Oral pollovaccine: Will it help eradicate polio or cause the next epidemic?

Lester M. Shulman, Yosef Manor, Danit Sofer, Tiberio Swartz, Ella Mendelson

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Poliovirus rapidly evolves by nucleic acid substitutions and genetic recombination with other polioviruses non-polio enteroviruses. Evolving oral poliovaccine can rapidly revert to neurovirulence and undergo antigenic alterations. Objectives: To evaluate the threat of vaccine-derived poliovirus (1-15% divergence from the respective Sabin strain) for a polio-myelitis-free population in a country with a long-standing routine vaccination program. Methods: We characterized genetic and antigenic changes in OPV (Sabin) strains isolated from sewage in Israel and evaluated intestinal immunity by measuring fecal excretion after OPV challenge of vaccinated children. Results: Characterization of poliovirus from sewage revealed eight type 2 and three type 3 vaccine polioviruses that had replicated and started to evolve (vaccine that replicated and diverged by 0.5 to ≤ 1.0%) and nine highly diverged type 2 vaccine-derived polioviruses (1-15% divergence from the respective Sabin strain) with 8-14% divergence between the years 1998 and 2005. Six of the eleven VRPV uniquely recombined with OPV and/or NPEV. The nine VDPV were epidemically related, genotypically neurovirulent, and had 10-15 amino acid substitutions in antigenic sites altering their antigenicity, but shared a single recombination. Type 2 OPV was excreted by 23% and 17% of infants challenged with OPV 3 months after partial immunization (two doses each of OPV and enhanced inactivated poliovirus) or full immunization (three doses of each) respectively, despite high humoral antibody titers. Conclusions: Our findings, which show that OPV is excreted for a significant period by children with high humoral immunity, emphasize the long-term potential threat from VDPV in highly vaccinated populations. An adequate immunization program, combined with environmental surveillance, is necessary to prevent poliomyelitis a community transmission of poliovirus.

Original languageEnglish
Pages (from-to)312-315
Number of pages4
JournalIsrael Medical Association Journal
Volume8
Issue number5
StatePublished - May 2006
Externally publishedYes

Keywords

  • Combined polio vaccination program
  • Environmental surveillance
  • Molecular epidemiology
  • Polio intestinal immunity
  • Vaccine-derived poliovirus
  • Vaccine-induced immunity

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