AIDS is characterised by

Options

A. (a) decrease in the number of killer T-cells
B. (b) decrease in the number of suppressor T-cells
C. (c) decrease in the number of helper T-cells
D. (d) increase in the number of helper T-cells

Explanation

**Step-by-Step Text Solution:**

1. **Understanding AIDS**: AIDS stands for Acquired Immunodeficiency Syndrome, which is caused by the Human Immunodeficiency Virus (HIV). It is essential to know that AIDS is a condition that results from the progression of HIV infection.

2. **HIV Characteristics**: HIV is a retrovirus that has an RNA genome. Upon entering the host's cells, it uses an enzyme called reverse transcriptase to convert its RNA into DNA. This newly formed viral DNA integrates into the host's genome.

3. **Target of HIV**: The primary target of HIV is the T-helper cells, also known as CD4+ cells. These cells play a crucial role in the immune system by helping to activate other immune cells, including T-cytotoxic cells, which are responsible for killing infected cells.

4. **Impact on the Immune System**: As HIV infects and destroys T-helper cells, the immune system becomes compromised. This leads to a decrease in the number of these vital cells, which in turn impairs the body's ability to fight off infections and diseases.

5. **Conclusion**: Therefore, AIDS is characterized by a decrease in the number of helper T cells (CD4+ cells), which is critical for maintaining a healthy immune response.

**Final Answer**: AIDS is characterized by a decrease in the number of helper T cells (CD4+ cells).

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