Clinical characteristics and genetic variation in respiratory syncytial virus isolated from infants hospitalized due to acute bronchiolitis in Korea during winter season 2016–2017

ABSTRACT

PURPOSE: Circulating patterns of predominant respiratory syncytial virus (RSV) genotypes in the community may be helpful in understanding molecular epidemiology and predicting future outbreaks of the RSV genotype. We investigated the association of genetic variations in RSV with acute severe bronchiolitis in infants. METHODS: We reviewed medical records of infants younger than 1 year of age hospitalized due to acute bronchiolitis between November 2016 and February 2017. Subjects were classified as severe or mild based on the use of mechanical or noninvasive ventilation. The associations between severity of the disease, sex, age at admission, oxygen saturation at admission and laboratory test results were analyzed. RSV sequence analysis was performed in the severe group. RESULTS: Among 114 infants, 80 underwent respiratory viral polymerase chain reaction using nasopharyngeal swab; of these, 53 (66.3%) showed positive for RSV. Of the 53 RSV-positive samples, 9 were categorized as the severe group and 44 were categorized as the mild group. Male sex, young age, longer duration of admission, minimum SaO2 at admission and bronchiolitis severity score were significantly correlated with disease severity in the severe group than in the mild group (all variables, P < 0.001). Phylogenetic and sequence analysis in the severe group revealed 8 RSV-A, ON1 genotype and 1 RSV-B, BA4 genotype. CONCLUSION: Phylogenetic types of RSV in subjects of the severe group were RSV-A, ON1 genotype or RSV-B, BA4 genotype which were prevalent in the Korean community at the same time. Our study showed that disease severity was not significantly associated with RSV genotypic evolution or antigenic drift in Korea during winter season 2016–17.