Question

Explain the mechanism by which HIV multiplies and leads to AIDS.

Answer 1

HIV also is known as the human immunodeficiency virus leads to AIDS which is a complex stage that decreases the ability of the body to fight diseases. The virus can be transmitted by contact with the infected blood, semen, or vaginal fluid.

Complete answer:
HIV is a virus that evades the human immune system and decreases the ability of the body to fight infections. The immune system is the fuel of the body that helps fight off the disease. HIV targets the CD4 cells, also known as immune cells or T cells. Over a period of time, as the virus infects and kills more of T cells, the body becomes weak and exposed to various infections and cancer. Transmission of HIV does not take place by air, water, and casual contact.

Transmission of HIV takes place by the following-

Breast milk
Vaginal fluids
Rectal fluids
Blood
Semen
If the early stage of HIV is not treated, it leads to a more severe condition known as AIDS. Here, the body becomes weak to fight off any disease. With untreated HIV, the lifespan continues to only 3 years. However, treating the patient by antiretroviral therapy can increase life expectancy nearly equal to a normal disease-free person.

Mechanism
The HIV virus has two ssRNA molecules. As discussed earlier, HIV invades the macrophages and CD4 cells. Conversion of viral RNA to viral DNA takes place. To produce the viral DNA from viral RNA, the enzyme reverse transcriptase is used. Furthermore, the enzyme integrase helps the viral DNA to integrate into the genome of the host cell. This structure is known as the provirus which synthesizes all the proteins of the virus by transcription and translation. The infected cell releases the virus particle. Therefore, the virus infects the CD4 cells slowly. With this, the number of CD4 cells decreases
leading to the weakening of the immune system and ultimately the person suffers from AIDS.

Note:
HIV spreads in three stages, acute HIV, chronic HIV, and AIDS.
Acute HIV- During this time,flu-like symptoms occur with mild fever days to weeks after contracting HIV. The rapid multiplication of the virus takes place inside the body. Therefore, CD4 cells start decreasing.

Chronic HIV- This stage is generally known as an asymptomatic stage. During this stage, a person does not experience many symptoms as acute HIV. This happens because the virus does not multiply.
AIDS- It is the final stage at which the CD4 cells are completely destroyed. People with developed AIDS can get several cancers and infections easily like cervical cancer, leukemia, tuberculosis, etc.