Fig. 2.

Leptospire detection in tissues of hamsters or mice infected with virulent L. interrogans serovar Icterohaemorrhagiae. (A to D) Quantification of 16S rRNA by RT-qPCR as described in Materials and Methods for blood (A), liver (B), kidneys (C), and lungs (D) of hamsters (filled bars) or mice (open bars) injected with virulent L. interrogans serovar Icterohaemorrhagiae strain Verdun. Quantification at day 4 (D4) p.i. for hamsters was compared to quantification at day 5 p.i. in mice (*). As kinetics ended after 4 days p.i. for hamsters, no quantification was established at day 15 p.i. (NE), whereas no detection of 16S rRNA was possible for mice at day 15 p.i. (ND). For clarity, results are expressed as the relative normalized expression ratio of 16S rRNA using results for individuals at 3 h p.i. as calibrators (dotted lines). Values are means ± SEMs (n = 3 animals). (E and F) Warthin-Starry silver stain for spirochetes observation in liver (E) and kidneys (F) of hamsters moribund or deceased at 4.5 days after injection. The arrows indicate large clusters of leptospires in liver sinusoids and individual spirochetes in a renal glomerulus. Magnification, ×1,000.