Molecular survey and characterization of tick-borne pathogens in sheep from Qinghai, China

摘要

Information regarding the prevalence and genetic characterization of Anaplasma spp., Babesia spp. and Theileria spp. infecting sheep in Qinghai province, northwestern China, is limited. In this study, 277 sheep blood samples were collected from 7 counties in Qinghai and tested by PCR to detect and identify the above mentioned tick-borne pathogens. Among the 277 sheep, 176 (63.5%) were infected with at least one pathogen. A. ovis was the most prevalent pathogen (n = 112, 40.4%), followed by T. luwenshuni (n = 108, 39.0%), T. uilenbergi (n = 65, 23.5%) and B. motasi sp. L/N/T (n = 11, 4.0%). Interestingly and importantly, 83 (30.0%) infections with two or more pathogens were identified. The analysis of the nucleotide sequences of targeted genes showed that A. ovis msp4, B. motasi sp. L/N/T rap-1b, T. luwenshuni 18S rRNA and T. uilenbergi 18S rRNA sequences from Qinghai were not conserved. These sequences shared 97.7-99.7%, 87.0-99.8%, 98.2-100% and 91.3-100% identities with previously published isolates, respectively. The phylogenetic analysis revealed that all A. ovis msp4 sequences belonged to the same Glade. On the other hand, B. motasi sp. L/N/T rap-1b isolates showed a closer relationship with B. motasi sp. BQ1/Lintan. One T. luwenshuni and one T. uilenbergi sequence from this study formed branches divergent from the remaining T. luwenshuni and T. uilenbergi isolates. Overall, these results provide a better understanding of the prevalence and molecular characterization of TBPs in sheep in Qinghai and suggest that these pathogens require more attention from veterinarians.