PHASE VARIATION OF RICKETTSIA (COXIELLA) BURNETI: STUDY OF THE ANTIBODY RESPONSE IN GUINEA PIGS AND RABBITS

Abstract

Further studies of the phase variation of Rickettsia burneti described by Stoker (12, 13) and Stoker and Fiset (14) are reported. Animals (guinea pigs and rabbits) infected or vaccinated (with killed purified suspensions) with either Phase 1 or Phase 2 of R. burneti (Nine Mile and Christie strains) develop antibodies that are detectable very early (within 21 days after inoculation) when their sera are tested with antigens in Phase 2. Except for the group of guinea pigs vaccinated with killed purified suspensions of Nine Mile Phase 2, all the animals also produce antibodies against the Phase 1 strains but these appear much later than the anti-Phase 2 antibodies. It is believed that R. burneti when reverting from the non-reactive Phase 1 to the reactive Phase 2 through egg adaptation loses some of its surface antigens.