Use of a recombinant Burkholderia intracellular motility a protein for immunodiagnosis of glanders

Glanders, caused by the Gram-negative, nonmotile bacterium Burkholderia mallei, is a contagious and highly fatal disease of equines. During the last decade, the number of glanders outbreaks has increased steadily. The disease also has high zoonotic significance and B. mallei is listed biological warfare agent. The complement fixation test (CFT) is a routinely used and internationally recognized test to screen equine sera for the glanders. However, discrepant results have been observed using the CFT. The low sensitivity and specificity of the CFT and enzyme-linked immunosorbent assay (ELISA) have been linked to the use of crude test antigens. We expressed a novel recombinant Burkholderia intracellular motility A (rBimA) protein in Escherichia coli for the diagnosis of equine glanders. Purified rBimA was used in an indirect ELISA format. All of the 21 true-positive serum samples used in the study tested positive, whereas only 17 of the 1,524 potentially negative sera tested positive by indirect ELISA, thus exhibiting 100% sensitivity and 98.88% specificity. Also, rBimA protein did not react with melioidosis patient and normal healthy human serum samples, showing its high specificity. The developed assay can be used as a simple and rapid tool for diagnosis of glanders in equine serum samples. An Indian patent (1328/DEL/2010) has been filed for the reagent.