Coreceptor activity

Abstract: Entry of HIV-1 into target cells requires cell-surface CD4 and additional host cell cofactors. A cofactor required for infection with virus adapted for growth in transformed T-cell lines was recently identified and named fusin. However, fusin does not promote entry of macrophage-tropic viruses, which are believed to be the key pathogenic strains in vivo. The principal cofactor for entry mediated by the envelope glycoproteins of primary macrophage-tropic strains of HIV-1 is CC-CKR-5, a receptor for the β-chemokines RANTES, MIP-1α and MIP-1β.

Abstract: The β-chemokines MIP-1α, MIP-1β and RANTES inhibit infection of CD4+ cells by primary, non-syncytium-inducing (NSI) HIV-1 strains at the virus entry stage, and also block env-mediated cell–cell membrane fusion. CD4+ T cells from some HIV-1-exposed uninfected individuals cannot fuse with NSI HIV-1 strains and secrete high levels of β-chemokines. Expression of the β-chemokine receptor CC-CKR-5 in CD4+ , non-permissive human and non-human cells renders them susceptible to infection by NSI strains, and allows env-mediated membrane fusion. CC-CKR-5 is a second receptor for NSI primary viruses.

Abstract: Evidence suggests that CD8 + T lymphocytes are involved in the control of human immunodeficiency virus (HIV) infection in vivo, either by cytolytic mechanisms or by the release of HIV-suppressive factors (HIV-SF). The chemokines RANTES, MIP-1α, and MIP-1β were identified as the major HIV-SF produced by CD8 + T cells. Two active proteins purified from the culture supernatant of an immortalized CD8 + T cell clone revealed sequence identity with human RANTES and MIP-1α. RANTES, MIP-1α, and MIP-1β were released by both immortalized and primary CD8 + T cells. HIV-SF activity produced by these cells was completely blocked by a combination of neutralizing antibodies against RANTES, MIP-1α, and MIP-1β. Recombinant human RANTES, MIP-1α, and MIP-1β induced a dose-dependent inhibition of different strains of HIV-1, HIV-2, and simian immunodeficiency virus (SIV). These data may have relevance for the prevention and therapy of AIDS.