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RealTime HIV-1

CE Marked

The Abbott RealTime HIV-1 assay is an in vitro reverse transcription-polymerase chain reaction (RT-PCR) assay for the quantitation of Human Immunodeficiency Virus type 1 (HIV-1) on the automated m2000 System or with m24sp extraction in human plasma from HIV-1 infected individuals over the range of 40 to 10,000,000 copies/mL. The Abbott RealTime HIV-1 assay is intended for use in conjunction with clinical presentation and other laboratory markers for disease prognosis and for use as an aid in assessing viral response to antiretroviral treatment as measured by changes in plasma HIV-1 RNA levels. This assay is not intended to be used as a donor screening test for HIV-1 or as a diagnostic test to confirm the presence of HIV-1 infection.

Abbott RealTime HIV-1
Sensitivity

40 copies/mL for 1.0 mL sample volume

40 copies/mL for 0.6 mL sample volume

75 copies/mL for 0.5 mL sample volume

150 copies/mL for 0.2 mL sample volume

Linear range 40 copies/mL (1.6 log copies/mL) to 10 million copies/mL (7.0 log copies/mL)
Specificity 100%1
Target region Integrase region of polymerase gene
Subtype detection Group M subtypes A—H, Group O and Group N
Internal control Non-competitive pumpkin RNA, added to lysis buffer during extraction
Standardization

Virology Quality Assurance (VQA) Laboratory of the AIDS Clinical Trial Group

World Health Organization (WHO) 1st International Standard for HIV-1 RNA (97/656)

Specimen type Plasma (ACD-A and EDTA)
Input volume 0.2 mL; 0.5 mL; 0.6 mL; 1.0 mL
Sample preparation m2000sp, m24sp and manual


1
The specificity of the RealTime HIV-1 assay was evaluated at three external sites by testing 514 HIV-1 seronegative plasma specimens from volunteer blood donors. HIV-1 RNA was not detected for all 514 specimens and the RealTime HIV-1 assay specificity was estimated to be 100% (514/514), (95% CI 99.28 to 100%).

Detection of HIV-1 Subtypes and Groups
Group/
Subtypes
n RealTime
Detected
Comparator 1
Detected
Comparator 2
Detected
M/Subtype A 10 10 10 (1) 10 (1)
M/Subtype B
10 10 10 (0) 10 (0)
M/Subtype C
10 10 10 (0) 10 (0)
M/Subtype D
10 10 10 (0) 10 (0)
M/Subtype AE 10 10 10 (0) 10 (0)
M/Subtype F 10 10 10 (0) 10 (0)
M/Subtype AG 10 10 10 (3) 10 (1)
M/Subtype G 10 10 10 (2) 10 (1)
Group O 10 10 0 (NA) 7 (7)

 

A total of 90 clinical specimens, ten of each Group M subtype (A, B, C, D, CRF01-AE, F, CRF02-AG, G) and of Group O, were tested with the RealTime HIV-1 assay and by two other approved HIV-1 quantitative assays referred to as Comparator 1 (FDA-approved version used) and Comparator 2 (CE-Marked version used). The numbers in parentheses are the number of specimens that had lower quantitation values by more than 1.00 log copies/mL when compared to RealTime HIV-1 assay.

 

Correlation to Comparator Assay

Correlation to Comparator Assay

A total of 301 specimens collected from HIV-1 infected patients were tested with the RealTime HIV-1 assay at three external sites and with the comparator method at a central laboratory site. The results from a total of 259 specimens that fell within the common assay dynamic range were analyzed by the Passing-Bablok linear regression method.

Development Philosophy
Today's clinical molecular diagnostics laboratory must have confidence in the quality of the HIV-1 patient results. As a result of our real-time PCR development philosophy, Abbott RealTime HIV-1 is engineered to tolerate the genetic diversity of HIV-1 Subtypes.

HIV-1 diversity can be attributed to:

  • Error-prone reverse transcriptase enzyme
  • Recombination of subtypes
  • Cross-species transmission


Accurate quantitation is dependent upon a combination of:

  • Primer Design
  • Probe Design
  • Cycling Conditions
Primers and Probe are Targeted to the Integrase Region of the Polymerase Gene

 

Primers and Probe are Targeted to the Integrase Region of the Polymerase Gene

The integrase region of the polymerase gene is a conserved region of the HIV-1 genome.

Partially Double Stranded Probe Design

Partially Double Stranded Probe Design

In the absence of target, the probe hybridizes to the quencher digoneucleotide, preventing fluorescent signal generation.

Partially Double Stranded Probe Design

In the presence of target, the probe prefers to hybridize with the target sequence, disassociating from the quencher oligonucleotide and allowing fluorescent detection.

Cycling Conditions: Low Temperature Read Cycles

Cycling Conditions: Low Temperature Read Cycles

The cycling conditions for Abbott RealTime HIV-1 encompass a low temperature read cycle. This read cycle allows the probe to tolerate mismatches more effectively than a probe required to bind during the extension phase.

CE Marked