Recombinant-based competitive anti-HIV assay: solution of some operating problems.

Using the Wellcozyme anti-HIV recombinant assay at 47 degrees, a strongly reactive result with an anti-HIV positive serum sample could not be reproduced when the corresponding plasma sample was used. Dilution in anti-HIV negative serum or kaolin treatment of the plasma specimen produced the clear reactivity seen with the serum sample, and a reduction in incubator temperature was also found to reduce this 'plasma effect'. Problems were also encountered initially when haemolysed serum or plasma with non-standard concentrations of anticoagulant were tested. These phenomena were not apparent when the same manufacturer's test based on cell-derived antigen was used, indicating that the introduction of new technology may cause unforeseen problems although these can usually be overcome.