Molecular detection and genetic diversity of Babesia gibsoni in dogs in India.

Babesia gibsoni is a tick borne intraerythrocytic protozoan parasite causing piroplasmosis in dogs and has been predominantly reported in Asian countries, including Japan, Korea, Taiwan, Malaysia, Bangladesh and India. The present communication is the first evidence on the genetic diversity of B. gibsoni of dogs in India. Blood samples were collected from 164 dogs in north and northeast states of India and 13 dogs (7.9%) were found positive for B. gibsoni infection by microscopic examination of blood smears. Molecular confirmation of these microscopic positive cases for B. gibsoni was carried out by 18S rRNA nested-PCR, followed by sequencing. Nested-PCR for the 18S rRNA gene was also carried out on microscopically B. gibsoni negative samples that detected a higher percentage of dogs (28.6%) infected with B. gibsoni. Genetic diversity in B. gibsoni in India was determined by studying B. gibsoni thrombospondin-related adhesive protein (BgTRAP) gene fragments (855bp) in 19 isolates from four north and northeast states of India. Phylogenetic analysis of the BgTRAP gene revealed that B. gibsoni parasite in India and Bangladesh formed a distinct cluster away from other Asian B. gibsoni isolates available from Japan, Taiwan and Korea. In addition, tandem repeat analysis of the BgTRAP gene clearly showed considerable genetic variation among Indian isolates that was shared by B. gibsoni isolates of Bangladesh. These results suggested that B. gibsoni parasites in a different genetic clade are endemic in dogs in India and Bangladesh. Further studies are required for better understanding of the genetic diversity of B. gibsoni prevalent in India and in its neighbouring countries.