Objective:To investigate the effects of pre-existing antibody on seroconversion rate after influenza vaccination.Methods:This study recruited 1 900 healthy volunteers to receive influenza split vaccines in Xinjiang Uygur Autonomous region and Yunnan Province from September 2009 to October 2018. Hemagglutinin agglutination inhibition assay was used to detect the titers of specific antibodies in blood samples collected before vaccination and 28 d after vaccination and the effects of pre-existing antibody on the seroconversion to different influenza vaccine components were analyzed.Results:Trend analysis showed that with the increasing titer of pre-existing antibody, the seroconversion rates to A/H1N1, A/H3N2, B/Victoria and B/Yamagata vaccine components were gradually decreased (χ 2=121.76, P<0.001; χ 2=67.58, P<0.001; χ 2=45.25, P<0.001; χ 2=54.55, P<0.001). After adjusting for factors such as region, gender and age, multivariate logistic regression showed that pre-existing antibody titer equal to or higher than 40 was an independent factor that affected the seroconversion to A/H1N1, A/H3N2 and B/Victoria vaccine components, and the adjusted OR (95%CI) values were 2.50(2.00-3.13)、1.64(1.35-2.00) and 2.50(1.79-3.45), respectively. Conclusions:The seroconversion rate to each vaccine component was negatively correlated with the pre-existing antibody titer. The factor that pre-existing antibody titer equal to or higher than 40 was detrimental to the seroconversion to A/H1N1, A/H3N2 and B/Victoria vaccine components, but had no significant influence on B/Yamagata seroconversion.

Objective To investigate the role of hydrogen sulfide (H2S) synthases/H2S pathway in the pathogenesis of renovascular hypertension.Methods Wistar rats were subdivided into 4 groups:(1) 2-kidney,1-clip (2K-1C group,n=7),(2) control (n=7),(3)sham (n=7),and (4) 2K-1C plus sodium hydrosulfide (NariS) (NariS-treated group,n=7).The systolic blood pressure (SBP) was measured by a tail-cuff method using a pulse transducer once a week.Four weeks later,all rats were killed and the concentration of plasma hydrogen sulfide (H2S),the activity of the H2S syntha.ses in the kidneys on both sides,the plasma angiotensin Ⅱ concentration,and the left-to-whole heart weight ratio were measured.Results The SBP was significantly increased in the 2K-IC group (185.4± 14.0mmHg) comparing with those in the sham group (112.9±6.5mmHg,,or the NariS-treated group(134.8±9.5mmHg) (both P＜0.01).At 4 weeks,the angiotensin Ⅱ concentration in the plasma was increased in the 2K-1C and NariS-treated group,comparing with the control and the sham group (306.92±7.03 pg/ml and 240.73±13.22 pg/ml vs 122.6±25.49 pg/ml and 125.95±10.55 pg/ml,respectively,both P＜0.05).The plasma H2S concentration and the activity of H2S synthases in the left kidney were decreased in the 2K-1C group comparing with those in the sham and the control groups.There was no difference of the activity of the H2S synthases in the right kidneys among the 4 groups.The left-to-whole heart weight ratio was increased in the 2K-1C and the NariS-treated group camparing with that in the sham and natural control groups.Conclusions Dysfunction of the H2S synthases/H2S pathway was involved in the 2K-1C-induced renovascular hypertension in rat.Exogenous administration of H2S donor can attenuate the development of hypertension.These findings suggest that the H2S synthases/H2S pathway participates in the pathogenesis of renovascular hypertension.

Data based on the antiviral-resistant phenotyping characteristics of 884 influenza B viruses circulating in mainland China from October 2013 to March 2014 were analyzed to assess the susceptibility of influenza B viruses to neuraminidase inhibitors. All 884 viruses were sensitive to oseltamivir; two viruses (0.23%) had reduced sensitivity to zanamivir and all other viruses were sensitive to zanamivir. Among the 38 viruses with a B/Victoria lineage, B/Shandong-Kuiwen/1195/2014 exhibited a half-maximal inhibitory concentration (IC50) for zanamivir that was elevated by 5. 12-fold (1.78 nM) compared with neuraminidase inhibitors sensitive to the reference virus (0.34 nM), suggesting that it exhibited reduced inhibition by zanamivir. D35G, N59D and S402T (39, 64 and 399 with N2 number) amino-acid substitutions in the NA gene were detected with no previously reported antiviral-resistant substitutions. Among viruses with the 846 B/Yamagata lineage, B/Hunan-Lingling/350/2013 exhibited a 7.99-fold elevated IC50 for zanamivir (2.72 nM) compared with neuraminidase inhibitors sensitive to the reference virus (0.34 nM), suggesting that it exhibited reduced inhibition by zanamivir. D197N (N2 number), a previously reported antiviral resistant-related amino-acid substitution in the NA gene, was detected in B/Hunan-Lingling/350/2013. These data suggest that recently circulating influenza B viruses in mainland China have retained susceptibility to neuraminidase inhibitors.
Amino Acid Substitution ; Antiviral Agents ; pharmacology ; China ; epidemiology ; Drug Resistance, Viral ; Enzyme Inhibitors ; pharmacology ; Humans ; Influenza B virus ; drug effects ; enzymology ; genetics ; isolation & purification ; Influenza, Human ; epidemiology ; virology ; Microbial Sensitivity Tests ; Neuraminidase ; antagonists & inhibitors ; genetics ; metabolism ; Viral Proteins ; antagonists & inhibitors ; genetics ; metabolism

Objective To analyze the phenotypic characteristics of antiviral-resistant influenza B viruses circulating in mainland China and to analyze the susceptibility of influenza B viruses to neuraminidase inhibitors ( NAIs) . Methods Antiviral-resistant phenotyping test was performed to analyze the NAI suscep-tibility of 1 386 influenza B viruses isolated in mainland China from April 2014 to March 2015, including the test of susceptibility to oseltamivir and zanamivir. Results All of the 94 B-Victoria lineage viruses were sensitive to oseltamivir and zanamivir. Of all 1 292 B-Yamagata lineage viruses tested, 1 virus showed re-duced sensitivity to oseltamivir with NA gene containing I221T amino acid mutation, 10 viruses showed re-duced sensitivity to zanamivir with 4 having D197N amino acid mutation in NA gene, 3 viruses showed re-duced sensitivity to both oseltamivir and zanamivir with NA gene possessing D197N amino acid mutation and 1 virus carrying the A245T amino acid mutation in NA gene showed reduced sensitivity to oseltamivir and highly reduced sensitivity to zanamivir. Conclusion The majority of influenza B viruses circulating in main-land China during 2014 to 2015 were sensitive to NAIs, which indicated that NAIs could be used continually for clinical treatment of patients with influenza. Sustained monitoring of antiviral susceptibility of influenza B viruses should be emphasized for timely detection of antiviral resistant viruses and more attention should be paid to the D197N mutations in NA gene of influenza B viruses.

To analyze the antigenic and genetic characteristics of the influenza A (H3N2) virus in mainland China during the surveillance year of 2013-2014, the antigenic characteristics of H3N2 virus were analyzed using reference ferret anti-sera. The nucleotide sequences of the viruses were determined by Sanger dideoxy sequencing, phylogenetic trees were constructed with the neighbor-joining method, and the genetic characteristics of the viruses were determined in comparison to current vaccine strains. The results showed that most of the H3N2 viruses were antigenically closely related to the A/Victoria/361/2011 vaccine strain cell-propagated prototype virus (99.6%). Using the A/Texas/50/2012 egg isolate as the reference antigen, 15.1% of the viruses were found to be closely antigenically related to it, while 11.9% of strains were closely antigenically related to the egg-propagated epidemic strain, A/Shanghai-Changning/1507/2012. Phylogenetic analysis of HA genes indicated that the A(H3N2) viruses in this surveillance year were in the same clade, but no drug resistant mutation was identified in the NA genes. During the 2013-2014 influenza surveillance year, no significant genetic change was detected in either the HA or NA genes of the A(H3N2) viruses, while significant mutations were found in egg isolates resulting from their adaptation during propagation in eggs. The antigenic and genetic changes should be investigated in a timely manner to enable the selection of an appropriate vaccine strain in China.
Animals ; Antigenic Variation ; Base Sequence ; Chick Embryo ; China ; Genetic Variation ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; immunology ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; immunology ; isolation & purification ; Influenza, Human ; virology ; Molecular Sequence Data ; Mutation ; Phylogeny

Objective: Influenza H1N1 subtype vaccine candidate strains from a 2015—2016 year epidemic strain in China were prepared and identified by themethod of classical reassortment. Methods: The influenza H1N1 epidemic strain and H3N2 high-yield reassortant parental strain (X-157) were mixed and inoculated into embryonated chicken eggs by the classical reassortmentmethod . The negative selection of mixed culture virus was carried out with the antiserum of H3 protein and the antiserum of X-157 strain. Real-time PCRmethod was used to test the HA and NA genes. Restriction enzyme digestionmethod was used to identify the internal genes. HA and NA genes of selected strains were sequenced. The strain which HA and NA genes possessed the same amino acid constitution with the wild type virus was selected and immunized to ferret. Two-way test was carried out. Results: Five strains with expected HA and NA genes were selected by real-time PCR. Internal genes were identified, with 4 strains had 6+ 2 constitution, 1 strain had 5+ 3 constitution. Comparing with the wild type virus, HA and NA genes of the 5 strains had no mutation. HA titer of reassortant strains was above 1 024. HI titer of the selected NO.12 reassortment strain reached 5 120, and two-way test was passed. The yield of reassortant strain was 64 times that of the wild type strain. Conclusions A circulating influenza A (H1N1) strain of influenza A (2015—2016) was successfully prepared in China and laid the foundation for vaccine storage and disease prevention and control.

Objective To understand the antigenic and genetic characteristics of highly pathogenic avian influenza H5N1 viruses isolated from poultry related environments of surrounding areas of Qinghai Lake.Methods Poultry and wild birds related environments from surrounding areas of Qinghai lake were collected and handled.Viruses were isolated with embryonated chicken eggs.The virus subtyping was performed by real-time RT-PCR.The highly pathogenic avian influenza H5N1 viruses were chosen to conduct next generation sequencing and hemagglutination inhibition ( HI) assay.Results In total of 19 H5N1 virus strains were isolated, they were all from poultry related environments and collected in January-March of year 2013.Seven representative highly pathogenic avian influenza H5N1 viruses were sequenced and analyzed for antigenicity.According to phylogenetic analysis of HA gene, 6 viruses were belong to clade 2.3.2.1c except A/Environment/Qinghai/XN02032/2013 which belongs to clade 7.2.Antigenic analysis showed that 6 viruses were antigenically similar to A/Barn swallow/Hong Kong/D10-1161/2010, while A/Environment/Qinghai/XN02032/2013 presented low reaction with all reference antisera.Conclusions The existence of highly pathogenic avian influenza H5N1viruses in poultry related environments of surrounding areas of Qinghai Lake was confirmed.The status of highly pathogenic avian influenza H5N1 viruses with evolution diversity emphasized the necessary of strengthening the avian influenza surveillance in these areas.

Objective:The antigenic and genetic characteristics of influenza A(H1N1)pdm09 virus isolated from the mainland of China during the 2018-2019 influenza surveillance year were analyzed.Methods:Two thousand nine hundred and fifty-eight influenza A(H1N1)pdm09 virus strains in the 2018-2019 influenza surveillance year were analyzed by hemagglutination inhibition test. The hemagglutinin(HA) gene of 279 influenza A(H1N1)pdm09 virus strains was sequenced and analyzed. The representative strains of the dominant clades were performed for antigenic characteristics using post-vaccination human antisera.Results:Two thousand eight hundred and sixty-one (97%, 2 861/2 958) viruses characterized were antigenically similar to A/Michigan/45/2015. All HA gene of the sequenced viruses belonged to 6B.1 clade, and 269(96%, 269/279) viruses belonged to 6B.1A subclade. Compared with the vaccine virus, it had the common amino acid substitutions of S74R, S164T and I295V in the HA protein. There were several small groups with common amino acid substitutions in the 6B.1A subclade, and 51% sequenced viruses had S183P amino acid substitution in this subclade. The result of antigenic analysis using post-vaccination human antiserums showed that most of the representative strains were well inhibited by the sera.Conclusions:The antigenicity of influenza A(H1N1)pdm09 viruses in the mainland of China in 2018-2019 influenza surveillance year matched well with the corresponding vaccine strain, but the HA gene had genetically diverse characteristic.

OBJECTIVETo analyze the susceptibility of influenza A (H3N2) viruses to neuraminidase inhibitors during 2011-2012 in Mainland China.

METHODSAll the tested viruses were obtained from the Chinese National Influenza Surveillance Network, which covers 31 provinces in mainland China, including 408 network laboratories and 554 sentinel hospitals. In total 1 903 viruses were selected with isolation date from January 1, 2011 to December 31, 2012 in Mainland China, among these viruses, 721 were confirmed to be influenza A (H3N2) virus by Chinese National Influenza Center and tested for the susceptibility to oseltamivir and zanamivir using chemiluminescence-based assay. The neuraminidase inhibitor sensitive reference virus A/Washington/01/2007 (119E) and oseltamivir resistant virus A/Texas/12/2007 (E119V) were used as control in this study. The t -test was used to compare the difference of NAI susceptibility of viruses isolated from different years.

RESULTSThe half maximal inhibitory concentration (IC₅₀) of A/Washington/01/2007 for oseltamivir and zanamivir was (0.10 ± 0.02) and (0.30 ± 0.05) nmol/L, respectively. The IC₅₀ of A/Texas/12/2007 for oseltamivir and zanamivir was (4.27 ± 1.60) and (0.20 ± 0.03) nmol/L, respectively. Among the 721 influenza A (H3N2) viruses, 132 influenza A (H3N2) viruses were isolated in 2011 and 589 influenza A (H3N2) viruses were isolated in 2012. The IC50 for oseltamivir ranged from 0.04 to 0.62 nmol/L for viruses isolated in 2011 and ranged from 0.02 to 0.95 nmol/L for viruses in 2012, and the IC₅₀ of all the viruses tested was within 10-fold IC₅₀ (1.0 nmol/L) of the neuraminidase inhibitor sensitive reference virus A/Washington/01/2007. The IC50 of zanamivir ranged from 0.12 to 0.80 nmol/L for viruses in 2011 and ranged from 0.04 to 0.72 nmol/L for viruses in 2012, and was within 10-fold IC₅₀ (3.0 nmol/L) of the neuraminidase inhibitor sensitive reference virus A/Washington/01/2007.

CONCLUSIONThe influenza A(H3N2) viruses isolated during 2011-2012 in Mainland China were tested to be sensitive to oseltamivir and zanamivir.

Antiviral Agents ; China ; Drug Resistance, Viral ; Enzyme Inhibitors ; Epidemiological Monitoring ; Humans ; Influenza A Virus, H3N2 Subtype ; Influenza, Human ; Neuraminidase ; Oseltamivir ; Zanamivir