Susceptibility of the Siberian polecat to subcutaneous and oral Yersinia pestis exposure

To determine if the Siberian polecat (Mustela eversmannii) represents a sui table model for the study of plague pathogenesis and prevention in the blac k-footed ferret (Mustela nigripes), polecats were exposed to 10(3), 10(7) o r 10(10) Yersinia pestis organisms by subcutaneous injection; an additional group was exposed to Y. pestis da ingestion of a plague-killed mouse. Plag ue killed 88% of polecats exposed to Y. pestis (71% mortality in the 10(3) group, 100% mortality in the 10(7) and 10(10) groups, and 83% mortality in the mouse-fed group), Within the challenged group, mean day of death post-c hallenge ranged from 3.6 to 7.6 days; all polecats died on or before day 12 post-challenge. Animals receiving the lowest parenteral dose survived sign ificantly longer than those receiving higher parenteral doses. Within chall enged animals, mean survival time was lower in those presenting vith signif icant weight loss by day 3, lethargy, and low fecal output; time to onset o f lethargy and other signs was also related to risk of dying and/or plague dose. Six polecats developed serum antibody titers to the Y. pestis F1 prot ein. Three seropositive polecats survived the initial challenge and a subse quent exposure to a plague-killed mouse, while two seropositive animals lat er died. This study confirms that the Siberian polecat is susceptible to pl ague and suggests that this species will offer an appropriate surrogate for black-footed ferrets in future plague studies and related vaccine trials.