Studies of the Immunoglobulin Responses to Viral Infections of Chickens.

This thesis describes the study of antibody class responses in the serum and tracheal mucosa of virus infected chickens. It examines the use of a rapid method for the detection of virus-specific IgM antibody, as a means for the detection of recent infection, as a tool for serological diagnosis or for research into virus infections. SPF chickens were infected with infectious bronchitis virus (IBV), infectious laryngotracheitis virus (ILTV) or infectious bursal disease virus (IBDV) and serum, collected at regular intervals, was fractionated by gel chromatography, for the separation of IgM and IgG or treated with IgM-immunoadsorbents, for the affinity chromatography purification of IgM. Fractions of sera and eluants from the immunoadsorbents were assayed by ELISA to identify and quantify virus-specific antibodies and their immunoglobulin class. The separation of IgM using the IgM-immunoadsorbents was achieved and the results compared favourably with those obtained by gel chromatography as regards rapidity and simplicity. Viruses of three distinct pathogeneses were studied and it was shown that IgM always appeared first and rapidly reached the highest serum concentration, declining also rapidly. The IgM response to ILTV was shown to recur, invalidating the use of IgM detection for the diagnosis of recent infection. IgM response to IBV and IBDV could be associated to the recent infection and its detection could be validated for the diagnosis of recent infection. In these studies, the profiles of antibody seemed to be independent of many aspects relating to viral pathogeneses, e.g., target cell and organ of replication, and although ILTV induced a state of intermittent IgM antibody response, its initial profile was also characterized by a rapid rise and decline following infection, which period compared to the response to the other viruses