Use of antifilarial IgG4‐ELISA to detect Brugia malayi infection in an endemic area of Malaysia

Abstract

SummaryOBJECTIVE To evaluate the usefulness of antifilarial IgG4 antibody assay in detecting B. malayi infection in a filaria endemic area in Malaysia. METHODS A sandwich ELISA using B. malayi soluble antigen was employed to detect antifilarial IgG4 antibodies in serum samples of 330 individuals who comprised 88 healthy individuals from nonendemic areas, 15 B. malayi microfilaraemic cases, 22 individuals with soil-transmitted helminthiases, 9 elephantiasis cases and 196 residents from a B. malayi-endemic area. An O.D. value of Ͼ 0.420 at serum dilution of 1:400 was used as the cut-off point. This cut-off point was obtained by taking the mean optical density (0.252 ϩ 4 S.E.) of 36 negative sera which had O.D. values greater than 0.1 at serum dilution of 1: 400. RESULTS All 15 microfilaraemic persons were positive for antifilarial IgG4 antibody. Non-endemic normals, soil-transmitted helminth infected persons and chronic elephantiasis cases were negative for antifilarial IgG4 antibody. Of the 196 individuals from the filaria endemic area, 37 (18.8%) demonstrated presence of antifilarial IgG4 antibodies; and only eight individuals (4.1%) were positive for microfilariae. All eight microfilaraemic individuals were also positive for antifilarial IgG4 antibodies. CONCLUSION Antifilarial IgG4-ELISA could detect 4.6 times more positive cases than the microfilaria detection method. With appropriate cut-off values that eliminate cross-reactivities, this serological tool is very useful for Brugia malayi prevalence surveys and diagnosis.keywords antifilarial IgG4-ELISA, Brugia malayi, Malaysia correspondence Dr Rahmah Noordin,

Development and Evaluation of a Rapid Flow‐Through Immuno Filtration Test Using Recombinant Filarial Antigen for Diagnosis of Brugian and Bancroftian Filariasis

“…Recent studies have reported the use of recombinant antigens for the detection of filarial specific IgG4 subclass antibody for the detection of brugian (17)(18)(19) and bancroftian (22) infections. IgG4 antibody levels are significantly elevated in individuals with microfilaremia and the levels decline after treatment (12,17,24). Antibody assay based on IgG4 subclass would be useful to identify active filarial infection (7,9,17).…”

“…IgG4 antibody levels are significantly elevated in individuals with microfilaremia and the levels decline after treatment (12,17,24). Antibody assay based on IgG4 subclass would be useful to identify active filarial infection (7,9,17). However, total IgG antibody-based assay with high specificity could be used for diagnosis of individuals with active infection as well as clinical cases in travellers and expatriates, primary surveillance in areas of unknown endemicity, detection of early infection in childhood (26) and to monitor chemotherapeutic program for the GPELF.…”

“…It has been observed that total IgG antibody assay is comparatively more sensitive than IgG4 antibody assay though the latter is more specific. IgG4 assay might be suitable for identification of current infection (1,7,9,17) and the total IgG assay might be preferable for epidemiological monitoring of infection, assessment of endemicity and early exposure of the individuals to infection (26). The recombinant WbSXP-1 antigen-based immunoassay has now been further developed into a rapid flow-through immuno filtration test format and an evaluation study performed on this test is reported here.…”

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“…Studies assessing antibody prevalence of lymphatic filariasis have employed assays that use either soluble worm antigens or recombinant antigens [12,13,18-21]. These antigens may not bind to the same set of anti-filarial antibodies and probably display different cross-reactivities to antibodies against other infections.…”

Real-time PCR detection of the HhaI tandem DNA repeat in pre- and post-patent Brugia malayi infections: a study in Indonesian transmigrants

“…Exposure to brugian parasites is determined by brugian specific IgG4 serology using recombinant antigens in ELISAs [13,14] or rapid-format assays (BmR1-Brugia Rapid ™ [15] and CELISA [16]) with up to 95% sensitivity in Mf-positive samples. The ELISA format using soluble worm antigen (SWA) was shown to be more sensitive compared to the rapid-format which could be due to the mixture of antigens used in the ELISA.…”