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Problems in the interpretation of HIV‐1 viral load assays using commercial reagents
Author(s) -
O'Shea Siobhan,
Chrystie Ian,
Cranston Ross,
Mullen Jane,
Corbett Karen,
Murphy Gary,
Parry John V.,
De Ruiter Annemiek,
Banatvala Jangu
Publication year - 2000
Publication title -
journal of medical virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 121
eISSN - 1096-9071
pISSN - 0146-6615
DOI - 10.1002/(sici)1096-9071(200006)61:2<187::aid-jmv3>3.0.co;2-8
Subject(s) - nasba , viral load , virology , biology , dna , rna , polymerase chain reaction , virus , bdna test , viral disease , human immunodeficiency virus (hiv) , microbiology and biotechnology , nucleic acid sequence , genetics , gene
Abstract During routine monitoring of human immunodeficiency virus (HIV) viral load, two problems arose. First, a number of patients, the majority being African, were found to have low viral loads by the Chiron branched‐chain DNA assay in conjunction with low CD4 + cell numbers. In order to determine whether this was due to failure of the branched‐chain DNA assay to detect non‐B subtypes of HIV, selected samples were subtyped and HIV RNA quantified by branched‐chain DNA, NASBA, and the Roche Monitor RT‐PCR assay. Twenty‐eight (97%) of 29 Africans were infected with a non‐B subtype of HIV and 15 (93.7%) of 16 non‐Africans with subtype B. Twenty‐three samples had a low viral load by branched‐chain DNA, which was confirmed by the NASBA and RT‐PCR assays. All three assays detected B and non‐B subtypes with similar efficiency; NASBA failed to detect HIV RNA in a small number of non‐B samples. Discrepancies between viral load and CD4 + cell numbers did not appear therefore to be related to subtype. Second, while quantification of HIV RNA was being conducted using version 2 of the branched‐chain DNA assay (lower detection limit 500 HIV RNA copies/ml) the manufacturers had developed a more sensitive assay and a comparative evaluation was therefore conducted. In approximately 30% of samples the viral load was up to 10 times higher with the more sensitive assay. These experiences emphasise the importance of close collaboration between the clinic and the laboratory. J. Med. Virol. 61:187–194, 2000. © 2000 Wiley‐Liss, Inc.