Genetic characterization of human respiratory syncytial virus detected in hospitalized children in the Philippines from 2008 to 2012.
BACKGROUND
Human respiratory syncytial virus (HRSV) is the leading cause of acute lower respiratory tract infection in infants and young children. However, molecular characteristic of HRSV is still unknown in the Philippines.


OBJECTIVE
To describe the molecular epidemiology of circulating HRSV detected in the Philippines.


METHODS
From May 2008 to April 2012, nasopharyngeal swabs were collected from infants and children aged between 7 days and 14 years who were hospitalized with severe pneumonia. HRSV was detected by nested PCR targeting M2 gene, and C-terminus of the G gene was sequenced for phylogenetic analysis.


RESULTS
Out of total 2150 samples, 19.3% (n = 415) were positive for HRSV, and 65.0% of them (n = 270) were identified as HRSV-A and 35.0% (n = 145) as HRSV-B. There were two major HRSV outbreaks: between June 2008 and February 2009, and between June and March 2012. Majority of HRSV strains detected during the former outbreak were HRSV-A (97.5%, 203/208) whereas during the later outbreak, both HRSV-A (54/158, 34.2%) and HRSV-B (104/158, 65.8%) were detected. All HRSV-A strains were classified as genotype NA1 and all HRSV-B as genotype BA, which had 60-nucleotide duplication in secondary hypervariable region of the G gene. Among HRSV-B positive samples, there were 2 distinct clusters with unique amino acid changes and low homology in compared to other strains in BA, suggesting emergence of new variant of HRSV-B.


CONCLUSIONS
The study provides an overview of the genetic variation in circulating HRSV viruses in the Philippines along with identification of possibly a novel variant of HRSV-B.
Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryou machi, Aoba, Sendai, Miyagi 980-8575, Japan.
Ayumu
A
Ohno
Akira
A
Suzuki
Socorro
S
Lupisan
Hazel
H
Galang
Lydia
L
Sombrero
Rapunzel
R
Aniceto
Michiko
M
Okamoto
Mariko
M
Saito
Naoko
N
Fuji
Hirono
H
Otomaru
Chandra Nath
CN
Roy
Dai
D
Yamamoto
Raita
R
Tamaki
Remigio
R
Olveda
Hitoshi
H
Oshitani
D000293:Adolescent; D000595:Amino Acid Sequence; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D005838:Genotype; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009017:Morbidity; D009305:Nasopharynx; D010679:Philippines / Q000453:epidemiology; D010802:Phylogeny; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000821:virology*; D012136:Respiratory Syncytial Viruses / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D016415:Sequence Alignment; D014759:Viral Envelope Proteins / Q000235:genetics
D014759:Viral Envelope Proteins