Comparative evaluation of particle agglutination test for antibody to human immunodeficiency virus.

Abstract

SUMMARY A comparative evaluation of a new serological test for human immunodeficiency virus (HIV) was carried out. The test used the agglutination of gelatin particles coated with HIV antigen. It was found to be more sensitive than current enzyme linked immunosorbent assays (ELISAs) and more specific than the western blot test. Because of its simplicity, it promises to be of value, especially in developing countries.Enzyme linked immunosorbent assays (ELISAs) for antibody to human immunodeficiency virus (HIV) are widely used to diagnose and control HIV infection. Many of these tests have high levels of sensitivity and specificity.' Although these tests are useful, they are technically difficult to perform and require expensive equipment, such as a spectrophotometer and a plate washer.A new serological test that overcomes many ofthese problems has been described.2 It is an agglutination assay in which tanned gelatin particles have been coated with HIV antigen. The test involves a one step reaction of antibody to antigen. The particles are dyed so that the results can be read visually.After a preliminary evaluation had shown that the test was promising, we carried out a more extensive study. This paper presents our findings. Materials and methodsThe particle agglutination test was supplied by Fujirebio Inc, Tokyo. The kit came with a microtitre plate, two reagent droppers, and the necessary reagents. Basically, the test consisted of preparing serum dilutions in the microtitre plate, and adding sensitised and unsensitised particles to the appropriate serum dilutions. After being incubated for two hours, the plate was read macroscopically for agglutination.The test results were compared with those of the Abbott enzyme immunoassay (EIA) and Abbott recombinant EIA (REIA) The confirmatory tests used were the Diagnostic Biotechnology western blot, Commonwealth Serum Laboratories western blot, and the Abbott confirmatory EIA (CEIA). The Abbott CEIA uses a competitive immunoassay method in which polystyrene beads are separately coated with p24 and gp41 recombinant antigens. We tested for HIV antigen by a solid phase sandwich type enzyme immunoassay for p24 which was produced by Abbott Laboratories.The methods adopted for all the tests were according to the manufacturers' instructions. As not all the tests were available throughout the study period, the particle agglutination test was compared with those that were available at a particular time.The serum samples came from different sources. One batch of 400 was from routine samples sent for HIV screening during a three week period. These were from prostitutes, high risk groups, and other patients. Another 103 serum samples were collected during an 18 month period. They had shown either initial or repeated reactivity in the ELISA and had been kept at -20°C for confirmatory tests. Ten serum samples that gave positive results for antinuclear antibodies were also tested. We used two familiarisation serum panels (from Abbott Laboratories and Electro-Nucleonics). ResultsThe re...