Molecular Detection and Identification of Candidatus Ehrlichia Hainanensis, A Novel Ehrlichia Species in Rodents from Hainan Province, China.

Ehrlichia (Anaplasmataceae family) are obligatory intracellular bacteria that infect humans and animals. They are hosted by mammals such as canines, bovines and wild rodents, and are vectored by ticks. In this study, we collected 121 rodent samples comprising 67 Niviventer fulvescens, 27 Rattus tanezumi, 24 Chiromyscus sp., 2 Rattus nitidus and 1 Leopoldamys edwardsi from Hainan province, which includes the second largest island in China. The presence and genetic diversity of Ehrlichia species was evaluated and characterized by amplification and sequencing of 16S rRNA, groEL and gltA genes. An Ehrlichia species was detected in 5 of the 67 Niviventer fulvescens samples (7.46%). The 16S rRNA, groEL and gltA genes showed the highest identity to known Ehrlichia sequences (99.20%, 89.87% and 83.86%, respectively). In the phylogenetic trees they formed a cluster distinct from all other species. We propose that this species is a putative novel Ehrlichia species, which we suggest be named Candidatus Ehrlichia hainanensis. Its pathogenicity to humans remains to be further researched, and molecular surveillance in local populations is needed.