ORAL REVALIDA 3 Flashcards
What family does HIV belong to?
Retroviridae
What disease does HIV cause?
Acquired Immunodeficiency Syndrome (AIDS)
What are the two main HIV serogroups?
• HIV-1 (predominant, found worldwide).
• HIV-2 (mainly in West Africa).
What are the three subtypes of HIV-1?
M, N, and O, with M being the major subtype.
What cells does HIV bind to?
CD4+ T helper cells, monocytes, and macrophages
What role do co-receptors play in HIV infection?
They assist viral binding to host cells.
How does HIV enter the host cell?
It penetrates the plasma membrane, releasing its RNA.
What enzyme transcribes HIV RNA into DNA?
Reverse transcriptase.
How is viral DNA integrated into the host genome?
Using the viral enzyme integrase.
How does HIV replicate inside the host cell?
- Viral DNA is transcribed into mRNA.
- mRNA is translated into viral proteins.
- New viruses bud from the host cell.
What is the effect of HIV replication on the immune system?
It kills infected T helper cells, reducing their number over time.
When do HIV antibodies first appear?
Around 12 weeks after infection.
What tests detect these initial antibodies?
ELISA and Western blot.
What are neutralizing antibodies, and when do they appear
• Antibodies that interfere with viral infection.
• Appear 1 year after infection.
Why is the immune system unable to eliminate HIV?
HIV undergoes antigenic variation, allowing it to evade the immune response.
What happens to CD4+ T helper cells as HIV progresses?
They decrease, leading to worsening immune deficiency
Why is the loss of T helper cells critical?
They are essential for both humoral and cellular immunity.
How does HIV affect the CD4:CD8 ratio?
It decreases from the normal 2:1 ratio.
How does HIV affect other immune cells?
• Decreased natural killer (NK) cell activity.
• Defective monocyte and macrophage chemotaxis.
• Increased release of interleukin-1 and cachectin by monocytes.
How is HIV-1 transmitted?
Through:
• Unprotected sex
• Contaminated blood/products
• Contaminated needles
• Perinatal transmission
AIDS in the us
AIDSVis the leading cause of death in people aged 20–35 in the US
What are the symptoms of acute HIV infection?
Usually asymptomatic, but may resemble infectious mononucleosis (IM).
What is clinical latency in HIV?
A stage where the virus replicates in lymphoid tissue without major symptoms.
What is AIDS-related complex (ARC)?
A stage where opportunistic infections (e.g., Candida, herpes simplex, CMV) begin as T cells decline
What defines full-blown AIDS?
Severe CD4+ T cell depletion and life-threatening opportunistic infections/cancers, including:
• Esophageal candidiasis
• Cryptococcosis
• Cytomegalovirus (CMV) & herpes simplex infections
• Pneumocystis jiroveci pneumonia (PJP)
• Kaposi’s sarcoma
How is the severity of HIV/AIDS staged?
By CD4+ T cell counts and the presence of opportunistic infections.
What is the primary screening test for HIV?
ELISA, which detects HIV antibodies and antigens.
How is an HIV diagnosis confirmed?
By a Western blot or immunofluorescence assay.
What criteria make a Western blot positive?
The presence of at least two of the following bands:
• p24
• gp41
• gp120/gp160
What molecular tests detect HIV?
• Genetic probes detect replicating viruses.
• RT-PCR (Reverse Transcriptase PCR) detects HIV-1 and HIV-2 nucleic acids.
• Indirect immunofluorescence assay detects HIV antigen in infected cells.
What is the main HIV treatment?
Antiretroviral therapy (ART), including Zidovudine (Retrovir).
How does Zidovudine help?
• Increases survival time
• Decreases mortality
What are the roles of GP-120 and GP-41 inhibitors in HIV treatment?
• GP-120 inhibitors: Prevent virus attachment and entry into cells.
• GP-41 inhibitors: Block virus fusion with immune cells.
Does ART cure HIV?
No, it suppresses the virus but does not eliminate it. The virus can still hide in tissues (latency phase) and reactivate if treatment stops.
What are the six classes of antiretroviral drugs?
- Attachment Inhibitors
- Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
- Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
- Protease Inhibitors
- Integrase Inhibitors
- Pharmacokinetic Enhancers (Boosters)
What are the key HIV prevention strategies?
• Modifying sexual behavior (e.g., using condoms, reducing partners)
• Protecting blood supply (e.g., donor screening, heating plasma at 68°C for 24 hours)
• Encouraging self-referral among high-risk groups
Why is an HIV vaccine difficult to develop?
• Rapid mutations create multiple strains.
• HIV hides in immune cells, making it hard to target.
• The virus infects the very immune cells a vaccine would stimulate.
