Identification of Tick-Borne Pathogens and Genotyping of Coxiella burnetii in Rhipicephalus microplus in Yunnan Province, China

Abstract

<i>Rhipicephalus microplus</i>, a vector that can transmit many pathogens to humans and domestic animals, is widely distributed in Yunnan province, China. However, few reports on the prevalence of tick-borne pathogens (TBPs) in <i>Rh. microplus</i> in Yunnan are available. The aim of this study was to detect TBPs in <i>Rh. microplus</i> in Yunnan and to analyze the phylogenetic characterization of TBPs detected in these ticks. The adult <i>Rh. microplus</i> (<i>n</i> = 516) feeding on cattle were collected. The pooled DNA samples of these ticks were evaluated using metagenomic next-generation sequencing (mNGS) and then TBPs in individual ticks were identified using genus- or group-specific nested polymerase chain reaction (PCR) combined with DNA sequencing assay. As a result, <i>Candidatus Rickettsia jingxinensis</i> (24.61%, 127/516), <i>Anaplasma marginale</i> (13.18%, 68/516), <i>Coxiella burnetii</i> (3.10%, 16/516), and <i>Coxiella-</i>like endosymbiont (CLE) (8.33%, 43/516) were detected. The dual coinfection with <i>Ca. R. jingxinensis</i> and <i>A. marginale</i> and the triple coinfection with <i>Ca. R. jingxinensis</i>, <i>A. marginale</i>, and CLE were most frequent and detected in 3.68% (19/516) and 3.10% (16/516) of these ticks, respectively. The results provide insight into the diversity of TBPs and their coinfections in <i>Rh. microplus</i> in Yunnan province of China, reporting for the first time that <i>C. burnetii</i> had been found in <i>Rh. microplus</i> in China. Multilocus variable number tandem repeat analysis with 6 loci (MLVA-6) discriminated the <i>C. burnetii</i> detected in <i>Rh. microplus</i> in Yunnan into MLVA genotype 1, which is closely related to previously described genotypes found primarily in tick and human samples from different regions of the globe, indicating a potential public health threat posed by <i>C. burnetii</i> in <i>Rh. microplus</i> in Yunnan.