HIGH-LEVEL EXPRESSION OF THE B-MICROPLUS BM86 ANTIGEN IN THE YEAST PICHIA-PASTORIS FORMING HIGHLY IMMUNOGENIC PARTICLES FOR CATTLE

Recently, a gene coding for the Bm86 tick gut glycoprotein was cloned, expressed in Escherichia coli and shown to induce an immunological re sponse in cattle to damage ticks engorging on these animals (Rand et a l., 1989). We report here the increased expression of the Bm86 antigen from the cattle tick Boophilus microplus in the methylotrophic yeast Pichia pastoris. The recombinant protein was obtained with a purity hi gher than 95% by a procedure with a high yield. The conducted biochemi cal studies demonstrated the antigen to be glycosylated and found to f orm particles of around 17 to 45 nm in diameter with enhanced immunoge nic properties. Ticks engorging on vaccinated cattle were significantl y damaged as a result of the immune response against the recombinant a ntigen. This system permits the obtainment in a high yield of the tick Bm86 antigen, in a glycosylated and particulated form.