Feeding on a Bartonella henselae infected host triggers temporary changes in the Ctenocephalides felis microbiome

The effect of Bartonella henselae on the microbiome of its vector, Ctenocephalides felis (the cat flea) is largely unknown, as a majority of C. felis microbiome studies have utilized wild-caught pooled fleas. Therefore, we surveyed the microbiome of laboratory-origin C. felis fed on B. henselae-infected cats to identify changes to microbiome diversity and microbe prevalence compared to unfed fleas, and fleas fed on uninfected cats. To evaluate changes over time, fleas were fed on cats for 24 hours or 9 days. Utilizing Next Generation Sequencing (NGS) on the Illumina platform, we documented an increase in microbial diversity, richness, and evenness in C. felis fed on Bartonella-infected cats for 24 hours, changes that returned to baseline (unfed fleas or fleas fed on uninfected cats) after 9 days on the host. The increased diversity in the C. felis microbiome when fed on B. henselae-infected cats may be related to the mammalian, flea, or endosymbiont response, factors that remain to be explored and potentially exploited for pathogen control. In addition, poor B. henselae acquisition was documented in these laboratory-maintained C. felis. Potential hypotheses to account for this finding include poor acquisition by adult fleas, the influence of flea genetic variation on B. henselae acquisition, and lack of co-feeding with B. henselae-infected C. felis. This study provides an investigation of the C. felis microbiome response to blood feeding and blood-feeding on B. henselae-infected cats; however, future studies are necessary to fully characterize the effect of endosymbionts and C. felis diversity on B. henselae acquisition.