Sarcocystis tenella is a common tissue coccidian parasite of sheep. It is reported worldwide with high prevalence rate ranging from 9 to 100%. However, there are very limited reports of this parasite from the Indian context and those reports are totally based on the morphology alone. When it comes to molecular characterization, such studies are absent from India. The present communication reports the first characterization study of S. tenella from India. 18S rRNA ribosomal gene and mitochondrial cytochrome c oxidase subunit I (cox1) genes were used for molecular characterization and phylogenetic analysis alongside standard histopathology of sarcocysts. Five Indian isolates were characterized for each gene, and respective sequences were submitted in the NCBI. Two haplotypes were noticed, both for the 18S rRNA and cox1 gene showing 99.8-100.0% and 99.7-100.0% nucleotide homologies within themselves, respectively. When compared with other sequences of S. tenella across the globe, the present isolates showed 93.3-99.9% nucleotide homology based on 18S rRNA gene and 95.2-99.8% nucleotide homology based on cox1 gene, respectively. In both the 18S and cox1 phylogenetic trees, respective sequences of S. tenella were placed with monophyletic cluster which was sister to a cluster comprising of sequences of S. gracilis and S. alces.
Keywords: 18S rRNA; Molecular characterization; Phylogenetic analysis; Sarcocystis tenella; cox1.