Evaluation of an immunochromatographic fourth generation test for the rapid diagnosis of acute HIV infection]

The early diagnosis of human immunodeficiency virus (HIV) infection is important to provide effective antiviral treatment and to prevent transmission of HIV. One of the key issues to achieve this goal is to shorten the so-called "diagnostic window period" when the humoral immune response toward the virus is not fully developed during the acute phase of HIV-1 infection. In 2008, the Espline HIV Ag/Ab test kit (E4G, Fujirebio Inc. Japan) was marketed in Japan belonging to the fourth generation of HIV test kits characterized by its ability to detect both viral antigens (Ag) and anti-HIV-1/2 antibodies (Ab). E4G is the first and only fourth generation immunochromatographic HIV test kit approved in Japan at present. To evaluate its performance to diagnose acute HIV infection (AHI), E4G was compared with fourth generation Ag/Ab ELISA test kits, a third generation PA test kit, WB and real-time PCR for the testing of 25 AHI clinical specimens. E4G detected HIV infection in 18/25 specimens (sensitivity : 72.0%), of which the viral Ag was detected in only 2 specimens (8.0%) bearing a viral load > 10 million copies/mL. No spesimens were simultaneously reactive to both Ag and Ab against HIV. The third generation PA achieved a positive score of 17/ 25 specimens (68.0%), which was almost the same as the E4G figure. In contrast the fourth generation Ag/ Ab ELISA scored all the 25 AHI specimens positive (sensitivity : 100%). Overall, although having the merit of offering a rapid diagnostic test for HIV infection, E4G does not provide a sensitivity in AHI diagnosis superior to test kits currently available.