Identification of tick-borne pathogens by metagenomic next-generation sequencing in Dermacentor nuttalli and Ixodes persulcatus in Inner Mongolia, China

Abstract

Background Hard ticks act as arthropod vectors in the transmission of human and animal pathogens and are widely distributed in northern China. The aim of this study is to screen the important tick-borne pathogens (TBPs) carried by hard ticks in Inner Mongolia using metagenomic next-generation sequencing (mNGS) and to estimate the risk of human infection imposed by tick bites. Methods The adult Dermacentor nuttalli (n = 203) and Ixodes persulcatus (n = 36) ticks feeding on cattle were collected. The pooled DNA samples prepared from these ticks were sequenced as the templates for mNGS to survey the presence of TBPs at the genus level. Individual tick DNA samples were detected by genus--specific or group-specific nested polymerase chain reaction (PCR) of these TBPs and combined with DNA sequencing assay to confirm the results of mNGS. Results R. raoultii (45.32%, 92/203), Candidatus R. tarasevichiae (5.42%, 11/203), Anaplasma sp. Mongolia (26.60%, 54/203), Coxiella-like endosymbiont (CLE) (53.69%, 109/203), and Babesia venatorum (7.88%, 16/203) were detected in D. nuttalli, while R. raoultii (30.56%, 11/36), Anaplasma sp. Mongolia (27.80%, 10/36), and CLE (27.80%, 10/36) were detected in I. persulcatus. The double- and triple-pathogen/endosymbiont co-infections were detected in 40.39% of D. nuttalli and 13.89% of I. persulcatus, respectively. The dual co-infection with R. raoultii and CLE (14.29%, 29/203) and triple co-infection with R. raoultii, Anaplasma sp. Mongolia, and CLE (13.79%, 28/203) were most frequent in D. nuttalli. Conclusions This study provides insight into the microbial diversity of D. nuttalli and I. persulcatus in Inner Mongolia, China, reporting for the first time that Candidatus R. tarasevichiae had been found in D. nuttalli in China, and for the first time in the world that Anaplasma sp. Mongolia has been detected in I. persulcatus. This study proves that various vertically transmitted pathogens co-inhabit D. nuttalli and I. persulcatus, and indicates that cattle in Inner Mongolia are exposed to several TBPs. Graphic Abstract

The Symbiotic Continuum Within Ticks: Opportunities for Disease Control

“…It usually engaged in mutualistic interactions with tick hosts ( Brenner et al, 2021 ; Nardi et al, 2021 ). Several tick genera have been found to harbor CLE, including Amblyomma ( Clay et al, 2008 ), Dermacentor ( Jiao et al, 2021 ), Haemaphysalis ( Lee et al, 2004 ), Rhipicephalus ( Špitalská et al, 2018 ), Ixodes ( Kurtti et al, 2002 ; Schabereiter-Gurtner et al, 2003 ; Špitalská et al, 2018 ), Ornithodoros ( Duron, 2015 ), and Carios ( Reeves et al, 2005 ). Douglas (2007) proposed that the benefits derived from the symbiotic relationship with CLE is limited in ticks, but it is considered that they play an important role in the synthesis of several nutrients that are required by their tick hosts ( Moran et al, 2003 ; Douglas, 2007 ).…”

Co-existence of Multiple Anaplasma Species and Variants in Ticks Feeding on Hedgehogs or Cattle Poses Potential Threats of Anaplasmosis to Humans and Livestock in Eastern China

“…With increasing awareness about TBPs, the co-infections/coexistence of multiple pathogens in ticks or their hosts have greatly attracted scholars' attention (Cutler et al, 2021;Fang et al, 2021;Jiao et al, 2021;Soong and Dong, 2021). Anaplasma spp.…”

“…Several studies have investigated the prevalence of Anaplasma spp. in animal and tick hosts in the Northeastern, Northwestern, Southern, and Central China (Jiang et al, 2011;Liu et al, 2012;Zhang et al, 2012;Li et al, 2015;Yang et al, 2015;Wei et al, 2016;Fang et al, 2021;Jiao et al, 2021;Yan et al, 2021), while few studies have been carried out in Eastern China (Lu et al, 2019;Yang et al, 2020). The Anaplasma species, their distribution, and prevalence in Eastern China have remained elusive.…”

“…For screening Anaplasma-positive samples, a set of nested PCR primers (Table 1) targeting a short sequence of the 16S ribosomal RNA (rrs) gene with a length of about 280 bp was used, as previously described (Wen et al, 2003;Jiao et al, 2021). The amplified products were analyzed with 1.5% agarose gel electrophoresis and detected with GelStain Dye (Transgene, Beijing, China) under ultraviolet (UV) light.…”

Advances in the Study of the Tick Cattle Microbiota and the Influence on Vectorial Capacity

“…In contrast, the sequencing of internal tissue and salivary glands from unfed larvae and female ticks of I. ricinus revealed commensal bacteria, endosymbionts, and several pathogenic microorganisms (54,55). Also, metagenomic analysis of Ixodes persulcatus and Dermacentor nuttalli revealed 10 predominant genera of cattle pathogens and also coinfections (56).…”