title: Differential effects of the G118R, H51Y, and E138K resistance substitutions in different subtypes of HIV integrase.
abstract: Dolutegravir (DTG) is the latest antiretroviral (ARV) approved for the treatment of human immunodeficiency virus (HIV) infection. The G118R substitution, previously identified with MK-2048 and raltegravir, may represent the initial substitution in a dolutegravir resistance pathway. We have found that subtype C integrase proteins have a low enzymatic cost associated with the G118R substitution, mostly at the strand transfer step of integration, compared to either subtype B or recombinant CRF02_AG proteins. Subtype B and circulating recombinant form AG (CRF02_AG) clonal viruses encoding G118R-bearing integrases were severely restricted in their viral replication capacity, and G118R/E138K-bearing viruses had various levels of resistance to dolutegravir, raltegravir, and elvitegravir. In cell-free experiments, the impacts of the H51Y and E138K substitutions on resistance and enzyme efficiency, when present with G118R, were highly dependent on viral subtype. Sequence alignment and homology modeling showed that the subtype-specific effects of these mutations were likely due to differential amino acid residue networks in the different integrase proteins, caused by polymorphic residues, which significantly affect native protein activity, structure, or function and are important for drug-mediated inhibition of enzyme activity. This preemptive study will aid in the interpretation of resistance patterns in dolutegravir-treated patients.
  
  
  OBJECTIVE
  Recognized drug resistance mutations have never been reported for naive patients treated with dolutegravir. Additionally, in integrase inhibitor-experienced patients, only R263K and other previously known integrase resistance substitutions have been reported. Here we suggest that alternate resistance pathways may develop in non-B HIV-1 subtypes and explain how "minor" polymorphisms and substitutions in HIV integrase that are associated with these subtypes can influence resistance against dolutegravir. This work also highlights the importance of phenotyping versus genotyping when a strong inhibitor such as dolutegravir is being used. By characterizing the G118R substitution, this work also preemptively defines parameters for a potentially important pathway in some non-B HIV subtype viruses treated with dolutegravir and will aid in the inhibition of such a virus, if detected. The general inability of strand transfer-related substitutions to diminish 3' processing indicates the importance of the 3' processing step and highlights a therapeutic angle that needs to be better exploited.
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada Division of Experimental Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Quashie
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.
authors.forename: Maureen
authors.initials: M
authors.lastname: Oliviera
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.
authors.forename: Tamar
authors.initials: T
authors.lastname: Veres
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Nathan
authors.initials: N
authors.lastname: Osman
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.
authors.forename: Ying-Shan
authors.initials: YS
authors.lastname: Han
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada Division of Experimental Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Said
authors.initials: S
authors.lastname: Hassounah
authors.affiliation: Monogram Biosciences, South San Francisco, California, USA.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Lie
authors.affiliation: Monogram Biosciences, South San Francisco, California, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.
authors.forename: Thibault
authors.initials: T
authors.lastname: Mesplède
authors.affiliation: McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada Division of Experimental Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, Canada Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada mark.wainberg@mcgill.ca.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wainberg
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019380:Anti-HIV Agents / Q000494:pharmacology; D002460:Cell Line; D024882:Drug Resistance, Viral; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D019427:HIV Integrase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015497:HIV-1 / Q000145:classification / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D016415:Sequence Alignment
chemical_list: D019380:Anti-HIV Agents; D019427:HIV Integrase