AWidefield Light Microscopy-Based Approach Provides Further Insights into the Colonization of the Flea Proventriculus by Yersinia pestis

03/21/2023

Yersinia pestis (the agent of flea-borne plague) must obstruct the flea’s proventriculus to maintain transmission to a mammalian host. To this end, Y. pestis must consolidate a mass that entrapped Y. pestis within the proventriculus very early after its ingestion. We developed a semiautomated fluorescent image analysis method and used it to monitor and compare colonization of the flea proventriculus by a fully competent flea-blocking Y. pestis strain, a partially competent strain, and a noncompetent strain.

Our data suggested that flea blockage results primarily from the replication of Y. pestis trapped in the anterior half of the proventriculus. However, consolidation of the bacteriaentrapping mass and colonization of the entire proventricular lumen increased the likelihood of flea blockage. The data also showed that consolidation of the bacterial mass is not a prerequisit for colonization of the proventriculus but allowed Y. pestis to maintain itself in a large flea population for an extended period of time. Taken as the whole, the data suggest that a strategy targeting bacterial mass consolidation could significantly reduce the likelihood of Y. pestis being transmitted by fleas (due to gut blockage), but also the possibility of using fleas as a long-term reservoir.