The Human Immunodeficiency Virus (HIV) is a virus that attacks the body's immune system, specifically the CD4 cells (T cells), leading to a progressive failure of the immune system. When left untreated, HIV can lead to Acquired Immunodeficiency Syndrome (AIDS). The HIV virus is not a human cancer virus by itself, but it is associated with an increased risk of certain cancers due to the immunocompromised state it induces.
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1. Human Immunodeficiency Virus (HIV)
A. Characteristics
- Type: HIV is a retrovirus belonging to the lentivirus subgroup.
- Genomic Structure: It has a single-stranded RNA genome.
- Envelop: The virus has an outer lipid envelope derived from the host cell membrane, containing viral proteins.
- Subtypes: There are two main types of HIV: HIV-1 (most common and virulent) and HIV-2 (less common and generally less severe).
B. Transmission
- Modes: HIV is primarily transmitted through:
- Unprotected sexual contact (anal, vaginal)
- Sharing needles or syringes with an infected person
- Blood transfusions or organ transplants from an infected individual
- From mother to child during childbirth or breastfeeding
- Not Transmissible By: Casual contact, insects, sharing utensils, or hugging.
C. Pathogenesis
- Entry: HIV enters the body through mucous membranes (often via sexual contact or through the bloodstream).
- Immune Response: The virus targets CD4+ T cells, leading to their gradual depletion.
- Chronic Infection: This prolonged infection results in a weakened immune system, making the individual susceptible to opportunistic infections and certain cancers, such as Kaposi's sarcoma and non-Hodgkin lymphoma.
D. Treatment
- Antiretroviral Therapy (ART): There is no cure for HIV, but effective treatment is available. ART involves a combination of HIV medicines that help control the virus, helping people with HIV live longer, healthier lives.
- Pre-exposure prophylaxis (PrEP): A preventive treatment for high-risk individuals to reduce the likelihood of contracting HIV.
E. Prevention
- Safe Practices:
- Use of condoms during sexual intercourse
- Regular HIV testing and screening
- Avoid sharing needles
- Pre-exposure prophylaxis (PrEP) for at-risk populations
- Post-exposure prophylaxis (PEP) after potential exposure
- Education: Comprehensive sex education and awareness campaigns to reduce stigma.
- Mother-to-child transmission (MTCT): Pregnant women with HIV can take ART to significantly reduce the risk of transmission to the baby.
2. Human Cancer Viruses Associated with HIV
While not cancer viruses themselves, HIV-infected individuals are at heightened risk for several malignancies due to their immunocompromised state. The most prevalent cancer viruses associated with increased risk in this population include:
- Human Papillomavirus (HPV): Leading cause of cervical and other cancers.
- Epstein-Barr Virus (EBV): Associated with certain lymphomas, notably Burkitt's lymphoma.
- Kaposi's Sarcoma-associated Herpesvirus (KSHV): Responsible for Kaposi's sarcoma, a common cancer in AIDS patients.
Key Points
- While HIV itself is not classified as a cancer virus, it plays a pivotal role in the development and progression of multiple cancers by weakening the immune system. Preventing HIV infection and managing it effectively are critical for reducing cancer risk associated with the virus.
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