Molecular identification and genotyping of Enterocytozoon bieneusi in experimental rats in China

Experimental rats are important animal models, and a history of pathogenic infections in these animals will directly affect the animal trial results. Enterocytozoon bieneusi is a ubiquitous potential pathogen transmitted via the fecal-oral route. To determine the prevalence and genotypic distributions of E. bieneusi in experimental rats in China, 291 fresh fecal samples were collected from four medical experimental animal centers. Enterocytozoon bieneusi was screened via nested-PCR amplification of the internal transcribed spacer (ITS) region. Of the rats tested, 4.8% (14/291) were positive for E. bieneusi. Five E. bieneusi ITS genotypes (four known: EbpA, EbpC, CHY1, and N; one novel: SHR1) were detected among 14 sequenced samples. The dominant E. bieneusi genotype was EbpA (50.0%, 7/14). In the phylogenetic analysis, genotypes EbpA and EbpC belonged to the previously described group 1, genotypes N and SHR1 belonged to group 2, and genotype CHY1 belonged to the novel group 12. To our knowledge, this is the first report of E. bieneusi in experimental laboratory rats in China. Infections with this pathogen must be monitored in laboratory animals, and quality control officers in the medical experimental centers should attempt to trace the pathogen's source and stop its transmission.