Objective: To analyze epidemiological and genetic characteristics of the fifth avian influenza A (H7N9) wave in Suzhou, and to provide scientific basis for prevention and control of H7N9 virus infection. Methods: Respectively, influenza A/B, H1N1 (pdm09), H3, H5N1, and H7N9 real-time PCR kits were used to detected pharyngeal swab samples which were collected from severe acute respiratory syndrome infection (SARI) cases in Suzhou. The H7N9-positive samples were further examined for virus isolation and gene sequencing. Results: The H7N9 virus was mainly prevalent in winter in Suzhou City. In the fifth H7N9 virus epidemic, the overall fatality rate of human infection with H7N9 virus in Suzhou city was 40% (22/55). Additionally, most were older people (median age was 58 years) and more than 80% of H7N9 patients had live poultry exposure history. The nucleic acid homology of HA gene was 98.7-100%. There were no mutations in the key sites of the HA gene sequence. Conclusions The H7N9 virus can not be effectively spread in the crowd currently, with no significant changes in receptor binding sites (RBS). In addition, exposure to live poultry or contaminated environment is still the main source of human infection with H7N9. At present, the viruses circulating in Suzhou city are low pathogenic to poultry.

Objective: To investigate the epidemical features, etiological and clinical characteristics of HFMD in Suzhou city, from 2011 to 2015, providing the scientific supports for HFMD prevention and control. Methods: In each district of Suzhou city, at least five specimens of mild cases were collected per month, while all of the severe cases were sampled. The RNA from each sample was examined using a commercially available real-time PCR kit. Statistical analysis was performed using SPSS version 11.5 software. Results: We retrospectively analyzed HFMD epidemiological data in Suzhou from 2011 to 2015, a total of 4 552 outpatients in Suzhou city were diagnosed with HFMD, including 2 818 positive specimen, the total positive rate was 61.90%, and there was a significant difference in the positive rates between the adjacent years (χ²=186.09, P<0.0001). From 2011 to 2015 in Suzhou, HFMD mainly affected children aged 1 to 5 years old, 66.17% of them were 1to 3 years old. Enterovirus 71(EV71) and coxsackievirus A16(CVA16) were the predominant viral genotypes in Suzhou from 2011 to 2012, and 2014. In 2013, other EVs were dominant, the severe cases mainly correlated with EV71 subtypes, and the proportion of patients with severe disease was significantly decreased in 2013. Conclusions EV71 and CVA16 are still the important pathogens of HFMD, other EVs also occupy a certain proportion, it is the time to select one or two advantage pathogens from the other EVs into the HFMD monitoring.

Objective:To analyze the activity of lithium chloride (LiCl) against influenza virus A (H3N2) in human non-small cell lung cancer cells (A549).Methods:Different concentrations of LiCl were incubated with A549 cells, and the cytopathic effect (CPE) was observed after 24 hours, and the effect of LiCl on cell activity was determined by CCK-8 method. After H3N2 (MOI=1) infected A549 cells, different concentrations of LiCl were added and incubated for 24 hours, and the viral load was measured by real time/reverse transcription quantitative polymerase chain reaction (RT-qPCR), and the CPE was observed, and the viral titer was determined. Different concentrations of LiCl were incubated with A549 at 37 ℃ and 5% CO 2 for 2 hours, virus was added and incubated for 24 hours, and the viral load was determined by RT-qPCR. LiCl, H3N2 and A549 were incubated at 4 ℃ for 1 hour, 35 ℃, 5% CO 2 for 24 hours, and viral load was determined by RT-qPCR. H3N2 and A549 were incubated at 4 ℃for 1 hour, then different concentrations of LiCl were added, incubated at 35 ℃ with 5% CO 2 for 24 hours, and the viral load was determined by RT-qPCR. After H3N2 infected A549 cells, different concentrations of LiCl were added and incubated for 24 hours, and the viral RNA load and viral titer of the supernatant and cells were measured, respectively, and then the corresponding ratios of the supernatant and the cells were calculated. After H3N2 (MOI=10) and BV (MOI=1) infected A549 cells, different concentrations of LiCl were added for 24 h, and the viral load was determined by RT-qPCR. Results:When the concentration of LiCl was<50 mmol/L, the cell viability of A549>90%. Different concentrations of LiCl could significantly reduce the viral load of H3N2 ( P<0.000 1), and the CPE of the LiCl treatment group was more dose-dependent than that of the control group. LiCl did not inhibit viral replication by affecting the cell itself; Different concentrations of LiCl significantly inhibited the entry of H3N2 into A549 ( P<0.000 1), and also had a certain inhibitory effect on the adsorption of A549 cells ( P<0.1). LiCl did not affect the assembly and release of H3N2 ( P>0.05), and it was also found that LiCl had a broad spectrum of antiviral effects against multiple influenza virus strains ( P<0.000 1). Conclusions:LiCl may exert antiviral effect by inhibiting the adsorption and entry of H3N2 into A549 cells and the replication of H3N2 in A549 cells, which provides a data reference for the prevention and treatment of viral infection by LiCl.

Objective In order to investigate the epidemical characteristics of the Influenza-like illness (ILI) in Suzhou from 2010 to 2014,providing the scientific supports for influenza prevention and control of Suzhou.Methods The influenza samples were collected from the department of respiration of Suzhou Municipal Hospital Division and Suzhou city children's hospital,using fluorescent-PCR method to detect influenza virus nucleic acid and classifying influenza virus subtypes.Results 8035 throat swabs of ILI specimens were collected from 2010-2014 in Suzhou,959 samples were positive (11.94％),the positive rate of difference of adjacent years was statistically significant (x2 =77.78,P ＜ 0.0001).The positive rate was highest in the age group of 10-19 and lowest in the age group of 40-49 among all detected age groups.The influenza epidemic season were winter-spring and summer in Suzhou,type B influenza main in spring and winter,and influenza A in prevalent throughout all year,each subtype showing alternating popular.Conclusions From 2011-2014,influenza virus infected people in every age group of Suzhou,the peak popular time are winter-spring and summer of every year,all kinds of influenza subtype epidemic alternately,so it needs to supervise influenza etiology of Suzhou for a long-term to providing theoretical basis for further control the spread of the flu.

Objective:To disclose the epidemiological characteristics of the first human case of H9N2 subtype avian influenza and genetic characteristics of hemagglutinin (HA) gene of H9N2 avian influenza virus in Jiangsu province.Methods:Reverse transcription polymerase chain reaction (RT-PCR) assay was used to detect the nucleic acid of influenza virus A/B and various subtypes from throat swab specimens of patients with acute and severe respiratory infections of unknown cause. Sanger method was used to sequence the vial HA gene of H9N2 positive specimens. N-J phylogenetic tree of HA gene was constructed by using MEGA X software.Results:The first laboratory confirmed case of human infection with H9N2 avian influenza virus in Jiangsu province in March 2019 was reported by Suzhou Center for Disease Control and Prevention. Sequence analysis of the HA gene showed that the A/Suzhou/S683/2019 (H9N2) strain belonged to Y280-like sub-lineage of the Eurasian lineage, which had 99.23% nucleic acid identity with A/chicken/Shanghai/S1171/2018 (H9N2) strain. The amino acid sequence of the HA protein cleavage site is PSRSSR↓GLF, and the key amino acid in receptor binding site shared Q226L mutation. The location of potential glycosylation sites of HA protein of A/Suzhou/S683/2019 (H9N2) have changed.Conclusions:The H9N2 avian influenza virus obtained from the first case in Jiangsu province has low pathogenicity, but it may have acquired part of the ability to adapt to human hosts.

Objective:To investigate the viral molecular mutations of 2019 novel coronavirus (2019-nCoV) and host adaptability in Suzhou City.Methods:The throat swab specimens from nine local cases and six imported cases with 2019-nCoV viral nucleic acid test positive in Suzhou City were sequenced for the whole genome of the virus, and the Wuhan-Hu-1 strain was used as the reference sequence for alignment and analysis. The phylogenetic tree of the viral whole genome sequence was constructed by MEGA 7.0 software.Results:According to the Chinese typing method, Nextstrain typing method, Pangolin classification method and Global Initiative on Sharing All Influenza Data (GISAID) typing method, the 15 2019-nCoV genome sequences could be divided into seven types, six types, eight types and five subtypes, respectively. Compared with Wuhan-Hu-1 strain, the median number of amino acid sequence mutation sites based on nucleotide translation was three (ranging from 0 to 12). D614G mutation of spike protein was identified from all six imported viral strains, which could enhance the transmissibility. No Alpha, Beta, or Gamma mutants, which also could enhance the transmissibility, was found in the genomic sequences of the imported cases. The median number of nucleotide mutation sites in 15 sequences was eight (ranging from three to 23).Conclusions:2019-nCoV is constantly mutating, and a variety of evolutionary lineages/genotypes have been derived. All imported viruses in Suzhou City carry mutations that can increase infectivity.