Abstract: An HIV-1 type (or subtype) O retrovirus protein, or a natural or synthetic polypeptide or peptide including at least a part of said protein, which is capable of being recognised by antibodies isolated from a serum resulting from infection by an HIV-1 type O VAU strain or an HIV-1 type (or subtype) O DUR strain.

Abstract: An in vitro, single cycle, recombinant virus assay (RVA) for determining inhibition of HIV replication by a protease inhibitor comprises transfecting a human epithelial cell line with amplified HIV protease sequences of an HIV virus; an HIV, envelope defective, molecular clone having a complete deletion of its protease coding sequence; and a plasmid containing HIV envelope coding sequence under the control of a promoter for phenotypic complementation of the envelope defective molecular clone. The transfected cells are cultured in the presence of a protease inhibitor to produce a testable stock of infectious particles that can be used to infect indicator cells containing an indicator gene without amplification of the infectious particles prior to infecting the indicator cells. Accumulation of indicator gene product is a measure of inhibition of HIV replication by the protease inhibitor.