An evaluation of Pasteurella pestis fraction-1-specific antibody for the confirmation of plague infections.

Owing to the relatively long duration of specific serum plague antibodies in the host, the serological diagnosis of plague has substantial advantages over the conventional method of isolation of the causative agent. For the performance of both the complement-fixation (CF) and passive haemagglutination (HA) tests, the use of highly purified, specific Fraction 1 antigen is essential, and its preparation is discussed in this paper. Although both tests measure the same antibodies, the passive HA test is the more sensitive and constitutes the most effective means of detecting recovery from plague infection in nature. The CF test is nevertheless invaluable for such purposes as determining the antibody content of sera from immunized or infected hosts, indicating the amount of Fraction 1 developed by strains of Pasteurella pestis in cultures and therefore present in a vaccine, or detecting and estimating the amount of Fraction 1 antigen in extracts prepared from infected animal tissues and therefore for the field diagnosis of wild rodent plague after contamination or decomposition of rodents' carcasses.