GENETIC DETERMINATION OF O ANTIGENS OF SALMONELLA GROUPS B (4,5,12) AND C1 (6,7)

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  • 1 January 1966
    • journal article
    • research article
    • Vol. 91  (3) , 1115-+
Abstract
The genetic determination of the O antigens of Salmonella was studied by Hfr or F'' crosses between strains of groups B (antigens 4,5,12) and C1 (antigens 6,7). The main genetic determinants of the specificities 4 of group B and 7 of group C1 behaved as alleles of one locus, called O or O-4/7. This is probably identical with O-4/9, responsible for the serological difference between groups B and D, and with the "rough" locus rouB. At least parts of the antigens 12 of group B and 62 of group C are determined at the same locus. The gene 0-5 is closely linked to 0-4/7, both mapping in the approximately 2 minutes distance between his and metG in the order his - O-4/7 - O-5 - metG. In crosses of group B donors with group C1 recipients, a serologically new type, called semirough (SR), appeared in most recombinants that had inherited the O-4 allele of the group B donor. These SR froms are serologically intermediate between smooth and rough forms, showing poor stability in saline but possessing the specificities 4 and 12 and (some of them) 5. On the basis of previous biochemical studies, the hypothesis has been put forward that the side chains of their lipopoly-saccharide are much shorter than normal group B side chains, probably containing only one repeating unit per side chain. A gene SR-4 responsible for the elongation of group B side chains beyond the first repeating unit was mapped between gal and try, group B and D bacteria being SR-4+, and group C being SR-4-.