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TABLE 2-5:

Comparison of FDA-approved Assay Methods for Viral Load
  Roche Siemens bioMérieux
Trade name Amplicor
HIV Monitor 1.5		 Versant
HIV-1 RNA 3.0		 NucliSens
HIV-1 QT
Technique RT-PCR bDNA NASBA
Comparison of
results		 Results with the RT-PCR assay are similar to bDNA (Versant) results using version 2.0 or 3.0. Results with are comparable with RT-PCR (Amplicor) assays. Results appear comparable with RT-PCR and bDNA assays, but supporting data are less robust.
Advantages/
disadvantages
  • Fewer false-positives in patients without HIV infection compared with lo DNA.
  • Less technician time.
  • Good dynamic range, but higher threshold for undetec table virus.
  • May be used with tissue or body fluids such as genital secretions.
  • Greatest dynamic range.
Dynamic range
  • Standard: (Amplicor 1.5) 400 to 750,000 c/mL
  • Ultrasensitive: (Ultra-Direct 1.5) 50 to 100,000 c/mL
 bDNA Version 3.0: 75 to 500,000 c/mL* NucliSens HIV-1 QT: 176-3,500,000 c/mL depending on volume
Subtype amplified
  • Version 1.5: A to H
 A to H A to H
Specimen volume
  • Amplicor: 0.2 mL
  • Ultrasensitive: 0.5 mL
 1 mL 10 μL to 2 mL
Tubes EDTA
(lavender top)		 EDTA
(lavender top)		 EDTA, heparin,
whole blood, any
body fluid, PBMC,
semen, tissue, etc.
Requirement Separate plasma <6 hours and freeze prior to shipping at -20°C or -70°C. Separate plasma <4 hours and freeze prior to shipping at -20°C or -70°C. Separate serum or plasma <4 hours and freeze prior to shipping at -20°C or
-70°C.
Contact 800-526-1247 800-434-2447 800-682-2666

* The FDA-cleared lower threshold is 75 c/mL. Outside the U.S. the lower threshold is 50 c/mL.

16 weeks, and at 16 to 24 weeks. An expected response to therapy is a decrease of 0.75-1.0 log10 c/mL at 1 week (Lancet 2001;358:1760; JAIDS 2002;30:167), a decrease of 1.5-2 log10 to <5,000 c/mL at 4 weeks (JAIDS 2000;25:36; AIDS 1999;13:1873; JAIDS 2004;37: 1155), <500 c/mL at 8 to 16 weeks (Ann Intern Med 2001;135:945; JAIDS 2000;24:433), and <50 c/mL at 24-48 weeks. The 2003 Swiss guidelines define treatment failure by the failure to decrease VL by 1.5 log10 c/mL within 4 weeks or to achieve undetectable virus by 4 months
2007 © John G. Bartlett, M.D. All rights reserved.23

Chapter 2: Laboratory Tests

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