THE GENETIC-CONTROL OF VIRULENCE IN GROUP-A STREPTOCOCCI .2. TRIGGER EFFECT BY PLASMIDS ON ANTI-PHAGOCYTIC ACTIVITY, OPACITY FACTOR AND IGG AND IGA FC-RECEPTORS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 91  (1) , 61-67
Abstract
The erythromycin-resistance marker [Emr] of 2 plasmids, pSM19035 and pERL1, was transferred by conjugation in matings within group A streptococci and between group H and group A streptococci, with a frequency of 10-5-8 .times. 10-7. Two of the recipients strains used, 22v-1 and 22v-2, showed traces of opacity factor (OF) activity. This activity increased markedly upon transfer of both plasmids to the strains; other recipients (22h-21, 12Teiko-1, Challis 6-1) remained OF-negative after conjugation. The transconjugants resulting from matings using strains 22v-1 and 22v-2 as recipients expressed anti-phagocytic activity. Attempts were made to type the transconjugants, but they did not belong to type M12 or M22 (the types from which the parents were derived), M3 or M1. Concomitant with the expression of anti-phagocytic activity, IgG and IgA Fc-receptor activity occurred in the transconjugants of 22v-1 and 22v-2; the donor and recipient cells were without receptors. It was not possible to demonstrate extrachromosomal DNA in transconjugants possessing anti-phagocytic, OF or Fc-receptor activity, although they retained their ability to serve as donors of the Emr marker. Apparently, the triggering by plasmids of anti-phagocytic activity, OF and IgG and IgA Fc-receptors is due to insertion of plasmid DNA into the chromosome.

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