Effects of Shiga toxin 2 on lethality, fetuses, delivery, and puerperal behavior in pregnant mice

Shiga toxin 2 (Stx2) is produced by enterohemorrhagic Escherichia coli (EHE C) and is known as the major virulence factor of EHEC, The aim of this stud y was to evaluate the effects of Stx2 on (i) maternal lethality, (ii) fetus es, (iii) delivery period, and (iv) maternal behavior after delivery. Timed pregnant ICR mice were injected intravenously with Stx2 on day 5 of pregna ncy (early stage) or on day 15 (late stage). In early-stage experiments, th e number of normal fetuses of mice injected with Stx2 was significantly low er than that of control mice. In late-stage experiments, mothers injected w ith Stx2 delivered normal numbers of neonates, but could not take care of t hem. The lethal doses of Stx2 were not different for pregnant and nonpregna nt female mice at either stage. We conclude that Stx2 is toxic to the fetus in early pregnancy and affects maternal puerperal behavior in late pregnan cy.