Explain the process of replication of retrovirus after it gains entry into the human body.

Explanation

(i)After getting into the body of the person, the virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help of the enzyme reverse transcriptase.
(ii)This viral DNA gets incorporated into the DNA of host cells and directs the infected cells to produce viral particles.
(iii)The macrophages continue to produce virus and in this way acts like a HIV factory .
(iv)Simultaneously , HIV enters into helper T-lymphocytes , replicates and produces progeny viruses . The progeny viruses released in the blood attack other helper T-lymphocytes.
(v)During this period , the person suffers from bouts of fever, diarrhoea and weight loss. Due to decrease in the number of helper T lymphocytes , the person starts suffering from infections and becomes immune deficient and unable to protect against any infection.