Question

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

Answer 1

Retrovirus is composed of RNA as its genetic material. It inserts its RNA into the DNA of the host and changes its genome. It has a special enzyme called reverse transcriptase which reverse transcribes RNA to DNA.

Complete answer:
To answer this question, we must know about the life cycle of retrovirus after it enters humans.
Retrovirus is a unique virus having single stranded RNA. After it enters the host, it incorporates its gene into the host and starts replicating. There are three human retrovirus HIV which causes AIDS, HTLV1 and HTLV2 which causes acute leukemia.
There are two phases of infection:

The early phase refers to the infection from cell binding and integration of viral cDNA into the genome of the host- The virus enters the human body. It uses the enzyme reverse transcriptase to produce cDNA. These DNA copy inserts into the nucleus by the help of integrase.
The late phase begins with the expression of viral genes. When the host DNA transcribes, the viral genome replicates. The virus particles come out of the host cell and further infect new cells.
Note: Retrovirus consist of an envelope made up of glycoprotein, single stranded RNA as a genetic material, and gag proteins, proteases, pol proteins and env proteins. The retrovirus causes human illness and is transmitted through sexual contact, infected blood and tissue exposure, during pregnancy or childbirth. The virus can remain dormant for years in the human body.