High genotype diversity and zoonotic potential of Enterocytozoon bieneusi in laboratory mice from two medical experimental animal centers.

Enterocytozoon bieneusi is a common zoonotic pathogen in wild, farmed and pet rodents worldwide. Recently, one study reported E. bieneusi infection in laboratory mice. To investigate the positive rate and genotype distribution of E. bieneusi in laboratory mice and assess the zoonotic potential of E. bieneusi isolates, 390 mixed mouse fecal specimens were collected from two medical experimental animal centers in Heilongjiang Province, China. E. bieneusi was identified and genotyped by nested PCR amplification and sequence analysis of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene. Seventy-one specimens (18.2%) were positive for E. bieneusi, and 38 genotypes were identified, including eight known genotypes (EbpC, D, Peru8, CS-4, Henan-III, CHC5, ETMK4 and SHWR14) and 30 novel genotypes (HLJLM1 to HLJLM30). Genotypes CHC5 and ETMK4 were firstly detected in rodents. Genotype EbpC showed a dominance (50.7%, 36/71) in positive specimens. Zoonotic genotypes (EbpC, D, Peru8, Henan-III and CS-4) accounted for 64.8% (46/71) of E. bieneusi-positive specimens. In phylogenetic analysis, the novel genotypes fell into three subgroups (1a, 1d, 1e) of Group 1. The identification of known zoonotic genotypes and the phylogenetic result of novel genotypes indicate the potential of laboratory mice in the transmission of E. bieneusi to humans. The routine detection of E. bieneusi should be a recommended practice in laboratory animals to ensure the accuracy of the experimental results. Meanwhile, health education of the potential zoonotic transmission of E. bieneusi should be provided to those people having close contact with laboratory mice and their feces.