Phylogeny and Genetic/Morphological Variation of Strombidinopsis minima-like Species (Ciliophora: Choreotrichia).

Enterocytozoon bieneusi is an important opportunistic pathogen widely distributed in humans and animals that causes diarrhea or fatal diarrhea in immunocompromised hosts. To examine the infection status and molecular characteristics of E. bieneusi in pigs, 725 fecal samples were collected from pigs in six areas of Fujian Province. The E. bieneusi genotypes were identified based on the internal transcribed spacer (ITS) regions of the ribosomal RNA (rRNA) gene by nested PCR, and its population genetics were analyzed by multilocus sequence typing (MLST). The results showed that the infection rate of E. bieneusi was 24.4% (177/725), and 11 known genotypes (EbpC, EbpA, CHN-RR2, KIN-1, CHG7, CHS5, CM11, CHG23, G, PigEBITS, and D) and 2 novel genotypes (FJF and FJS) were identified. All the genotypes were found to be clustered into zoonotic Group 1. Moreover, 52 positive samples were successfully amplified at minisatellite and microsatellite loci and formed 48 distinct multilocus genotypes (MLGs). Further population structure analyses showed strong genetic linkage disequilibrium (LD) and several recombination events (Rm), indicating that E. bieneusi has a clonal population structure. This study is the first to investigate the prevalence and molecular characteristics of E. bieneusi in Fujian Province and could provide baseline data to control E. bieneusi infection in pigs and humans and deepen our understanding of the zoonotic risk of E. bieneusi and its distribution in China.