Evaluation of Abundant Larval Transcript (ALT-2) peptide in Lymphatic Filariasis Diagnosis and Exposure

Abstract

Lymphatic Filariasis (LF) is a major public health problem and has been targeted for global elimination by 2020, through repeated annual mass administration of antifilarial drugs to the endemic communities. The programme now requires cheaper and high sensitivity tools for antibody monitoring. The aim of this study is to develop and validate an antibody detection method useful for this purpose. B-cell epitopes of Abundant Larval Transcript -2 (Wb-ALT-2) antigen of Wuchereria bancrofti was explored as tools for the detection and exposure to filarial infection and hence transmission. The epitopes were predicted on the basis of Amino Acid Pair/ Kernel method by using ABCpred, BCpred and Bepipred servers. One epitope from Wb-ALT-2 was selected and their diagnostic potential in clinical samples by indirect Enzyme Linked Immuno Sorbent Assay (ELISA) was evaluated. The peptide P1 of Wb-ALT-2 antigen showed high reactivity against microfilaraemic (MF) sera samples and a low reactivity against a few samples of endemic normal (EN) individuals, but not against chronic patients (CP) and non-endemic normal (NEN) individual sera samples, in indirect ELISA. Upon testing against large number of sera samples the peptide P1 based assay could detect all the MF as positives and all the NEN normals as negatives in both IgG1 and IgG4 format. The sensitivity (%) and specificity (%) of peptide P1 based IgG1 and IgG4 ELISAs were 100%, 96.77% and 100%, 100% respectively. The results indicate that peptide P1 of ALT-2 antigen have potential application in the diagnosis and pre- and post-MDA transmission assessment of LF.