Background/introduction Detection of acute HIV infection is important in preventing HIV transmission and for consideration of early antiretroviral therapy. Fourth generation (4G) HIV tests detect p24 antigen and HIV antibody and should detect acute HIV infection prior to the development of antibodies. An early version fourth generation (4G) point-of-care (POCT) test demonstrated low levels of sensitivity for p24Ag.

Aim(s)/objectives To assess the ability of the new Alere™ HIV Combo 4G POCT to detect p24 antigen in patients with laboratory confirmed p24 antigenaemia.

Methods P24 antigen positive serum samples were tested using the Alere™ HIV-Combo POCT and read at 20 and 40 min. One sample gave an invalid result and was excluded. P24 antigen levels from the VIDAS quantitative HIV p24 11 assay, used as routine HIV confirmatory tests by our laboratory, were recorded for comparison.

Results Twenty-four out of 27 samples (89%) were p24 antigen positive at 20 min and 25/27 (93%) samples were positive at 40 min. There were two false negative samples, shown to have the lowest levels of p24 antigen (27.6 and 8.3 pg/ml) of the 27 samples. The mean p24 antigen level with the VIDAS quantitative HIV p24 11 assay for the cohort was 236.2 (Range 8.3- >400 pg/ml). The Alere™ HIV Combo POCT detected all P24 antigen at levels >30 pg/ml.

Discussion/conclusion The Alere™ HIV Combo POCT has 89% sensitivity for p24 antigen at 20 min and 93% at 40 min. These preliminary results suggest that the new Alere™ HIV Combo POCT may be able to detect early infection adequately.