Molecular Study on Cryptosporidium andersoni Strains Isolated from Sheep Based on 18S rRNA Gene

Background: Cryptosporidiosis is one of the most important parasitic diseases infecting a broad variety of animals and humans. In the present study, Nested PCR-RFLP-based assay was applied for genotyping of sheep cryptosporidiosis. The target of amplification was the 18S rRNA gene used to identify Cryptosporidium species Materials and Methods: In the first step, 1300 faecal samples were collected from sheep in Tehran province, then the samples were examined for the presence of Cryptosporidium using modified acid fast staining. In the second step, DNA was extracted from the positive samples. Next, 18S rRNA gene was amplified by Nested-PCR in order to differentiate between the species. The PCR product was digested by Ssp1 restriction enzyme. Results: Twenty two positive sheep samples were detected by modified acid fast method. The results were confirmed by molecular techniques. The 845 bp fragment of 18S rRNA was digested by restriction enzymes. Twenty samples showed a similar band on 2.5% agarose gel whereas 2 samples demonstrated different pattern. The sequences of two patterns indicated two species of C. andersoni and C. parvum. Conclusion: In spite of other studies results introducing C. parvum as the major agent of cryptosporidiosis in sheep, in our study, C. andersoni was found to be dominant.