MP Board · Class 12 · Biology · Human Health and DiseasesAnswer the following regarding AIDS (Acquired Immuno Deficiency Syndrome): (a) Name the causative agent and describe its genetic material. (b) Explain the step-by-step mechanism of HIV infection and replication inside the human host. (c) Name the diagnostic test used for detecting AIDS. (d) Mention preventive measures to control the spread of AIDS.
Step-by-Step Solution
(a) Causative Agent
- Causative Agent: AIDS is caused by Human Immunodeficiency Virus (HIV).
- Genetic Material: HIV is an enveloped virus containing two single-stranded RNA (ssRNA) molecules as its genome along with the enzyme Reverse Transcriptase. It belongs to the group called Retroviruses.
(b) Mechanism of HIV Infection and Replication
- Entry into Host Cells: Upon entering the human body, HIV attacks macrophages and Helper T-lymphocytes ($T_H$ cells).
- Reverse Transcription: The viral RNA genome replicates to form viral DNA with the help of the enzyme Reverse Transcriptase.
- Integration: The viral DNA incorporates into the host cell's genome/DNA using the enzyme Integrase.
- Viral Multiplication: The infected host cell is directed to produce new viral particles. Macrophages continue to produce virus particles, acting like an HIV factory.
- Destruction of Helper T-cells: Newly formed HIV particles are released into the blood and attack other Helper T-lymphocytes ($T_H$ cells).
- Immune Breakdown: This process repeats continuously, leading to a progressive decrease in the count of Helper T-lymphocytes in the infected person's body.
- Immunodeficiency: Due to a severe drop in $T_H$ cells, the person suffers from opportunistic infections by pathogens like Mycobacterium, viruses, fungi, and parasites like Toxoplasma.
(c) Diagnostic Test
- The widely used diagnostic test for AIDS is ELISA (Enzyme-Linked Immunosorbent Assay).
- Confirmation is done using the Western Blot test.
(d) Prevention and Control Measures
- Safe Blood Transfusion: Ensuring screened HIV-free blood for blood transfusions.
- Disposable Needles: Using disposable sterile syringes and needles in hospitals and clinics.
- Safe Sex Practices: Advocating the use of condoms during sexual contact.
- Awareness Programs: Educating people through organizations like NACO (National AIDS Control Organisation) and WHO.
- Avoiding Drug Abuse: Controlling intravenous drug abuse.
💡 Study Guide: This question tests core syllabus concepts from Human Health and Diseases. For formulas, key summaries, and mock exam reference guides, read the full Human Health and Diseases Revision Notes.