A highly defective HIV-1 strain isolated from a healthy Gabonese individual presenting an atypical western blot

• Published in: AIDS (London) Vol. 3; no. 11; p. 707
• Main Authors: Huet, T, Dazza, M C, Brun-Vézinet, F, Roelants, G E, Wain-Hobson, S
• Format: Journal Article
• Language: English
• Published: England 01.11.1989
• Subjects: Acquired Immunodeficiency Syndrome - diagnosis; Acquired Immunodeficiency Syndrome - microbiology; Amino Acid Sequence; Base Sequence; Blotting, Western; Gabon; Gene Products, env - genetics; Gene Products, gag - genetics; Gene Products, tat - genetics; Genes, env; Genes, gag; Genes, tat; Genes, Viral; HIV-1 - genetics; Humans; Molecular Sequence Data; Polymerase Chain Reaction; Proviruses - genetics; Sequence Homology, Nucleic Acid; tat Gene Products, Human Immunodeficiency Virus; Transcriptional Activation; Gabon
• ISSN: 0269-9370
• DOI: 10.1097/00002030-198911000-00004

In central equatorial Africa the frequency of uninterpretable or atypical Western blots (WB)--ie. antibodies to gag proteins only--can represent up to 50% of enzyme-linked immunosorbent assay (ELISA)-positive samples. To date the significance of such serology remains unknown. Nevertheless, an unusual HIV-1 strain has been isolated from the blood of a healthy Gabonese individual who presented an atypical WB. This virus, identified as isolated HIV-1OYl, grew to low titres of reverse transcriptase activity (less than 50,000 cpm/ml) and was not obviously cytopathic. Radioimmunoprecipitation and peptide ELISA studies indicated that the lack of env-specific reactivity was probably due to the absence of antibodies to the viral glycoproteins, rather than the virus encoding a highly divergent envelope protein. Molecular cloning and sequencing of the provirus proved it to be a string of HIV-1 which was genetically closer to European and North American than to African strains. Furthermore the envelope protein sequence contained all the features of a typical HIV-1 env gene. However, the tat gene derived from the proviral clone was functionally defective. Site-directed mutagenesis of this gene showed that this was due to the substitution of an essential cysteine residue for a serine. Polymerase chain reaction amplification of the tat gene, as well as parts of the gag and env gene sequences of HIV-1OYl, showed that essentially all of the proviruses were defective. These data emphasize the need to view HIV isolates as populations of distinct genomes capable of complementing each other.