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Objective:To understand the genome sequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and spike protein variations during different epidemic periods in Wuxi City.Methods:Nucleic acid was extracted from the nasopharyngeal swab samples of six local cases of coronavirus disease 2019 (COVID-19) (from January to February, 2020) and 13 imported cases of COVID-19 (from March to September, 2021) in Wuxi City, and the whole genome was amplified to construct the sequencing library. The second-generation sequencer was used for sequencing. The CLC Genomics Workbench (21 version) software was used to analyze the offline data with NC_045512.2 as the reference strain, and MEGA 7.0 software was used to construct the phylogenetic tree.Identification of type was conducted by Nextstrain typing method and phylogenetic assignment of named global outbreak lineages (Pangolin) typing method.Results:There were five subtypes in Nextstrain and seven subtypes in Pangolin of the nineteen patients with COVID-19. Compared with NC_045512.2, the median nucleotide mutation sites were 29 (range 0 to 42) and amino acid mutation sites were 20 (range 0 to 34). The six local and 13 imported cases had no common nucleotide mutation sites and were in different evolutionary branches. The sequences of the six local cases were highly homologous with the reference strain sequences (NC_045512.2) at the early stage of the pandemic, and the evolutionary distance was close to that of the reference strain. The 13 imported cases were obviously divided into three evolutionary branches (Alpha, Beta, Delta variant).The four Beta variants shared eight amino acid mutation sites in spike protein, and the two Alpha variants shared eight amino acid mutation sites in spike protein, and the seven Delta variants shared five amino acid mutation sites in spike protein.Conclusions:New mutations of SARS-CoV-2 are constantly emerging during the epidemic. The increase of the nucleotide sites number may result in the change of spike protein amino acid. Therefore, the whole-genome sequencing analysis plays an important role in the accurate tracing of epidemic origin and adjustment of prevention and control measures.
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Objective:Analysis of the antibiotic resistance profiles and molecular typing of Salmonella typhimurium ( S. typhimurium) isolated in Wuxi city from 2011 to 2018. Methods:A total of 109 S. typhimurium isolates were detected from different types monitoring samples in Wuxi city from 2011 to 2018. Microbroth dilution method was used to test antimicrobial susceptibility of S. typhimurium for 17 antimicrobial agents. Pulsed field gel electrophoresis (PFGE) was used to conduct molecular typing. Statistical analysis was carried out using Chi-square test. Results:Tetracycline-resistance and ampicillin-resistance were most frequency in 109 S. typhimurium isolates, 69.72% (76/109) and 68.81% (75/109), respectively. For compound sulfamethoxazole, chloramphenicol, ciprofloxacin, ampicillin/sulbactam, azithromycin, nitrofurantoin, cefotaxime and aztreonam, the resistance rates were 23.85%(26/109), 22.02%(24/109), 11.93%(13/109), 4.59%(5/109), 3.67%(4/109), 3.67%(4/109), 0.92%(1/109), 0.92%(1/109), respectively. All isolates were susceptible to amikacin, ertapenem, imipenem, meropenem, ceftazidime and ceftazidime-avibactam. Azithromycin-resistance isolates were decreasing year by year gradually. The aztreonam and cefotaxime-resistant isolates were found since 2018, while chloramphenicol and compound sulfa-resistant isolates showed upward trend simultaneously. Conclusions:S. typhimurium in Wuxi city exhibited highly resistant to tetracycline and ampicillin. The significant variability existed between genotype and phenotype of S. typhimurium.
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Objective@#To investigate the epidemiological characteristics and causes of an outbreak of respiratory infection in schools.@*Methods@#Epidemiological investigation was carried out on respiratory infection cases in schools. Pharyngeal swab samples of children were collected for respiratory tract virus nucleic acid detection, and hexon genes were amplified. Positive PCR result were sequenced.@*Results@#All cases were in school, involving 2 classes, 12 cases in class 2 (3) and 13 cases in class 3 (4), all on the west side of the 2nd and 3rd floors of teaching building 2. From September 3 to September 12, a total of 25 cases were involved, with the onset peak on the 10th and 11th. The clinical features were fever, cough, sore throat and aching limbs, etc. The onset was aggregated, the course of the disease was about 5 d, the prognosis was good, and there were no deaths. There are 13 males and 12 females. The males to females ratio is 1.08∶1. The age distribution is 7-9 years, with an average of 8.6 years. The result of fluorescence quantitative PCR were negative for influenza A/B virus and positive for adenovirus. The products of positive samples after PCR amplification were sequenced as AdV-3 and AdV-4.@*Conclusions@#The combined result of epidemiological investigation and laboratory tests demonstrated that this epidemic of school respiratory tract infection is an upper respiratory tract infection caused by adenovirus B3 and E4 mixed infection.
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Objective To investigate the epidemiology of respiratory viruses in children from Wuxi area.Methods A total of 2 747 cases of children diagnosed with acute respiratory infection in Wuxi during 2011 —2014 were collected.Reverse transcription-polymerase chain reaction was used to detect nine kinds of respiratory viruses,including influenza virus A (Flu A),influenza virus B (Flu B),parainfluenza virus (PIV)Ⅰ-Ⅳ,adenovirus (ADV),respiratory sycytial virus (RSV),human metaneumovirus (hMPV), human bocavirus (HBov),human coronaviruses (hCov)and human rhinovirus (HRV).The categorical data were compared using chi square test.Results A total of 856 among the 2 747 samples were tested positive for respiratory virus nucleic acid,with the positive rate of 31 .16%.The viral distribution was uneven in different seasons,and the infection peaked in winter and spring.The virus detection rate was highest in age 1 to 2 year group (up to 40.18%),and followed by age 6 to 12 year group (32.63%).Flu A virus was the most frequently detected virus,accounting for 7.54% (207/2 747);followed by PIV, accounting for 6.95 % (191/2 747);and Flu B accounted for 4.22%(116/2 747).There were 84 cases of mixed infection of two or more kinds of respiratory viruses,with positive rate of 3.06% (84/2 747 ). Conclusions Our study suggests that Flu A is the most common pathogen in children with acute respiratory infections in Wuxi area during 2011 —2014;virus detection rate is highest in age 1 to 2 year group;and parainfluenza virus is almost detected throughout the year,while the rest of respiratory viruses are commonly seen in winter and spring.
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Objective To study the mucosal and systemic immune response after intranasal immunization with mucosal complex vaccine for Toxoplasma gondii,and to observe the protective effect on mice. Methods The mucosal complex vaccine was made of soluble tachyzoite antigen (STAg) and cholera toxin (CT),which were mixed and dissolved in PBS (1 ml PBS containing 1 mg STAg and 50 ?g CT). Fifty-two BALB/c mice were randomly divided into two groups: immunized group and control. Mice were intranasally immunized with 20 ?l mucosal complex vaccine (20 ?g STAg and 1?g CT) per mouse twice at an interval of two weeks,while the control mice were given PBS solution instead. Six mice of each group were killed by dislocation of cervical vertebra on day 14 after the last immunization. The specific IgG antibodies in serum and IgA in feces were detected by ELISA. Lymphocytes in spleen,Peyer's patches (PP) and intestinal intraepithelial lymphocyte(IEL) were isolated and counted. Percentage of CD4+ and CD8+ T cells was determined by immunocytochemistry. Other mice were challenged intragastrically each with 4?104 tachyzoites of RH strain Toxoplasma gondii on day 14 after the last immunization. Their health condition was observed and the number of tachyzoites in liver and brain was determined microscopically on the 30 th day after challenge. Results IgG antibodies in serum and IgA antibodies in feces of immunized mice were higher than the control (P