Detection of primary HIV infections with a fourth generation test

• Published in: AIDS (London) Vol. 14; p. S108
• Main Authors: De Lejarazu, RO, Ortega, M, Hernandez, B, Eiros, J M, Labayru, C, Rodriguez-Torres, A
• Format: Journal Article
• Language: English
• Published: 01.10.2000
• Subjects: Human immunodeficiency virus; p24 antigen; p24 protein
• ISSN: 0269-9370

Description of primary HIV infections detected by a 4th generation HIV test (GT), which aim is to shorten the immunologically silent 'window period' by simultaneous detection of p24 antigen (p24 Ag) and HIV antibodies. 2647 serum samples were tested with both a 3rd and a 4th GT (VIDAS HIV 1/2 NEW and VIDAS HIV DUO respectively, bioMerieux). Reactive samples were confirmed by Western blotting (WB) (Bioblot HIV-1 plus, Biokit) according to WHO criteria. Quantitative measure of p24 Ag (ELAVIA registered Ag I, Sanofi Pasteur) was also performed and reactive samples were confirmed by blocking with an anti-HIV serum. When plasma samples were available quantitative PCR (HIV 1 Monitor Amplicor, Roche) was carried out. 167 samples out of 2647 analysed were positive. Primary HIV infection (during the window period) was detected in five patients. Most of them were negative by 3rd GT (four patients). WB was negative or indeterminate in most of those cases. Ag p24 (blocked) and/or PCR were positive in all patients. New 4th GT allow an earlier diagnosis of HIV. Therefore, we can reduce the risk of missing any unsuspected primary HIV infections in routine testing infection (2.9% over total positive test). Confirmation of primary HIV infection can be obtained by either p24 Ag and/or PCR. Use of 4th GT may facilitate early HIV therapy and avoiding new infections during the silent 'window period'.