Question

How does HIV infect T-lymphocytes?

Answer 1

HIV can lodge itself on membrane receptor of T lymphocyte and then injects viral RNA and viral enzymes in host cell.

Explanation:

Human immunodeficiency virus abbreviated as `HIV` is a host-specific retrovirus that targets the major components of human immune system i.e `T`-`lymphocytes` or `T`-`cells`.

Infection cycle of HIV:

• Attachment:
  Firstly the HIV virus attaches to the `Cd4` receptor site on the T-cells. These fuse with the t-cell membrane and get entry into the cell's cytoplasm where they are uncoated.
• Reverse transcription and Integration:
  HIV virus being a retrovirus has a special enzyme known as reverse trancriptase on the `RNA` `"genome"`. This enzyme uses the `"viral RNA"` as a template to make a strand of `DNA` and then uses the DNA strand as a template to make a DNA double helix. Original viral RNA gets degraded.
  The viral DNA integrates into the chromosomal DNA of T-cell of the host, now becoming a provirus.
• Translation:
  The proviral DNA is transcribed into RNA which uses host cell's machinery to translate viral proteins to encase newly generated viral genome.
• Assembly and Release:
  So, new capsids assemble around `"viral RNA"` and reverse transcriptase molecules. And they bud off from plasma membrane of T-cell as mature HIV viruses, ready to attack more T cells.

Increasing number of Cd4 cells start to die due to HIV infection.