Cell fusion of HIV with target cell is done by

Ans. is 'b' i.e., gp 41 gp 120 - Binding of HIV to CD4 antigen on T-cell.gp 41 - Fusion of HIV to torget cell (T-cell)The HIV envelop contains two glycoproteins, surface gp120 that is noncovalently altached to transmembrane protein, gp41.The initial step in infection is the binding of gp120 envelop glycoprotein to CD4 molecules.This binding leads to a conformational change that result in the formation of a new recognition site on gp120 for the coreceptor CCR5 or CXCR4.The next step involves conformational changes in gp41.These changes results in the inseion of fusion peptide at the tip of gp41 into the cell membrane of target cell (CD4 T-cells or macrophages).After fusion, the virus core containing the HIV genome enters the cytoplasm of the cell.