ROLE OF THE YERSINIA-PESTIS HEMIN STORAGE (HMS) LOCUS IN THE TRANSMISSION OF PLAGUE BY FLEAS

Yersinia pestis, the cause of bubonic plague, is transmitted by the bi tes of infected fleas. Biological transmission of plague depends on bl ockage of the foregut of the flea by a mass of plague bacilli. Blockag e was found to be dependent on the hemin storage (hms) locus. Yersinia pestis hms mutants established long-term infection of the flea's midg ut but failed to colonize the proventriculus, the site in the foregut where blockage normally develops. Thus, the hms locus markedly alters the course of Y. pestis infection in its insect vector, leading ro a c hange in blood-feeding behavior and to efficient transmission of plagu e.