HIV Overview and Case Definitions

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Questions and Answers

Which statement accurately describes the pathology of HIV?

HIV can infect both humans and animals.

HIV causes immune dysfunction by attacking CD4 T cells. (correct)

HIV primarily targets red blood cells in the body.

HIV leads to increased production of CD4 cells.

What is a common clinical presentation of acute HIV infection?

Flu-like symptoms occurring 2-6 weeks post-exposure. (correct)

Nausea and abdominal pain lasting 2 weeks.

Development of chronic cough within 1 month.

Persistent joint pain lasting longer than 3 months.

Which laboratory test result is most indicative of HIV infection?

Normal CD4 count of 800 cells/mm3.

Elevated white blood cell count.

Presence of high viremia shortly after exposure. (correct)

Low cholesterol levels.

What happens to the CD4 count in an asymptomatic (latent) stage of HIV infection?

The CD4 count gradually decreases over time. (B) Signup and view all the answers

Which condition can be a complication associated with a CD4 count below 200 cells/mm3?

A higher risk of opportunistic infections. (C) Signup and view all the answers

What is a recognized clinical indication for antiretroviral drugs?

To prevent the replication of HIV in infected individuals. (B) Signup and view all the answers

Which symptom is frequently associated with acute HIV infection but not often recognized?

Skin rashes. (C) Signup and view all the answers

How does HIV primarily affect the body's defense mechanism?

By directly attacking and destroying CD4 T cells. (B) Signup and view all the answers

In what time frame can symptoms of acute HIV infection typically appear after exposure?

2 weeks to 6 weeks post-exposure. (D) Signup and view all the answers

What is the potential outcome for individuals 10 years post-HIV infection regarding CD4 counts?

50% may progress to AIDS. (D) Signup and view all the answers

What body fluids are associated with high titers of HIV?

Blood and semen (A) Signup and view all the answers

Which factor significantly increases the risk of sexual transmission of HIV?

Presence of other sexually transmitted diseases (C) Signup and view all the answers

In untreated women, what is the range of mother-to-infant transmission rates of HIV?

13% to 40% (A) Signup and view all the answers

What is defined as treatment success for patients undergoing antiretroviral therapy (ART)?

A decline in viral load to < 50 copies/mL within 6 months (A) Signup and view all the answers

Which route of HIV transmission is NOT mentioned as a risk during the perinatal period?

Infection via maternal vaccination (B) Signup and view all the answers

Which statement correctly identifies the type of HIV that is most common globally?

HIV-1, which is widely prevalent worldwide (A) Signup and view all the answers

What is a defining feature of the structure of the HIV virion?

It has a cylindrical core and is an enveloped RNA virus. (C) Signup and view all the answers

What accounts for the classification of retroviruses based on their genomic sequence?

Their evolutionary relatedness. (C) Signup and view all the answers

Which gene in the HIV genome encodes for the structural proteins of the virus?

gag gene, which encodes matrix, capsid, and nucleocapsid proteins (D) Signup and view all the answers

What major HIV-related statistic indicates the severity of the issue in the WHO African region?

1 in every 25 adults are living with HIV. (A) Signup and view all the answers

What method is NOT commonly used in the laboratory for HIV testing?

Fluorescent microscopy (D) Signup and view all the answers

What can be inferred about HIV's impact on global health based on the reported number of deaths in 2022?

HIV continues to remain a significant global health issue despite a reduction in deaths. (C) Signup and view all the answers

How has the global number of people living with HIV changed compared to historical data?

It has shown a steady increase reaching approximately 40 million. (C) Signup and view all the answers

What role does the env gene play in the HIV structure?

It encodes two membrane glycoproteins in the viral envelope. (C) Signup and view all the answers

What is necessary for the HIV virus to enter a host cell after binding to CD4?

A secondary coreceptor (B) Signup and view all the answers

Which HIV coreceptor is primarily used by macrophage-tropic strains?

CCR5 (B) Signup and view all the answers

What is the function of reverse transcriptase in the HIV replication cycle?

It converts the viral RNA genome into DNA. (B) Signup and view all the answers

What occurs after HIV RNA is released into the cytoplasm?

Uncoating of the virion. (D) Signup and view all the answers

Which mutation offers some level of protection against HIV-1 infection?

Homozygous deletion in the CCR5 gene (C) Signup and view all the answers

What enzyme catalyzes the integration of linear DNA into host DNA during HIV replication?

Integrase (A) Signup and view all the answers

Which protein undergoes conformational changes to enable HIV membrane fusion?

gp41 (A) Signup and view all the answers

What is the first step in the replication cycle of HIV upon entering a host cell?

Binding to the CD4 receptor (D) Signup and view all the answers

Which of the following is NOT a role of the env gene in HIV?

Regulates viral gene expression (B) Signup and view all the answers

Which state of the provirus occurs when there is no viral expression?

Latency (D) Signup and view all the answers

What is the primary reservoir of HIV in the human body?

Gut-associated lymphoid tissue (C) Signup and view all the answers

Which cytokine is NOT specifically mentioned as being released by dendritic cells in response to HIV?

IL-6 (C) Signup and view all the answers

What role do proteases play in the HIV replication cycle?

They are needed for the maturation of an infectious virus. (B) Signup and view all the answers

Which innate immune cells are known to destroy pathogen-infected cells during HIV infection?

NK cells (D) Signup and view all the answers

Which feature distinguishes ‘low level chronicity’ in the context of HIV infection?

Sporadic expression of viral particles (B) Signup and view all the answers

What type of immunity do dendritic cells transition from upon recognizing HIV?

Innate to adaptive immunity (A) Signup and view all the answers

Which cellular reservoir has been identified as one of the key sources of HIV in the human body?

Memory CD4+ T cells (D) Signup and view all the answers

What is the significance of the provirus in terms of HIV infection?

It permanently integrates into the host genome. (A) Signup and view all the answers

What hinders the immune response to HIV after initial infection?

Interference by HIV with innate immunity components (B) Signup and view all the answers

What role do CD8+ T-lymphocytes play in controlling HIV infection?

They kill HIV-infected cells and produce INF-γ. (B) Signup and view all the answers

What is a significant challenge to the effectiveness of neutralizing antibodies against HIV?

The presence of nonneutralizing anti-envelope antibodies. (C) Signup and view all the answers

How does HIV infection affect CD4+ T-lymphocytes over the course of the disease?

They are progressively depleted, impacting immune response. (B) Signup and view all the answers

What factor contributes to the persistence of HIV within an infected individual?

Integration of proviral DNA into host chromosomes. (A) Signup and view all the answers

What mechanism allows HIV to evade recognition by neutralizing antibodies?

Viral replication leading to the emergence of escape variants. (C) Signup and view all the answers

What role does glycosylation play in the immune response to HIV?

It inhibits neutralizing antibody binding to the envelope protein. (C) Signup and view all the answers

Which explanation accounts for the immune system's inability to eliminate HIV?

High mutation rates resulting in antigenic variation. (A) Signup and view all the answers

What effect do mutations in HIV have on the virus's interaction with the immune system?

They create CTL escape variants and allow immune evasion. (C) Signup and view all the answers

Which cytokine plays a key role in helping B lymphocytes respond to HIV antigens?

IL-2 (D) Signup and view all the answers

What immune deficiency results primarily from HIV infection?

Diminished ability of T-lymphocyte precursors to mature. (D) Signup and view all the answers

Study Notes

Human Immunodeficiency Virus (HIV)

HIV is a retrovirus causing progressive immune system dysfunction, increasing susceptibility to opportunistic infections and malignancies.
It infects only human cells.
HIV invades helper T cells (CD4 cells), a crucial component of the human immune system.

Learning Objectives (LOs)

Recognize HIV as a significant disease requiring reporting to national and international healthcare systems.
Apply standard case definitions for HIV diagnosis.
Describe the viral structure, replication, and infection cycle.
Understand the role of CD4 cells in HIV pathogenesis and immune response.
Recognize HIV's clinical presentations across different stages.
Identify HIV as a cause of persistent diarrhea and lymphadenopathy.
Categorize HIV complications based on CD4 counts.
Interpret laboratory results for HIV diagnosis.
Identify indications and adverse effects of antiretroviral drugs.
Demonstrate knowledge of post-exposure prophylaxis (PEP) for HIV.

What is HIV?

HIV is a unique retrovirus that causes progressive immune deficiency.
It predisposes individuals to various opportunistic infections and malignancies.

Natural History of HIV Infection

1. Acute Retroviral Syndrome (Acute HIV Infection)

Typically presents as flu-like symptoms (fever, myalgia, pharyngitis, lymphadenopathy, rash, arthralgia, GI symptoms, oral ulcers, weight loss) within 2-6 weeks after exposure.
Symptoms last 10-15 days.
Characterized by lymphopenia and thrombocytopenia.
High viral load and high transmission risk.
In 10–20% of cases, aseptic meningitis occurs.

2. Asymptomatic (Latent) Stage

HIV infects and replicates within CD4+ T lymphocytes (lymph nodes).
Normal CD4 count ranges from 500-1100 cells/mm³.
CD4 count declines gradually at a rate of approximately 60-100 cells/mm³ per year.
Over 10 years after infection, 50% of individuals progress to AIDS, 30% experience milder symptoms, and 20% remain asymptomatic if left untreated.

3. AIDS

Defined by a CD4+ T-lymphocyte count of less than 200 cells/µL or a CD4+ T-lymphocyte percentage of total lymphocytes less than 14% or documentation of an AIDS-defining condition.

Relationship between CD4 Cell Count, Viral Load, and Anti-HIV Antibodies

The graph displays the relationship between CD4 cell count, viral load, and anti-HIV antibodies over time.
CD4 count decreases as viral load increases, and anti-HIV antibodies appear during the acute phase and decline slightly during the asymptomatic phase.

Symptomatic Stage (CD4 Thresholds for Classic Clinical Manifestations)

Different clinical manifestations emerge at various CD4 thresholds.
Clinical manifestations, such as oral hairy leukoplakia and Kaposi's sarcoma, are prevalent at a CD4 cell count of less than 500 cells per cubic millimeter.
Other opportunistic infections and conditions are tied to different CD4 count thresholds, such as Pneumocystis jiroveci pneumonia (<200 cells/µL), Mycobacterium avium complex (<75 cells/µL), and Cytomegalovirus (<50 cells/µL).

Testing Options for HIV

Enzyme-linked immunosorbent assay (ELISA)
Western blot (confirmatory test)
Rapid antibody test
CD4 count (predicts progression)
Viral load tests (best for diagnosing acute HIV infection)

Treatment of HIV

Nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs)
CCR5 receptor blocker
Integrase strand inhibitors (INSTIs)
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
Fusion inhibitors
Protease inhibitors (PIs)

Target Sites for Antiretroviral Drugs

Drugs target different stages of HIV’s lifecycle within the human cell.
- Fusion inhibitors
- CCR5 antagonists
- Reverse transcriptase inhibitors (RTIs)
- Integrase inhibitors

ART Recommended for All HIV+ Individuals

ART is strongly recommended for all HIV-positive individuals, regardless of CD4 cell count, according to current guidelines. A "treat all" strategy is highly recommended.

Reasons to not start ART

Drug toxicities
Risk of drug resistance in non-adherent patients.
Cost of ARVs
Lack of evidence that ART prevents HIV-associated complications.

Reasons to start ART

Highly effective and convenient regimens.
Improved tolerance of therapy.
Decreased long-term toxicity.
Improved immune recovery.
Increased treatment options.
Reduced risk of uncontrolled viremia.
Decreased HIV transmission.
Lower rates of subclinical atherosclerosis.
Decreased hospitalization rates for cardiovascular disease (CVD).
CD4 count increase, improved CD4/CD8 ratio, decrease in T-cell activation.

Health Care Follow-up of HIV-Infected Patients

Regularly monitor CD4 cell counts and viral loads.
Treat opportunistic infections and malignancies as needed.
Implement preventative strategies such as tuberculosis screening, pneumococcal vaccination, and vaccination against other infectious diseases. Routine preventative care for HIV patients is crucial.

HIV Post-exposure Prophylaxis (PEP)

PEP's effectiveness is highest when administered within two hours of exposure.
Prompt reporting of exposure and initiation of appropriate therapy is crucial, as delays in starting therapy can hinder its efficacy.
Begin with basic 2-drug regimen and change as needed once expert advice is obtained. PEP is a recommended protocol that should be started as quickly as possible following exposure. It is a time-sensitive procedure requiring prompt action.

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Description

This quiz focuses on Human Immunodeficiency Virus (HIV), its impact on the immune system, and the importance of reporting and diagnosing the disease. You will learn about the viral structure, the role of CD4 cells, clinical presentations, and complications associated with HIV. Test your understanding of laboratory interpretation and antiretroviral treatment.