Evaluation of commercially available third-generation anti-hepatitis C virus enzyme-linked immunosorbent assay in patients on haemodialysis.

Restricted antibody reactivity to hepatitis C virus (HCV) synthetic peptides has been observed in HCV-infected patients on haemodialysis (HD). The aim of this study was to evaluate third-generation anti-HCV enzyme-linked immunosorbent assay (ELISA) test systems containing either synthetic peptide HCV antigens or recombinant HCV antigens or a combination of synthetic and recombinant antigens in screening of 69 chronic renal failure patients on HD for HCV infection. Seven patients were detected to have antibodies to HCV by the 'recombinant HCV antigens'-containing kits, of which the recombinant immunoblot assay for HCV confirmed four cases. The recombinant kits had a sensitivity of 100% and a specificity of 66%. However, the ELISA kits with only synthetic HCV antigens failed to detect antibodies in any of the cases (zero sensitivity). Hence a recombinant protein containing ELISA test system is ideal for screening of HCV infection in patients on hemodialysis.

DTH responsiveness of HIV-infected Thai adults.

A study was carried out in Thailand to determine the frequency of reactivity to delayed-type hypersensitivity (DTH) skin tests used for the staging of HIV patients in the United States. A four-antigen panel which included tetanus toxoid (1:10), Candida (1:10), mumps and Trichophyton antigens was assessed in 221 adult subjects from across the full immunological spectrum of HIV disease. Complete anergy was found in 38 per cent of 73 subjects with CD4 counts of 0-200 cells/ml and in 6 per cent of 78 subjects with 201-400 cells/ml. Partial anergy (response to 1 of 4 antigens) was found in 26 per cent of the 0-200 cell/ml group and decreased progressively with increasing CD4 cell count. Results suggested that a 3-member recall antigen panel would provide nearly all the clinically useful information gained by the more standard 4-member panel. In conclusion, DTH skin testing was confirmed to provide a method of assessing the integrity of cellular immune function of HIV-infected Thai adults which correlated with disease progression.

IgM capture ELISA for detection of IgM antibodies to dengue virus: comparison of 2 formats using hemagglutinins and cell culture derived antigens.

The highly sensitive AFRIMS format IgM capture ELISA for the diagnosis of dengue virus infections requires the use of mouse brain derived hemagglutinins and consequently also the use of 20% acetone extracted normal human serum to eliminate high background. These reagents are not always easily available and we have thus compared the AFRIMS format with another published format which uses cell culture derived antigens (culture fluid, CF, format) in order to determine if it is reasonable to use cell culture derived antigens in situations where hemagglutinins and normal human serum are difficult to obtain. The study shows that using AFRIMS results as the reference point, the CF format described here has a sensitivity of 90% and a specificity of 96%.