Rm. Tsolis et al., Identification of a putative Salmonella enterica serotype typhimurium hostrange factor with homology to IpaH and YopM by signature-tagged mutagenesis, INFEC IMMUN, 67(12), 1999, pp. 6385-6393
The genetic basis for the host adaptation of Salmonella serotypes is curren
tly unknown. We have explored a new strategy to identify Salmonella enteric
a serotype Typhimurium (S. typhimurium) genes involved in host adaptation,
by comparing the virulence of 260 randomly generated signature-tagged mutan
ts during the oral infection of mice and calves. This screen identified fou
r mutants, which were defective for colonization of only one of the two hos
t species tested. One mutant,,which only displayed a colonization defect du
ring the infection of mice, was further characterized. During competitive i
nfection experiments performed with the S. typhimurium wild type, the mutan
t was defective for colonization of murine Peyer's patches but colonized bo
vine Peyer's patches at the wild-type level. No difference in virulence bet
ween wild type and mutant was observed when calves were infected orally wit
h 10(10) CFU/animal. In contrast, the mutant possessed a sixfold increase i
n 50% lethal morbidity dose when mice were infected orally. The transposon
in this mutant was inserted in a 2.9-kb pathogenicity islet, which is locat
ed between uvrB and yphK on the S. typhimurium chromosome. This pathogenici
ty islet contained a single gene, termed slrP, with homology to ipaH of Shi
gella flexneri and yopM of Yersinia pestis. These data show that comparativ
e screening of signature-tagged mutants in two animal species can be used f
or scanning the S. typhimurium genome for genes involved in host adaptation
.