Untangling the knots: Co‐infection and diversity of Bartonella from wild gerbils and their associated fleas

Abstract

Based on molecular data, previous studies have suggested a high overall diversity and co‐infection rates of Bartonella bacteria in wild rodents and their fleas. However, partial genetic characterization of uncultured co‐infecting bacteria limited sound conclusions concerning intra‐ and inter‐specific diversity of the circulating Bartonella. To overcome this limitation, Bartonella infections of wild populations of two sympatric gerbil species and their fleas were explored by multiple isolations of Bartonella organisms. Accordingly, 448 pure Bartonella isolates, obtained from 20 rodent blood and 39 flea samples, were genetically characterized to the genotype and species levels. Results revealed a remarkable diversity and co‐infection rates of Bartonella among these sympatric rodents and their associated fleas. Specifically, 38 genotypes, classified into four main Bartonella species, were identified. Co‐infection was confirmed in 56% of the samples, which contained two to four Bartonella genotypes per sample, belonging to up to three different species. Recombination within and between these species was demonstrated, serving as a direct evidence of the frequent bacteria–bacteria interactions. Moreover, despite the noticeable interchange of common Bartonella genotypes between rodents and fleas, the co‐occurrence of genotypes was not random and differences in the overall diversity, and the ecological and phylogenetic similarities of the infection compositions were significantly associated with the carrier type (rodent vs. flea) and the rodent species. Thus, comprehensive identification of the co‐infecting organisms enabled the elucidation of ecological factors affecting the Bartonella distribution among reservoirs and vectors. This study may serve as a model for the investigation of other vector‐borne organisms and their relationships with Bartonella.

Genetic diversity ofBartonellaspp. in vampire bats from Brazil

“…All samples were tested in duplicates in each PCR reaction to evaluate the presence of appropriate melting curves and possible contamination. “ Candidatus Bartonella krasnovii” (Gutiérrez et al, ) and ultrapure water were used as positive and negative controls, respectively, in all real‐time PCR assays.…”

“…The cycling conditions and oligonucleotides used in the above‐mentioned cPCR assays are described in Table . “ Candidatus Bartonella krasnovii” DNA (Gutiérrez et al, ) and ultrapure Water (Promega ® ) were used as positive and negative controls in all cPCR assays.…”

Bartonellagene transfer agent: Evolution, function, and proposed role in host adaptation

“…This finding suggests that ecological opportunities may drive recombination frequencies between different clonal isolates, at the strain or species level. Importantly, rodents and their associated flees are one of the most important Bartonella reservoirs in terms of both incidence and genetic diversity, with more than half of the described species sharing this potentially overlapping niche (Buffet, Kosoy, & Vayssier‐Taussat, ; Chomel et al, ; Gutierrez et al, ). This implies a great potential for HGT‐mediated genetic diversification (gene pool) to these otherwise isolated organisms.…”

“…Concordant results were obtained in studies performed on wild Gerbillus spp. rodents and their associated fleas in the West Negev region of Israel (Gutierrez, Cohen, et al, ; Gutierrez, Morick, Cohen, Hawlena, & Harrus, ). In that case, a high rate of multiple coinfections by different Bartonella species was observed, and coinfections were directly associated with intraspecies and interspecies recombination (Gutierrez, Cohen, et al, ).…”

“…rodents and their associated fleas in the West Negev region of Israel (Gutierrez, Cohen, et al, 2018;Gutierrez, Morick, Cohen, Hawlena, & Harrus, 2014). In that case, a high rate of multiple coinfections by different Bartonella species was observed, and coinfections were directly associated with intraspecies and interspecies recombination (Gutierrez, Cohen, et al, 2018). Whereas these studies primarily focused on recombination events happening in housekeeping genes, other investigations revealed a dramatically increased fixation rate for recombination events in the gene clusters encoding T4SSs and their associated effector proteins (Guy et al, 2012;Paziewska, Sinski, & Harris, 2012;Saenz et al, 2007).…”