Evaluation of a new western blot strip for human immunodeficiency virus.

With the isolation of the human immunodeficiency virus (HIV), numerous assays have been developed to detect antibodies to the retrovirus. The manufacturers' recommend that all sera exhibiting a positive enzyme immunoassay be confirmed by the more specific Western blot test (WBT). Recently, a new WBT strip was released for detection of antibodies to HIV. Four hundred patients' sera and 22 CDC proficiency samples were each tested with these strips and with a WBT strip prepared within the laboratory using the CDC techniques. The strips were then evaluated for banding pattern with the reactions recorded on a scale of 0 to 4+ for each band consistent with HIV response. Criteria for positive results were based on the ASTPHLD/CDC criteria. Primary emphasis was on antibody banding to gp41 (envelope protein) and p24 (core protein). The new strips showed appropriate changes in level of antibody, especially for declining antibody to p24. When the banding pattern for antibody to gp41 was compared to the standard strips, the new strips showed a sensitivity of 99.6% and specificity of 99.4%. The presence or absence of antibody to p24 on the new strips versus the standard strips showed a sensitivity of 93.7% and specificity of 99.5%.