title: Differences in viral load among human respiratory syncytial virus genotypes in hospitalized children with severe acute respiratory infections in the Philippines.
abstract: Human respiratory syncytial virus (HRSV) is a leading viral etiologic agent of pediatric lower respiratory infections, including bronchiolitis and pneumonia. Two antigenic subgroups, HRSV-A and B, each contain several genotypes. While viral load may vary among HRSV genotypes and affect the clinical course of disease, data are scarce regarding the actual differences among genotypes. Therefore, this study estimated and compared viral load among NA1 and ON1 genotypes of HRSV-A and BA9 of HRSV-B. ON1 is a newly emerged genotype with a 72-nucleotide duplication in the G gene as observed previously with BA genotypes in HRSV-B.
  
  
  
  Children <5 years of age with an initial diagnosis of severe or very severe pneumonia at a hospital in the Philippines from September 2012 to December 2013 were enrolled. HRSV genotypes were determined and the viral load measured from nasopharyngeal swabs (NPS). The viral load of HRSV genotype NA1 were significantly higher than those of ON1 and BA9. Regression analysis showed that both genotype NA1 and younger age were significantly associated with high HRSV viral load.
  
  
  
  The viral load of NA1 was higher than that of ON1 and BA9 in NPS samples. HRSV genotypes may be associated with HRSV viral load. The reasons and clinical impacts of these differences in viral load among HRSV genotypes require further evaluation.
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Francois Marie Ngako
authors.initials: FM
authors.lastname: Kadji
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Furuse
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Raita
authors.initials: R
authors.lastname: Tamaki
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Suzuki
authors.affiliation: Tohoku-RITM Collaborating Research Center on Emerging and Reemerging Diseases, Muntinlupa City, the Philippines.
authors.forename: Irene
authors.initials: I
authors.lastname: Lirio
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Clyde
authors.initials: C
authors.lastname: Dapat
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Rungnapa
authors.initials: R
authors.lastname: Malasao
authors.affiliation: Tohoku-RITM Collaborating Research Center on Emerging and Reemerging Diseases, Muntinlupa City, the Philippines.
authors.forename: Mariko
authors.initials: M
authors.lastname: Saito
authors.affiliation: Biliran Provincial Hospital, Naval City, the Philippines.
authors.forename: Gay Anne Granada
authors.initials: GA
authors.lastname: Pedrera-Rico
authors.affiliation: Research Institute for Tropical Medicine, Muntinlupa City, the Philippines.
authors.forename: Veronica
authors.initials: V
authors.lastname: Tallo
authors.affiliation: Research Institute for Tropical Medicine, Muntinlupa City, the Philippines.
authors.forename: Socorro
authors.initials: S
authors.lastname: Lupisan
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan. msaitop@gmail.com.
authors.forename: Mayuko
authors.initials: M
authors.lastname: Saito
authors.affiliation: Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Oshitani
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006760:Hospitalization; D006801:Humans; D008297:Male; D010679:Philippines / Q000453:epidemiology; D010802:Phylogeny; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000821:virology*; D018113:Respiratory Syncytial Virus, Human / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D019562:Viral Load
keywords: Children; Genotype; Pneumonia; Respiratory syncytial virus; Viral load