJVR 68: 208-212, 2007.