Extraction of capsular material from Pasteurella haemolytica.

Water and phosphate-buffered saline solution suspensions of early log-arithmic phase cells of Pasteurella haemolytica were incubated for 1 hour at various temperatures to remove capsular material with a minimum of cell lysis or death. Criteria used to determine capsular removal included change in agglutinability of the organism and disappearance of an antigenic component by the fluorescent antibody test and the agar-gel diffusion technique. The capsular material could be removed in a saline solution suspension at 41 C with little decrease in viability, thereby providing comparable cell populations with and without capsules for use in subsequent studies.