Assessment of poliovirus eradication in Japan: genomic analysis of polioviruses isolated from river water and sewage in toyama prefecture

Abstract

Seventy-eight poliovirus strains isolated from river water and sewage in Toyama Prefecture, Japan, during 1993 to 1995 were characterized by the PCR-restriction fragment length polymorphism (RFLP) method and by partially sequencing the VP3 and VP1 regions of the viral genome. Of these isolates, 36 were identified as Sabin vaccine strains, and 42 were identified as vaccine variant strains that had less than 1.4% nucleotide divergence from the Sabin strains, including 7 isolates with patterns different from those of Sabin strains as determined by PCR-RFLP analysis. These findings suggest that wild-type poliovirus was not circulating in Toyama Prefecture.

FIG. 1

Distribution of poliovirus strains isolated from river water and sewage samples. Each dot indicates one poliovirus strain.

FIG. 2

Poliovirus isolates from river water and sewage samples.

FIG. 3

RFLP patterns of the reference strains and isolates. Reference strains: Sabin 1, 2, and 3, Mahoney, Lansing, and Saukett. Isolates: G17-21, G4-2, G3-1, O41-1, G27-14, G4-18, and G19-4. UC, uncut; MW, DNA molecular weight marker (MspI digest of pBR322). Strains G17-21, G3-1, and G4-18 had restriction patterns similar to those of Sabin strains. G4-2, O41-1, G27-14, and G19-4 had patterns different from those of Sabin strains.