Objective: To analyze the genotypes and the genetic evolution of the hemagglutinin genes of measles viruses in the city of Yancheng in 2016. Methods: Using a set of primers and probes for screening positive for measles viruses, specimens of throat swab were detected using the method of real time RT-PCR. The sequences of the nucleoprotein and hemagglutinin genes of measles viruses were amplified through one step RT-PCR method and the PCR products were sequenced. The sequences of nucleotide and amino acid of the nucleoprotein and hemagglutinin genes of measles viruses were analyzed and the evolutional trees were generated using bioinformatics software. Results: The genotypes of measles viruses in the Yancheng area in 2016 included subgenotype H1a and genotype D8. Phylogenetic trees analysis showed that the five representative strains of subgenotype H1a in Yancheng area and Jiangxi representative strain (KJ136545) clustered into independent evolutionary branches, belonged to the clade of H1a -1 evolutionary genes. The seven representative strains of genotype D8 in Yancheng area were clustered with the American representative strain in 2009 (JN635404), belonged to the D8-3-2 small clade genes. Compared with vaccine strain of Shanghai S191, the amino acid site in 240^thof the five representative strains of subgenotype H1a in Yancheng area mutated from serine to asparagine, leading to a loss of the N-glycosylation site NLS_238-240. The seven representative strains of genotype D8 in Yancheng area had no change in N-glycosylation. Conclusions In 2016, the prevalent strains of measles viruses in Yancheng area were mainly Chinese H1a dominant subgenotype and D8 imported genotype. In addition to a loss of the N-glycosylation site NLS_238-240in 240^thof the five representative strains of subgenotype H1a, most of the major neutralizing antigen sites of hemagglutinin gene of measles viruses in Yancheng area did not mutate. The Chinese vaccine of Shanghai S191 can effectively prevent infection caused by subgenotype H1a and subgenotype D8 strains.

Objective: To analyze the genetic characteristics of the hemagglutinin(HA) and neuraminidase(NA) genes of the influenza A/H1N1(09pdm) viruses isolated in the city of Yancheng in 2014-2017. Methods: The throat swab specimens of patients with influenza-like illness (ILI) from sentinel surveillance hospitals and outbreak sites were detected using the method of real time RT-PCR. The influenza A/H1N1(09pdm) viruses were isolated using MDCK cell culture method in 2014-2017. The strains in 2014-2017 were selected randomly and their sequences of the HA1 and NA genes were amplified through one step RT -PCR method and the PCR products were sequenced. The mutations of genes and acid locus were analyzed and the evolutional trees were generated using bioinformatics software. Results: The clustering relationships of the respective branches of HA1 and NA genes of seventeen A/H1N1(09pdm) strains isolated in Yancheng area were basically the same and the phylogenetic trees of HA1 and NA genes were respectively clustered into four evolutionary branches. Compared with the vaccine strain A/California/07/2009(H1N1pdm)in the Northern Hemisphere, a total of three antigen epitopes (Ca, Sa, Sb) in HA1 genes of strains in Yancheng area were involved in six antigenic sites (K154R, S162N, K163Q, S185T, L191I, S203T); there were three mutations (D222G/N, G223R, E224K) in the 220 ring and one locus (L191I) in the 190 helix of the receptor binding sites; the two strains (A/Jiangsu-YC/SWL1540/2017, A/Jiangsu-YC/SWL1545/2017) isolated in 2017 increased the 162NQS glycosylation site. Because the strains of the antigen epitopes, receptor binding sites and glycosylation sites in the HA1 genes had a certain degree of variations in Yancheng area in 2014-2017, the protective effects of vaccine strain A/California/07/2009 (H1N1pdm) was limited at the gene level. The two strains (A/Jiangsu-YC/SWL1540/2017 and A/Jiangsu-YC/SWL1545/2017) isolated in 2017 were clustered with vaccine strain A/Michigan/45/2015(H1N1pdm) and had better protective effects. Seventeen A/H1N1(09pdm) strains had no mutations in catalytic residues and drug resistant sites of NA genes, but a part of strains had a certain degree of variations in glycosylation sites of NA genes. Conclusions These results indicated the HA1 and NA genes of influenza A/H1N1(09pdm) viruses circulated in Yancheng area in 2014-2017 changed gradually. The accumulation of these mutations would result in antigenic drift of influenza A/H1N1(09pdm) viruses.