SUSCEPTIBILITY OF PIGEONS TO AVIAN INFLUENZA

Susceptibility to infection with avian influenza virus (AN) was studie d in pigeons inoculated via oculonasal (Experiment 1) or intravenous ( Experiment 2) route. Chickens were included as susceptible hosts in bo th experiments. Two subtypes each of the highly pathogenic AIV (HPAIV; HP CK/PA H5N2 and HP CK/Australia H7N7) and nonpathogenic AIV (NPAIV; NP CK/PA H5N2 and NP emu/TX H7N1) at a dose of 10(5) embryo infective dose per bird were used as inoculum. The pigeons inoculated with HP C K/PA H5N2 or HP CK/Australia H7N7 remained apparently healthy througho ut the 21-day observation period, did nor shed viruses on 3, 7, 14, an d 21 days postinoculation (DPI), and had no demonstrable levels of ant ibodies on 21 DPI. On the other hand, 3 of 12 chickens inoculated with the HPAIV died of highly pathogenic avian influenza; the viruses were recovered from their respiratory and intestinal tissues, and the surv iving chickens had antibodies to AIV. Regarding responses of pigeons t o inoculation with NP CK/PA H5N2 or NP emu/TX H7N1, the pigeons remain ed clinically healthy throughout the 21-day observation period and did nor have detectable levels of antibodies on 21 DPI; only one pigeon y ielded the NP emu/TX H7N1 on 3 DPI, The virus was isolated from a trac heal swab and was believed to be the residual inoculum virus. Based on the responses of pigeons to NPAIV and HPAIV, it was concluded that th e pigeons were resistant or minimally susceptible to infection with HP AIV or NPAIV.