Efficacy of indirect ELISA for serodiagnosis of melioidosis using immunodominant antigens from non-pathogenic Burkholderia thailandensis

Enhanced serodiagnosis of melioidosis by indirect ELISA using the chimeric protein rGroEL-FLAG300 as an antigen

Background

The accurate and rapid diagnosis of melioidosis is challenging. Several serological approaches have been developed using recombinant antigens to improve the diagnostic indices of serological tests for melioidosis.

Methods

Fusion proteins from Burkholderia pseudomallei (rGroEL-FLAG300) were evaluated as a potential target antigen for melioidosis antibodies. A total of 220 serum samples from 38 culture proven melioidosis patients (gold standard), 126 healthy individuals from endemic (n = 37) and non-endemic (n = 89) Thai provinces and 56 patients with other proven bacterial infections as negative controls were tested using indirect enzyme-linked immunosorbent assays (ELISA).

Results

Using an optical density (OD) cut-off of 0.299148, our assay had 94.74% sensitivity (95% confidence interval (CI) = 82.3–99.4%), 95.05% specificity (95% CI = 90.8–97.7%), and 95% accuracy, which was better than in our previous work (90.48% sensitivity, 87.14% specificity, and 87.63% accuracy).

Conclusion

Our results suggest that the application of chimeric antigens in ELISA could improve the serological diagnosis of melioidosis and should be reconfirmed with greater patient numbers.

Comparison of Dot ELISA Using GroEL Recombinant Protein as an Antigen and an Indirect Hemagglutination Assay for Serodiagnosis of Melioidosis

Background:

Melioidosis is a disease caused by the Burkholderia pseudomallei bacterium. The mortality rate of infected patients is quite high because the symptoms are similar to those of various diseases, making it difficult to diagnose clinically and preventing the immediate treatment with effective antibiotics that is required for the management of acute infections. To provide appropriate treatment, accurate and rapid diagnosis is required.

Objective:

The aims of this study were to develop Dot ELISA using purified GroEL B. pseudomallei recombinant protein as an antigen and to compare the newly developed assay with an indirect hemagglutination assay (IHA) for the diagnosis of melioidosis.

Methods:

The GroEL recombinant protein was purified by immobilized metal affinity chromatography before being used as an antigen. The optimal conditions of the Dot ELISA were determined and used for subsequent experiments. A total of 291 serum samples were evaluated by the established Dot ELISA and IHA, using the bacterial culture method as the gold standard of melioidosis diagnosis.

Results:

The results from Dot ELISA and IHA revealed sensitivity, specificity, and accuracy of 85.7% (Dot ELISA)/64.3% (IHA), 94.4%/85.5%, and 93.1%/82.5%, respectively.

Conclusion:

These results indicate that the Dot ELISA developed is an efficient, simple, rapid and cost-effective technique for the early diagnosis of melioidosis and can be used in a local laboratory without specialized equipment.