Molecular Epidemiology of Respiratory Syncytial Virus A G-Protein for 9 Years and Emergence of ON1 Genotype Having 72 Nucleotide Duplication in Korea

BACKGROUND: Respiratory syncytial virus (RSV) is a major pathogen causing seasonal epidemics of lower respiratory tract infection in young children. The attachment (G) glycoprotein is a major virulence factor and a target of human neutralizing antibodies. The G protein shows the evidence of changes of amino acid over time, making its study important in vaccine development strategies. We aimed to explore the molecular epidemiology of G protein of RSV A in Korea. METHODS: One hundred and thirty-six RSV strains were obtained from children who were hospitalized at Seoul National University Children’s Hospital, from October 2005 to September 2014. The frozen stock viruses were propagated in HEp-2 cells and the infected cell lysates were collected when cytopathic effects were apparent. The polymerase chain reaction and sequencing were performed using cDNA constructed from viral RNA and primers from previous studies. Phylogenetic analysis and putative antigenicity plotting were performed using CLC Main Workbench ver. 6.6.5 software (CLC bio, Aarhus, Denmark). RESULTS: The entire G-genes were sequenced from all 136 RSV A strains: most (n = 99, 72.8%) strains had 895 nucleotide-span, but the others (n = 45, 27.2%) had 72 nucleotide (nt) duplication, which are well-known ON1 genotype. On phylogenetic grouping, three different genotypes 1–3 except ON1 were additionally defined. During the 2005–2006 season, the prevalence of genotypes 1, 2, and 3 were comparable (36.4%, 27.3%, and 36.4%, respectively), but genotype 1 became predominate (69.2%) in the 2006–2007 season. The genotype 3 increased since 2007–2008 (80.0%) and was identified exclusively during three consecutive seasons thereafter (2009–2011). In the 2011–2012 season, the first ON1 strain was identified in Korea, and the prevalence increased to 91.7% in the 2012–2013 season, then to 100% thereafter (2013–2015). In spite of 72-nt duplication, the putative antigenicity patterns of G protein were comparable between ON1 genotype and the others. CONCLUSION: Our findings highlight the genotype change of circulating RSV A in 3–4 years interval, which might explain the reason for annual local epidemics of RSV A. Also in Korea, RSV A ON1 genotype increased since 2011 and was circulating exclusively since 2013. DISCLOSURES: All authors: No reported disclosures.