Describe how HIV attacks its host cells by explaining its li

Describe how HIV attacks its host cells by explaining its life cycle. Make sure to include/explain these terms in your answer: GP120, CD4, reverse transcriptase, integrase, protease

Solution

Answer: Different stages in the lifecycle of HIV are described below:

Viral attachment / binding of the HIV virus to the host cell and fusion:In this step, the HIV virus binds to the T helper cell and releases HIV virus particles into the cell. The viral particle attachment occurs via interaction between GP120 glycoprotein present on the surface of the HIV envelop and CD4 antigen receptor present on the surface of the T-cell. The core of the HIV virus contains ssRNA and three enzymes reverse transcriptase, integrase and protease. After attachment, the fusion of the viral envelope and host membrane occurs leading to the entry of the HIV virus into the cell and release of the viral RNA into the cytoplasm of host cell by a process called as Uncoating. After this the reverse transcriptase enzyme makes a DNA copy of the viral RNA genome..

Integration: For integration to happen the DNA has to be transported to the host cell nucleus. Viral integrase enzyme then integrates the circular DNA into the host cell chromosome (this is called as pro-viral DNA).

Replication and Protein Synthesis and Assembly: From the viral DNA, two strands of RNA are synthesized and transported out of the nucleus. One strand is translated to important components like structural proteins, reverse transcriptase, integrase, protease etc and the other strand is used as genomic material for new virus particles.

Cleavage/Budding: This is the final step of the HIV life cycle and in this step HIV particles are released from T-helper cells by a process called as Budding. Newly synthesized virion enters into the bloodstream where they infect other cells.