Abstract

The apical membrane antigen-1 (AMA-1) is a leading malaria vaccine candidate that is expressed in mature stage parasites and is thought to be essential for invasion. In Plasmodium falciparum, AMA-1 is localized initially to the micronemes, apical organelles of the parasite. A similar apicomplexan parasite, Theileria parva infects and transforms lymphocytes of cattle and African buffalo causing the disease called East Coast fever (ECF). The AMA-1 homolog in T. parva was isolated, cloned and sequenced.  The predicted amino acid sequence was further analyzed. The partial gene sequence, which is 1422 bp long and encoding 473 amino acid residues, is located on chromosome 1 of the T. parva genome. The AMA-1 homolog in T. parva shares conserved sequences with apicomplexan homologs. It is 64% similar to the AMA-1 in Babesia bigemina, and 56% similar to the homolog in P. falciparum. Given the importance of AMA-1 in invasion and the central role invasion plays in pathogenesis, the T. parva AMA-1 may likely have implications for vaccine design in East Coast fever disease.

Key words: Theileria parva, East Coast fever, apical membrane antigen-1, apicomplexan parasite.