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. 2021 Oct 14;17(10):e1009995. doi: 10.1371/journal.ppat.1009995

Fig 1. A Y. pestis Ymt mutant induces PIER in X. cheopis fleas when brown rat blood is used for the infectious blood meal.

Fig 1

A) Incidence of post-infection esophageal reflux (PIER) in groups of 25 to 220 X. cheopis fleas 24 h after feeding on brown rat (Rn), black rat (Rr), mouse (M), or human blood (H) containing 1.5 x 108–1.1 x 109 CFU/ml KIM6+ or KIM6+ymtH188N Y. pestis. Bars show the mean and standard error of 3 independent experiments (n = 164–438 mixed sex fleas). *p < 0.005 by chi-square test. B) Female X. cheopis with PIER 24 h after feeding on black rat blood containing GFP-positive Y. pestis KIM6+; blue arrow indicates where blood and Y. pestis has been refluxed from the proventriculus and/or midgut into the esophagus. C) light and D) fluorescence microscopy images of the digestive tract dissected from this flea showing the presence of partially digested blood components and bacteria in the proventriculus (PV) and esophagus (E). Scale bar = 50 μm.