Related Experiment Videos
Circulation of type 1 wild poliovirus in northern Vietnam during 1991-1994
H Yoshida1, T Yoneyama, K Yoshii
1Department of Virology II, National Institute of Health, Tokyo, Japan.
Abstract:
From 1991 to 1994, 143 polioviruses were isolated from patients with acute flaccid paralysis in northern Vietnam. Of these 143 isolates, 133 were type 1 and five of each were type 2 and type 3. These isolates were intratypically differentiated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Of the 133 type 1 isolates, 113 were wild strains and only 20 isolates were of Sabin vaccine-like strains. These 113 isolates were divided into seven groups by PCR-RFLP patterns and were also classified into three genomic groups by nucleotide sequencing and phylogenetic analysis. One of the three genomic groups accounted for the majority (75) of these isolates. The isolates belonging to the predominant group were found during 1991-1993. The second group, which included 17 isolates, were detected only in 1993. These isolates had genome sequence similar to isolates in southern Vietnam in the same year. The third group of isolates were detected only in 1991 and were considered to be Mahoney-like wild strains. All isolates examined were different from those obtained in other countries. In 1994, however, no wild-type polioviruses were isolated in our study. These results reveal that three unique strains were circulating in northern Vietnam in recent years, and indicate that the incidence of poliomyelitis due to wild poliovirus is decreasing.
Insights
Wild poliovirus type 1 was prevalent in northern Vietnam between 1991-1993, with three distinct genomic groups identified. By 1994, wild poliovirus circulation ceased, indicating a decrease in poliomyelitis incidence.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Poliomyelitis remains a significant public health concern, particularly in regions with ongoing wild poliovirus circulation.
- Understanding poliovirus epidemiology is crucial for effective disease control and eradication efforts.
Purpose of the Study:
- To characterize poliovirus isolates from patients with acute flaccid paralysis in northern Vietnam.
- To determine the genetic diversity and origins of circulating poliovirus strains.
- To assess trends in wild poliovirus incidence.
Main Methods:
- Isolation and identification of polioviruses from clinical samples.
- Intratypic differentiation using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).
- Nucleotide sequencing and phylogenetic analysis for genomic classification.
Main Results:
- 143 poliovirus isolates were identified; 133 were type 1, with 113 confirmed as wild strains.
- PCR-RFLP and genomic analysis revealed three distinct wild poliovirus type 1 groups circulating.
- A significant decrease in wild poliovirus isolates was observed, with none detected in 1994.
Conclusions:
- Northern Vietnam experienced circulation of three unique wild poliovirus strains between 1991 and 1993.
- The findings suggest a declining incidence of poliomyelitis due to wild poliovirus in the region.
- Continued surveillance is essential to confirm eradication and prevent re-emergence.