Abstract
Accurate HIV-2 plasma viral load quantification is crucial for adequate HIV-2 patient management and for
the proper conduct of clinical trials and international cohort collaborations. This study compared the homogeneity
of HIV-2 RNA quantification when using HIV-2 assays from ACHIEV2E study sites and either in-house
PCR calibration standards or common viral load standards supplied to all collaborators. Each of the 12
participating laboratories quantified blinded HIV-2 samples, using its own HIV-2 viral load assay and standard
as well as centrally validated and distributed common HIV-2 group A and B standards (http://www.hiv
.lanl.gov/content/sequence/HelpDocs/subtypes-more.html). Aliquots of HIV-2 group A and B strains, each at 2
theoretical concentrations (2.7 and 3.7 log10 copies/ml), were tested. Intralaboratory, interlaboratory, and
overall variances of quantification results obtained with both standards were compared using F tests. For
HIV-2 group A quantifications, overall and interlaboratory and/or intralaboratory variances were significantly
lower when using the common standard than when using in-house standards at the concentration levels of 2.7
log10 copies/ml and 3.7 log10 copies/ml, respectively. For HIV-2 group B, a high heterogeneity was observed and
the variances did not differ according to the type of standard used. In this international collaboration, the use
of a common standard improved the homogeneity of HIV-2 group A RNA quantification only. The diversity of
HIV-2 group B, particularly in PCR primer-binding regions, may explain the heterogeneity in quantification
of this strain. Development of a validated HIV-2 viral load assay that accurately quantifies distinct circulating
strains is needed.
Damond, F