Anti-HIV chemokines: domain mapping and HIV-2 lentivirus delivery.
Int Conf AIDS 1998 Jun 28-Jul 3; 12:3 (abstract no. 11104)
Arya S, Owais M, Davis-Warren A National Institutes of Health, National Cancer Institutes, Bethesda, MD, USA.
HIV has expropriated chemokine receptors to gain entry into the host cell, with M- and T-tropic viruses respectively using CCR5 and CXCR4 as co-receptors. This also subjects the virus to suppression by the natural ligand of these receptors. Indeed, C-C or beta and C-X-C or alpha chemokines inhibit HIV infection, presumably by interfering with the binding of the viral envelop to the co-receptor. The mechanism of this three component interaction--natural ligand (chemokine), bandit ligand (viral envelop), and the co-receptor--in virus infection and signal transduction is not well understood. We envision two models--'same site' model where the two ligands compete for the same site on the receptor and distant site model where competition occurs at distance by way of stearic hindrance or conformational change. To address these issues and to design a dual tropic minimal chemokine, we have created a number of mutants of both C-C (prototype: RANTES) and C-X-C (prototype: SDF-1) chemokines focused on the defined structural elements (flexible coil, beta sheets and a helix) and expressed them in lentivirus and baculovirus expression systems. Domain mapping studies have revealed that the amino-terminus (N-loop) as well as carboxy terminus (alpha helix) of RANTES as well as SDF-1 could be deleted without adverse effect on their antiviral activity. Deletion of more central beta 1 domain of RANTES resulted in the loss of its anti-M-tropic but not of its anti-T-tropic activity. Lentivirus vector delivery of recombinant chemokine to relevant target cell could achieve phenotypic knockout by causing intercellular trapping and extracellular occupancy of the receptor, thus suppressing virus infection and its spread. Our HIV-2 based lentivirus vector clearly express recombinant chemokines. They can also be packaged in homologous packaging system as well as pseudotyped with VSV-G protein. Domain mapping studies suggest that large segments of both C-C and C-X-C chemokines are not essential for their antiviral activity, that they are composed of subdomains determining receptor specificity, and that their antiviral effect and chemtaxis or signal transduction function employ different pathways. The recombinant chemokines in HIV-2 lentivirus vector will be useful for gene transfer studies in achieving intracellular immunization and extracellular protection in HIV infection and AIDS.
Keywords: AEGIS, HIV-2, HIV, Chemokines, HIV Infections, Receptors, Chemokine, RANTES, Receptors, HIV, Acquired Immunodeficiency Syndrome, HIV Seropositivity, Chemokines, CXC, Anti-HIV Agents, HIV Envelope Protein gp120, HIV Core Protein p24, Greece, stromal cell-derived factor-1alpha, immunology, ICA12
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