Limited development and progression of resistance of HIV-1 to the nucleoside analogue reverse transcriptase inhibitor lamivudine in human primary macrophages.
OBJECTIVE
The aim of this study was to investigate the development and progression of phenotypic resistance to the HIV-1-reverse transcriptase (RT) inhibitor lamivudine, and genotypic variations of HIV-1-RT occurring under lamivudine treatment in HIV-1-infected human primary monocytes-macrophages (M/M).


METHODS
Cellular passages in the presence of lamivudine were performed every 2 weeks by transferring supernatants of infected M/M to fresh M/M. A fitness assay using wild-type virus and a lamivudine-resistant HIV-1 virus (harbouring the M184V RT mutation) was performed in peripheral blood mononuclear cells. Culture supernatants were tested for p24 antigen production and RT activity. The M184V RT mutant virus was obtained by site-directed mutagenesis on a CCR5-using HIV-1 backbone.


RESULTS
The mutagenized M184V RT virus showed full resistance to lamivudine in M/M. However, no detectable phenotypic and genotypic resistance (neither virus breakthrough, nor RT resistance-related mutations) developed in M/M infected by HIV-1 and cultured for up to seven passages in vitro (i.e. 105 days). This inefficiency of M/M to develop M184V RT mutated virus is tightly related to the low 2'-deoxynucleotide (dNTP) pool in such cells, which in turn decreases the kinetics of HIV-1-RT. Despite this, the M184V RT mutant virus replicates in M/M, although with a 30% decreased efficiency compared with the wild-type.


CONCLUSIONS
Our results show that the chances of development of resistance are far lower in M/M than in lymphocytes. This underlines the importance and the peculiar role of M/M as reservoirs of either wild-type or resistant strains in human organs.
Aquaro
Stefano
S
Department of Experimental Medicine and Biochemical Sciences, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome. aquaro@uniroma2.it
Svicher
Valentina
V
Ceccherini-Silberstein
Francesca
F
Cenci
Alessandra
A
Marcuccilli
Fabbio
F
Giannella
Sara
S
Marcon
Luisa
L
Caliò
Raffaele
R
Balzarini
Jan
J
Perno
Carlo-Federico
CF
D019380:Anti-HIV Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology*; D008264:Macrophages / Q000821:virology*; D009154:Mutation; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*
D019380:Anti-HIV Agents; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D054303:HIV Reverse Transcriptase