LAUSR

The present study describes genetic diversity in the Tams1 gene (733 bp) of Theileria annulata along with the sequence, phylogenetic and haplotype analyses of Indian isolates. The phylogenetic analyses displayed distinct clustering of Indian isolates into three groups suggesting the presence of three genotypes, hitherto designated as T. annulata genotypes 1-3 (G1-G3). Genotype 3 seems to be novel containing only two newly generated sequences. Indian isolates displayed 88.4-100% and 82.2-100% similarity with each other at nucleotide (nt) and amino acid (aa) levels, respectively. However, the newly generated sequences (n=36) showed 90.5-100% and 84.3-100% identity between them at nt and aa levels, respectively. The most diverse and heterogeneous genotype, G1, exhibited the highest number of polymorphic sites (S=148), haplotypes (h=16) and nucleotide differences (k=43.23) besides haplotype (Hd=0.903 ± 0.031) and nucleotide (π=0.059 ± 0.005) diversities. Neutrality indices suggested a respective decrease and increase in population sizes of G1 and G2 genotypes in India. The nucleotide sequence analyses indicated the presence of extensive sequence variations between nucleotide positions 1-124, 194-257 and 396-494. The N-terminus of Tams1 protein displayed considerable sequence variability with extensive variations in two regions between amino acid positions 1-39 and 127-172 as compared to the conserved carboxyl terminus. A total of 31 signature amino acid residues were identified between genotypes in Tams1 protein. Our results suggest Tams1 gene to be a suitable molecular marker for genotyping of T. annulata based on the differences in nucleotide and amino acid residues between genotypes.