title: Low accumulation of L90M in protease from subtype F HIV-1 with resistance to protease inhibitors is caused by the L89M polymorphism.
abstract: BACKGROUND
  This work evaluates the role of subtype F human immunodeficiency virus type 1 (HIV-1) protease (PR) substitutions L89M and L90M in viral replication and resistance to PR inhibitors (PIs).
  
  
  METHODS
  Subtype B and F PR genes were subjected to site-directed mutagenesis, to create and reverse the methionine at positions 89 and 90. Viruses were re-created in cell culture, and their replicative capacity was assessed by fitness assay. Generated viruses were also phenotyped for PI resistance.
  
  
  RESULTS
  The subtype F clone (89M90L) showed a replicative capacity comparable to that of the PI-susceptible subtype B clone (89L90L) and was more fit than the L89M mutated subtype B clone (89M90L). Both 89M90M subtype B and F clones presented the lowest fitness s values. The L89M mutation impacted phenotypic resistance to all PIs in half of the subtype F isolates but not in the subtype B isolates. Subtype F isolates presented a phenotypic profile similar to that of subtype B isolates when the M89L mutation was introduced.
  
  
  CONCLUSIONS
  The L89M mutation in subtype F viruses is a high genetic barrier to the accumulation of the L90M resistance mutation and can function as a resistance mutation, depending on the presence of other polymorphisms in the subtype F PR backbone.
authors.affiliation: Department of Genetics, Biology Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Calazans
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Brindeiro
authors.forename: Patricia
authors.initials: P
authors.lastname: Brindeiro
authors.forename: Hugo
authors.initials: H
authors.lastname: Verli
authors.forename: Monica B
authors.initials: MB
authors.lastname: Arruda
authors.forename: Luis Manuel Felipe
authors.initials: LM
authors.lastname: Gonzalez
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Guimaraes
authors.forename: Ricardo Sobhie
authors.initials: RS
authors.lastname: Diaz
authors.forename: Octavio A C
authors.initials: OA
authors.lastname: Antunes
authors.forename: Amilcar
authors.initials: A
authors.lastname: Tanuri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D016384:Consensus Sequence; D024882:Drug Resistance, Viral / Q000235:genetics*; D005838:Genotype; D016333:HIV Protease / Q000737:chemistry / Q000235:genetics*; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics*; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D013997:Time Factors
chemical_list: D017320:HIV Protease Inhibitors; D016333:HIV Protease