Genetic and antigenic characterization of influenza A(H1N1)pdm09 in Yantai, China, during the 2009-2017 influenza season.

OBJECTIVE: This study was performed to determine the antigenic and genetic characteristics and evaluate potential vaccine efficacy of influenza A (H1N1)pdm09 in Yantai from August 2009 to August 2017. MATERIALS AND METHODS: A total of 10 236 swabs were collected among patients with an influenza-like illness who were admitted to two sentinel surveillance hospitals in Yantai, East China, from August 2009 to August 2017. All specimens were cultured in Madin-Darby canine kidney cells and identified by haemagglutination-inhibition assay. Complete sequences of haemagglutinin (HA) and neuraminidase of 51 influenza A(H1N1)pdm09 strains circulating in Yantai were amplified, sequenced and analysed using molecular and phylogenetic methods. The potential vaccine efficacy was calculated using the p epitope model which measured the antigenic variation based on the changes in the dominant epitope of HA. RESULTS: The results showed that most Yantai strains were grouped into genetic clades 1.7, 6C, 6B.1 and 6B.2. The amino acid substitutions accumulated gradually in HA proteins and considerable genetic variation were observed in circulating A(H1N1)pdm09 viruses during the seven influenza seasons. The V241I, N369K, N386K and K432E mutations which may change the binding pattern and affinity of oseltamivir for neuraminidase were detected in the strains circulating in 2016/2017 and 2017/2018 seasons and the recommended vaccine strains could afford optimal protection against the influenza A/H1N1pdm09. CONCLUSIONS: Although influenza A(H1N1)pdm09 viruses acquired significant genetic variation over the course of seven influenza seasons, the recommended vaccine strains still afforded protection against main circulating strains. Continuous epidemiological and virological surveillance are necessary.

Seroprevalence and evolutionary dynamics of genotype 4 hepatitis E virus in Shandong Province, China.

AIM: To investigate the seroprevalence and evolutionary dynamics of hepatitis E virus (HEV) and assess the ancestor of HEVs in China's Shandong Province. METHODS: A total of 2028 serum, 60 fecal and 82 bile samples were collected from the general human population, patients and swine, respectively. This seroepidemiological study was conducted using an immunnosorbent assay and HEV RNA was detected by the reverse transcription-nested polymerase chain reaction (RT-nPCR) method. Complete genome sequences of the prevalent strains (CH-YT-HEV01, CH-YT-HEV02 and CH-YT-sHEV01) were determined, and the sequences were analyzed phylogenetically. In addition, the evolutionary dynamics of three HEV isolates were determined using the framework of coalescent analysis in the program package BEAST, and the time of the most recent common ancestors (TMRCAs) of China-indigenous genotype 4 HEV isolates was calculated. RESULTS: The overall viral burden in the general human population was 0.1%, and the positive rates of anti-HEV IgG and IgM in the serum specimens were 25.1% (509/2028) and 2.3% (51/2028), respectively. In addition, IgG positivity increased with age. The phylogenetic analysis based on the full-length nucleotide sequences showed that the strain CH-YT-HEV02 was directly related to CH-YT-sHEV01 with a 94% identity, suggesting that they were involved in cross-species transmission. The isolate CH-YT-HEV01 was close to HB-3 and CHN-SD-sHEV with a bootstrap value of 100%, sharing a 96.1%-96.4% identity with each other. Surprisingly, the HB-3 strain was a representative strain prevalent in swine in Hubei, and the isolate CHN-SD-sHEV was obtained from swine in Shandong in a previous report. TMRCA for the clade of CH-YT-HEV01 and HB-3 was 2003, which was consistent with the TMRCA for the clade of CHN-SD-sHEV and HB-3, and they were both earlier than the TMRCA for the clade of CH-YT-HEV01 and CHN-SD-sHEV (2004). CONCLUSION: The strains CH-YT-HEV01, CHN-SD-sHEV and HB-3 are involved in trans-regional transmission, and the ancestors of HEVs in Shandong come from Hubei Province.

[The coastal areas of Yantai human and swine hepatitis E virus genotyping analysis].

OBJECTIVE: Survey of the coastal city of Yantai, from human and swine hepatitis E virus (HEV) genotype correlation. METHOD: Application of reverse transcription nested polymerase chain reaction (RT-nPCR) method for local acute sporadic hepatitis E patients,normal population of HEV-IgM positive and local pig farm pigs were HEV RNA detection. And HEV RNA positive samples for cloning sequencing and sequence analysis. RESULTS: In 16 patients with acute sporadic hepatitis E in 7 cases of RNA positive stool specimens of HEV; 51 IgM positive sera of normal people in specimens with 1 HEV RNA positive; 34 pig bile specimens with 1 HEV RNA positive. Sequence analysis revealed the region HEV strains and swine strains in the ORF2 region of nucleotide sequence homology is 87%-98.1%. 7 strains of hepatitis E virus genotype in patients and 1 strains of swine hepatitis E virus genotypes are type IV, gene sequence homology between the 87%-98.1%; there were 6 patients and porcine gene sequence homology in 93.9%-98.1% between,for type a subtype; 1 patients and porcine gene sequence homology in 87%, for the type D subtype. Normal population of 1 cases of hepatitis E virus genotype for I type D subtype. Human and porcine HEV ORF2 gene fragment and HEV part I-IV representative strains were compared, and the nucleotide sequence homology were 82.5%-100%, 81.7%-92.9%, 81.4%-93.9%, 84.9%-100%. CONCLUSION: The area population prevalence of HEV in the presence of 2 genotype 3 subtype genes, mainly to IV A, in pigs with popular HEV gene with a high homology; HEV type I in the crowd disperses in the presence of.

[Isolation and sequence analysis on virus of HFMD with encephalitis in Yantal city].

OBJECTIVE: To learn about the pathogen spectrum and genetic characterization of HFMD with encephalitis in Yantai city. METHODS: Stool samples and cerebrospinal fluids (CSF) collected from HFMD with encephalitis cases in Yantai. Virus were isolated from stool samples and identified by fluorescence reverse transcription-polymerase chain reaction. The VPl region was amplified and sequenced from positive specimens. Genetic characterization was identified by sequence analysis. RESULTS: Getting 3 virus strains from 10 stool specimens and all of them belong to EV71. The nucleotide and amino acid homogeneity with the representative isolates of C4a were 98%-99% and 98.90%-99.45% respectively. CONCLUSION: The pathogen of HFMD with encephalitis in Yantai city were mainly EV71 wich belong to subgenogroup C4 cluster C4a.

[Epidemiological study on risk factors of hepatitis E in Yantai, Shandong province].

OBJECTIVE: To study the prevalent characteristics and risk factors of viral hepatitis E in Yantai and the relative for strategy on viral hepatitis E control in the area. METHODS: Data on viral hepatitis E incidence reported by the Notifiable Infectious Disease Reporting System in 2005-2009 was analyzed. 2028 persons were chosen for hepatitis E virus (HEV) antibody detection by enzyme linked immunosorbent assay method. RT-nPCR method was applied to obtain the sequence of HEV in HEV cases. A case-control study was used to identify the risk factors of HEV infection. RESULTS: The distribution of HEV cases was sporadic in Yantai, and the annual incidence rate was 5.70/100 000, with spring as the prevalent season. Farmers were the main population involved and with those over the age of 40. Regional distribution was mainly along the coastline. Data from the sequential analysis showed that gene type of local patients was type 4 and healthy person whose HEV-IgM was positive was type l. Finding from the case-control study suggested that eating seafoods, living condition in the households and unhealthy habits played important roles in the infection of HEV. Results from multiple logistic regression showed that eating seafood, with eat-out history, drinking alcohol and un-boiled water were the main risk factors in the infection of HEV. CONCLUSION: The level of HE in Yantai will maintain in a high level, but there is no chance of epidemic outbreak of HE in large range. Population of incidence mainly concentrates on farmers.

[Serum antibody response and Hantavirus RNA sequencing in patients with hemorrhagic fever renal syndrome in Yantai areas].

OBJECTIVE: To understand antibody responses to and RNA sequences of Hantavirus in patients with hemorrhagic fever renal syndrome (HFRS) in Yantai areas and to demonstrate the type of the prevalent viruses caused HFRS. METHODS: Serum specimens collected at acute and convalescent stages from 90 patients with HFRS and IgM and IgG antibodies against Hantavirus were detected with ELISA, and cross plaque reduction neutralizing tests were performed to detect neutralizing antibody. Viral RNA was extracted from the patients? sera by using Trizol method and nested PCR was utilized to amplify the specific segments of the viral cDNA and the products of the PCR were TA cloned and then the nucleotide sequences were determined. RESULTS: The IgM antibody was positive in 82.2% (88/107) of the patients while the IgG antibody was positive in 85.7% (66/77) of the patients. Both the serologic and sequence analyses demonstrated that the epidemic of HFRS in Yantai areas was caused by mixed types of Hantavirus. The prevalent strains of Hantavirus had higher homology with the strains isolated in Korea than with those isolated previously in China. CONCLUSIONS: The serologic and sequencing analyses indicated that the epidemic of HFRS in Yantai areas was caused by mixed types of Hantavirus dominated by type SEO.