Identification of a major co-receptor for primary isolates of HIV-1

The CC-CRK-5 beta-chemokine receptor functions as a co-receptor for the primary macrophage-trophic strains of the human immunodeficiency virus 1 (HIV-1) and acts along with CD4 to enable the entry of the virus into host cells. Cells co-expressing CD4 and CC-CRK-5 are highly susceptible to HIV infection while those co-expressing CD4 and other members of the CC-CRK-5 family are resistant to infection. CC-CRK-5 activates the fusion of plasma membrane with the HIV-1 envelope. Beta-chemokines are cytokines that suppress HIV infection by blocking its entry and replication in cells.