Abstract:

[Objective] This study was conducted to characterize the prevalence and the subgenotype distribution of Cryptosporidium in diarrheal lambs from a large-scale sheep farm in southern Xinjiang. [Method] A total of 60 fresh fecal samples were collected from the diarrheal lambs of four breeds less than 1 month old in a large-scale sheep farm in Xinjiang Uygur Autonomous Region, China. The species identification of Cryptosporidium oocysts was carried out by saturated sucrose flotation technique combined with microscopic examination. After the fecal genomic DNA was extracted, PCR amplifications and sequencing analyses targeting on SSU rRNA gene and gp60 gene were performed to confirm the species of Cryptosporidium and the subgenotypes of C. parvum, respectively. Furthermore, the phylogenetic tree based on the gp60 gene was constructed to reveal the molecular genetic characteristics of Cryptosporidium. [Result] Thirty-eight fecal samples were found to be positive for the presence of Cryptosporidium oocysts which were preliminarily identified as C. parvum by morphology observation. Based on the SSU rRNA gene sequence comparison, a total of 52 fecal samples were positive for C. parvum, with the infection rate of 86.67% （52/60）. Among them, 49 sequences of gp60 gene were obtained by PCR amplification, and the phylogenetic tree demonstrated that they all belonged to the subgenotype of ⅡdA19G1. [Conclusion] A high prevalence of C. parvum with the subgenotype of ⅡdA19G1 was observed in the diarrheal lambs in this farm. The results obtained in this study provides basic data for the species identification and genetic evolution analysis of Cryptosporidium in the sheep flocks in southern Xinjiang.

Key words: Cryptosporidium, infection, identification, subg-enotype, lamb