Downloaded from www.microbiologyresearch.org by IP: 54.147.215.157 On: Sun, 11 Dec 2016 23:56:04 Journal of General Virology (2002), 83, 1107–1111. Printed in Great Britain ................................................................................................................................................................................................................................................................................... Prevalence of vaccine-derived polioviruses in the environment Hiromu Yoshida, 1 Hitoshi Horie, 2 Kumiko Matsuura, 3 Takashi Kitamura, 3 So Hashizume 2 and Tatsuo Miyamura 1 1 Department of Virology II, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan 2 Japan Poliomyelitis Research Institute, Kumegawa 5-34-4, Higashimurayama, Tokyo 189-0003, Japan 3 Department of Virology, Toyama Institute of Health, Nakataikoyama, Kosugi-machi, Imizu-gun, Toyama 939-0363, Japan A survey of poliovirus in river and sewage water was conducted from October 1993 to September 1995 in Toyama Prefecture, Japan. In this study, 25 isolates differentiated as type 2 vaccine- derived polioviruses (VDPVs) were characterized using mutant analysis by PCR and restriction- enzyme cleavage (MAPREC) to estimate the ratio of 481-G revertants correlated to neurovirulence in a virus population. Of these isolates, 23 (92 %) comprised between 44 and 96 % 481-G revertants by MAPREC. The other two isolates had revertant percentages close to the 06 % of the attenuated reference strain. It was presumed that these 23 isolates would be variant with potential neurovirulence by MAPREC analysis. Of the 23 isolates, three were isolated from river water. Moreover, our results by MAPREC showed that type 2 poliovirus was phenotypically more variable than type 1 (69 %) or type 3 (55 %), as determined in previous studies. The prevalence of virulent- type VDPVs in river and sewage water suggested that the oral poliovaccine itself had led to wide environmental pollution in nature. To terminate the cycle of virus transmission in nature, the ecology of VDPVs should be studied further. A hygiene programme, inactivated poliovirus vaccine immunization and well-maintained herd immunity may play key roles in reducing the potential risk of infection by virulent VDPVs. Introduction Although it is known that poliovirus exists widely in nature, in soil, sewage, wastewater, drinking water and food such as shellfish, there is very little evidence to connect it directly with an outbreak of poliomyelitis (Jaykus, 1997 ; Metcalf et al., 1979; Goyal et al., 1979). Because most cases of infection by poliovirus are not apparent, it is not until secondary, person-to-person spread leads to the onset of poliomyelitis that the infection is recognized. Therefore, it is difficult to address the risk of infection from the environment (Metcalf et al., 1995). The polio eradication program is close to the final stage of replacing wild-type poliovirus in the population with vaccine- type by mass live oral poliovaccine (OPV) immunization. After the termination of OPV in the near future, the possibility of an outbreak caused by vaccine-derived poliovirus (VDPV) must Author for correspondence : Hiromu Yoshida. Fax 81 42 561 4729. e-mail hyoshidanih.go.jp be considered, since it has been shown in many studies that nucleotide substitution in the virus genome occurs gradually during replication in the human gut after OPV administration and the phenotype of excreted viruses changes from attenuated to virulent (Abraham et al., 1993 ; Dunn et al., 1990 ; Japan Live Poliovaccine Research Commission, 1967 ; Benyesh-Melnick et al., 1967 ; Guillot et al., 1994; Wood & Macadam, 1997). It is therefore difficult to distinguish whether vaccine-associated paralytic poliomyelitis (VAPP) cases are recipient VAPP or contact VAPP by sequencing the genome of excreted virus. On the other hand, environmental surveillance is still epidemiologically important for the following reasons : (i) the results of virus surveillance retrospectively reflect the proper- ties of virus circulating in the community (Divizia et al., 1999 ; Shulman et al., 2000 ; Tambini et al., 1993; Po  yry et al., 1988; van der Avoort et al., 1995) and (ii) it assesses the potential risk of infection from the environment and food (Jaykus, 1997 ; Richards, 1999; Haas, 1983; Haas & Heller, 1988; Haas et al., 1993). In Toyama, Japan, routine OPV immunization has been administered annually in May and October. We have shown in 0001-8181  2002 SGM BBAH