Molecular mechanisms of diversity of theileria parasite genes and control of the disease

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Theileria sergenti is a tick-borne protozoa of cattle. Benign bovine theileria parasites, which are presumed to be of the T.sergenti/buffeli/orientalis group are distributed in Asian countries. The parasites have the major piroplasm surface protein (MPSP) gene which is one of the means of parasite evasion of host immunity. T.sergenti has 4 chromosomes similar to T.parva.Most of genes used for molecular karyotype showed a conserved synteny between T.sergenti and T.parva.To underatand the genome mapping of theileria parasites, characterization of bovine genes expressed in T.parva transformed T-lymphoblastoid cell lines was performed by using expressed sequence tag (EST) sequencing approach of random cDNA clones from libraries. Single pass sequencing was done on 394 cDNA clones and the sequences search for significant homolgies in GeneBank, EBML and DDBJ databases. About 141 clones showed significant homology to genes in the databases. The majority of these ESTs (47) showed homology to human sequences and only a few (19) matched bovine sequence. 126 clones did not match database sequences and may represent novel transcripts.The EST sequencing approach has recently contributed tremendously to discover of new genes in several parasites. Thus, we performed the sequencing of 461 cDNA clones from the schizont stage of T.parva. The cDNA colnes were mapped to the 4-T.parva chromosomes and 20 of these clones were mapped to the 33 Sfil fragments of the T.parva genome. EST sequencing demonstrated its potential in the identification of new genes in this stage of the parasite and has contributed greatly to the addition of ESTs into the T.parva database. The sequence data reported is invaluable for T.parva genome mapping and in the comparative genome mapping of theileria parasites.