Identification of Burcholderia pseudomallei peotein as antigen for diagnosis of melioidosis

Abstract

The gold standard method for laboratory diagnosis of melioidosis is bacteriological culture. However, this method is time-consuming. Currently, a serological method with high sensitivity and specificity for diagnosis of melioidosis has not been available. Specific antigens for serological diagnosis are highly needed. The aim of this study was to identify immunodominant proteins from B. pseudomallei as antigen for laboratory diagnosis of melioidosis. In this study, a partial Sau3A library of B. pseudomallei genomic DNA was constructed in pUC18 vector. The E. coli clones expressing immunogenic protein of B. pseudomallei were selected by a colony blot assay using pre-absorbed pooled melioidosis sera as the probe. One clone, PHE191, expressing a 40 kDa recombinant protein with high homology to zinc-binding dehydrogenase family protein was chosen for further study. The recombinant protein was purified and evaluated by Western blot analysis for its diagnostic utility using a total of 107 serum samples from culture-proven melioidosis patients, patients with other related diseases and healthy individuals from endemic and non-endemic areas. The results showed that this protein had sensitivity and specificity of 78.9 % and 72.5 %, respectively, whereas indirect hemagglutination assay (IHA) gave sensitivity and specificity of 86.8 % and 66.7 %, respectively. This protein had higher specificity but low sensitivity than IHA. With a higher specificity, this protein is warranted for further study to determine whether its native conformation would provide better diagnostic potential for laboratory diagnosis of melioidosis.