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Lowering the Detection Limits of HIV-1 Viral Load Using Real-Time Immuno-PCR for HIV-1 p24 Antigen

Janet M. Barletta PhD, Daniel C. Edelman MS, Niel T. Constantine PhD
DOI: http://dx.doi.org/10.1309/529T2WDNEB6X8VUN 20-27 First published online: 1 July 2004


Presently, the assay that attains maximal sensitivity and dynamic range of HIV-1 viral copy number (50 copies per milliliter) is nucleic acid amplification of HIV RNA in plasma. Enzyme-linked immunosorbent assay (ELISA) methods for quantification of HIV-1 p24 antigen have been relatively insensitive. In this report, we show data that indicate real-time immuno–polymerase chain reaction (IPCR), a combination of the ELISA and PCR techniques, is more sensitive for HIV-1 p24 antigen detection than other currently reported methods. When derived from an IPCR standard curve, a dose response was observed from patient samples with known viral loads diluted within a 3-log range (1.68–6,514 viral RNA copies per milliliter). IPCR detected 42% (22/52) of patient samples that had fewer than 50 viral RNA copies per milliliter by reverse transcriptase–PCR. IPCR shows the potential to become the most analytically sensitive test available for determination of HIV-1 viral load by the detection of HIV-1 p24 antigen.

Key Words:
  • Immuno-PCR
  • IPCR
  • Polymerase chain reaction
  • p24 antigen
  • HIV-1
  • Viral load
  • Enzyme-linked immunosorbent assay
  • Real-time PCR