ObjectiveTo investigate norovirus infection status and indentify its epidemiological characteristics and genotype distribution in infantile viral diarrhea in Jiangsu.MethodsFour hundred and ninety-eight fecal specimens of infantile virus diarrhea cases were collected from Suzhou Children's hospital and Nanjing Children's hospital in 2010.Norovirus genegroup were detected by real-time RT-PCR,and genetype were determined by sequence analysis.Results Among all fecal specimens,2 (0.4％) cases were positive for norovirus G Ⅰ,and 190 (38％) cases for G Ⅱ.Nucleotide sequence analysis revealed that in the 2 samples for G Ⅰ,one strain was G Ⅰ 1 and another was G Ⅰ 3.Twenty-one strains were belonged to G Ⅱ 4 and 2 strains were G Ⅱ 3 in the 23 samples for G Ⅱ.ConclusionAs one of the most important pathogens causing infantile viral diarrhea in Jiangsu province,subtype G Ⅱ 4 was the main epidemic strain of norovirus,meanwhile other genotypes also existed.

Objective: To analyze the molecular epidemiology, genetic variations and evolution of enterovirus 71 (EV71) strains isolated in Jiangsu Province from 2009 to 2018. Methods: Statistical methods were used to analyze the data about epidemiological characteristics and results of pathogen detection in cases with EV71 infection in Jiangsu Province from 2009 to 2018. The complete VP1 sequences of 80 EV71 strains were amplified and sequenced for analysis of diversity and phylogenesis. Results: A total of 41 858 enterovirus-positive hand, foot and mouth disease cases were reported in Jiangsu Province from 2009 to 2018. EV71 was the predominant pathogen, accounting for 36.52%, and responsible for most of the severe cases. However, the percentage of EV71 among all pathogens gradually decreased over time. EV71 infection reached the peak in April to June and mainly occurred in children aged six months to five years old with higher incidence in males than in females. In terms of regional distribution, EV71 infections were characterized by area clustering in Jiangsu Province, mainly detected in Nanjing, Suzhou, Wuxi and Lianyungang. The 80 EV71 isolates belonged to C4a genotype. Nucleotide differences between them and three vaccine strains (H07, FY23 and FY7VP5)were 0.6%-5.5%, 0.8%-5.7% and 1.9%-6.9% and amino acid difference were 0-1.4%, 0.3%-2.0% and 0.3%-2.0%, respectively. Amino acid mutations in the epitopes of the 80 EV71 strains did not marked by years or regions. Conclusions EV71 strains showed obvious epidemiological characteristics in time, population and regional distribution in Jiangsu Province from 2009 to 2018.All of the 80 EV71 isolates belonged to C4a subgenotype. The nucleotide sequences between them and the vaccine strains varied greatly, but the homology of amino acids was relatively high, indicating the existence of some synonymous mutations and no risk of antigenic drift. This study would provide reference for EV71 vaccination in Jiangsu Province.

Since the first outbreak of avian influenza A(H7N9) virus in humans was identified in 2013, there have been five seasonal epidemics observed in China. An earlier start and a steep increase in the number of humans infected with H7N9 virus was observed between September and December 2016, raising great public concern in domestic and international societies. The epidemiological characteristics of the recently reported confirmed H7N9 cases were analysed. The results suggested that although more cases were reported recently, most cases in the fifth epidemic were still highly sporadically distributed without any epidemiology links; the main characteristics remained unchanged and the genetic characteristics of virus strains that were isolated in this epidemic remained similar to earlier epidemics. Interventions included live poultry market closures in several cities that reported more H7N9 cases recently.

Objective To analyze the molecular characteristics of Brucella strains isolated from Nanjing,understand strains genotying and clustering,and to provide a basis for prevention and treatment of brucellosis.Methods Multilocus sequence typing (MLST) and multiple locus variable-number tandem repeat analysis (MLVA) were used to analyze and characterize Brucella ovis strains isolated from 7 cases of sporadic cases in Nanjing Drum Tower Hospital,the Affiliated Hospital of Nanjing University Medical School,from 2011-2016,and cluster analysis was did with reference strain data from Jiangsu Province.Results The results showed that 7 strains were defined as sequence type (ST) 8 by MLST.They were typed into 7 subtypes and clustered in the "Middle Mediterranean Cluster" by MLVA.Strain NJ-2011-1 and two strains isolated from other cities in Jiangsu had the same MLVA genotype.Conclusions The results reveal ST8 is the predominant genotype in Nanjing.They have clustered in the "Middle Mediterranean Cluster" by MLVA.The 7 strains are sporadic.The transmission routes and risk factors are more complicated in the city.Various departments should strengthen the cooperation to control the source.

Objective To investigate the clinical features and viral load of persons infected with HCV and the risk factors for severe outcomes.Methods Medical testing and questionnaire survey were conducted on 465 cases who were infected with HCV,20-30 years back.HCV RNA,alanine transaminase (ALT),aspartate transaminase (AST),albumin,globulin and bilirubin were tested for these subjects.Factors as demography,tobacco and alcohol consumption,SNP of rs7453920 and rs2856718 on HLA-DQ gene of subjects with HCV RNA,were analyzed by multiple logistic regression method to explore the risk factors for severe outcomes among the patients.Result Totally,465 subjects had symptoms as hypodynamic (15.70％,73/465),digestive system (17.63％,82/465),and arthrodynia (10.32％,48/465).HCV RNA was positive in 68.60％ (319/465) of the subjects with median viral load as 76.01 × 104 copies/ml (min-max:592 copies/m1-1.08 × 1010 copies/ml).Totally,11.83％ (55/465) of the cases appeared having liver inflammation by routine ultrasound exams.ALT and AST was seen higher than 80 (IU/L) in 12.70％ (59/465) and 11.18％ (52/465) of the subjects,separately.Factors as being male (OR=2.298,95％CI:1.247-4.238),GA genotype compared with AA type in rs2856718 (OR=1.716,95％CI:1.070-2.752),alcohol intake ≥7 times per-week (OR=2.966,95％ CI:0.979-8.988) etc.,were independently related to HCV RNA sustained positivity.Factors as:being male (OR=1.694,95％CI:0.975-2.942),in 50-59 years age group (OR=2.414,95％ CI:1.156-5.042),having other liver diseases (OR=2.592,95％CI:1.105-6.079) and carrying positive HCV RNA (OR=3.479,95％CI:1.648-7.343) etc.were independent risk factors for abnormal liver function.Conclusion High rates of carrying sustained positive HCV RNA and abnormal liver function appeared in subjects who got the HCV infection 20-30 years ago.Factors as being male,in old age,being frequent alcohol taker,GA genotype in rs2856718 and with other liver diseases etc.were related to higher risk for developing severe outcomes.

Objective To retrospectively analyze the antimicrobial resistance phenotype and molecular typing characteristics of Salmonella (S.) typhi and S. paratyphi in Jiangsu province from 2012 to 2015. Methods The samples were collected from typhoid and paratyphoid patients in Jiangsu province. The biochemical identification and serotyping were carried out after isolation and culture. Kirby-Bauer (K-B) testing was used to detect the drug susceptibility of the strains. The molecular typing characteristics of S. typhi and S. paratyphi were analyzed by pulsed field gel electrophoresis (PFGE). Results The resistant rates of 134 S. typhi and S. paratyphi A strains to nalidixic acid were highest (61.2%and 86.7%), while the resistant rates to remaining antibiotics were less than 15.0%. Most of S. typhi and S. paratyphi A strains were resistant to only one antibiotic. Multidrug-resistant (MDR) strains of S. typhi and S. paratyphi A accounted for 2.6% and 13.3%respectively. The composition of the all-sensitive strains of S. typhi increased by 44.3%in 2015, at the same time, there were also MDR S. pa ra typhi A strains, which were resistant to 5 and 6 antibiotics. S. paratyphi A could be divided into eight molecular patterns by PFGE, showing that the similarity between the MDR strains and other strains was relatively low. The S. paratyphi A strains with same pattern were resistant to same antibiotics. S. typhi could be divided into 68 molecular patterns by PFGE, with large variability between different patterns. There was no corresponding relationship between the patterns and the drug resistance characteristics. Conclusions The overall antibiotic resistance of S. typhi and S. paratyphi A strains showed a decreasing trend, but the number ofantibiotics to which they were resistant increased. PFGE patterns of S. typhi showed diversity without correspondence to antibiotic characteristics. PFGE patterns of S. paratyphi A were less with correspondence to antibiotic characteristics. We should pay more attention to key patterns in key areas.

Objective To analyze the molecular characteristics and genetic origin of a novel avian influenza A H7N4 virus casuing a case of human infection in China. Methods Specimens were collected from the patient and chickens and ducks kept by the patient and neighbours and then detected by real-time quantitative PCR. The original specimens and virus isolates were analyzed by next-generation sequencing technology to obtain viral whole-genome sequences. Pairwise sequence alignments and phylogenetic analysis were performed by BLASTs,ClustalX and MEGA 6. 1 softwares. Results In January 2018, a human case infected with avian influenza A H7N4 virus was confirmed. Seven H7N4 viruses were isolated from speci-mens collected from chicken and ducks kept in the patient`s backyard. H7N4 virus was a novel reassortant vi-rus with all eight gene fragments derived from wild waterfowl in Eurasia. HA protein contained a single basic amino acid residue R in cleavage site, suggesting that H7N4 virus was low pathogenic. The receptor-binding sites of HA had QSG at 226-228 residues, which indicated that the virus retained avian-type receptor speci-ficity (SAα2-3Gal). Different from H7N4 viruses in avian, the virus isolated from the patient had substitu-tion at position 627 ( E→K) in PB2 protein, which might increase its adaptation in human host. Conclusion This study reported a case of human infection with a novel reassortant avian influenza A H7N4 virus, which revealed that the traditional backyard breeding models might facilitate cross-species transmission of avian in-fluenza viruses in southern China.

Objective:To identify human infection with Brucella suis, analyze its biological and molecular characteristics, and to provide basis for prevention and control of brucellosis. Methods:Brucella suis strains were isolated from the body of the first case of human Brucella suis infection in Jiangsu Province. Serum agglutination test was used for serotyping. The specific gene bcsp-31 of Brucella was detected by PCR. AMOS-PCR was used to identify IS-711. The species and biotypes were identified by multiplex PCR. The wboA gene products were sequenced and phylogenetic tree was constructed. Multilocus sequence analysis (MLSA) was used for molecular typing, and cluster analysis was performed with reference strains. Results:The strain was confirmed to be Brucella suis biotype 3 by serum agglutination test and PCR. After sequencing the wboA gene, cluster analysis of the reference sequence showed that the wboA gene was closest to the biotype 3 strain Brucella suis str. 686 (CP007719). MLSA was typed into ST17(1-6-4-1-5-3-5-2-4). Conclusions:Brucella suis biotype 3 is reported in Jiangsu Province for the first time. The MLSA type is ST17. In the future, the prevention and control of human brucellosis should be carried out. We should actively cooperate with the animal husbandry and veterinary department to increase the quarantine, immunization and other control measures.

Objective:To analyze the whole-genome sequences of coxsackievirus A10 (CVA10) strains isolated in Jiangsu Province from 2015 to 2022 and their molecular epidemiological characteristics.Methods:Forty-five CVA10 isolates circulating in Jiangsu Province during 2015 to 2022 were selected for whole-genome sequencing. Phylogenetic trees were constructed based on the whole genome, VP1, P1, P2 and P3 sequences of CVA10 strains. Bioinformatics software, including DNAStar, MEGA7.0 and Similarity plots3.5.1, was used for analysis of homology, genetic recombination and major amino acid variation sites.Results:The nucleotide and amino acid sequence homology of the whole-genome sequences of 45 CVA10 strains was 90.3%-99.1% and 97.9%-99.8%, respectively. The nucleotide sequence homology of P1 region was the highest (92.1%-100.0%), while the nucleotide sequence homology of P3 region ranged from 84.7% to 100.0%. In contrast to the diversity of nucleotide sequences, the amino acid sequences of each region were conserved. A phylogenetic analysis based on the complete VP1 sequences of CVA10 strains revealed eight genotypes: A-H. The CVA10 isolates in Jiangsu Province and other prevalent strains in China mainly belonged to genogroup C. Results of the phylogenetic analysis based on the whole-genome sequences and complete VP1 sequences were consistent. Phylogenetic analysis bases on different gene segments and Simplot recombination analysis revealed that Jiangsu isolates GD07/Lianyungang/2017 and N180/Suqian/2016 showed high homology with the CVA10 prototype in the P1 region, but had recombination sites with other strains of enterovirus group A in the P2, P3, 5′-UTR and 3′-UTR regions. Compared with the prototype strain AY421767/Kowalik/2004, the Jiangsu isolates showed frequent variations in the VP1 region and many other major amino acid sites, which might result in some imperceptible changes in capsid structure and potential receptor-binding sites.Conclusions:By analyzing the evolution and genetic recombination features of CVA10 strains at the genome level in Jiangsu Province, this study elucidated the influence of genetic recombination and amino acid site mutation on CVA10 infection, providing basic data for the prevention and control of hand-foot-mouth disease in Jiangsu Province.

Objective:To retrospectively analyze the molecular epidemiological features and genetic recombination of coxsackievirus A4 (CVA4) strains isolated in Jiangsu from 2015 to 2022.Methods:Throat or anal swab samples were collected from patients with herpangina or hand, foot and mouth disease (HFMD). Real-time PCR was used to detect CVA4. A comprehensive and systematic phylogenetic analysis was conducted based on 72 whole genomes and 99 VP1 sequences of CVA4 strains. Several bioinformatics software including DNAStar, MEGA7.0 and Similarity plots3.5.1 was used for analysis of homology, genetic recombination and amino acid variation sites.Results:Four genotypes (A, B, C and D) and five sub-genotypes (C1-C5) of CVA4 were identified based on the VP1 nucleotide sequences. C2 was the predominant sub-genotype causing HFMD. The Jiangsu strains showed high homology with the CVA4 prototype in the P1 region, and higher identity with other strains of enterovirus group A (EV-A) in the P2 and P3 regions. Genetic recombination analysis revealed that the Jiangsu strains had three genetic recombination patterns with other EV-A epidemic strains in the P2, P3 and 3′-UTR regions. These recombination patterns took place during the sustained and widespread circulation of CVA4 in people and increased the transmissibility of CVA4.Conclusions:This study analyzes the phylogenetic and molecular features of 28 whole genomes of Jiangsu CVA4 strains, which helps to better understand the genomic diversity of CVA4. By analyzing the genetic recombination and amino acid mutations in the VP1 region, this study elucidates the evolution and transmission of CVA4, which is conducive to the control and prevention of CVA4 infection.