title: Resistance profile of a neutralizing anti-HIV monoclonal antibody, KD-247, that shows favourable synergism with anti-CCR5 inhibitors.
abstract: BACKGROUND
  The high-affinity humanized monoclonal antibody (MAb) KD-247 reacts with a tip region in gp120-V3 and cross-neutralizes primary isolates with a matching neutralization sequence motif.
  
  
  METHODS
  We induced an HIV-1 variant that was resistant to KD-247 by exposing the JR-FL virus to increasing concentrations of KD-247 in PM1/CCR5 cells, which expressed high levels of CCR5 in vitro. We determined the amino acid sequence of the gp120-encoding region of the JR-FL escape mutant from KD-247. To confirm that this substitution was responsible for the KD-247-resistance, a single-round replication assay was performed. We further evaluated the anti-HIV-1 interactions between KD-247 and various CCR5 inhibitors in vitro.
  
  
  RESULTS
  At passage 8 of the culture in the presence of 1000 mug/ml KD-247, one amino acid substitution, Gly to Glu at position 314 (G314E), was identified in the V3-tip of gp120. A pseudotyped virus with the G314E mutation was highly resistant to KD-247. Unexpectedly, this mutant virus was sensitive to CCR5 inhibitors, RANTES, recombinant human soluble CD4 (rsCD4) and an anti-CCR5 MAb, but resistant to an anti-CD4 MAb, compared with the wild-type virus. We also found that combinations of KD-247 and CCR5 inhibitors were highly synergistic.
  
  
  CONCLUSIONS
  The present data suggest that KD-247 has certain advantages for possible passive immunotherapy. They are: high concentrations of KD-247 are needed for viral acquisition of KD-247 resistance; the escape variants are more sensitive to CCR5 inhibitors and rsCD4; and there are high levels of synergism between KD-247 and CCR5 inhibitors at all concentrations tested.
authors.affiliation: Division of Clinical Retrovirology and Infectious Diseases, Center for AIDS Research, Graduate School of Medical Sciences, Kumamoto, University, Kumamoto, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Junji
authors.initials: J
authors.lastname: Shibata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kimura
authors.forename: Akiko
authors.initials: A
authors.lastname: Honda
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Maeda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Koito
authors.forename: Toshio
authors.initials: T
authors.lastname: Murakami
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mitsuya
authors.forename: Shuzo
authors.initials: S
authors.lastname: Matsushita
mesh_terms: D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000914:Antibodies, Viral / Q000276:immunology; D065100:CCR5 Receptor Antagonists; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004306:Dose-Response Relationship, Immunologic; D004357:Drug Synergism; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D019713:Receptors, CCR5 / Q000378:metabolism; D014162:Transfection
chemical_list: D019380:Anti-HIV Agents; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D065100:CCR5 Receptor Antagonists; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D019713:Receptors, CCR5