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Molecular characterization of enterovirus-A71 in children with acute flaccid paralysis in the Philippines
Lea Necitas Apostol1,2, Hiroyuki Shimizu3, Akira Suzuki4,5
1Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan. leianecitas9780@yahoo.com.
Insights
Molecular epidemiology of enterovirus-A71 (EV-A71) in the Philippines reveals C2 cluster strains linked to Asia-Pacific circulation. This genetic data is crucial for understanding EV-A71 and developing effective vaccines.
Area of Science:
- Virology
- Molecular Epidemiology
- Public Health
Background:
- Enterovirus-A71 (EV-A71) causes hand, foot, and mouth disease (HFMD) and acute flaccid paralysis (AFP).
- Laboratory confirmation of EV-A71 in the Philippines was lacking until 2012.
- Understanding EV-A71 molecular epidemiology is vital for vaccine development.
Purpose of the Study:
- To perform molecular epidemiologic analysis and genetic characterization of EV-A71 isolates in the Philippines.
- To investigate the circulation of EV-A71 strains in the country through AFP surveillance.
Main Methods:
- Retrospective study of nonpolio enteroviruses (NPEVs) associated with AFP.
- Identification and molecular characterization of nine EV-A71 positive samples.
- Phylogenetic analysis of the complete viral protein 1 (VP1) gene.
Main Results:
- Nine EV-A71 isolates from 2000-2010 were characterized.
- All isolates belonged to the EV-A71 genogroup C, specifically the C2 cluster.
- Genetic linkage was observed with strains from Japan and Taiwan, indicating regional circulation.
Conclusions:
- The study provides genetic data on circulating EV-A71 strains in the Philippines.
- Findings contribute to the incomplete knowledge of EV-A71 molecular epidemiology in the Asia-Pacific region.
- Understanding EV-A71 circulation is important for regional vaccine formulation.
Background:
Several inactivated enterovirus-A71 (EV-A71) vaccines are currently licensed in China; however, the development of additional EV-A71 vaccines is ongoing, necessitating extensive analysis of the molecular epidemiology of the virus worldwide. Until 2012, laboratory confirmation of EV-A71 for hand, foot, and mouth disease (HFMD) and other associated diseases had not occurred in the Philippines. Because EV-A71 has been linked with cases of acute flaccid paralysis (AFP), AFP surveillance is one strategy for documenting its possible circulation in the country. To expand current knowledge on EV-A71, molecular epidemiologic analysis and genetic characterization of EV-A71 isolates were performed in this study.
Methods:
A retrospective study was performed to identify and characterize nonpolio enteroviruses (NPEVs) associated with AFP in the Philippines, and nine samples were found to be EV-A71-positive. Following characterization of these EV-A71 isolates, the complete viral protein 1 (VP1) gene was targeted for phylogenetic analysis.
Results:
Nine EV-A71 isolates detected in 2000 (n = 2), 2002 (n = 4), 2005 (n = 2), and 2010 (n = 1) were characterized using molecular methods. Genomic regions spanning the complete VP1 region were amplified and sequenced using specific primers. Phylogenetic analysis of the full-length VP1 region identified all nine EV-A71 Philippine isolates as belonging to the genogroup C lineage, specifically the C2 cluster. The result indicated a genetic linkage with several strains isolated in Japan and Taiwan, suggesting that strains in the C2 cluster identified in the Asia-Pacific region were circulating in the Philippines.
Conclusion:
The study presents the genetic analysis of EV-A71 in the Philippines. Despite some limitations, the study provides additional genetic data on the circulating EV-A71 strains in the Asia-Pacific region, in which information on EV-A71 molecular epidemiology is incomplete. Considering that EV-A71 has a significant public health impact in the region, knowledge of its circulation in each country is important, especially for formulating vaccines covering a wide variety of strains.
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