title: The Antiviral Activity of Approved and Novel Drugs against HIV-1 Mutations Evaluated under the Consideration of Dose-Response Curve Slope.
abstract: OBJECTIVE
  This study was designed to identify common HIV-1 mutation complexes affecting the slope of inhibition curve, and to propose a new parameter incorporating both the IC50 and the slope to evaluate phenotypic resistance.
  
  
  METHODS
  Utilizing site-directed mutagenesis, we constructed 22 HIV-1 common mutation complexes. IC50 and slope of 10 representative approved drugs and a novel agent against these mutations were measured to determine the resistance phenotypes. The values of new parameter incorporating both the IC50 and the slope of the inhibition curve were calculated, and the correlations between parameters were assessed.
  
  
  RESULTS
  Depending on the class of drug, there were intrinsic differences in how the resistance mutations affected the drug parameters. All of the mutations resulted in large increases in the IC50s of nucleoside reverse transcriptase inhibitors. The effects of the mutations on the slope were the most apparent when examining their effects on the inhibition of non-nucleoside reverse transcriptase inhibitors and protease inhibitors. For example, some mutations, such as V82A, had no effect on IC50, but reduced the slope. We proposed a new concept, termed IIPatoxic, on the basis of IC50, slope and the maximum limiting concentrations of the drug. The IIPatoxic values of 10 approved drugs and 1 novel agent were calculated, and were closely related to the IIPmax values (r > 0.95, p < 0.001).
  
  
  CONCLUSIONS
  This study confirms that resistance mutations cannot be accurately assessed by IC50 alone, because it tends to underestimate the degree of resistance. The slope parameter is of very importance in the measurement of drug resistance and the effect can be applied to more complex patterns of resistance. This is the most apparent when testing the effects of the mutations on protease inhibitors activity. We also propose a new index, IIPatoxic, which incorporates both the IC50 and the slope. This new index could complement current IIP indices, thereby enabling predict the efficacy of pre-clinical drugs for which human pharmacokinetic is not available.
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Chang
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Daomin
authors.initials: D
authors.lastname: Zhuang
authors.affiliation: NO. 201 hospital, Liaoyang, Liaoning, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, China.
authors.forename: Wenfu
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Siyang
authors.initials: S
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Hanping
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Yongjian
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Zuoyi
authors.initials: Z
authors.lastname: Bao
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Jingwan
authors.initials: J
authors.lastname: Han
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, China.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Song
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Science, Beijing, China.
authors.forename: Jingyun
authors.initials: J
authors.lastname: Li
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D024882:Drug Resistance, Viral / Q000187:drug effects; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D017320:HIV Protease Inhibitors / Q000494:pharmacology; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D020128:Inhibitory Concentration 50; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000187:drug effects*; D018894:Reverse Transcriptase Inhibitors
chemical_list: D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D018894:Reverse Transcriptase Inhibitors