RETROVIRUS – HIV
Definition:
- Human Immunodeficiency Virus (HIV) is a retrovirus that attacks the body's immune system.
Types:
- HIV-1
- HIV-2
Causes:
- HIV is caused by the transmission of infected body fluids from one person to another.
- This can occur through unprotected sex, sharing needles, or from mother to child during birth.
Morphology:
- HIV is a spherical virus with a diameter of 120 nanometers.
- It has a lipid envelope and a core containing two types of RNA (single-stranded and double-stranded).
- The virus has two main proteins: gp120 and gp41.
- It also has two enzymes: reverse transcriptase and protease.
Major Antigens:
- gp120 (glycoprotein 120)
- gp41 (glycoprotein 41)
- p24 (capsid protein)
- p55 (matrix protein)
- p18 (envelope protein)
Pathogenesis:
- HIV enters the body through the bloodstream or lymphatic system.
- The virus infects CD4+ T cells (helper T cells).
- The virus replicates inside the cells, producing new viral particles.
- The viral particles are released into the bloodstream, infecting more CD4+ T cells.
→ HIV infection → CD4+ T cell infection → Viral replication → New viral particles release → Infection of more CD4+ T cells
Memory Trick:
- H.I.V. = Helps Infect Viruses
Clinical Features:
- Acute retroviral syndrome (ARS)
- Chronic HIV infection
- AIDS (Acquired Immunodeficiency Syndrome)
ARS:
- Fever
- Headache
- Fatigue
- Rash
- Enlarged lymph nodes
Chronic HIV Infection:
- Persistent fever
- Weight loss
- Diarrhea
- Fatigue
- Skin rashes
AIDS:
- Severe weight loss
- Recurring infections
- Cancer
- Neurological problems
Complications:
- Opportunistic infections (e.g., pneumonia, tuberculosis)
- Cancer (e.g., Kaposi's sarcoma, lymphoma)
- Neurological problems (e.g., dementia, seizures)
Confirmatory Tests:
- ELISA (enzyme-linked immunosorbent assay)
- Western blot
- HIV RNA test
Management:
- Antiretroviral therapy (ART)
- HIV prevention counseling
- Safe sex practices
- Avoidance of sharing needles
ART:
- Combination of antiretroviral medications to suppress HIV replication
- Examples: zidovudine, lamivudine, and efavirenz
Prevention:
- HIV testing and counseling
- Safe sex practices (condoms, dental dams)
- Avoidance of sharing needles
- PrEP (pre-exposure prophylaxis)