Question

How does AIDS virus enter the human body? Describe its life cycle. Why does this infection shatter the immunity of the victim?

Answer 1

Acquired Immuno Deficiency Syndrome (AIDS) is caused by the Human Immunodeficiency Virus (HIV). HIV enters the body mainly in three ways:

1. Through sexual act: It is the most common route of HIV transmission from an infected partner to an unaffected partner.

2. Transmission through blood transfusion and contaminated equipments: It occurs due to use of contaminated syringes and needles or any other material by which blood from an infected person can be transferred to a healthy person.

3. Transmission from mother to baby: Pregnant woman transfers HIV to her baby through the placenta before birth or through milk feeding after birth.

LIFE CYCLE OF HIV:

• HIV enters the T cells of the host by endocytosis.
  
• It releases its viral RNA into the cytoplasm of the host cell along with the enzyme reverse transcriptase.
  
• HIV produces a complementary DNA from the template RNA strand. RNA is degraded and the leftover single strand of DNA undergoes replication and double helical DNA is produced.
  
• The DNA gets circularised and Integrated into the human chromosome.
  
• The DNA is then transcribed to form RNA.
  
• Membrane proteins are synthesized and assembled with the viral RNA and new viral particles are released.
  

The HIV shatters the immunity of the victim because it destroys the T lymphocytes in the body. As a result, even a normal cough can transform into TB or tuberculosis.