Genotypic Resistance of Archived and Circulating Viral Strains in the Blood of Treated HIV-Infected IndividualsTurriziani, Ombretta PhD*; Bucci, Mauro BSc*; Stano, Armando BSc*; Scagnolari, Carolina PhD*; Bellomi, Francesca PhD*; Fimiani, Caterina MD†; Mezzaroma, Ivano MD†; D'Ettorre, Gabriella MD‡; Brogi, Andrea MD‡; Vullo, Vincenzo MD‡; Antonelli, Guido PhD*JAIDS Journal of Acquired Immune Deficiency Syndromes: April 15th, 2007 - Volume 44 - Issue 5 - p 518-524 doi: 10.1097/QAI.0b013e3180315515 Clinical Science Abstract The aim of this study was to evaluate patterns of antiretroviral resistance of HIV-1 in peripheral blood mononuclear cells (PBMCs) and in the plasma of patients whose therapeutic regimen is failing. Plasma and PBMC samples were collected from 95 HIV-infected patients undergoing long-term treatment. Genotyping of the reverse transcriptase (RT) and protease genes of HIV-1 was undertaken using the fluorescent dideoxy-terminator method. Comparison of the amino acid sequence of the RT and protease genes in cell-associated variants of HIV-1 with that of the plasma revealed that 62 of the 95 patients' samples tested exhibited different genotypic resistance patterns (discordant samples [DSs]). In 27% of samples, the patterns of resistance detected were concordant in both compartments. In 51% of DSs, the greatest number of mutations was found in plasma; however, in 37% of DSs, greater numbers of mutations were found in PBMC DNA. The HIV mutation patterns detected in plasma do not necessarily reflect those found in the cell-associated compartment. The observation that the cellular compartment may contain an archive of the resistance variant makes this reservoir an interesting substrate for analysis of the “resistance potential” in a given patient. © 2007 Lippincott Williams & Wilkins, Inc.