The Biology of AIDS

Section 1: Human Immunodeficiency Virus (HIV)

• HIV Definition:

  • Human Immunodeficiency Virus is a retrovirus that primarily attacks the immune system, specifically CD4 lymphocytes (T cells).

  • Causes Acquired Immunodeficiency Syndrome (AIDS) if untreated.

• Components of HIV:

  • HIV Envelope: Outer surface structure composed of lipids, which helps the virus enter host cells.

  • HIV RNA: Genetic material of HIV, coded in single-stranded RNA.

  • HIV Capsid: Protective coating that houses the RNA.

  • HIV Enzymes: Proteins that carry out steps in the HIV life cycle.

  • Reverse Transcriptase: Converts viral RNA to DNA.

  • Integrase: Integrates viral DNA into host's genome.

  • Protease: Assists in the maturation of viral proteins.

  • HIV Glycoproteins: The spikes projecting from the viral envelope (specifically gp120 and gp41) essential for binding to host cells.

• Further Details:

  • Types of HIV:

  • HIV-1: Predominantly found worldwide, mutates rapidly.

  • HIV-2: Less transmissible, primarily in West Africa, has a longer incubation period before progressing to illness.

Retrovirus

• Retrovirus Definition:

  • A type of virus that uses RNA as its genetic material and replicates by reverse transcription.

  • Unlike traditional viruses, retroviruses can integrate their genetic material into the host's DNA.

• HIV's replication process:

  1. HIV RNA enters host cell.

  2. Reverse Transcriptase converts RNA to single-stranded DNA (ssDNA).

  3. ssDNA is converted to double-stranded DNA (dsDNA) and integrated into host genome.

  4. Viral genes are transcribed and translated into proteins.

  5. New viral particles assemble and bud out of the host cell.

Section 2: HIV/AIDS Cases and Facts

• AIDS:

  • Definition: Acquired Immunodeficiency Syndrome, a late stage of HIV infection characterized by a severely compromised immune system (CD4 count < 200 cells/mm³).

• HIV Statistics:

  • Global: 36 million infected with HIV globally (2000 estimates).

  • U.S. Cases: 1.155 million living with HIV; 770,000 AIDS cases and 448,000 deaths reported by end of 2000.

  • Annual New Infections:

  • Approximately 40,000 new infections in the U.S. annually.

• Transmission:

  • HIV can be transmitted through:

  1. Blood

  2. Semen

  3. Vaginal secretions

  4. Breast milk

  • Sexual transmission risk increases with existing sexually transmitted infections (STIs).

Section 3: Symptoms and Diagnosis

• Initial Infection Symptoms:

  • Many individuals remain asymptomatic for years or decades.

  • Common early symptoms may include fever, fatigue, rashes, and swollen lymph nodes.

• Diagnosis:

  • ELISA Test: Primary screening tool for HIV infection. Confirmed by Western Blot test.

  • P24 Antigen Test: Detects HIV earlier than antibody tests.

  • Regular monitoring of CD4+ counts and viral load is essential for managing HIV infection and guiding treatment decisions.

Section 4: Prevention and Treatment

• Prevention:

  • Adopting preventive strategies such as safe sex practices and abstinence can significantly lower the risk of HIV infection.

  • Research is ongoing for vaccines; no fully effective vaccine is currently available.

• Treatment Options:

  • Classes of antiretroviral drugs available include:

  1. Nucleoside reverse transcriptase inhibitors (NRTIs)

  2. Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

  3. Protease inhibitors

  • Combination therapies are preferred to avoid drug resistance and improve efficacy.

  • Treatment can reduce viral loads to undetectable levels, allowing for healthier lives with HIV.

Prognosis

• Impact of HIV Treatment:

  • With effective treatment, many individuals live for many years, transforming AIDS into a manageable condition.

  • While no cure exists, advancements in treatment continue to improve life expectancy and quality of life for those living with HIV/AIDS.

• Future Research:

  • Ongoing efforts focus on discovering a viable cure and effective vaccines to prevent and manage HIV infections in the global population.