Transmissible plasmid factors and fertility inhibition in Vibrio cholerae.

SUMMARY Conjugation in Vibrio cholerae is mediated by a sex factor, designated the P factor. The present report is concerned with the identification of another trans- missible factor, labelled the V factor, in a strain of non-cholera vibrio. Although the P and V factors are compatible and may coexist in a cell, a pheno- menon of repression of P is observed in the presence of the V factor. There is, however, a brief time lag during which P-V+ cells, newly infected with the P factor, are fertile. The evidence points to the development of a repression mechanism after infection with the P factor in these strains. Rare recombinants having the 0 antigens of the non-cholera vibrio strain (donor) were isolated from a strain of V. cholerae (recipient) after conjugation. One such recombinant was P+V- and could therefore be used to obtain similar antigenic hybrids from other strains of V. cholerae.