title: Natural selection results in conservation of HIV-1 integrase activity despite sequence variability.
abstract: BACKGROUND
  Integration of the HIV genome by integrase is absolutely required for productive infection.
  
  
  OBJECTIVE
  To determine the role of natural selection on HIV integrase biology.
  
  
  METHODS
  To study the activities of HIV integrases from a limited panel of North American clinical isolates from HIV-infected patients and to compare these proteins with integrases from two laboratory adapted reference strains (HI(VIIIRF) and HIV(NL4--3)).
  
  
  METHODS
  HIV was isolated and the particle-associated RNA was reverse transcribed and sequenced. Replication kinetics of molecularly cloned viruses containing each variant integrase were studied in tissue culture. The mutant integrase proteins were expressed, purified and specific activities of the enzymes were derived for both 3' end-processing and disintegration reactions.
  
  
  RESULTS
  Despite 3--5% variability in integrase at the amino acid level, viruses showed no statistically significant differences in growth kinetics compared with the reference HIV(NL4--3) virus and only minor differences were observed in 3' end-processing and disintegration activities. All integrase proteins demonstrated similar sensitivity to an integrase inhibitor l-chicoric acid.
  
  
  CONCLUSIONS
  These results demonstrate that integrase genes derived from HIV-infected individuals can differ from reference sequences but these mutations do not result in loss of function, including susceptibility to an integrase inhibitor; therefore, integrase remains an attractive target for antiviral drug design, as mutability appears to be restricted by function.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California, Irvine, 92967-4800, USA.
authors.forename: R
authors.initials: R
authors.lastname: Reinke
authors.forename: N R
authors.initials: NR
authors.lastname: Steffen
authors.forename: W E
authors.initials: WE
authors.lastname: Robinson
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology; D002109:Caffeic Acids; D015870:Gene Expression; D014644:Genetic Variation; D015658:HIV Infections / Q000821:virology*; D019427:HIV Integrase / Q000235:genetics / Q000378:metabolism*; D019428:HIV Integrase Inhibitors / Q000494:pharmacology; D015497:HIV-1 / Q000145:classification / Q000201:enzymology* / Q000254:growth & development; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D010802:Phylogeny; D012323:RNA Processing, Post-Transcriptional; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D013386:Succinates / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D016662:Virus Integration
chemical_list: D019380:Anti-HIV Agents; D002109:Caffeic Acids; D019428:HIV Integrase Inhibitors; D013386:Succinates; D019427:HIV Integrase; C100435:chicoric acid