Design, expression, and evaluation of novel multiepitope chimeric antigen of Wuchereria bancrofti for the diagnosis of lymphatic filariasis - A structure-based strategy.

The Global Program for Elimination Lymphatic Filariasis (GPELF) is in an advanced stage and requires tools for diagnosing infection, assessing transmission and certification. This study was aimed at developing an antibody-based assay using a chiemric antigen containing multi-B-cell epitopes from antigens highly expressed in different stages of Wuchereria bancrofti to detect LF infection and its transmission. The antigen was express cloned and two indirect ELISA based (IgG1 & IgG4 based) antibody assays were developed using the recombinant antigen. The chimeric antigen displayed 1 and 3-fold reactivity with IgG1 and IgG4 antibodies, respectively in microfilaraial (mf) positive sera when compared to that in sera samples of Non-endemic normal sera (NEN) (O.D, 0.13 ± 0.20 and 0.18 ± 0.07), thus differentiating infected from uninfected individuals. In IgG1 and IgG4 antibody assays, the multiepitope antigen also showed reactivity (O.D, 0.27 ± 0.18 and 0.16 ± 0.03) in a small proportion (18 and 30, respectively out of 156) endemic normal individuals and in IgG1 antibody in a few (4) chronic patients (CP). The antigen did not react with IgG1 or IgG4 antibodies in the sera samples of malaria, scrub typhus, dengue, hookworm, and roundworm helminth cases (0.139 ± 0.018, 0.144 ± 0.007 0.17804 ± 0.007 and 0.162 ± 0.006), thus showing its high specificity. The sensitivity (%) and specificity (%) of the multi-epitope antigen-based IgG1 and IgG4 antibody assays are 100, 98.1 and 100, 99.52, respectively. Thus, the recombinant multiepitope antigen appears to have good potential in detecting active LF infection and in assessing its transmission in endemic communities.