Dot immunogold filtration assay (DIGFA) for the rapid detection of specific antibodies against the rat lungwormAngiostrongylus cantonensis(Nematoda: Metastrongyloidea) using purified 31-kDa antigen

Abstract

AbstractA rapid dot immunogold filtration assay (DIGFA) was adopted for specific immunodiagnosis of human cerebral angiostrongyliasis, using purified 31-kDa glycoprotein specific toAngiostrongylus cantonensisas diagnostic antigen and protein A colloidal gold conjugate as antigen–antibody detector. A total of 59 serum samples were assayed – 11 samples from clinically diagnosed patients with detectableA. cantonensis-specific antibody in immunoblotting; 23 samples from patients with other related parasitic diseases, i.e. gnathostomiasis (n= 8), cysticercosis (n= 5), toxocariasis (n= 2), filariasis (n= 4), paragonimiasis (n= 2) and malaria (n= 2); and 25 samples from normal healthy subjects. The sensitivity and specificity of DIGFA to detect anti-A. cantonensisspecific antibodies in serologically confirmed angiostrongyliasis cases, were both 100%. No positive DIGFA was observed in cases with other parasitic diseases, and the healthy control subjects. The 3-min DIGFA is as sensitive and specific as the 3-h immunoblot test in angiostrongyliasis confirmed cases that revealed a 31-kDa reactive band. The gold-based DIGFA is more rapid and easier to perform than the traditional enzyme-linked immunosorbent assay (ELISA). The test utilizing purifiedA.cantonensisantigen is reliable and reproducible for specific immunodiagnosis of human infection withA. cantonensis– thus can be applied as an additional routine test for clinical diagnostic support. Large-scale sero-epidemiological studies in endemic communities in north-east Thailand are under way to evaluate its usefulness under field conditions.