Babesia caballi is a tick-borne haemoprotozoan parasite, and is one of the causes of equine piroplasmosis. Although less severe than Theileria equi infections, animals that recover often remain carriers for long periods of time. Stringent import restrictions are therefore in place to prevent introductions into non-endemic areas. Serological assays are currently the prescribed methods for certifying animals free of these parasites. However, the inability of a commercial cELISA assay (Bc48 gene) to detect South African B. caballi isolates, led to the conclusion that an alternative, conserved protein be identified for use as a target antigen in the development of diagnostic assays. A South African culture of B. caballi was thus sequenced using the Illumina® HiSeq2000. Six million paired reads (250bpx250bp) were obtained and quality trimmed. Assembly using CLC Genomics Workbench resulted in ~6000 contigs (N50 = 64423), that incorporated 31% of the reads. An average coverage of 49 was observed for contigs >7000 bp (203 contigs). These accounted for 82% of all mapped reads with BLASTN hits to the Babesia bigemina genome. The cumulative contigs size (~9.1 Mbp), corresponds to the genome sizes of other Babesia parasites (8.1-13.8Mb), and is estimated to cover ~66% of the total genome based on that of B. bigemina. Reciprocal BLASTP analysis of the translated ORFs retrieved ~75% orthologs from the genome of B. bigemina. The draft genome is considered to be of high quality and represents major features of the genome, which may be used in a targeted approach to identify alternative immuno-dominant antigens.
