HIV and AIDS Overview
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Questions and Answers

During the acute stage of HIV infection, what are typically elevated?

  • CD4 cell counts
  • Opportunistic infections
  • Antibody levels
  • Viral RNA levels (correct)

    • Which route of transmission is least likely for HIV?

  • Intravenous drug abuse
  • Accidental medical needle sticks
  • Airborne particles (correct)
  • Sexual contact

    • What is the role of gp41 in the pathogenesis of HIV?

  • To stimulate the immune response
  • To degrade viral RNA
  • To facilitate fusion of the viral envelope with the endosome membrane (correct)
  • To transport the virus through blood

    • What CD4 count level is considered AIDS-defining?

    <p>200 cells/µL</p> Signup and view all the answers

    Which of the following is NOT a common symptom of AIDS-related complex (ARC)?

    <p>Severe joint pain</p> Signup and view all the answers

    What happens to the number of helper T cells over the course of 5-10 years in untreated HIV infection?

    <p>They decline significantly</p> Signup and view all the answers

    In the latent period of HIV infection, what is a common occurrence?

    <p>Asymptomatic behavior</p> Signup and view all the answers

    Which of the following is NOT associated with the acute stage of HIV infection?

    <p>Low CD4 cell count</p> Signup and view all the answers

    What is a key characteristic in diagnosing AIDS?

    <p>Presence of one or more rare diseases</p> Signup and view all the answers

    Which method is considered the definitive diagnosis for HIV infection?

    <p>Western blot analysis</p> Signup and view all the answers

    Which is NOT an opportunistic infection associated with AIDS?

    <p>Aspiration pneumonia</p> Signup and view all the answers

    What percentage of AIDS patients is observed to have Kaposi's sarcoma?

    <p>20%</p> Signup and view all the answers

    What is the main symptom combination used to diagnose AIDS?

    <p>Weight loss, fatigue, fever, and low CD4 count</p> Signup and view all the answers

    Which organism is commonly associated with opportunistic fungal infections in AIDS patients?

    <p>Candida albicans</p> Signup and view all the answers

    What can cause a false-negative serologic test result in HIV diagnosis?

    <p>Testing too soon after infection</p> Signup and view all the answers

    Which of the following statements is true regarding opportunistic tumors in AIDS?

    <p>Kaposi's sarcoma is strongly associated with human herpes virus 8 (HHV-8).</p> Signup and view all the answers

    What characterizes the condition known as AIDS?

    <p>Low helper T cell counts along with several opportunistic infections</p> Signup and view all the answers

    Which glycoprotein of HIV is primarily responsible for attachment to host cells?

    <p>gp120</p> Signup and view all the answers

    Which statement is true regarding the genetic material of HIV?

    <p>HIV carries two copies of single-stranded positive-polarity RNA</p> Signup and view all the answers

    How does HIV challenge the immune response in patients?

    <p>By rapidly mutating its gp120 gene, leading to many antigenic variants</p> Signup and view all the answers

    What is the general classification of HIV in terms of virus families?

    <p>Retroviridae</p> Signup and view all the answers

    What role does the gp41 glycoprotein play in the HIV lifecycle?

    <p>It facilitates the fusion of the viral envelope to host cells</p> Signup and view all the answers

    During HIV infection, what is a common consequence seen in untreated patients?

    <p>Progression from HIV infection to AIDS</p> Signup and view all the answers

    What is the hallmark lab finding in diagnosing AIDS related to lymphocyte levels?

    <p>Lymphocyte counts lower than 200 cells/μL</p> Signup and view all the answers

    What role does the viral load play in managing HIV infection?

    <p>It guides treatment decisions and prognosis.</p> Signup and view all the answers

    When is a CD4 count of 200 cells/µL considered significant?

    <p>It is an AIDS-defining condition.</p> Signup and view all the answers

    Which of the following is NOT one of the mechanisms by which HIV evades the immune system?

    <p>Production of cytokines that enhance T cell activation.</p> Signup and view all the answers

    What is the significance of monitoring CD4 T cell counts in patients with HIV?

    <p>It determines the effectiveness of antiviral therapy.</p> Signup and view all the answers

    What increases the risk of disseminated tuberculosis in patients with AIDS?

    <p>Low CD4 counts and cellular immunity deficiency.</p> Signup and view all the answers

    How often should patients with HIV be monitored for signs of disease progression?

    <p>Regularly throughout their treatment.</p> Signup and view all the answers

    What happens to the frequency and severity of opportunistic infections as CD4 counts fall?

    <p>They significantly increase.</p> Signup and view all the answers

    Which assay is typically used to measure HIV viral load?

    <p>Polymerase chain reaction (PCR).</p> Signup and view all the answers

    Study Notes

    Acquired Immunodeficiency Syndrome (AIDS)

    • AIDS is a syndrome caused by infection with the retrovirus human immunodeficiency virus (HIV).
    • Infection with HIV leads to AIDS in untreated patients.
    • HIV belongs to the lentivirus subfamily of the retroviridae
    • HIV infection is considered a lifelong infection.

    Important Properties of HIV

    • HIV is an enveloped virus.
    • It has an icosahedral capsid
    • Two copies of a single-stranded, positive-polarity RNA (+ssRNA) genome.
    • It uses reverse transcriptase to make a DNA copy of its genome.
    • The HIV envelope is characterized by two antigenic glycoproteins: gp120 and gp41.
    • gp120 is the primary attachment molecule of HIV.
    • gp41 promotes fusion of the viral envelope to a target cell.

    HIV Transmission

    • HIV transmission occurs through sexual contact, intravenous drug abuse, blood transfusions, organ transplants, tattooing, accidental medical needle sticks, and across the placenta and breast milk.

    HIV Pathogenesis

    • HIV uses gp120 and gp41 to attach to and enter target cells through CD4 on a target cell.
    • The CD4-gp120 complex binds to another membrane receptor, called Fusin (also known as CXCR4), which triggers the cell’s membrane to move out and surround the virus forming an endosome.
    • GP 41 on the viral envelope facilitates fusion of the envelope with the endosome membrane letting the viral capsid to be introduced intact into the cell’s cytosol.
    • The viral capsid uncoats, releasing viral RNA and proteins.

    Clinical Course of HIV Infection

    • Acute Stage:
      • Begins 2 to 4 weeks after infection.
      • Symptoms include fever, lethargy, sore throat, generalized lymphadenopathy, and a maculopapular rash.
      • Leukopenia may occur, but CD4 cell count is usually normal.
      • High-level viremia typically occurs, and the infection is readily transmissible during this stage.
      • Normal CD4 count is 500 cells/µL.
    • Middle Stage (Latent Period):
      • Lasts 7-11 years.
      • Patients typically asymptomatic during this period.
      • AIDS-related complex (ARC) can occur with symptoms like persistent fevers, fatigue, weight loss, and lymphadenopathy.
      • Integrated viruses continue to replicate and virions are released into the blood.
      • Helper T cell count declines over time.
    • Late Stage (AIDS):
      • Defined by CD4 cell count below 200/µL and increased frequency and severity of opportunistic infections.

    Immunological Virological Basis of HIV/AIDS

    • AIDS is diagnosed based on unexplained weight loss, fatigue, fever, fewer than 200 CD4 lymphocytes per microliter (μl) of blood, and other opportunistic infections.
    • Diagnosis also includes demonstration of antibodies against HIV.

    Opportunistic Infections

    • Common opportunistic infections include:
      • Protozoal: Pneumocystis carinii pneumonia (PCP), toxoplasmosis, cryptosporidosis
      • Fungal: Candidiasis, Cryptococcosis meningitis, Coccidiodomycosis, disseminated histoplasmosis
      • Bacterial: Mycobacterium avium complex, Mycobacterium tuberculosis (MTB), atypical mycobacterial disease, Salmonella septicemia, multiple or recurrent pyogenic bacterial infections

    Opportunistic Tumors

    • Kaposi's sarcoma (KS): most frequent opportunistic tumor, seen in 20% of AIDS patients, associated with human herpes virus 8 (HHV-8).
    • Malignant lymphomas: also frequent in AIDS patients.

    Laboratory Diagnosis

    • Serology is used for diagnosing HIV infection.
    • Screening assays: ELISA
    • Confirmatory assays: Western blot
    • Detection of antibodies to p24 protein of HIV using ELISA is a presumptive diagnosis.
    • Western blot analysis provides a definitive diagnosis.
    • OraQuick rapid screening immunoassay for HIV antibody uses an oral swab sample and provides results in 20 minutes.
    • Polymerase chain reaction (PCR) to detect viral RNA in plasma (viral load) is used if antibody test is negative but HIV infection is suspected.
    • CD4-positive T cell count guides management of infected patients.
    • A CD4 count of 200/µL or below is an AIDS-defining condition.

    Prognostic tests

    • Monitoring HIV viral load and CD4 counts is important for disease progression and response to antiviral chemotherapy.

    HIV Evasion of the Immune System

    • HIV evades the immune system through:
      • Integration of viral DNA into host cell DNA for persistent infection.
      • High rate of mutation of the env gene.
      • Production of proteins that downregulate class I MHC proteins needed for cytotoxic T cell recognition and killing of HIV-infected cells.

    HIV and Tuberculosis

    • Patients with AIDS (CD4 count less than 200/mL) are at high risk for disseminated, life-threatening tuberculosis.
    • Dissemination can occur early if cell-mediated immunity fails to contain the initial infection or late if a person becomes immunosuppressed.

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    Description

    This quiz explores the fundamental aspects of HIV and AIDS, including the virus's properties, transmission methods, and its pathogenesis. Understanding the scientific basis of HIV infection is crucial for both healthcare professionals and the general public. Test your knowledge on this critical public health issue.

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