| Which of the following statements about the life cycle of the HIV (Human Immunodeficiency Virus) are false? |
| (I) The HIV particles recognise the host cell through the sialic acid containing proteins or lipids on the membrane of the host cell. |
| (II) Upon entry of the HIV into the host cell, a drop of pH will result in a conformational change in the HIV structure, consequently releasing the viral genome into the host cell. |
| (III) The viral DNA which enters the host cell's nucleus will be integrated into the genetic material of the host cell using the host cell's enzyme, integrase. |
| (IV) The viruses are released from the host cell by exocytosis. |
A) (I) and (III)
B) (II) and (IV)
C) (I), (III) and (IV)
D) All of these
Correct Answer: D
Solution :
All of the statements are incorrect. These can be corrected as- In statement (i) and (ii) the glycoprotein 120 on the HIV envelope must attach to both a \[{{\operatorname{CD}}_{4}}\] molecule and a chemokine receptor. The interaction between gp 120 and chemokine receptor brings about a conformation change in gp 41 on the HIV virion, allowing the fusion of HIV envelope S and host cell membrane. The fusion allows the nucleocapsid to enter the host cell. The capsid is removed by cellular enzymes and the viral RNA genome and various enzymes are released into the host cell. In statement (iii) the viral DNA which enters the host cell's nucleus will be integrated into the genetic material of the host cell using the HIV virus enzyme, integrase and not the host cell's enzyme. In statement (iv) the viruses bud out from the host cell's plasma membrane and are not released by exocytosis.
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