Epidemiological characteristics and G gene variation analysis of respiratory syncytial virus in children in Wuxi city, Jiangsu province, 2016−2018

Objective To analyse the epidemiological characteristics of respiratory syncytial virus (RSV) infection and RSV- G gene variation among children in Wuxi city, Jiangsu province from January 2016 to December 2018, and to provide scientific data for the prevention and control of RSV in Wuxi city, Jiangsu province.

Methods To collect specimens of acute upper respiratory tract infections from Wuxi Children's Hospital from 2016 to 2018, use real-time fluorescence quantitative polymerase chain reaction to detect RSV in the collected specimens, use double fluorescence polymerase chain reaction method to clarify A/B subtypes, select some positive specimens to perform G-gene sequencing, and compare the sequencing results with the known RSV gene sequences, to determine genotypes and to analyse the variability of the G-gene.

Results The overall RSV detection rate in 2016−2018 was 9.01% (281/3120), 4.07% (127/3120) for RSV subtype A, 4.87% (152/3120) for RSV subtype B, and only 2 cases of mixed subtypes A and B infections. The highest detection rate was 10.77% (196/1820) in infants and young children. The proportion from November to February each year (69.97%, 191/281) was much higher than other months. Subtype B predominated from January 2016 to April 2017, and subtype A predominated from September 2017 to December 2018. There was one genotype for RSV subtype A: ON1, and one genotype for RSV subtype B: BA10. The nucleotide homology of RSV subtype A was 95.70%–99.00% and the nucleotide homology of RSV subtype B was 97.10%–99.50%. Subtype A is prone to E262K and L274P mutations, and subtype B has T270I and V271A mutations. only 237 N-glycosylation sites in ON1 are identical to those in the prototype ON1 strain, and the N-glycosylation sites in BA10 are identical to those in the prototype BA strain.

Conclusion Infants are the main population infected with RSV in Wuxi city, Jiangsu province, and the peak period of RSV infection is from November to February every year, showing the characteristics of alternating epidemics of subtypes A and B. The ON1 and BA10 genotypes are the only genotypes of subtypes A and B of RSV, respectively. The homozygosity of the RSV-G gene is relatively small, and both of them have the typical amino acid site mutations of the ON1 and BA10 genotypes, and the N-glycosylation site of the ON1 type is more prone to mutation than that of the BA10 type. N-glycosylation sites were more likely to be mutated in the ON1 type than in the BA10 type.