Molecular identification of Cryptosporidium ryanae isolate from dairy cows in Harbin / 中国人兽共患病学报

ABSTRACT

One Cryptopsoridium isolate from a 3 month-old calf in a dairy cow farm of Harbin was identified by molecular method, in which the common genes of 18S rRNA and actin used in Cryptosporidium genotyping were selected, the primers were designed, and the approximate 840 bp and 1066 bp fragments of these two genes were amplified respectively by nested PCR. The PCR products were sequenced by two directions, and then the sequences were analyzed by using the soft wares of ClustlX, DNAstar, and PHLIP. The experimental result showed that in the 18SrRNA gene, there was the highest identities compared to other reported isolates of cow-derived C. ryanae (DQ871345, AY587166, and EU410344), with 100% of similarity. Likewise, at actin locus, the present isolate also had 100% similarity with an American cow-derived C. ryanae isolate (EU410345) and a deer-like genotype isolate (AY741309). Phylogenetic analysis indicated that the present isolate shared the same evolution branch in the two gene loci. These analyses demonstrated that the present isolate belonged to C. ryanae. These results provide a significant reference for the study on the species distribution and assessment in the public health significance of Cryptosporidium in cow milk in China.