Antibody response detected by immunoblot in respiratory tract washings of chickens after infection with Mycoplasma gallisepticum.

Two experiments were conducted to test the sensitivity of Western blotting for detection of M. gallisepticum antibodies in respiratory washings and sera of infected chickens by mouse monoclonal antibodies to chicken IgG, IgM and IgA. In the first experiment, birds infected at 10 days of age were examined 2 weeks later. In the respiratory washings, IgA antibodies reacted with eight polypeptides of M. gallisepticum, while IgM and IgG reacted with three. In the serum IgA antibodies were not detected but IgM antibodies reacted with eight polypeptides and IgG with 16. In the second experiment birds were infected at 3 weeks of age and a subgroup was examined every week for 3 weeks post-infection. In the respiratory washings IgA was the principle immunoglobulin detected in the first week and it reacted to six major polypeptides of M. gallisepticum (p72, p64-67, p60, p56, p45, p40). In serum IgM was predominant in the first week and reacted to nine polypeptides. From the second week IgG antibodies were the most important as they reacted to 13 polypeptides in respiratory washings and to 11 polypeptides in the serum, while they reacted to nine polypeptides in respiratory washings and to 13 in the serum in the third week.