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Prevalence of vaccine-derived polioviruses in the environment
Hiromu Yoshida1, Hitoshi Horie2, Kumiko Matsuura3
1Department of Virology II, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan1.
Abstract:
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.
Insights
Type 2 vaccine-derived polioviruses (VDPVs) found in Japanese water showed high potential for neurovirulence. This suggests oral poliovirus vaccine use may cause environmental contamination, necessitating further VDPV ecology studies.
Area of Science:
- Environmental microbiology
- Virology
- Public health
Background:
- Poliovirus circulates in water sources, posing public health risks.
- Vaccine-derived polioviruses (VDPVs) can emerge and spread, particularly in areas with low vaccination rates.
- Understanding VDPV characteristics is crucial for disease control.
Purpose of the Study:
- To characterize type 2 VDPVs isolated from river and sewage water in Toyama Prefecture, Japan.
- To assess the neurovirulence potential of these VDPV isolates.
- To investigate the phenotypic variability of type 2 poliovirus compared to types 1 and 3.
Main Methods:
- Environmental water samples (river and sewage) were collected from October 1993 to September 1995.
- Twenty-five type 2 VDPV isolates were identified.
- Mutant analysis by PCR and restriction-enzyme cleavage (MAPREC) was used to determine the ratio of 481-G revertants, an indicator of neurovirulence.
Main Results:
- Of 25 type 2 VDPV isolates, 23 (92%) exhibited high percentages (44-96%) of 481-G revertants, indicating potential neurovirulence.
- Three of these potentially virulent VDPVs were isolated from river water.
- Type 2 poliovirus showed greater phenotypic variability (69%) than type 1 (69%) or type 3 (55%) in previous studies.
Conclusions:
- The high prevalence of potentially neurovirulent type 2 VDPVs in environmental water suggests widespread contamination linked to oral poliovirus vaccine use.
- Further research into VDPV ecology is essential to interrupt virus transmission.
- Hygiene, inactivated poliovirus vaccination, and herd immunity are vital for mitigating VDPV infection risks.