Resistance of immune-suppressed pigeons to subtypes H5N2 and H6N1 low pathogenic avian influenza virus.

Abstract

Resistance to infection with avian influenza virus (AIV) was studied in healthy and immune-suppressed pigeons, which were treated with the immunosuppressant cyclophosphamide (Cy) before infection. Two subtypes of low pathogenic AIV (LPAIV; CK/TW/H5 and CK/TW/H6) were inoculated via the oculonasal route. Nested reverse transcriptase-polymerase chain reaction (nested RT-PCR) and virus isolation were used as detection methods. The Cy-treated and -untreated pigeons in both experiments did not shed viruses or become antibody positive throughout the 21-day observation period. All pigeons were negative for AIV RNA when trachea, lung, pancreas, spleen, kidney, and rectum tissues were examined. Negative results were also obtained in uninoculated contact chickens, which were housed together with H6N1 AIV-inoculated pigeons. Therefore, it was concluded that the pigeons are resistant to infection with these two LPAIVs and do not serve as transmission hosts, even in the presence of immune dysfunction.