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8) Which is responsible for binding of HIV to receptors of host cells?

a. Surface glycoprotein

b. Transmembrane protein

c. Protease

d. Integrase

e. Capsid protein

Ans: (a)

The surface glycoprotein (SU) is responsible for binding to receptors of host cells. The external viral protein gp120 plays a key role in interacting with the CD4 receptor and/or co-receptor of host cells.

The transmembrane protein gp41 is responsible for anchoring gp120 to the target host cell. Gp41 mediates the fusion process between viruses and target cells. Peptides inhibitors have been developed that specifically bind to gp41 and thus block virus entry.

9) What is the host cell receptor for HIV binding?

a. Middle half of CD8 molecule

b. gp41

c. Reverse transcriptase

d. Host cell DNA

e. None of the above

Ans: (e)

The CD4 molecule is the receptor for gp120 protein. The replication cycle begins with binding of gp120 protein to the CD4 molecule. The CD4 molecule is a protein found predominantly on T helper or inducer lymphocytes. They are also expressed on the surface of monocytes/macrophages and dendritic/Langerhans cells. CCR5 and CXCR4 are the major co-receptors used by HIV.
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