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Questions and Answers
Why does HIV primarily target CD4+ cells in the human immune system?
Why does HIV primarily target CD4+ cells in the human immune system?
- HIV's gp120 protein specifically binds to the CD4 molecule on these cells. (correct)
- CD4+ cells lack the necessary defense mechanisms to prevent HIV entry.
- CD4+ cells are the only cells susceptible to viral infections.
- CD4+ cells directly produce the proteins required for HIV replication.
An individual with a homozygous genetic mutation in CCR5 would most likely exhibit which of the following characteristics?
An individual with a homozygous genetic mutation in CCR5 would most likely exhibit which of the following characteristics?
- Development of X4 strains of HIV earlier in the course of infection.
- Increased susceptibility to HIV infection due to enhanced viral entry.
- Resistance or immunity to HIV infection, especially from the R5 strain. (correct)
- Faster progression from HIV infection to AIDS due to increased viral load.
What is the primary function of reverse transcriptase in the HIV lifecycle?
What is the primary function of reverse transcriptase in the HIV lifecycle?
- Synthesizing a DNA copy from the viral RNA genome. (correct)
- Integrating viral RNA directly into the host cell's genome.
- Cleaving the viral polyprotein into functional viral proteins.
- Facilitating the initial attachment of the virus to the host cell.
During the chronic phase of HIV infection, what immunological event is most indicative of disease progression towards AIDS?
During the chronic phase of HIV infection, what immunological event is most indicative of disease progression towards AIDS?
Why is male-to-female HIV transmission more common in resource-limited settings compared to the United States?
Why is male-to-female HIV transmission more common in resource-limited settings compared to the United States?
Which of the following methods is most effective in preventing mother-to-child transmission of HIV?
Which of the following methods is most effective in preventing mother-to-child transmission of HIV?
What is the primary advantage of using an antibody/antigen combination test over a traditional antibody test for HIV screening?
What is the primary advantage of using an antibody/antigen combination test over a traditional antibody test for HIV screening?
How does antiretroviral therapy (ART) primarily benefit individuals infected with HIV?
How does antiretroviral therapy (ART) primarily benefit individuals infected with HIV?
During HIV replication, errors made by reverse transcriptase contribute to:
During HIV replication, errors made by reverse transcriptase contribute to:
Which of the following conditions is considered an 'AIDS-defining' condition, indicating progression to AIDS?
Which of the following conditions is considered an 'AIDS-defining' condition, indicating progression to AIDS?
Flashcards
What is HIV?
What is HIV?
Human Immunodeficiency Virus; targets immune cells, leading to immunodeficiency and increased risk of infections.
What is AIDS?
What is AIDS?
Acquired Immunodeficiency Syndrome; complications arising from HIV, marked by a severely compromised immune system.
What cells does HIV target?
What cells does HIV target?
CD4+ cells, including macrophages, T-helper cells, and dendritic cells, all crucial for immune response.
What is gp120?
What is gp120?
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What are HIV co-receptors?
What are HIV co-receptors?
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What is reverse transcriptase?
What is reverse transcriptase?
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What is the R5 strain of HIV?
What is the R5 strain of HIV?
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What is Antiretroviral Therapy (ART)?
What is Antiretroviral Therapy (ART)?
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How is HIV diagnosed?
How is HIV diagnosed?
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What is the X4 strain of HIV?
What is the X4 strain of HIV?
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Study Notes
Overview of HIV and AIDS
HIV (human immunodeficiency virus) targets immune cells, causing immunodeficiency, which increases infection and tumor risks. AIDS (acquired immunodeficiency syndrome) arises from HIV complications. There are two types: HIV-1 is common globally, while HIV-2 is rarer, found mainly in western Africa and southern Asia.
- rity of HIV-2.
HIV's Cellular Targets and Mechanisms
- HIV targets CD4+ cells, such as macrophages, T-helper cells, and dendritic cells, which possess the CD4 molecule. This molecule facilitates communication during immune responses. HIV uses the gp120 protein to attach to CD4 and also requires co-receptors (CXCR4 or CCR5) for entry. Some genetic mutations in CCR5 can confer resistance or slow disease progression.
Viral Structure and Replication
- HIV is a single-stranded, enveloped RNA retrovirus that uses reverse transcriptase to form proviral DNA, which integrates into host T-helper cell DNA. Immune cell activation leads to new virus production, while replication errors create diverse viral strains with specific host preferences.
Stages of HIV Infection
- IInitial entry of HIV often occurs through sexual intercourse. During acute infection, the R5 strain infects macrophages, dendritic cells, and T cells, with dendritic cells migrating to lymph nodes, causing increased HIV replication. Patients may experience flu-like symptoms. The immune system counters the virus, reducing it by 12 weeks, leading to the chronic phase, which lasts 2-10 years and damages the immune system. T cell counts typically remain above 500 cells/mm<sup>3</sup>. In the chronic phase, some develop X4 strains targeting T cells. T cell counts below 200 cells/mm<sup>3</sup> indicate AIDS, characterized by fever, fatigue, and opportunistic infections.
Transmission and Prevention
- Male-to-male transmission is the most common in the US, while male-to-female is more common in resource-limited settings.
- Female-to-male transmission can occur due to HIV presence in vaginal and cervical fluids.
- Over 75% of HIV cases are contracted from sexual intercourse.
- Other transmission routes include intravenous drug abuse and mother-to-child transmission.
- Less common modes include accidental needlesticks and blood transfusions.
Diagnosis and Treatment
- HIV tests include antibody tests, antibody/antigen tests, and RNA/DNA tests.
- Antibody tests detect antibodies made against HIV.
- Antigen tests and RNA tests detect the virus directly.
- The recommended screening test is the antibody/antigen test, which is better at identifying early infection.
- A confirmatory test (antibody or nucleic acids) is recommended following a positive screening test.
- There is currently no cure for AIDS, but treatment can help individuals live longer, healthier lives and reduce transmission risk.
- Antiretroviral therapy (ART), a combination of medicines, is the primary treatment method.
- ART slows down HIV replication, allowing the immune system to recover and fight off other infections.
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