Evaluation of recombinant hemolysin co-regulated protein 1 (hcp1) for rapid diagnosis of melioidosis (Whitmore’s disease) using ELISA assay

Abstract

Melioidosis (also called Whitmore’s disease) is a fatal infectious disease caused by a Gram-negative soil-dwelling bacterium Burkholderia pseudomallei. Due to the diverse clinical manifestations, final diagnosis of the disease mostly relies on the examination of bacterial culture. However, the sensitivity of the culture method depends on various factors, leading to the misdiagnosis of the disease in the clinical setting. In this study, the authors amplified BPSS1498 gene coding hemolysin co-regulated protein 1 (hcp1), cloned and expressed the recombinant protein using E. coli BL21(DE3) pLysS. The recombinant hcp1 protein antigen with 18.7 kDa was then purified and demonstrated a highly specific binding with human IgG of the culture-confirmed patient with melioidosis using Western blot. Hcp1-ELISA was established and evaluated on 94 sera collected from 32 culture-confirmed patients with melioidosis, 32 patients infected with other bacteria, and 30 healthy persons. Using a cut-off value of 0.595, hcp1-ELISA showed a sensitivity of 93.7% and a specificity of 98.4%. Those results lead to a potential application of hcp1-ELISA in the diagnosis of melioidosis in Vietnam, especially on the diagnosis of the disease in patients with fever of unknown origin due to the limitation of the routine culture methods.