Podcast
Questions and Answers
Why is HIV reverse transcriptase a significant factor in the virus's ability to evade immune responses and develop drug resistance?
Why is HIV reverse transcriptase a significant factor in the virus's ability to evade immune responses and develop drug resistance?
- It promotes the production of viral proteins that directly inhibit the function of cytotoxic T lymphocytes.
- It lacks proofreading ability, leading to frequent mutations and genetic variability in the virus. (correct)
- It facilitates the integration of viral DNA into the host cell's genome, allowing the virus to remain dormant indefinitely.
- It enhances the virus's ability to bind to CD4 receptors, increasing its infectivity.
During the chronic phase of HIV infection, what immunological process primarily contributes to the gradual depletion of CD4+ T cells?
During the chronic phase of HIV infection, what immunological process primarily contributes to the gradual depletion of CD4+ T cells?
- Antibody-dependent cell-mediated cytotoxicity (ADCC) targeting HIV-infected cells.
- Suppression of T cell proliferation by regulatory T cells (Tregs).
- Apoptosis of uninfected CD4+ T cells due to chronic immune activation and bystander effects.
- Direct viral lysis of infected CD4+ T cells and immune-mediated killing. (correct)
How do mutations in the CCR5 co-receptor gene impact HIV infection, and what is the basis for this effect?
How do mutations in the CCR5 co-receptor gene impact HIV infection, and what is the basis for this effect?
- Homozygous mutations prevent HIV from binding, heterozygous mutations result in fewer co-receptors, making it harder for the virus to spread. (correct)
- Mutations in CCR5 lead to increased expression of CXCR4, compensating loss of CCR5 function.
- Homozygous mutations enhance HIV entry into cells, whereas heterozygous mutations have no significant impact on viral entry.
- Mutations in CCR5 result in increased production of antibodies, ultimately neutralizing the virus.
What is the primary mechanism by which HIV establishes a latent reservoir within infected individuals, and why does this pose a challenge for curative therapies?
What is the primary mechanism by which HIV establishes a latent reservoir within infected individuals, and why does this pose a challenge for curative therapies?
How does the development of X4-tropic HIV strains during the chronic phase of infection contribute to disease progression, and what cellular mechanism underlies this phenomenon?
How does the development of X4-tropic HIV strains during the chronic phase of infection contribute to disease progression, and what cellular mechanism underlies this phenomenon?
What is the significance of monitoring viral load and CD4+ T cell counts in HIV-infected individuals, and how do these parameters guide clinical management?
What is the significance of monitoring viral load and CD4+ T cell counts in HIV-infected individuals, and how do these parameters guide clinical management?
How does HIV exploit normal immune cell activation pathways to enhance its own replication, and what specific cellular processes are involved?
How does HIV exploit normal immune cell activation pathways to enhance its own replication, and what specific cellular processes are involved?
What is the role of dendritic cells in the transmission and early pathogenesis of HIV infection, and how do they contribute to viral dissemination within the host?
What is the role of dendritic cells in the transmission and early pathogenesis of HIV infection, and how do they contribute to viral dissemination within the host?
What are the major challenges associated with developing a broadly neutralizing antibody-based vaccine for HIV, and what viral characteristics contribute to these challenges?
What are the major challenges associated with developing a broadly neutralizing antibody-based vaccine for HIV, and what viral characteristics contribute to these challenges?
Aside from sexual contact, IV drug use, and mother-to-child transmission, what other less common modes of HIV transmission exist, and what factors contribute to their lower incidence?
Aside from sexual contact, IV drug use, and mother-to-child transmission, what other less common modes of HIV transmission exist, and what factors contribute to their lower incidence?
Flashcards
HIV (Human Immunodeficiency Virus)
HIV (Human Immunodeficiency Virus)
Virus that targets immune system cells, leading to immunodeficiency and increased risk of infections and tumors.
AIDS (Acquired Immunodeficiency Syndrome)
AIDS (Acquired Immunodeficiency Syndrome)
Advanced stage of HIV infection where the immune system is severely compromised, leading to opportunistic infections and tumors.
CD4+ Cells
CD4+ Cells
Cells with CD4 molecules on their surface, including T helper cells, macrophages, and dendritic cells, targeted by HIV.
GP120
GP120
Signup and view all the flashcards
Chemokine Co-receptors
Chemokine Co-receptors
Signup and view all the flashcards
Reverse Transcriptase
Reverse Transcriptase
Signup and view all the flashcards
Viral Mutations
Viral Mutations
Signup and view all the flashcards
Opportunistic Infections
Opportunistic Infections
Signup and view all the flashcards
Antiretroviral Therapy (ART)
Antiretroviral Therapy (ART)
Signup and view all the flashcards
Single-Stranded RNA Retrovirus
Single-Stranded RNA Retrovirus
Signup and view all the flashcards
Study Notes
- HIV (Human Immunodeficiency Virus) is an icosahedral, enveloped, positive-sense, single-stranded RNA retrovirus.
Key Terms
- AIDS (Acquired Immunodeficiency Syndrome)
- CD4+ cells
- Chemokine co-receptors
- Reverse transcriptase
- Viral mutations
- Opportunistic infections
HIV Overview
- HIV targets cells in the immune system, leading to immunodeficiency over time.
- Immunodeficiency increases the risk of infections and tumors, referred to as AIDS.
- HIV-1 is more common globally, including in the U.S., while HIV-2 is less common and mainly found in West Africa and South Asia.
Cellular Targets and Mechanisms
- HIV targets CD4+ cells like macrophages, T helper cells, and dendritic cells.
- GP120, a protein on HIV's envelope, attaches to the CD4 molecule on these cells.
- HIV requires a co-receptor (CCR5 or CXCR4) in addition to CD4 to enter the cell.
- CCR5 is found on macrophages, dendritic cells, and T cells, important during early infection.
- CXCR4 is mainly found on T cells and becomes important in later stages of the infection.
- Some individuals with homozygous mutations in CCR5 are resistant/immune to HIV.
- Heterozygous mutations in CCR5 can slow disease progression.
Viral Replication
- HIV injects single-stranded RNA into the T helper cell.
- Reverse transcriptase is used to transcribe a complementary double-stranded piece of proviral DNA, which then integrates into the host cell's DNA.
- Activation of immune cells inadvertently transcribes and translates new HIV viruses.
- HIV is prone to making errors during replication, leading to mutations and different viral strains.
- Viral tropism refers to the preference of different HIV strains for specific host cells.
Disease Progression
- Acute infection involves the R5 strain of HIV (binds to CCR5) getting into macrophages, dendritic cells, and T cells, dendritic cells capture the virus and migrate to the lymph nodes.
- The R5 strain replicates rapidly, causing flu-like symptoms.
- The immune system responds, controlling the virus, and the patient enters the chronic/latent phase.
- Chronic/latent phase can last 2-10 years, with a slow decline in T cells (1-2 billion lost daily).
- During the chronic phase, some patients develop the X4 strain of HIV (targets CXCR4), found mainly on T cells and can accelerate CD4+ T cell destruction.
- When T cell counts drop below 200 cells per cubic millimeter, the condition progresses to AIDS.
- AIDS is characterized by persistent fever, fatigue, weight loss, diarrhea, opportunistic infections, and certain tumors.
- Common AIDS-defining conditions include recurrent bacterial pneumonia, Pneumocystis pneumonia, candidiasis (esophagus), Kaposi sarcoma, and primary lymphoma of the brain.
Transmission and Diagnosis
- Male-to-male transmission is most common in the U.S., while male-to-female transmission is more common in resource-limited settings.
- Over 75% of HIV cases are contracted through sexual intercourse.
- Other transmission routes include intravenous drug abuse and mother-to-child transmission (via placenta, during delivery, or breast milk).
- Less common modes of transmission are accidental needle sticks and blood transfusions.
- Diagnostic tests include antibody tests, antigen tests, and RNA/DNA tests.
- Antibody tests detect antibodies against HIV, while antigen and RNA tests detect the virus directly, DNA tests look for copies of the viral RNA.
- The recommended screening test is the antibody/antigen test, with a confirmatory test for positive results.
- There is no cure for AIDS, but antiretroviral therapy (ART) can help people with AIDS live longer and healthier lives and reduce the risk of transmission.
- ART involves a combination of medicines that slow down HIV replication, allowing the immune system to recover.
Treatment
- ART slows down replication, prevents AIDS, and reduces transmission risk.
- HIV treatment is lifelong but allows people to live normal lives.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
