Molecular evidence of Theileria equi infection in Hyalomma anatolicum ticks infested on sero-positive Indian horses

Abstract

A sizeable Indian equine population is considered to be pre-immune carrier of Theileria equi infection. In this study we confirmed the presence of T. equi specific DNA in Hyalomma anatolicum ticks which were infested on sero-positive horses. Fifty two Indigenous horses were randomly selected from endemic areas and their blood and tick samples were collected. Tick salivary glands and blood samples were processed for separation of DNA and serum, respectively. Serum samples were analyzed by EMA-2ELISA and nine horses were found positive for T. equi specific antibodies. Species-specific primers were designed from EMA-2 gene of T. equi, so as to amplify 398 bp fragment in PCR. The gene fragment was amplified in PCR on the DNA samples (from blood) from these nine sero-positive horses. Corresponding six tick’s DNA samples collected from these nine seropositive animals were observed positive in PCR. Further, qPCR assay demonstrated presence of T. equi DNA in infected tick’s salivary glands, which was also confirmed by microscopic examination of infected acinar. This study concluded that Hyalomma anatolicum ticks infested on T. equi seropositive horses have sporozoite developmental stage in their salivary glands, which is an evidence for transmitting potential of these tick among Indian horse population.