Genetic Features Of Enteric Protozoans And Population Genetics Study Of Enterocytozoon Bieneusi In Pigs From Northeast China

Enterocytozoon bi eneusi and Crypt osporidium spp. are impor tant zoonotic protozoans with broad host and geographic ranges. The transmiss ion pathways and the natural r eser voirs of the paras ites remain unc ertain. Few data about population genetics of E. bieneusi limit us to assess potential reproductive patterns and track infection sources.This study an alyzed 563 fecal spec imens of asymptomatic pigs from f ive cities of northeast China for the pr evalence and genetic char acter istics of Cryptosporidium spp. and E. bieneusi. E. bieneusi and Cryptosporidi um spp. were detected in 267(47.4%) and 170(30. 2%) of 563 pigs by nested PCR of the ribosomal internal transcr ibed spacer(ITS) and SS U r RNA, respectively. Genotypic typing and phylogenetic analys is fac ilitated identif ic ation of s ix human-pathogenic E. bieneusi genotypes Ebp C, O, CS-4, Ebp A, Henan-I V, and P ig EBITS5 and s ix potentially zoonotic genotypes Ebp B, CC-1, CS-1, CS-3, CHN7, and CS-10. Genotypes CS-4 and Ebp C from Har bin and Henan-I V from Qiqihar determined in pigs herein repr esented the main caus ative agents of human microspor idios is in Harbin. The most dominant genotype Ebp C found in pigs from Daqing and Qiqihar contr ibuted s ignif icantly to human infections in Daqing. Bes ides, genotypes Ebp A, Ebp B, Ebp C, and O als o existed in wastewater and source water in centr al China. Thr ee Cryptospori dium spec ies were determined in this study. Among them, Cryptospori dium parvum was the most common zoonotic pathogen found in human cryptospor idios is. An age-related distr ibution of Cryptosporidium suis and Cryptosporidium scrofarum was seen in the study animals. C. suis inf ections commonly occurred in pre-weaned piglets and C. scrofarum in pigs older than two months. This study provided robust evidence that pigs could be an outstanding source of human micr ospor idios is and water contamination in China. Bes ides, some attention should be paid to the potential role of pigs in zoontic transmission of human cryptosporidios is.To get a better understanding of the tr ansmiss ion and repr oductive patterns of E. bieneusi, a combination of the ITS and four microsatellite and minis atellite markers(MS1, MS3, MS 4, and MS7) was us ed to inf er the population structur e of 101 E. bieneusi is olates from pigs in four cities of northeast China. Strong intr agenic linkage disequilibr ia( LD) and limited genetic r ecombination revealed an over all c lonal population structur e of E. bieneusi in pigs. For compar ative purposes, 106 isolates from humans and baboons were inc luded in the substructur e analys is of E. bieneusi population. F ive subpopulations were determined in phylogenetic, PCo A, ST RUCT URE, and Network analys is. We did not find any evidence for geographic segregation among the isolates. Population genetic analys is indicated all the f ive subpopulations(SP1 and SP2 from pr imates and SP3 to SP5 from pigs) were in strong LD with limited recombination. SP1 and SP5 with clonal structure(cons ist of the isolates belonging mainly to ITS genotypes D, I V, EbpC, etc. with wide host ranges) had weaker LD and some mor e Rms than the other thr ee subpopulations w ith epidemic structure or host-adapted featur es(cons ist of the isolates chief ly belonging to ITS genotypes A, Ebp A, Ebp B, etc.with narrow host ranges). Network analys is showed genetic correlation of SP1 and SP 5 and the two subpopulations had minor pairw ise genetic dis tanc e(FS T = 0.185) and s ignif icant gene f low. SP 1 and S P5 wer e genetically differ entiated fr om SP 2 to SP4. Directional evolutionar y trend from SP1 to SP2 and SP5 to SP3/SP 4 observed from genetic Network indicated the occurrence of host adaptation in E. bieneusi populations. Compar ative genetic analys is among SP 1 to SP5 s uggested a certain extent of genetic r ecombination might occur when E. bieneusi expanded its hosts, whereas it could sw itch to obligate as exuality and display an epidemic structur e that had implications f or reduction of host r ange dur ing long-term adaptation. In summary, this study eluc idated an overall clonal evolution pattern for E. bieneusi, but this paras ite could adjust patter ns of reproduction to cope with host var iations and envir onmental challenges. The r esults highlight th e high resolution power of MLST in investigating the infectivity, population structur es and substructur es, population genetic tr aits, and reproductive patterns of E. bieneusi. Thes e data can provide new ins ights into the control and prevention of human microsporidiosis.