G Vercauteren — Page 2

PubMed1987

Comparison of enzyme immunoassays and an immunofluorescence test for detection of antibody to human immunodeficiency virus in African sera.

A total of 152 sera from African subjects were tested for presence of antibody to human immunodeficiency virus using four enzyme immunoassays (EIA) marketed by Abbott Diagnostics, Organon Teknika, Wellcome and Diagnostics Pasteur respectively, an indirect immunofluorescence assay (IFA) and an immunoblot assay (IBA) as reference test. The sensitivity (95% confidence limits, CL) of the EIAs and the IFA ranged between 80.9% and 99.1%. The specificity of the Abbott EIA was lower (95% CL: 38.1-72%) than that of the other assays (95% CL: 83.5-100%). The use of an IFA or the Wellcome competitive EIA as confirmatory test on initially EIA positive sera yielded a specificity of 85.5-100% (95% CL) compared with the IBA. The costs of screening by an EIA, followed by confirmatory testing of reactive sera with IFA or the Wellcome EIA and IBA on discrepant test results was similar for all combinations with the exception of initial screening with the Abbott EIA which was more expensive. Using a limited number of sera from African subjects no one test system yielded a significantly superior degree of specificity or sensitivity.

Acquired Immunodeficiency Syndrome↗

PubMed1987

Immunofluorescence tests for HIV antibody and their value as confirmatory tests.

The enzyme-linked immunosorbent assay (ELISA) is currently being used as a sensitive screening test for HIV antibody. The immunoblot assay (IBA) and indirect immunofluorescence (IF) techniques are two recommended confirmation tests for EIA-positive sera. An indirect IF test has been developed by various laboratories using acetone fixed mixtures of uninfected and HIV-infected cells, which facilitated the reading, since nonspecific reactions were easily differentiated from specific staining. Similar results have been obtained with H9-, CEM-, and HUT78-HIV-infected and uninfected cells. Anti-nuclear antibodies and auto-antibodies resulting in false-positive EIA results, could easily be differentiated by the IF test. Aspecific fluorescence can be removed by absorption of the specimens with non-infected cells. However, IF is not suitable for the screening of large series of specimens. IF is especially well suited for quantitative analysis of serum antibody levels. Whereas serum antibody titers rise initially after infection, they decrease as AIDS develops. Heat inactivation of sera did not affect reactivity in IF, in contrast to a high rate of false-positive results obtained with heat inactivated sera in some ELISAs. A well characterized serum from an AIDS patient can be used to perform IF in order to monitor HIV infection of susceptible cells. It has been claimed that titers of neutralizing antibodies significantly correlate with the levels of IF anti-HIV antibodies. An overall correlation of 99% between IF and IBA was reported by different laboratories, when HIV ELISA-reactive European and North American sera were tested. The concordance with IBA was 97% when HIV ELISA-reactive African sera were tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Viral↗