Human Immunodeficiency Virus Book

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HIV Viral activity

Aka: HIV Viral activity, HIV Viral Load, Plasma Viral Load Test, PVL Test, HIV RNA, HIV PVL, HIV PCR, HIV bDNA, HIV NASBA, HIV-1 RNA Nucleic Acid Amplification Test, NAAT, HIV RNA Viral Activity
  1. See Also
    1. HIV Test
    2. HIV Treatment strategy
  2. Mechanism
    1. Plasma Viral Load measures HIV RNA Levels in copies/mm3
  3. Indications: Plasma Viral Load Testing
    1. HIV Detection
      1. Acute Retroviral Syndrome strongly suspected
      2. Indeterminate HIV Western Blot in high risk patient
    2. HIV Monitoring
      1. Baseline viral load in newly diagnosed HIV patient
      2. Surveillance of patients not taking Antiretrovirals
      3. Surveillance of patients on Antiretroviral drugs
        1. Before changes in Antiretroviral therapy
        2. Every 1-3 months while on therapy
  4. Labs: Available tests for HIV RNA
    1. Polymerase chain reaction (PCR) test
    2. Branched-chain DNA (bDNA) test
    3. Nucleic acid sequence-based amplification (NSBA) test
  5. Efficacy: Viral load by plasma HIV RNA Measurement
    1. Plasma viral load assays by PCR, bDNA, NASBA effective
      1. Use same assay type and lab for same patient
      2. Test Sensitivity: Detects 20 to 50 copies/ml
      3. Specificity: 100%
    2. Outcomes
      1. Single best predictor of HIV progression and death
      2. Used in combination with CD4 Count
  6. Prognosis: Risk of progression (retrospective study)
    1. Viral RNA load <500
      1. Relative Risk of progression: 1.0
      2. Relative Risk of death: 1.0
    2. Viral RNA load 500 to 3,000
      1. Relative Risk of progression: 2.4
      2. Relative Risk of death: 2.8
    3. Viral RNA load 3,000 to 10,000
      1. Relative Risk of progression: 4.4
      2. Relative Risk of death: 5.0
    4. Viral RNA load 10,000 to 30,000
      1. Relative Risk of progression: 7.5
      2. Relative Risk of death: 9.9
    5. Viral RNA load >30,000
      1. Relative Risk of progression: 13
      2. Relative Risk of death: 18.5
    6. References
      1. Paauw (2003) AAFP Board Review, Seattle
  7. Interpretation
    1. Seroconversion or Acute Retroviral Syndrome
      1. HIV Viral Load may exceed 100,000 copies
    2. Criteria for initiating Antiretroviral therapy
      1. HIV Viral Load >5,000 to 10,000
      2. CD4 Count <500 cells/mm3
    3. Antiretroviral therapy goals
      1. Each PVL 0.5-log drop lowers progression risk 30%
      2. First 4-8 weeks: 1-2 log PVL reduction
      3. Target after 16-24 weeks: <50 copies/ml
    4. Monitoring after PVL Suppression <50 copies/ml
      1. PVL suggesting Antiretroviral change: >5000 copies/ml
  8. Causes: Transient PVL Elevations
    1. Differences in lab and assay type
      1. Maintain consistency for each patient (same assay)
      2. Process specimens within 2-4 hours
    2. Concurrent illness
    3. Concurrent Vaccination
    4. Any missed doses of Antiretroviral therapy before test
  9. References
    1. Carpenter (2000) JAMA 283:381-90 [PubMed]
    2. Eleftherios (2001) Am Fam Physician 63(3):483-90 [PubMed]
    3. Lin (1998) J Clin Microbiol 36:835-9 [PubMed]
    4. Mellors (1997) Ann Intern Med 126:946-54 [PubMed]
    5. Mellors (1996) Science 272:1167-70 [PubMed]

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