Evaluation of the presence of avian influenza receptors in oviducts of forced moulting birds using immunofluorescence

During the 2012 highly pathogenic avian influenza outbreak in Mexico caused by the H7N3 subtype, infection led to the death of approximately 22 million laying hens. Thus, poultry farmers were faced with a challenge to ensure the continued commercial flow of eggs. In addition to implementing established sanitary protocols and vaccination programs, forced moulting management was utilized in the affected areas. This strategy guaranteed the maintenance of egg production in the quarantined areas by decreasing the mortality of the infected flock while re-stimulating egg production. To understand how forced moulting reduced mortality of the infected birds, we examined the distribution of the avian influenza receptor in the oviduct of hens subjected to forced moulting. We tested if changes in the reproductive tract caused by forced moulting generated a decrease in the expression of the specific virus receptor in the cell membranes. Host susceptibility to the influenza virus was determined by the presence of these specific receptors. We utilized immunofluorescence of the Maackia amurensis lectin to identify the presence of the virus receptor in histological sections of the oviducts of birds in egg production and birds undergoing forced moulting. The results showed the presence and distribution of the receptors for avian influenza. A strong signal of the receptor was observed in the histological sections of the oviducts of birds in egg production. Conversely, the signal was low in the oviducts of birds undergoing forced moulting. These results demonstrate a decrease in the number of receptors of birds subjected to forced moulting. A lack of receptors would affect virus infection and replication as well as virus-induced damage in the oviduct, which may help explain the observation in the field that birds infected with avian influenza and subjected to forced moulting have decreased mortality.A. Abundant amount of influenza-like receptors, labelled with apple-green fluorescence, on the apical region of the ciliated cylindrical pseudostratifiedepithelium of the uterine region of healthy hens in production. Bar: 100 μm.