title: Emerging genotypes of human respiratory syncytial virus subgroup A among patients in Japan.
abstract: Human respiratory syncytial virus (HRSV) is a common etiological agent of acute lower respiratory tract disease in infants. We report the molecular epidemiology of HRSV in Niigata, Japan, over six successive seasons (from 2001 to 2007) and the emerging genotypes of HRSV subgroup A (HRSV-A) strains. A total of 488 HRSV samples were obtained from 1,103 screened cases in a pediatric clinic in Niigata. According to the phylogenetic analysis, among the PCR-positive samples, 338 HRSV-A strains clustered into the previously reported genotypes GA5 and GA7 and two novel genotypes, NA1 and NA2, which were genetically close to GA2 strains. One hundred fifty HRSV-B strains clustered into three genotypes, namely, GB3, SAB3, and BA, which has a 60-nucleotide insertion in the second hypervariable region of the G protein. The NA1 strains emerged first, in the 2004-2005 season, and subsequently, the NA2 strain emerged in the 2005-2006 season. Both strains caused large epidemics in the 2005-2006 and 2006-2007 seasons. The average age of children who were infected with NA2 strains was significantly higher than that of those infected with GA5 and the frequency of reinfection by NA2 was the highest among all genotypes, suggesting that this genotype possessed new antigenicity for evading past host immunity. This is the first paper to show a possible correlation between an emerging genotype, NA2, and large outbreaks of HRSV in Japan. Continuing studies to follow up the genetic changes and to clarify the mechanism of reinfection in HRSV are important steps to understand HRSV infections.
authors: Department of Infectious Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Asahimachi-dori, Niigata City, Japan. yugo@med.niigata-u.ac.jp
authors: Yugo
authors: Y
authors: Shobugawa
authors: Reiko
authors: R
authors: Saito
authors: Yasuko
authors: Y
authors: Sano
authors: Hassan
authors: H
authors: Zaraket
authors: Yasushi
authors: Y
authors: Suzuki
authors: Akihiko
authors: A
authors: Kumaki
authors: Isolde
authors: I
authors: Dapat
authors: Taeko
authors: T
authors: Oguma
authors: Masahiro
authors: M
authors: Yamaguchi
authors: Hiroshi
authors: H
authors: Suzuki
mesh_terms: D002675:Child, Preschool; D016000:Cluster Analysis; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000821:virology*; D018113:Respiratory Syncytial Virus, Human / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology*; D017422:Sequence Analysis, DNA
chemical_list: D012367:RNA, Viral