ENTRY OF HIV INTO A CD4-POSITIVE CELL

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HIV binds to CD4 antigen on cells such as T helper lymphocytes or macrophages via the HIV surface glycoprotein, gp120.

The interaction of gp120 and CD4 antigen causes a conformational change in gp120 and the interaction is stabilized by  chemokine receptors. This causes gp41 to undergo a conformational change exposing hydrophobic regions that embed in the membrane of the host cell.

This causes the membrane of the virus to fuse with the membrane of the host cell and allows the nucelocapsid (containing the RNA genome) to enter the cytoplasm of the cell.

One of the viral proteins, vpr, contains a nuclear localization signal that allows the nucleocapsid to interact with the nuclear pore.

The ribonucleo- protein complex enters the nucleus where it is transcribed to cDNA (the copying of the viral genomic RNA to DNA probably starts after the nucleocapsid has entered the cytoplasm of the infected cell)

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