Nucleotide sequence heterogeneity in the small subunit ribosomal RNA gene within Theileria equi from horses in Sudan

This is a molecular epidemiological investigation on Theileria equi, a causative agent of equine piroplasmosis. Blood samples were collected from 127 horses from different geographical locations in Sudan. The small subunit of rRNA gene (18S; similar to 1,600 bp) was amplified from 20 positive field samples and subsequently subjected to direct sequencing and analysis to reveal possible strain differences and the presence of a novel species or genotypes. Sequences were compared with published sequences mainly from South African and Spanish isolates. Eleven distinct T. equi sequences within 18S rRNA gene were identified to have occurred, and three genotypes were lying within the three previously identified groups. Alignments demonstrated extensive sequence variation in the hypervariable region of the 18S rRNA gene and many SNPs within the Sudanese T. equi isolates.