After getting into the human body, Human Immune Deficiency Virus, enters the macrophages where the RNA genome of the virus undergoes a process of reverse transcription to form viral DNA with the help of enzyme reverse transcriptase. This being the reason to call HIV as retro – virus.
The Viral DNA gets incorporated into host cell’s DNA and directs the infected cell to produce virus particles.
The macrophages now, become factories to produce the virus.
The virus now enters into helper T- lymphocytes, replicates and produce progeny virus which are released into the blood, attack other helper T-lymphocytes. This process is repeated causing progressive depletion of helper T – lymphocytes in the body of the infected person. During this period, person suffers from –
- Bouts of fever
- Diarrhoea
- Weight loss.
Due to the decrease in number of helper T- lymphocytes, the person starts suffering from infections that could have been easily overcome such as those due to bacteria – Mycobacterium , viruses , fungi , Toxoplasma. The patient becomes immune – deficient.