title: Antiviral activity of 3(2H)- and 6-chloro-3(2H)-isoflavenes against highly diverged, neurovirulent vaccine-derived, type2 poliovirus sewage isolates.
abstract: BACKGROUND
  Substituted flavanoids interfere with uncoating of Enteroviruses including Sabin-2 polio vaccine strains. However flavanoid resistant and dependent, type-2 polio vaccine strains (minimally-diverged), emerged during in vitro infections. Between 1998-2009, highly-diverged (8 to >15%) type-2, aVDPV(2)s, from two unrelated persistent infections were periodically isolated from Israeli sewage.
  
  
  OBJECTIVE
  To determine whether highly evolved aVDPV(2)s derived from persistent infections retained sensitivity to isoflavenes.
  
  
  METHODS
  Sabin-2 and ten aVDPV(2) isolates from two independent Israeli sources were titered on HEp2C cells in the presence and absence of 3(2H)- Isoflavene and 6-chloro-3(2H)-Isoflavene. Neurovirulence of nine aVDPV(2)s was measured in PVR-Tg-21 transgenic mice. Differences were related to unique amino acid substitutions within capsid proteins.
  
  
  RESULTS
  The presence of either flavanoid inhibited viral titers of Sabin-2 and nine of ten aVDPV(2)s by one to two log(10). The tenth aVDPV(2), which had unique amino acid substitution distant from the isoflavene-binding pocket but clustered at the three- and five-fold axies of symmetry between capsomeres, was unaffected by both flavanoids. Genotypic neurovirulence attenuation sites in the 5'UTR and VP1 reverted in all aVDPV(2)s and all reacquired a full neurovirulent phenotype except one with amino acid substitutions flanking the VP1 site.
  
  
  CONCLUSIONS
  Both isoflavenes worked equally well against Sabin 2 and most of the highly-diverged, Israeli, aVDPV(2)s isolates. Thus, functionality of the hydrophobic pocket may be unaffected by selective pressures exerted during persistent poliovirus infections. Amino acid substitutions at sites remote from the drug-binding pocket and adjacent to a neurovirulence attenuation site may influence flavanoid antiviral activity, and neurovirulence, respectively.
authors: Central Virology Laboratory, Public Health Services Israel Ministry of Health, Chaim Sheba Medical Center, Tel Hashomer, Israel. lester.shulman@sheba.health.gov.il
authors: Lester M
authors: LM
authors: Shulman
authors: Danit
authors: D
authors: Sofer
authors: Yossi
authors: Y
authors: Manor
authors: Ella
authors: E
authors: Mendelson
authors: Jean
authors: J
authors: Balanant
authors: Anna Laura
authors: AL
authors: Salvati
authors: Francis
authors: F
authors: Delpeyroux
authors: Lucia
authors: L
authors: Fiore
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D005838:Genotype; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D017955:Poliovirus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D023321:Poliovirus Vaccines; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020121:5' Untranslated Regions; D000998:Antiviral Agents; D007529:Isoflavones; D023321:Poliovirus Vaccines; C063932:3(2H)-isoflavene; C063933:6-chloro-3(2H)-isoflavene