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Published on: January 26, 2019
Molecular Characterization of Human Respiratory Syncytial Virus in the Philippines, 2012-2013
Rungnapa Malasao1, Michiko Okamoto1, Natthawan Chaimongkol1
1Tohoku University Graduate School of Medicine, Sendai, Japan.
Insights
Human respiratory syncytial virus (HRSV) caused severe pneumonia in Philippine children. The ON1 genotype of HRSV-A emerged as predominant, showing rapid evolution and genetic changes, while HRSV-B strains were also identified.
Area of Science:
- Virology
- Molecular Epidemiology
- Public Health
Background:
- Human respiratory syncytial virus (HRSV) is a leading cause of severe lower respiratory tract infections in young children globally.
- Understanding HRSV genotypes and their circulation is crucial for disease control and prevention strategies.
Purpose of the Study:
- To investigate the molecular epidemiology of HRSV in infants and children with severe pneumonia in the Philippines.
- To identify circulating HRSV genotypes and analyze their evolutionary dynamics.
Main Methods:
- Molecular analysis of nasopharyngeal swabs from 1,505 children with severe pneumonia in the Philippines (June 2012-July 2013).
- Real-time and conventional PCR for HRSV detection and genotyping.
- Sequencing of the second hypervariable region (2nd HVR) of the G gene for genetic characterization.
Main Results:
- 423 out of 1,505 samples (28.1%) were HRSV-positive, with 72.1% HRSV-A and 27.9% HRSV-B.
- Two HRSV-A genotypes, NA1 and the novel ON1 (with a 72-nucleotide duplication), were identified. ON1 rapidly became predominant in 2013.
- ON1 showed higher evolutionary rates and evidence of positive selection and glycosylation changes. HRSV-B genotype BA9 was predominant, with rare GB2 genotype cases detected.
Conclusions:
- HRSV is a significant pathogen causing severe acute respiratory infections in children in the Philippines.
- The emergence and rapid predominance of the ON1 genotype highlight its adaptability and potential impact.
- The detection of ON1 and GB2 genotypes for the first time in the Philippines provides critical insights into regional HRSV evolution.
Abstract:
Human respiratory syncytial virus (HRSV) is a major cause of acute lower respiratory tract infections in infants and children worldwide. We performed molecular analysis of HRSV among infants and children with clinical diagnosis of severe pneumonia in four study sites in the Philippines, including Biliran, Leyte, Palawan, and Metro Manila from June 2012 to July 2013. Nasopharyngeal swabs were collected and screened for HRSV using real-time polymerase chain reaction (PCR). Positive samples were tested by conventional PCR and sequenced for the second hypervariable region (2nd HVR) of the G gene. Among a total of 1,505 samples, 423 samples were positive for HRSV (28.1%), of which 305 (72.1%) and 118 (27.9%) were identified as HRSV-A and HRSV-B, respectively. Two genotypes of HRSV-A, NA1 and ON1, were identified during the study period. The novel ON1 genotype with a 72-nucleotide duplication in 2nd HVR of the G gene increased rapidly and finally became the predominant genotype in 2013 with an evolutionary rate higher than the NA1 genotype. Moreover, in the ON1 genotype, we found positive selection at amino acid position 274 (p<0.05) and massive O- and N-glycosylation in the 2nd HVR of the G gene. Among HRSV-B, BA9 was the predominant genotype circulating in the Philippines. However, two sporadic cases of GB2 genotype were found, which might share a common ancestor with other Asian strains. These findings suggest that HRSV is an important cause of severe acute respiratory infection among children in the Philippines and revealed the emergence and subsequent predominance of the ON1 genotype and the sporadic detection of the GB2 genotype. Both genotypes were detected for the first time in the Philippines.
