Genetic Mapping of Vi and Somatic Antigenic Determinants inSalmonella

Abstract

The Vi antigen and somatic antigen 9 were transferred to Salmonella typhimurium recipients by mating with S. typhosa Hfr TD-7, and the genetic determinants of these antigens were located. A gene responsible for Vi antigen expression, ViB, was found to be associated with the inl-purA-pyrB linkage group, and the order ViB-inl-purA-pyrB was established. The determinant of somatic antigen 9 was found closely linked to the his gene, and cotransduction of these determinants was accomplished with phage PLT-22. Moreover, all conjugation and transduction hybrids which received the somatic antigen 9 determinant concurrently lost somatic antigen 4. Similarly, S. typhosa hybrids produced by transfer of his and the gene for somatic antigen 4 from S. typhimurium Hfr B2, or by cotransduction tion of these genes with PLT-22, also lost somatic antigen 9. These results indicated that the genetic determinants of the somatic antigens 9 and 4 are probably allelic. A second Vi antigen determinant, ViA, located near his, was discovered in matings of S. typhimurium Hfr B2 with a Vi-negative S. typhosa recipient. Vi-positive S. typhosa hybrids were obtained from this cross in which neither parent expressed the Vi antigen, indicating that this Vi determinant of S. typhosa is present also in S. typhimurium. The intricate serological pattern exhibited by members of the family Enterobacteriaceae has come, in recent years, within the scope of genetic

GENETIC ASPECTS OF BIOSYNTHESIS AND STRUCTURE OF SALMONELLA SOMATIC POLYSACCHARIDE

“…When a 9,12 his+ donor was crossed to a 4,5,12 his recipient the corresponding result was obtained: most recombinants with the donor his' character had also its 0 antigenic specificity 9, and no longer showed the recipient factors 4 and 5 . I n both these crosses, and in similar crosses reported by Johnson, Krauskopf and Baron (1965), factors 4 and 9 behave as if determined by alleles a t a locus closely linked to his. The only chemical difference known between the 4,12 and 9,12 0-specific repeat-unit is in the dideoxyhexose branch unit attached t o the mannose, which is abequose in 4,12 and tyvelose in 9,12.…”

“…The interval hisE-0 seems to be shorter than the other two intervals. So short, indeed, that when hisE is transduced by phage P22, the determinant of 0 factor 4 (or of 0 factor 9) is cotransduced with a frequency of about 4 per cent (Johnson et al, 1965;Makela, unpublished). T h e whole distance hisE-metG corresponds to about 2 minutes in an interrupted mating experiment (Sanderson & Demerec, 1965), and so t o about 1.5 per cent of the whole length of the bacterial chromosome, and to about 2 x lo5 nucleotide pairs of DNA.…”

Assay of Typhoid Vaccines with Salmonella typhosa-Salmonella typhimurium Hybrids

“…As reported previously (4, 5), the majority of his+-selected S. typhimurium hybrids obtained from mating with S. typhosa WR4000 also inherit the closely linked genetic determinant of somatic antigen 9. Because the genetic determinant of this antigen is the allele of the somatic antigen 4 determinant of S. typhimurium (4,5,8), recombination of this locus results in loss of expression of antigen 4 by those S. typhimurium recombinants which express antigen 9. In addition, such recombinants also lose antigen 5 because this antigen cannot be expressed in strains lacking the determinant of antigen 4 (4,5,8).…”

“…The genetic locus of the phase 1 flagellar antigen determinant of S. typhosa is sufficiently close to the his+ locus that some of the his+-selected hybrids of S. typhimurium undergo recombination at that locus as well (4). Inasmuch as the phase 1 flagellar antigens of all Salmonella species comprise an allelic series at this locus (7), we were able to obtain his+ hybrids of S. typhimurium WR5004 which, in addition to antigen 9, expressed also the phase 1 flagellar antigen d of S. typhosa.…”

The UDP‐GalNAcA biosynthesis genes gna‐gne2 are required to maintain cell envelope integrity and in vivo fitness in multi‐drug resistant Acinetobacter baumannii

“…In S. Typhi, UDP-GalNAcA is the monomeric precursor of the Vi capsular antigen (Johnson et al, 1965;Hashimoto et al, 1993;Waxin et al, 1993;Zhang et al, 2006), a crucial virulence factor and the target of all current vaccines against this pathogen. In P. aeruginosa, UDP-GalNAcA is a component of the O-antigen B-band (Knirel, 1990;Belanger et al, 1999;Lam et al, 2011).…”