title: HIV-1 dual/mixed tropic isolates show different genetic and phenotypic characteristics and response to maraviroc in vitro.
abstract: Dual/mixed-tropic HIV-1 strains are predominant in a significative proportion of patients, though few information is available regarding the genetic characteristics, quasispecies composition, and susceptibility against CCR5-antagonists of the primary-isolates. For this reason, we investigated in deep details, both phenotypically and genotypically, the characteristics of 54 HIV-1 primary-isolates obtained from HIV-infected patients. Tropism was assessed by multiple-cycles phenotypic-assay on U87MG-CD4(+)-CCR5(+)-/CXCR4(+)-expressing cells. In vitro selection in PBMCs of X4-tropic viral strains following maraviroc-treatment was also performed. Phenotypic-assay reported pure R5-tropic viruses in 31 (57.4%) isolates, dual/mixed-tropic viruses in 22 (40.7%), and pure X4-tropic virus in only 1 (1.8%). Among dual/mixed-tropic isolates, 12 showed a remarkably higher replication-efficacy in CCR5-expressing cells (R5(+)/X4), and 2 in CXCR4-expressing cells (R5/X4(+)). Genotypic-tropism testing showed a correlation between PSSM-scores, geno2pheno false-positive-rate, and V3-net-charge with both CCR5-usage and syncytium-inducing ability. Moreover, specific gp120- and gp41-mutations were significantly associated with tropism and/or syncytium-inducing ability. Ultra-deep V3-pyrosequencing showed the presence of a swarm of genetically distinct species with a preference for CCR5-coreceptor not only in all pure R5-isolates, but also in 6/7 R5(+)/X4-tropic isolates. In both pure-X4 and R5/X4(+)-isolates, we observed extensive prevalence of X4-using species. In vitro selection-experiments with CCR5-inhibitor maraviroc (up to 2 months) showed no-emergence of X4-tropic variants for all R5- and R5(+)/X4-isolates tested (while X4-virus remained fully-resistant). In conclusion, our study shows that dual/mixed-tropic viruses are constituted by different species, whereby those with characteristics R5(+)/X4 are genotypically and phenotypically similar to the pure-R5 isolates; thus the use of CCR5-antagonists in patients with R5(+)/X4-tropic viruses may be a therapeutic-option that deserves further investigations.
authors.affiliation: Department of Experimental Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Svicher
authors.forename: Emanuela
authors.initials: E
authors.lastname: Balestra
authors.forename: Valeria
authors.initials: V
authors.lastname: Cento
authors.forename: Loredana
authors.initials: L
authors.lastname: Sarmati
authors.forename: Luca
authors.initials: L
authors.lastname: Dori
authors.forename: Ina
authors.initials: I
authors.lastname: Vandenbroucke
authors.forename: Roberta
authors.initials: R
authors.lastname: D'Arrigo
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Buonomini
authors.forename: Herwig
authors.initials: H
authors.lastname: Van Marck
authors.forename: Matteo
authors.initials: M
authors.lastname: Surdo
authors.forename: Patrizia
authors.initials: P
authors.lastname: Saccomandi
authors.forename: Wendy
authors.initials: W
authors.lastname: Mostmans
authors.forename: Jeroen
authors.initials: J
authors.lastname: Aerssens
authors.forename: Stefano
authors.initials: S
authors.lastname: Aquaro
authors.forename: Lieven J
authors.initials: LJ
authors.lastname: Stuyver
authors.forename: Massimo
authors.initials: M
authors.lastname: Andreoni
authors.forename: Francesca
authors.initials: F
authors.lastname: Ceccherini-Silberstein
authors.forename: Carlo Federico
authors.initials: CF
authors.lastname: Perno
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D002460:Cell Line; D003510:Cyclohexanes / Q000494:pharmacology*; D015699:HIV Envelope Protein gp120 / Q000235:genetics; D015700:HIV Envelope Protein gp41 / Q000235:genetics; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D000077592:Maraviroc; D008969:Molecular Sequence Data; D011991:Receptors, Virus / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology*; D056189:Viral Tropism; D053585:Virus Attachment; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D019380:Anti-HIV Agents; D003510:Cyclohexanes; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D011991:Receptors, Virus; D014230:Triazoles; C514793:gp120 protein, Human immunodeficiency virus 1; C514787:gp41 protein, Human immunodeficiency virus 1; D000077592:Maraviroc