A study on the immunological response in chickens to the somatic antigen of Salmonella gallinarum.

The immune response in chickens to the O antigen of has been studied. Chickens were infected orally with organisms, inoculated intramuscularly (i.m.) with heat-killed organisms, both alone and in Freund's complete adjuvant, and inoculated i.m. with a Westphaltype lipopolysaccharide extract of the organism, administered both alone and in Freund's complete adjuvant. Serum was collected at intervals and fractionated in Sephadex G-200 gel and by linear sucrose density ultracentrifugation. The fractions were examined by bacterial agglutination, indirect haemagglutination and antiglobulin haemagglutination tests. In all experiments, except where lipopolysaccharide was injected with and without adjuvant, early production of specific IgM was accompanied and followed by increasing production of IgG. Early IgG often appeared to be incomplete because it was only detected by the antiglobulin method.