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Questions and Answers
What is the primary body fluid where high titers of HIV are found?
What is the primary body fluid where high titers of HIV are found?
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Which of the following increases the risk of sexual HIV transmission dramatically?
Which of the following increases the risk of sexual HIV transmission dramatically?
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What percentage of perinatal HIV infections in Africa is attributed to breastfeeding?
What percentage of perinatal HIV infections in Africa is attributed to breastfeeding?
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Which of the following is the estimated risk of transmission for healthcare workers after a needlestick incident?
Which of the following is the estimated risk of transmission for healthcare workers after a needlestick incident?
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What is defined as treatment success for HIV regarding viral load?
What is defined as treatment success for HIV regarding viral load?
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What classification of retroviruses is primarily based on genomic sequence and evolutionary relatedness?
What classification of retroviruses is primarily based on genomic sequence and evolutionary relatedness?
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Which of the following statements regarding HIV-1 and HIV-2 is accurate?
Which of the following statements regarding HIV-1 and HIV-2 is accurate?
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What does the gag gene in the HIV genome encode?
What does the gag gene in the HIV genome encode?
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As of the end of 2022, which region has the highest prevalence of HIV among adults?
As of the end of 2022, which region has the highest prevalence of HIV among adults?
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Which of the following best describes the structure of the HIV virion?
Which of the following best describes the structure of the HIV virion?
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What was the estimated number of people living with HIV globally at the end of 2022?
What was the estimated number of people living with HIV globally at the end of 2022?
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Which antiretroviral enzymes are encoded by the pol gene in HIV?
Which antiretroviral enzymes are encoded by the pol gene in HIV?
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What was the observed percentage reduction in HIV-related deaths since 2010?
What was the observed percentage reduction in HIV-related deaths since 2010?
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What best describes the state of latency in HIV infection?
What best describes the state of latency in HIV infection?
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Which component is essential for the production of infectious HIV?
Which component is essential for the production of infectious HIV?
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Which of the following is considered a cellular reservoir for HIV?
Which of the following is considered a cellular reservoir for HIV?
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What is the role of dendritic cells in HIV infection?
What is the role of dendritic cells in HIV infection?
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Which cytokines are primarily released by dendritic cells in response to HIV infection?
Which cytokines are primarily released by dendritic cells in response to HIV infection?
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What is the main tissue reservoir for HIV in the human body?
What is the main tissue reservoir for HIV in the human body?
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Which immune cells act as cytolytic cells responding to HIV infection?
Which immune cells act as cytolytic cells responding to HIV infection?
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What aspect of the provirus ensures that HIV infection remains permanent?
What aspect of the provirus ensures that HIV infection remains permanent?
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Which viral characteristic is primarily dependent on the expression of mRNA?
Which viral characteristic is primarily dependent on the expression of mRNA?
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What best describes low-level chronicity in HIV infection?
What best describes low-level chronicity in HIV infection?
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What is the primary function of HIV-specific CD8+ CTLs?
What is the primary function of HIV-specific CD8+ CTLs?
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What role do INF-γ and chemokines play in the immune response to HIV?
What role do INF-γ and chemokines play in the immune response to HIV?
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What is a significant reason for the failure of the immune system to eliminate HIV despite a robust response?
What is a significant reason for the failure of the immune system to eliminate HIV despite a robust response?
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How do HIV envelope glycoproteins complicate the immune response?
How do HIV envelope glycoproteins complicate the immune response?
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What effect does the infection with HIV have on CD4+ T-lymphocytes?
What effect does the infection with HIV have on CD4+ T-lymphocytes?
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Which factor contributes to the establishment of persistent HIV infection?
Which factor contributes to the establishment of persistent HIV infection?
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What leads to impaired functions of T- and B-lymphocytes in response to HIV?
What leads to impaired functions of T- and B-lymphocytes in response to HIV?
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Which statement best describes the role of B lymphocytes in response to HIV?
Which statement best describes the role of B lymphocytes in response to HIV?
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What is the impact of cell-to-cell spread of HIV on the immune response?
What is the impact of cell-to-cell spread of HIV on the immune response?
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What is a consequence of high mutation rates in HIV?
What is a consequence of high mutation rates in HIV?
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What are the roles of the env gene in HIV?
What are the roles of the env gene in HIV?
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Which receptor is primarily used by HIV-1 to enter T lymphocytes?
Which receptor is primarily used by HIV-1 to enter T lymphocytes?
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What is the significance of the coreceptor in HIV entry into cells?
What is the significance of the coreceptor in HIV entry into cells?
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What effect do homozygous deletions in the CCR5 gene have on individuals?
What effect do homozygous deletions in the CCR5 gene have on individuals?
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In which part of the cell does the HIV RNA get integrated into the host DNA?
In which part of the cell does the HIV RNA get integrated into the host DNA?
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What role does reverse transcriptase play in HIV infection?
What role does reverse transcriptase play in HIV infection?
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Which coreceptor is associated with macrophage-tropic strains of HIV-1?
Which coreceptor is associated with macrophage-tropic strains of HIV-1?
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What triggers membrane fusion during HIV entry into the host cell?
What triggers membrane fusion during HIV entry into the host cell?
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What is the role of integrase in HIV replication?
What is the role of integrase in HIV replication?
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How does HIV initially interact with host cells?
How does HIV initially interact with host cells?
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Study Notes
Introduction to HIV
- HIV is a retrovirus, a spherical, enveloped RNA virus
- Its genome contains three structural genes (gag-pol-env)
- Gag encodes structural proteins (matrix, capsid, nucleocapsid)
- Pol encodes protease, reverse transcriptase, and integrase
- Env encodes the two membrane glycoproteins (SU gp120 and TM gp41)
- There are two main types: HIV-1 (most common) and HIV-2, which is less virulent
- HIV-2 is primarily found in West Africa
HIV Classification
- Classification is based on genomic sequencing, grouping by evolutionary relatedness
- This method is currently the most widely accepted classification system
HIV Epidemiology
- Globally, approximately 39 million people lived with HIV in 2022
- 1.5 million children are living with HIV (0-14 years)
- In 2022, 630,000 people died from HIV-related causes globally, a 51% decrease since 2010.
- 84,000 children died from HIV in 2022
- The WHO African region is significantly affected (3.6% of adults have HIV)
- The majority of people living with HIV globally live in this region
HIV Replication Cycle
- HIV replication starts with binding to the CD4 receptor and a coreceptor (CCR5 or CXCR4).
- The viral RNA is then released into the cytoplasm
- Reverse transcriptase makes a DNA copy of the RNA
- The DNA is integrated into the host's chromosomal DNA, becoming a provirus
- The provirus is duplicated with the host cell's DNA, so it's a permanent infection
- The process produces more viral RNA and proteins that assemble into new viruses, which bud from the cell.
HIV Receptors
- HIV uses the CD4 molecule and a coreceptor (CCR5 or CXCR4) for entry into cells.
- CCR5 is the predominant coreceptor for macrophage-tropic HIV-1 strains
- CXCR4 is the predominant coreceptor for lymphocyte- tropic HIV-1 strains
HIV Reservoir
- HIV reservoirs include memory CD4+ T cells, macrophages, brain microglia, and astrocytes, the most commonly occurring in the gut-associated lymphoid tissue.
Immune Response to HIV
- Early HIV infection is controlled by innate immunity (cytokines, phagocytes, NK cells)
- Adaptive immunity involves CD8+ T cells (cytotoxic T lymphocytes) to control viral replication and B cells to produce neutralizing antibodies
- Viral variability (mutation) allows HIV to evade the immune response, causing chronic infection.
- CD4+ T-lymphocytes are critically important but are often infected and killed by HIV
HIV Transmission
- High viral loads increase transmission risk
- Transmission occurs through sexual contact, blood exposure, or mother-to-child transmission.
- Sexual transmission risk is exacerbated by other STIs
- Health care workers are at risk through needlestick injuries
Pathogenesis and Course of HIV Infection
- Acute HIV infection is characterized by a flu-like illness, followed by a period of clinical latency which leads to chronic infection
- cART treatment reduces viral load, which slows progression
- People with cART can stay in chronic HIV infection stage for several decades before AIDS.
Opportunistic Infections
- AIDS patients are vulnerable to opportunistic infections due to immune deficiency.
- Many infections are typically harmless to healthy individuals but can be life-threatening in people with AIDS
HIV-related Cancers
- AIDS patients are at a higher risk of developing certain cancers, due to immune deficiency.
- Kaposi sarcoma is a notable example
HIV Diagnosis
- Testing methods include antibody tests, antigen/antibody combinations, and nucleic acid tests (NATs) for viral RNA.
- The window period between HIV infection and antibody detection can vary, impacting test results.
HIV Treatment/Care
- Anti-retroviral therapy (ART) is a standard approach to treat HIV infection.
- Treatment aims to reduce viral load, improve CD4 T-cell counts, and prevent opportunistic infections.
- Treatment timing and strategies are important, and adherence to the treatment regiment is vital.
- Periodic viral load and CD4+ T-cell counts are tracked and monitored to assess treatment efficacy.
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Description
This quiz covers essential information about HIV, a retrovirus known for its structure and classification. It highlights key genomic components and epidemiological data, including global statistics and regional impacts. Test your knowledge on what you learned about HIV's biological characteristics and its global context.
