Genetic diversity within Theileria orientalis parasites detected in Sri Lankan cattle

In the present study, we investigated the genetic diversity of Theileria orientalis parasites circulating among Sri Lankan cattle. Nucleotide sequence analysis of the major piroplasm surface protein (MPSP) gene fragments amplified from T. orientalis-positive DNA samples (from bovine blood) revealed the presence of 4 parasite genotypes. The genotypes consisted of types 1, 3, 5, and 7. Phylogenetic analysis indicated that the Sri Lankan MPSP sequences were closely related to those reported from Vietnam (types 3 and 5), Mongolia (types 1 and 5), Thailand (types 1, 5, and 7), and Japan (type 7). Subsequently, genotype-specific PCR assays determined that the most common genotype was type 7, followed by types 5, 3, and 1. Genotype 7 has been reported to be involved in disease outbreaks in India. Therefore, preventive and control measures are essential to avoid potential economic losses due to T. orientalis infection in Sri Lanka. This is the first report that describes the genetic diversity of T. orientalis circulating among Sri Lankan cattle.