NEW ELISA FOR HIV SUBTYPES B,E

Currently, the third-generation sandwich enzyme-linked immunosorbent assays (ELISAs) are considered to be the most sensitive of test kits for detecting HIV-1 antibodies, especially in the first weeks-months of infection (Zaaijer et al, 1992). High sensitivity is required for protection of the blood supply for transfusion. However, in order to reduce the window period (time from infection to seroconversion), screening for p24 HIV antigen (Ag) has been introduced in some blood banks. This additional testing is not done worldwide because of the high cost per positive unit detected. Therefore, several manufacturers have sought to improve sensitivity for earlier diagnosis of HIV infection through combination antigen-antibody enzyme immuno-assays (EIAs). European investigators have recently reported evaluations of two such fourth-generation assays (Gurtler et al, 1998; Weber et al, 1998). Their results supported the concept that combination of antigen and antibody detection in a single assay is a more efficient anti-HIV screening tool. Most screening assays available in Thailand were originally developed using the subtype B virus found in North America and Europe, whereas the most common HIV-1 subtypes found throughout Southeast Asia are Thai B (or B’) and E (Expert Group of the Joint Unite