Question

Write a brief note on HIV

Answer 1

Hint: The virus belongs to the family retroviridae that contains an enzyme called reverse transcriptase that causes a transmissible, lethal disease called AIDS which makes the patient so immuno-deficient.

Complete answer:
HIV- human immunodeficiency virus causes a transmissible(mostly sexually transmitted) lethal disease called acquired immunodeficiency syndrome(AIDS). It is a retrovirus that has an envelope enclosing two single-stranded RNA (ssRNA) molecules as genetic material and it also contains two molecules of the enzyme reverse transcriptase.
The single-stranded RNA is surrounded by a protein coat, followed by a layer of proteins which is again surrounded by an outer lipid layer that contains a number of glycoproteins such as gp41 and gp120.
These proteins bind to the host cell’s surface receptors during infection.

Additional Information: - The first case of AIDS was reported in 1981 by the Center for disease control(CDC), USA and in the last 30 years, it has spread all over the world killing more than a 25million people.
- It generally occurs by sexual contact with an infected person, by transfusing the virus-contaminated blood, by sharing the infected needles, and from an infected mother to child through the placenta.
- After getting into the body of a person, HIV enters T helper cells, macrophages, or dendritic cells.
- The formation of the second DNA strand is catalyzed by the enzyme reverse transcriptase.

Note: -In HIV affected patients, there is always a time lag between the first infection and the appearance of symptoms.
-The period may vary from a few months to many years(usually 5 to 10 years).
-The patient becomes so immuno-deficient that he/she cannot protect themselves against minor infections.