12th International AIDS Conference Geneva, Switzerland - June 28-July 3, 1998

Int Conf AIDS 1998 Jun 28-Jul 3; 12:14 (abstract no. 11162)

Wang B, Lal RB, Dwyer DE, Cunningham AL, Saksena NK
Retroviral Genetics Lab CVR, WIHR, Westmead Hospital, NSW, Australia.

OBJECTIVES: To analyze the biology and molecular viral strains (recombinant and non-recombinant) from HIV-1 co-infected and multiply exposed individual.

DESIGN: Systematic study of viral sequences of different infecting strains, their replication kinetics on different cell types, and coreceptor usage by different strains in vivo.

METHODS: The HIV-1 viral quasispecies from the PBMCs of an HIV-1 infected IVDU was analyzed by PCR amplifying proviral DNA amplified in the gp120 env and the vpr gene from peripheral blood mononuclear cells (PBMCs). Full-length gp120 and Vpr gene fragments were cloned into PGEM-T vector, and sequencedon automated sequencer. Viral strains isolated by coculture were further analyzed for tropism and replication kinetics on PBMCs, monocytes, and monocyte-derived macrophages. In addition, the phenotypic detrmination was carriedout on MT-2 cells, and the coreceptor usage on HOS cells.

RESULTS: These data provide evidence in favor of coinfection of the patient with two divergent strains of HIV-1. Based on gp120 env region, the two groups differed by 14-15%, with more than 25% difference between various variable domains (V1-V5) of the gp120 region. Coculture experiments on different cell types further provided evidence in favour of co-passaging of two strains suggesting complementation between two strains present in the patient. Molecular analysis further revealed that complementation occurred between intact and defective strains, with one of the viruses acting as a helper virus for the other strain to survive. The study of viral replication kinetics in PBMCs, monocytes and monocyte derived macrophages (MDMs) revealed the virus to be T-cell tropic. Coreceptor usage data shows that one of the viral strains from the paitent may use CCR-5 or CCR-1, 2, 3 and CXCR4 independent pathway for its entry into the cell. Such strains are extremely rare in nature and suggest a usage of some unknown coreceptor molecule by this HIV-1 strain.

CONCLUSIONS: This study demonstrates for the first time that complementation between defective and intact HIV-1 strains can provide a mechanism for the continuation of defective/attenuated viral lineages in vivo. Molecular changes in the gp120 gene may lead to differential tropism and co-receptor usage in HIV-1 strains.

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