Abstract:

Aims: Bats are natural reservoir hosts of many zoonotic viruses and non-viral pathogens. Several lines of evidence indicate that bats harbor diverse groups of Bartonella species and genotypes. Little is still known about how prevalence varies and the genetic diversity of Bartonella spp. in bats in China.
Methods: Between 2015 and 2017, bats were captured in four areas in southwestern Yunnan by the net trapping method. Liver and spleen tissues of bats were collected, and nucleic acids were extracted after mixing and grinding. The ssrA gene of Bartonella spp. was detected by using the TaqMan real-time fluorescent quantitative PCR assay (qPCR). The positive products of qPCR were amplified and sequenced to identify the species of Bartonella. The phylogenetic relationships were constructed by binary and network methods.
Results: We present the results of the investigation of bat-borne Bartonella in four areas of Yunnan Province, which have shown a high prevalence of Bartonella and high genetic diversity in the local bat population. Bartonella gene ssrA was detected by using qPCR in 56.4% (172/305) bats captured from four sampling sites, including 22 Rhinolophus affinis, 18 Rhinolophus blythi, and 132 Rousettus leschenaultii. There was no statistically significant difference (χ² = 1.135, P = 0.567) in the infection rates among species. The infection rates of Lincang, Xishuangbanna, Baoshan, and Ruili were 50.0% (22/44), 61.7% (29/47), 62.1% (18/29), and 55.7% (103/185), respectively. Thirty-seven ssrA sequences of Bartonella were obtained by second amplification from qPCR and sequencing. The binary tree revealed 10 phylogroups, one of which was related to B. elizabethae, B. tribocorum and B. krasnovii, the other sequences were far from the known Bartonella spp. and were closely related to bat-borne Bartonella from bats in Asia, Europe, and America. The genetic diversity analysis showed that the nucleotide diversity index (π) was 0.11381 ± 0.00928, and the genotypic diversity index (Hd) was 0.985 ± 0.010, which brought about 29 genotypes. The genetic networks constructed by 115 ssrA sequences exhibited that Bartonella spp. from global bats had an incomplete geographical distribution and host specificity.
Conclusion: We found that the bat-borne Bartonella in Yunnan was genetically diverse, geographically widespread, and endemic and that bats play a part in transmitting Bartonella species locally. The analysis of phylogenetic networks based on the global dataset of ssrA sequences of bat-borne Bartonella points to an evolutionary association of Bartonella spp. with their bat hosts and the effect of geographical isolation.

Key words: Bartonella, bat, genetic diversity, phylogenetic analysis, reservoir