HIV Infection and Dynamics Overview

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Questions and Answers

What is the primary surface antigen expressed by certain subsets of monocytes that allows them to bind HIV?

CCR5 chemokine receptor

T-cell receptor

CD4 surface antigen (correct)

CD8 antigen

Which cells are primarily infected by HIV in the brain?

CD4 T cells

Neurons

B cells

Monocytes and macrophages (correct)

What characterizes the initial infections after HIV transmission?

High levels of CD8 T-cell response

Macrophage-tropic strains of HIV predominating (correct)

T-tropic strains of HIV predominating

Total absence of viral strains

HIV superinfection refers to which of the following?

Infection with a second strain of HIV after the initial infection Signup and view all the answers

What syndrome is characterized by significant suppression of the immune system in HIV-infected individuals?

AIDS Signup and view all the answers

What type of infections are common in individuals with AIDS?

Opportunistic infections and unusual neoplasms Signup and view all the answers

What role do monocytes and macrophages play in HIV infection?

They serve as major reservoirs for HIV Signup and view all the answers

Which of these symptoms is typically associated with acute HIV infection?

Night sweats Signup and view all the answers

Which of the following is a leading cause of morbidity and mortality in HIV-infected persons?

Liver disease due to coinfection Signup and view all the answers

What receptors are involved in the binding of HIV to macrophages?

CD4 and CCR5 chemokine receptor Signup and view all the answers

What is the main consequence of CD4 T-cell dysfunction associated with HIV infection?

Development of opportunistic infections and neoplasms Signup and view all the answers

What primarily indicates the advanced stage of HIV infection?

Higher levels of detectable virus in plasma Signup and view all the answers

How does the HIV reverse transcriptase affect the virus's mutation rate?

It contributes to a high inherent error rate, increasing mutation frequency Signup and view all the answers

Which statement best describes the characteristics of HIV strains found in late-stage disease compared to early infection?

They are more virulent and cytopathic Signup and view all the answers

What is the role of CD4 T lymphocytes in the immune response?

They help activate macrophages and coordinate immune functions Signup and view all the answers

What is a consequence of laboratory adaptation of HIV primary isolates in immortalized T-cell lines?

Loss of ability to infect monocytes and macrophages Signup and view all the answers

What happens to CD4 T-cell counts after primary HIV infection?

They show a sharp decrease Signup and view all the answers

What is a potential outcome of untreated HIV infection over time?

Risk of opportunistic diseases with low CD4 counts Signup and view all the answers

What is the primary method by which HIV can survive and be transported in the body?

By infecting macrophages Signup and view all the answers

How long is the average interval between primary HIV infection and the first appearance of clinical disease in adults?

8–10 years Signup and view all the answers

Which symptom is a common part of the prodrome associated with a serious HIV infection in adults?

Weight loss Signup and view all the answers

What is the significance of the plasma viral load in HIV patients?

It reflects the total number of infected cells Signup and view all the answers

Which organ system experiences major disease symptoms as a result of HIV infection?

Gastrointestinal tract Signup and view all the answers

Which cells play a central role in generating specific immune responses to HIV?

Lymphocytes in lymphoid organs Signup and view all the answers

What is one of the serious symptoms that can develop as HIV infection progresses?

Shortness of breath Signup and view all the answers

Which of the following is NOT a symptom mentioned as part of the HIV-associated prodrome?

Joint pain Signup and view all the answers

Where does HIV replication predominantly occur during the asymptomatic period?

In lymphoid tissues Signup and view all the answers

What causes the continual rounds of viral replication in HIV infected patients?

Macrophage production of HIV Signup and view all the answers

What role do macrophages play in HIV infection?

They carry the virus and help seed other tissues. Signup and view all the answers

Which characteristic of lentiviruses distinguishes them from other retroviruses?

They can infect nondividing, terminally differentiated cells. Signup and view all the answers

How do individuals with homozygous deletions in CCR5 respond to HIV infection?

They are protected from HIV-1 infection. Signup and view all the answers

What factor contributes to the long-term persistence of HIV infection in hosts?

Continuous mutations lead to new antigenic variants. Signup and view all the answers

What is the main target for antiretroviral therapies related to HIV entry?

The coreceptor needed for HIV fusion with cells. Signup and view all the answers

What is a characteristic difference between M-tropic and T-tropic strains of HIV-1?

M-tropic strains are associated with earlier stages of infection, while T-tropic strains are linked to progression to AIDS. Signup and view all the answers

What is the primary effect of HIV replication on CD4 T lymphocytes?

Leads to their depletion and death. Signup and view all the answers

Which receptor is crucial for HIV entry into CD4 T lymphocytes?

CXCR4 chemokine receptor Signup and view all the answers

What occurs to memory T cells during a successful antiretroviral therapy regimen?

They persist without significant virus gene expression. Signup and view all the answers

How does the size of the latent HIV reservoir change during long-term successful treatment?

It remains stable with little change over time. Signup and view all the answers

What happens to memory T cells when they are exposed to antigens or if drug therapy is stopped?

They become activated and can release infectious virus. Signup and view all the answers

What is the primary reason fewer than 1 per million resting CD4 T cells harbor latent HIV-1 provirus?

Latency restricts the expression of viral genes. Signup and view all the answers

What type of immune cells does HIV predominantly infect during the initial stages of infection?

CD4 T lymphocytes Signup and view all the answers

Which of the following is a consequence of HIV's impact on CD4 T cells?

Reduced ability to control secondary infections. Signup and view all the answers

What transition occurs in HIV strains as the disease progresses towards AIDS?

A shift from M-tropic to T-tropic strains. Signup and view all the answers

Study Notes

HIV Infection Dynamics

After primary infection, HIV rapidly disseminates, resulting in a significant decline of CD4 T cells.
The immune response initially reduces viral load, leading to a prolonged clinical latency phase.
HIV RNA is consistently detectable in plasma, indicating ongoing viral presence even during latency.
CD4 T-cell counts decrease progressively, increasing the risk of opportunistic infections once they fall below critical levels.

Viral Evolution and Pathogenesis

High inherent error rate of HIV reverse transcriptase leads to daily mutations, resulting in diverse viral quasispecies.
Laboratory adaptations can lead to loss of the virus's ability to infect monocytes and macrophages.
Advanced HIV strains are typically more virulent and cytopathic compared to early strains.

Role of Monocytes and Macrophages

Monocytes and macrophages significantly contribute to HIV dissemination and pathogenesis.
Specific subsets of monocytes express CD4, enabling HIV binding via the CCR5 receptor.
These cells serve as reservoirs for HIV, capable of transporting the virus to various organs, including the brain.

Clinical Manifestations

Acute HIV symptoms include fatigue, rash, headache, nausea, and night sweats.
AIDS is marked by severe immune suppression, leading to opportunistic infections (e.g., Kaposi sarcoma).
Prodromal symptoms may encompass chronic diarrhea, weight loss, fever, and lymphadenopathy.

Immune System Impact and Infections

Infection leads to profound CD4 T lymphocyte dysfunction, resulting in a wide range of complications, including opportunistic infections and neoplasms.
HIV superinfection (infection with multiple strains) is rare but documented, with cases occurring even amid strong immune responses.

Lymphoid Organ Involvement

Lymphoid organs are crucial for HIV infection; only a small fraction of lymphocytes circulate in peripheral blood.
Germinal centers in lymph nodes play a vital role in trapping antigens and stimulating immune responses.

Plasma Viral Load and Prognosis

Plasma viral load serves as a critical prognostic marker; continual viral replication occurs throughout the infection.
The viral set point varies among individuals and correlates with immune system status.

CD4 T Cells and Latency

HIV primarily targets CD4 T lymphocytes, leading to their depletion through direct viral replication and indirect mechanisms.
Memory T cells serve as a long-lasting reservoir for latent HIV, with minimal gene expression detectable in these cells.

Virus Entry and Coreceptors

HIV utilizes CXCR4 and CCR5 chemokine receptors for cell entry, found on various immune and non-immune cell types.
Some individuals possess genetic mutations in CCR5 that confer resistance to HIV infection.

Long-term Infection and Treatment Challenges

HIV infection is lifelong with persistent mutations, complicating treatment as new viral variants emerge.
Antiretroviral therapies can manage infections but do not eliminate latent reservoirs, requiring ongoing vigilance and management.

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Description

This quiz covers key concepts related to HIV infection dynamics, including the immune response, viral evolution, and the role of monocytes and macrophages. It discusses the progression of HIV and its impact on CD4 T-cell counts and overall health. Test your understanding of these critical topics in HIV pathogenesis.