HIV and AIDS: Understanding the Disease and Prevention

HIV and AIDS: An Introduction

AIDS (Acquired Immunodeficiency Syndrome) is caused by infection with the retrovirus HIV. This virus attacks and destroys T4 lymphocytes and macrophages. Affected individuals have a depressed immune system, which can lead to certain types of cancers.

Development of the Disease

HIV is found in the blood and other bodily fluids of infected persons. Transmission to a healthy person can occur through various routes. These include contaminated blood transfusions and sexual intercourse between an infected and healthy individual.

Once HIV enters the blood of a new host, it joins T cells and penetrates inside. There, a large number of viruses are created, ultimately destroying the infected cell.

AIDS: Treatment and Prevention

There is no curative treatment for AIDS. The drugs used slow the progression of the disease but do not eliminate the virus and are not curative. Some drugs inhibit the activity of transcriptase, others inhibit virus binding to the receptors of lymphocytes, and the most recent inhibit protease.

The only way to prevent the disease is to prevent its transmission by avoiding risky behavior.

Hypersensitivity Reactions

Hypersensitivity is an inappropriate immune response to an antigen, which causes damage to the tissues themselves. The substances that cause it are harmless substances such as food, medicines, and dust.

Allergic Reactions: IgE-Mediated Hypersensitivity

An allergic reaction is a hypersensitivity reaction mediated by IgE. The following stages are distinguished in an allergic reaction:

• The allergen enters the body.
• This causes the activation of T cells.
• T cells, together with the allergen, activate B cells.
• B cells differentiate into plasma cells and produce IgE.
• These IgE, by the Fc region, bind to receptors on the surface of mast cells, producing basophilia awareness of them.

Retrovirus: HIV and AIDS

HIV causes AIDS by attacking CD4 lymphocytes. The process involves the following steps:

1. Contact between the spicules of the viral membrane and host cell receptors allows the fusion of these membranes, into which the genetic material (capsid) is inserted.
2. Once inside, the virus sheds its capsid protein, and the RNA strands are free, carrying the enzyme reverse transcriptase.
3. The reverse transcriptase makes a DNA copy of the RNA chain.
4. The RNA-DNA hybrid helix is used by the same enzyme to generate a DNA double helix.
5. The double chains of viral DNA enter the nucleus and are inserted into the cell chromosome, where they can lie dormant in the form of a provirus for a longer or shorter period.
6. Finally, the viral DNA is transcribed and translated using the metabolic machinery of the cell, creating new copies of viral RNA, capsid proteins, the envelope, and reverse transcriptase enzymes.

Bacteriophage: The T4 Phage

The T4 phage is a complex virus with an icosahedral head and a tail, which includes a basal plate and fiber fixation. The genome is composed of a double-stranded DNA molecule that is heavily packed inside the head.

The phage attaches to the bacterial cell wall in regions called sticky points, through which it injects its DNA via the contraction of the sheath of the tail.