SEQUENCE HETEROGENEITY OF THE MAJOR ANTIGENIC PROTEIN-1 GENES FROM COWDRIA-RUMINANTIUM ISOLATES FROM DIFFERENT GEOGRAPHICAL AREAS

The genes for the immunodominant major antigenic protein 1 (MAP1) of C owdria ruminantium from four African and two Caribbean isolates were c loned, restriction mapped, and sequenced to identify conserved epitope s for development of serodiagnostic tools for heartwater. Restriction length polymorphisms were observed among the respective MAP1 genes ana lyzed and were confirmed by sequencing. The sequence data generated fo r these isolates were compared with data for the previously reported S enegal isolate MAP1 gene. These sequences were found to differ from ea ch other by 0.6 to 14.0%. These differences translate into a 0.8 to 10 .0% variation in the predicted protein sequence. In the entire coding sequence, several amino acid substitutions were identified in addition to deletions or insertions at three regions of the gene. These variab le regions are referred to as variable regions I, II, and III. From th e sequence data, an evolutionary distance tree was constructed; this t ree suggested that at least two genetically distinct C. ruminantium st rains exist in the Caribbean: the isolate from Antigua is similar to t hat from Senegal, while the isolate from Guadeloupe is closely related to that from Sudan.