Differential in vivo gene expression of major Leptospira proteins in resistant or susceptible animal models

Abstract

Transcripts of Leptospira 16S rRNA, FlaB, LigB, LipL21, LipL32, LipL36, LipL41, and OmpL37 were quantified in the blood of susceptible (hamsters) and resistant (mice) animal models of leptospirosis. We first validated adequate reference genes and then evaluated expression patterns in vivo compared to in vitro cultures. LipL32 expression was downregulated in vivo and differentially regulated in resistant and susceptible animals. FlaB expression was also repressed in mice but not in hamsters. In contrast, LigB and OmpL37 were upregulated in vivo. Thus, we demonstrated that a virulent strain of Leptospira differentially adapts its gene expression in the blood of infected animals.

Fig 1

In vivo regulation of Leptospira gene expression. Relative expression of the target genes was studied as previously described by Matsui et al. (13) by quantifying transcripts from the blood of hamsters (susceptible; n = 11 animals) or mice (resistant; n = 16 animals) infected with L. interrogans serovar icterohaemorrhagiae strain Verdun. The in vivo results represent the expression levels in samples collected at 3, 6, and 24 h postinfection and the combination of all time points (M) as indicated. Transcripts from in vitro cultures were obtained after incubation at 30°C (30; n = 3) or 37°C (37; n = 3). Values represent means ± standard errors of the means (SEMs). Significant differences in gene expression between conditions (M and 30°C) were evaluated using a Mann-Whitney's nonparametric t test. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, nonsignificant.