Shiga toxin type 2 (Stx2), a potential agent of bioterrorism, has a short distribution and a long elimination half-life, and induces kidney and thymus lesions in rats

Shiga toxin type 2, a major virulence factor produced by the Shiga toxin-producing Escherichia coli, is a potential toxin agent of bioterrorism. In this study, iodine-125 ( ¹²⁵I) was used as an indicator to describe the in vivo Stx2 biodistribution profile. The rats were injected intravenously (i.v.) with ¹²⁵I-Stx2 at three doses of 5.1-127.5 μg/kg body weight. Stx2 had a short distribution half-life (t _1/2α, less than 6 min) and a long elimination half-life in rat. The toxicokinetics of Stx2 in rats was dose dependent and nonlinear. Stx2 concentrations in various tissues were detected at 5-min, 0.5-h, and 72-h postinjection. High radioactivity was found in the lungs, kidneys, nasal turbinates, and sometimes in the eyes, which has never been reported in previous studies. In a preliminary assessment, lesions were found in the kidney and thymus.