Salmonella Typhimurium (ST313) has caused an epidemic of
invasive disease in sub-Saharan Africa and has been recently
identified in Brazil. As the virulence of this ST is poorly understood,
the present study aimed to (i) perform the RNAseq
in vitro of S. Typhimurium STm30 (ST313) grown in
Luria-Bertani medium at 37°C; (ii) compare it with the RNAseq
of the S. Typhimurium SL1344 (ST19) and S. Typhimurium
STm11 (ST19) strains under the same growing conditions;
and (iii) examine the colonization capacity and expression
of virulence genes and cytokines in murine colon. The
STm30 (ST313) strain exhibited stronger virulence and was
associated with a more inflammatory profile than the strains
SL1344 (ST19) and STm11 (ST19), as demonstrated by transcriptome
and in vivo assay. The expression levels of the hilA,
sopD2, pipB, and ssaS virulence genes, other Salmonella pathogenicity
islands SPI-1 and SPI-2 genes or effectors, and
genes of the cytokines IL-1β, IFN-γ, TNF-α, IL-6, IL-17, IL-22,
and IL-12 were increased during ST313 infection in C57BL/6J
mice. In conclusion, S. Typhimurium STm30 (ST313) isolated
from human feces in Brazil express higher levels of pathogenesis-
related genes at 37°C and has stronger colonization
and invasion capacity in murine colon due to its high expression
levels of virulence genes, when compared with the S.
Typhimurium SL1344 (ST19) and STm11 (ST19) strains.
STm30 (ST313) also induces stronger expression of pro-inflammatory
cytokines in this organ, suggesting that it causes
more extensive tissue damage.