Detection and genetic diversity of Neoehrlichia mikurensis in rodents from central and southern Shanxi, China.

Neoehrlichia mikurensis is vector-borne gram-negative intracellular bacteria that has a wide range of hosts, and are recognized as emerging human pathogens. This study aimed to investigate the prevalence and genetic characteristics of N. mikurensis infections in rodents from central and southern of Shanxi Province, China. The rodents were captured, and the liver, spleen and kidney were collected for N. mikurensis detection and identification by 16 S rRNA and groEL genes sequencing. N. mikurensis was detected in Apodemus agrarius from Yangquan and Eothenomys inez from Yuncheng, with a positivity rate of 0.66% (2/301). Phylogenetic analysis based on 16 S rRNA and groEL genes revealed that the sequences in this study formed distinct branches separate from reported clusters (Clusters I-IV), clustered near Clusters III and IV, which the pathogenicity was unclear. Analysis of groEL gene polymorphism identified 12 haplotypes (Hap-1 to Hap-12) among 64 sequences (one novel sequence from this study and 63 from GenBank), with high haplotype diversity (Hd = 0.770 ± 0.030). Dominant haplotypes (Hap-2, Hap-3, Hap-4; 82.8% of sequences) exhibited distinct geographic specific patterns. In addition, Asian sequences exhibited greater diversity than European sequences, and human-derived sequences showed the higher genetic diversity than rodent- and tick-derived sequences. Overall, the detection of N. mikurensis in rodents in Shanxi Province expands its known distribution and provides novel insights into the genetic diversity in different regions and hosts.