The effect of including anti-Ig sera in the haemagglutination inhibition test for Mycoplasma gallisepticum.

Addition of anti-immunoglobulin M (anti-IgM), G (anti-IgG) and A (anti-IgA) sera to the haemagglutination-inhibition (HI) test (anti-Ig HI test) for Mycoplasma gallisepticum resulted in 2- to 8-fold increases in the HI titres. On investigating the anti-Ig HI reaction using IgM and IgG antibodies separated by affinity chromatography, it was confirmed that, in the enhanced HI titres, specificity existed between the chicken Ig classes having antibody activity and the antisera used in the test. Four days after inoculation of M. gallisepticum, the anti-Ig HI reaction was markedly enhanced by anti-IgM antiserum in the intravenously inoculated chickens and by anti-IgA serum in the nasally inoculated chickens. Ten days after inoculation of M. gallisepticum marked enhancement of the reaction was produced by anti-IgG serum in both intravenously and nasally inoculated chickens, but the enhancement of the anti-Ig HI reaction diminished from the second week after inoculation.