Related Experiment Videos
Two major strains of type 1 wild poliovirus circulating in Indochina
1Department of Virology II, National Institute of Health, Tokyo, Japan.
Abstract:
Two hundred ninety-four isolates from 329 patients with acute flaccid paralysis in Cambodia and Vietnam during 1992-1995 were identified as type 1 wild polioviruses. Among these isolates, 85 were selected as geographic representatives and were examined by determining the nucleotide sequences of their genome in the VP1 region. The phylogenic analysis revealed that all of the isolates examined were classified into groups A and B. Isolates belonging to group A had been found only in northern Vietnam until 1993 but not in 1994 and 1995. Group B isolates were located in both northern and southern Vietnam and Cambodia. In 1994 and 1995, however, only group B isolates were found in the Mekong Delta area in southern Vietnam and Cambodia. Isolates of groups A and B were genetically different from strains previously isolated in other Asian countries. One of the two indigenous wild polioviruses still remains to be eliminated in this area.
Insights
Wild poliovirus type 1 was detected in Cambodia and Vietnam from 1992-1995. Phylogenetic analysis revealed two distinct groups, A and B, with evolving geographic distributions, highlighting the need for continued eradication efforts.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Acute flaccid paralysis (AFP) surveillance is crucial for poliovirus detection.
- Wild poliovirus (WPV) circulation poses a significant threat to global polio eradication.
- Understanding the genetic diversity and geographic distribution of WPV is essential for targeted interventions.
Purpose of the Study:
- To genetically characterize wild poliovirus type 1 isolates from Cambodia and Vietnam.
- To analyze the phylogenetic relationships and geographic spread of WPV strains.
- To inform ongoing polio eradication strategies in Southeast Asia.
Main Methods:
- Nucleotide sequencing of the VP1 region of 85 representative WPV type 1 isolates.
- Phylogenetic analysis to determine genetic relationships and classify isolates into groups.
- Geographic mapping of isolate distribution over time (1992-1995).
Main Results:
- All 85 WPV type 1 isolates belonged to two distinct phylogenetic groups, A and B.
- Group A isolates were initially found in northern Vietnam but disappeared by 1994.
- Group B isolates showed a broader distribution in Vietnam and Cambodia, with a notable presence in the Mekong Delta.
- Isolates from both groups were genetically distinct from other Asian WPV strains.
Conclusions:
- Two distinct WPV type 1 lineages circulated in Cambodia and Vietnam during 1992-1995.
- Shifting geographic patterns of WPV groups A and B were observed, particularly in southern Vietnam and Cambodia.
- The genetic distinctiveness of these strains underscores the importance of continued WPV surveillance and eradication efforts in the region.