False I50V resistance readings of HIV isolates: co-amplification of NASBA HIV-1 RNA QT internal calibrators and HIV-1 patient isolates may lead to a false I50V mutation resistance reading in genotypic tests.
The I50V protease inhibitor (PI) resistance mutation was found in 87.4% of protease gene fragments sequenced from 199 nucleic acid isolates extracted using an NASBA virus load assay, performed between 1997 and 2001 in Brazil. This mutation is an amprenavir-related mutation, and at that particular time this PI was seldom used in Brazil. This mutation was found both in patients with and without therapeutic success. Q calibrators showed the PI resistance mutation I50V when directly amplified and sequenced from the 423-bp PCR product targeting protease gene. The majority of the patients' samples had a mixture of I50I and I50V; however, this artifact was nor seen when a 989-bp PCR product was used. These results show that RNA extracted using virus load kits need to be critically evaluated before being used in home-brew genotypic tests.
Waléria-Aleixo
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Laboratório de Imunologia e Biologia Molecular, Infectious Diseases Service and School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Greco
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DB
Brindeiro
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Tanuri
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D019380:Anti-HIV Agents / Q000494:pharmacology / Q000627:therapeutic use; D024882:Drug Resistance, Viral / Q000235:genetics; D005189:False Positive Reactions; D015658:HIV Infections / Q000235:genetics / Q000821:virology; D016333:HIV Protease / Q000235:genetics / Q000378:metabolism; D017320:HIV Protease Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D009154:Mutation; D012367:RNA, Viral / Q000032:analysis; D011933:Reagent Kits, Diagnostic / Q000592:standards* / Q000706:statistics & numerical data; D019562:Viral Load
D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic; D016333:HIV Protease