Serum antibody response to purified Pasteurella haemolytica capsular polysaccharide in cattle.

Capsular polysaccharide (CP) of Pasteurella haemolytica, biotype A, serotype 1, was purified and combined with saline solution, aluminum hydroxide, and Freund's incomplete (oil) adjuvant. Three groups of calves were administered the various antigen preparations. The CP in saline preparation was also administered to 5 mature cows. Second injections were given 4 weeks after the first. Weekly obtained serum samples were analyzed for P haemolytica-specific antibody, using the indirect hemagglutination assay, and CP-specific antibodies were detected, using an isotype-specific ELISA. Purified CP stimulated production of CP-specific IgM, IgG1, and IgG2 in calves and predominantly IgM and IgG1 in mature cows. Significant increases in CP antibody titers were not observed after the second injection of CP antigen in either calves or mature cows. The CP in oil adjuvant stimulated the highest mean CP-specific IgG1 and IgG2 responses, whereas the CP in aluminum hydroxide adjuvant stimulated the highest mean CP-specific IgM response.