Epidemiology and molecular biology of respiratory syncytial virus among hospitalized children in Guangzhou from 2013 to 2017

Objective: To understand the genetic variation and epidemiological characteristics of human respiratory syncytial virus (HRSV) in Guangzhou. Methods: Nasopharyngeal swabs specimens were collected from 0-6 year old children hospitalized with acute respiratory infection, then HRSV was tested and genotyped by RT-PCR. Phylogenetic tree was bulit using MEGA 6.0 software. NetNGlyc 1.0 server was used to predict the potential N-linked glycosylation sites. Results: A total of 1 225 nasopharyngeal specimens were collected, including 783 males and 442 females. The median (P(25), P(75)) age was 8 (3, 24) months. Among the 209 HRSV-positive cases (17.06%), 117 cases (55.98%) were HRSV-A and 92 cases (44.02%) were HRSV-B. The two distinct subgroups (HRSV-A and HRSV-B) alternately played dominant role to cause HRSV infection and exchange almost once every two years. The HRSV prevalence rate decreased with age. The HRSV-positive rate among children under 2 years old was 18.83% (196 cases), accounting for 93.78% of the total positive cases. There were 32 HRSV positive cases co-infected with at least one respiratory virus, with the co-infection rate of 15.31%. Phylogenetic tree analysis of the second hypervariable region (HVR2) of the G protein classified the HRSV-A specimens into ON1 (n=62) and NA1 (n=2) genotypes while all HRSV-B specimens belonged to BA genotype (n=53). The HVR2 of the G protein varied in using stop condon, amino acid substitutions, glycosylation sites. Conclusion: Children under 2 years old were the high risk population of HRSV infection in Guangzhou. ON1 genotype turned into a primary genetype of the HRSV-A subgroup while BA genotype dominated the HRSV-B subgroup. A greater diversification of amino acid substitutions, and some deletion and insertion of glycosylation sites embodied the polymorphism of G protein as main protective antigen.