Three cases of HIV-1 subtype E primary infection and one case of atypical HIV-1 subtype B infection:: Results obtained with 4TH generation EIAs

Three cases of primary HIV-1 subtype E (CRF01-AE) and one case of atypical primary subtype B infection were tested with 3rd and 4th gen. assays, stand-alone HIV Ag EIAs and RT-PCR. Primary HIV-1 subtype E infections were detected between 3 and 7 days earlier with 4th gen. EIAs in comparison with the most sensitive 3rd gen. test. A 2nd diagnostic window was observed in one case of HIV-1 subtype B infection with 4th gen. EIAs with a low sensitivity of the antigen detection module while newer assays with a detection threshold of about 5 pg p24 Ag/ml remained positive in the transition period between decrease of antigenemia and delayed humoral immune response. These preliminary data from seroconversions indicate that the genetic diversity of HIV-1 does not represent a major challenge for the most sensitive EIAs of this new assay generation.