Og4C3 Circulating Antigen: A Marker of Infection and Adult Worm Burden in Wuchereria bancrofti Filariasis

Abstract

A population from the Wuchereria bancrofti-endemic island of Mauke was reevaluated retrospectively by use of the Og4C3 circulating antigen (CAg) enzyme-linked immunosorbent assay to assess active infection in relation to host responses by age and gender. Use of microfilaremia (Mf) alone misclassified 50% of infected people, although CAg and Mf levels were positively correlated. Levels of CAg peaked between those aged 31-60 years; men aged 60 years had a significantly higher CAg prevalence (90%) than women. Filaria-specific im-munoglobulin (Ig) G4 reached maximum levels in both genders at age 51-60 years. By analysis of variance, both age and gender significantly influenced CAg and IgG4, with men having higher levels of both in the total population. Individuals positive for CAg had significantly lower lymphocyte proliferation responses to parasite antigen than did CAg-negative people, regardless of clinical status. This study reemphasizes the importance of CAg measurements for accurately assessing filarial prevalence and clinical status and demonstrates the relationship between active infection and immune responsiveness.

Short communication: Wuchereria bancrofti antigenaemia in Sri Lanka

“…Despite its high sensitivity in finding filarial infection, the Ag-ELISA detected only 1 in 10 carriers with 1-3 mf/ml. Similar false negative results were reported by Chanteau et al (1994);and Dreyer et al (1996) confirmed a filarial 'dance sign' in several individuals with negative antigenaemia. Only 67% were antigen-positive of the mfnegatives with evidence of adult worm infection (Rocha et al 1996).…”

Circulating filarial antigen in the hydrocele fluid from individuals living in a bancroftian filariasis area - Recife, Brazil: detected by the monoclonal antibody Og4C3-assay

“…Studies from More and Cooperman (1990), Chanteau et al (1994), and Lalitha et al (1998), concluded that the mAb Og4C3 detects CFA from adult worms, excluding the contribution of MF in the production of CFA. Many studies (including this article), do not agree with this hypothesis (Rocha et al 1996, Nicolas et al 1997, Itoh et al 1999).…”

“…Both CFA tests using mAb Og4C3 and mAb AD.12 are commercially available. Many studies have demonstrated that the CFA detected by mAbs Og4C3 and AD.12 is an indication of the active infection and markers of adult worms burden (More & Coopermann 1990, Chanteau et al 1994, McCarthy et al 1995, Weil et al 1996, Rocha et al 1996.…”

Immunodiagnosis of human lymphatic filariasis: A review

“…Evidently, our results are in parallel with earlier findings where the levels of circulating antigen were monitored for a period of 18 months in endemic areas of other parts of the world and it remained unaltered. This suggests that Og4C3 antibody appears to recognize a particular antigen released by the adult worm (8). Currently such long term follow up of the MF patients using Og4C3 monoclonal antibody based ELISA is in progress in our laboratory.…”