Novel Variants of Respiratory Syncytial Virus A ON1 Associated With Increased Clinical Severity of Bronchiolitis

J Infect Dis. 2020 Jun 16;222(1):102-110. doi: 10.1093/infdis/jiaa059.


Background: A study of respiratory syncytial virus-A (RSV A) genotype ON1 genetic variability and clinical severity in infants hospitalized with bronchiolitis over 6 epidemic seasons (2012-2013 to 2017-2018) was carried out.

Methods: From prospectively enrolled term infants hospitalized for bronchiolitis, samples positive for RSV A ON1 (N = 139) were sequenced in the second half of the G gene. Patients' clinical data were obtained from medical files and each infant was assigned a clinical severity score. ANOVA comparison and adjusted multinomial logistic regression were used to evaluate clinical severity score and clinical parameters.

Results: The phylogenetic analysis of 54 strains showed 3 distinct clades; sequences in the last 2 seasons differed from previous seasons. The most divergent and numerous cluster of 2017-2018 strains was characterized by a novel pattern of amino acid changes, some in antigenic sites. Several amino acid changes altered predicted glycosylation sites, with acquisition of around 10 new O-glycosylation sites. Clinical severity of bronchiolitis increased in 2016-2017 and 2017-2018 and changed according to the epidemic seasons only.

Conclusions: Amino acid changes in the hypervariable part of G protein may have altered functions and/or changed its immunogenicity, leading to an impact on disease severity.

Keywords: bronchiolitis; clinical severity; genetic variability; genotypes; respiratory syncytial virus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bronchiolitis / epidemiology
  • Bronchiolitis / physiopathology*
  • Bronchiolitis / virology*
  • Female
  • Genetic Variation*
  • Genotype
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Phylogeny
  • Respiratory Syncytial Virus Infections / epidemiology
  • Respiratory Syncytial Virus Infections / genetics*
  • Respiratory Syncytial Virus Infections / physiopathology*
  • Respiratory Syncytial Virus, Human / genetics*
  • Rome / epidemiology
  • Severity of Illness Index*