A multicenter evaluation of a new antibody test kit for lymphatic filariasis employing recombinant Brugia malayi antigen Bm-14

Abstract

Antibody tests are useful for mapping the distribution of lymphatic filariasis (LF) in countries and regions and for monitoring progress in elimination programs based on mass drug administration (MDA). Prior antibody tests have suffered from poor sensitivity and/or specificity or from a lack of standardization. We conducted a multicenter evaluation of a new commercial ELISA that detects IgG4 antibodies to the recombinant filarial antigen Bm14. Four laboratories tested a shared panel of coded serum or plasma samples that included 55 samples from people with microfilaremic Wuchereria bancrofti or Brugia infections and 26 control samples. Qualitative results were identical in all four test sites. In addition, each laboratory tested samples from their own serum banks. The test detected antibodies in 32 of 36 samples (91%) from people with Brugian filariasis and in 96 of 98 samples (98%) from people with Bancroftian filariasis. Specificity testing showed that many serum or plasma samples from patients with other filarial infections such as onchocerciasis had positive antibody tests. Specificity was otherwise excellent, although 3 of 30 samples from patients with ascariasis and 4 of 51 with strongyloidiasis had positive antibody tests; it is likely that some or all of these people had previously lived in filariasis-endemic areas. Antibody test results obtained with eluates from blood dried on filter paper were similar to those obtained with plasma tested at the same dilution. This test may be helpful for diagnosing LF in patients with clinical signs of filariasis. It may also be a useful tool for use in LF endemic countries to monitor the progress of filariasis elimination programs and for post-MDA surveillance.

Lymphatic filariasis control in Tanzania: effect of six rounds of mass drug administration with ivermectin and albendazole on infection and transmission

“…Elution of the dried blood samples and subsequent determination of antibodies to Bm14 was done by use of the Filariasis CELISA test kit (Cellabs Pty Ltd, Brookvale, Australia). The test was performed according to the procedure from the manufacturer and as described elsewhere [9,10]. Each sample was tested in duplicate and the mean OD-value was recorded as the individuals’ result.…”

Dried Blood as an Alternative to Plasma or Serum for Trypanosoma cruzi IgG Detection in Screening Programs

“…Previous studies have shown that optical density (OD) cutoff values for some IgG diagnostic assays differ depending on the sample type (32). Others have reported that IgG antibodies decay in filter paper blood spots after long-term storage, failing to detect IgG in some reactive specimens, which affects the sensitivity of the assay (16).…”

Rapid Wuchereria bancrofti-Specific Antigen Wb123-Based IgG4 Immunoassays as Tools for Surveillance following Mass Drug Administration Programs on Lymphatic Filariasis

“…These antigens have included BmR1 and BmSXP (5), WbSXP-1 (6), and Bm33 (7). Perhaps the most widely used antigen in LF surveillance has been Bm14 (8), an antigen that is homologous/identical to BmSXP and WbSXP-1, which has been extensively studied in an enzymelinked immunosorbent assay (ELISA) format (4,(8)(9)(10)(11). More recently, this antigen and several of the others have been compared using a multiplex bead assay (3,12).…”