Studies on Commercial Typhus Vaccines

Abstract

Summary Purified suspensions of epidemic typhus rickettsiae have been disrupted by sonic vibration and fractionated by differential centrifugation, yielding preparations of varying physical, chemical and biological activity. The low speed sediment, representing rickettsial debris largely, yields a turbid suspension containing about half of the total rickettsial nitrogen, demonstrating about half of the in vitro complement fixing activity of the whole rickettsiae, and cross-reacting completely with murine and epidemic typhus antibodies. The high speed sediment yields an opalescent suspension and contains about a third of the original nitrogen, and two-thirds of the original complement fixing activity, with decreased cross-reactivity. The high speed supernate yields a water-clear solution, containing only small amounts of the nitrogen and complement-fixing activity of the whole rickettsiae, and is relatively non-specific in its in vitro antigenic effects. The low and high speed sediments subjected to proteolytic digestion, yield less turbid suspensions or solutions which lose one-fourth to one-third of their nitrogen in dialysis, but retain the complement fixing activity of the original suspension, with increased cross-reactivity.