Epidemiological analysis of rubella and genetic characteristics of 1E-L2 subtype strains in Liaoning Province in 2019 / 中国生物制品学杂志

ABSTRACT

@#Objective To understand the epidemiological characteristics of rubella in Liaoning Province in 2019,and analyze the epidemiological characteristics of rubella virus genotypes and gene subtypes at molecular level.Methods By collecting the incidence data of rubella in Liaoning Province in 2019 from the national notifiable infectious diseases reporting system,the epidemiological characteristics of rubella were analyzed.At the same time,the measles/rubella laboratory network of Liaoning Province was used to collect throat swab samples from suspected rubella outbreaks and sporadic cases.After three generations of blind transmission of positive samples,rubella virus isolates were obtained.Viral nucleic acid was extracted,amplified and the 739 bp nucleotide fragment sequence of E1 gene of positive rubella virus isolates was determined.The phylogenetic tree was constructed with the genotype reference strain sequences recommended by WHO and the published gene subtype reference strain sequences.The genotypes and subtypes were compared and the amino acid variation sites were analyzed.Results The reported incidence of rubella in Liaoning Province in 2019 was 0.927/100 000,which showed an obvious trend of recovery after a significant decrease in the incidence of rubella from 2017 to 2018,and the age of rubella patients was mainly 15 to 19 years old.A total of 55 rubella virus strains were isolated from 7 cities in Liaoning Province in 2019.Sequence phylogenetic analysis showed that all rubella isolates belonged to 1E-L2 gene subtype,which was also the dominant gene subtype of rubella epidemic in China.The nucleotide and amino acid homology among the strains were 99.051%～99.864% and 98.780%～100% respectively.Compared with the BRD-Ⅱ vaccine strain,the rubella isolates mainly showed A333T mutation and showed highly conserved amino acid sequence.Conclusion The 2019 rubella isolates in Liaoning Province were all 1E-L2 gene subtypes,which led to the resurgence of rubella epidemic.Therefore,molecular epidemiological surveillance of rubella virus should be further strengthened to provide a basis for the formulation and elimination of rubella prevention and control measures in Liaoning Province.