VIRULENT-AVIRULENT CONVERSIONS OF Rickettsia Rickettsii IN VITRO

Abstract
In this paper is reported (a) the in vitro conversion of virulent R. rickettsii to an avirulent state by para-aminobenzoic acid; (b) the in vitro reactivation or conversion of the PABA-avirulent and arthropod-avirulent rickettsiae to the virulent form by the addition of Coenzyme I or Coenzyme A; and (c) the observation that the state of virulence for guinea pigs parallels the adsorptivity of R. rickettsii to minced guinea pig tunica.