RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM OF THE DNA OF TYPHUS GROUP RICKETTSIAE

The DNA of 10 strains of Rickettsia prowazekii, 5 strains of Rickettsia typhi and 1 strain of Rickettsia canada was investigated by restriction fragment length polymorphism analysis. Interspecies differences were characterized by a great number of noncomigrating bands. Using the endonuclease HindIII and PstI fragments comigration as a quantitive criterion, genetic similarity coefficient was calculated for the pair Rickettsia prowazekii/Rickettsia typhi-32.0%, for Rickettsia prowazekii/Rickettsia canada-22.7 %, and for Rickettsia typhi/Rickettsia canada-23.5 %. Intraspecies differences expressed are very subtle and concern 1-2 noncomigrating fragments. The investigated strains of Rickettsia prowazekii and Rickettsia typhi can be divided into 2 groups without any correlation to the source and period of isolation, or to strain passage history.