Role of Yersinia Murine Toxin in Survival of Yersinia pestis in the Midgut of the Flea Vector

Abstract

Transmission by flea bite is a relatively recent adaptation that distinguishes Yersinia pestis, the plague bacillus, from closely related enteric bacteria. Here, a plasmid-encoded phospholipase D (PLD), previously characterized as Yersinia murine toxin (Ymt), was shown to be required for survival of Y. pestis in the midgut of its principal vector, the rat fleaXenopsylla cheopis. Intracellular PLD activity appeared to protect Y. pestis from a cytotoxic digestion product of blood plasma in the flea gut. By enabling colonization of the flea midgut, acquisition of this PLD may have precipitated the transition ofY. pestis to obligate arthropod-borne transmission.