Objective To analyze the genetic characteristics and the evolution of the influenza A (H3N2) virus strains circulating in Jiangsu province between 2013 and 2014.Methods This study analyzed thirty-one representative strains of influenza A (H3N2) virus, which were isolated in different regions of Jiangsu province and during different time periods from 2013 to 2014.Results Genetic distances in nucleic acid and amino acid between a strain used for vaccine production (A/Texas/50/2012) and the 31 strains were 0.010 5 and 0.012 4.Similarities between them in nucleic acid and amino acid sequences were 97.9%-99.6% and 97.2%-99.3%.Phylogenetic analysis showed that the hemagglutinin (HA) genes of the 31 strains were divided into three different groups.Three strains isolated in 2013 and three strains isolated in 2014 belonged to Group 1 and Group 2, respectively, while the others belonged to Group 3.Three positive selection sites (237, 366 and 367) in HA protein were observed by REL model.Compared with the strain used for vaccine production, the 31 strains were characterized by amino acid substitutions (N128A/T and P198S/A) in HA protein and all of the mutations located in B-cell epitopes.The total number of mutation sites reached 24.Compared with the A/Texas/50/2012 strain, seven strains presented the glycosylation site 126NWT, and three strains showed disappeared glycosylation sites of 45NSS and 144NNS.Evaluation of vaccine efficacy for A(H3N2) virus strains showed that the vaccine efficacy was not very well.Conclusion The HA gene of A(H3N2) virus had undergone a greater variation and the vaccine efficacy was not very well in Jiangsu province during 2013 to 2014, which made the influenza A(H3N2) virus become the circulating strain.

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 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 One H5N6 subtype avian influenza virus,A/environment/ Zhenjiang/C13/ 2013,was isolated from environment in Zhenjiang in 2013 during epidemiological surveillance and was identified by HA/HI test and specific RT-PCR test.H5N6 AIV was subjected to genome sequencing to investigate the genomic composition.Methods The next-generation sequencing (NGS) Illumina MiSeq Platform was used to obtain complete genome sequence information from influenza virus isolates.MEGA6.0 software was used to align the eight fragments of the virus.The phylogenetic and molecular characteristics of the isolate were analyzed by Neighbor-Joining method.Results Blast searches demonstrated that the NA gene belonged to the same clade with H6N6 viruses currently circulating in China,whereas the other seven genes were found to be more similar to those of eastern Asian H5N1 AIV strains gene.The amino acid motif of cleavage site between HA1 and HA2 was PLREKRRKR ↓ GLF,which was the typical characteristics of the HPAIVs.The receptor binding site in the viral HA gene possesses the residues Gln 226 and Gly 228 (H3 numbering),indicating an avian-like receptor binding specificity.Conclusion One H5N6 subtype avian influenza virus was isolated from environment,phylogenetic analysis showed that the NA gene belonged to the same clade with H6N6 viruses.The other seven genes belonged to H5N1 subtype.It suggests that strengthen the continuous surveillance of avian influenza A viruses is necessary.

Objective:To develop an integrated point-of-care testing (POCT) reagent for genotying respiratory syncytial virus (RSV) and evaluate its performance.Methods:Specific primers and probes were designed based on the conserved sequences of the genomes of RSV A and B as well as ON1 and BA9 genotypes. The PCR reaction system and conditions were optimized. The vitrification technology of reagents and multiplex detection platform were integrated to develop the RSV genotyping POCT reagent. The sensitivity, specificity, reproducibility, and clinical performance of the product were then evaluated.Results:The sensitivity of the developed integrated RSV genotyping POCT reagent reached 500 copies/ml. It exhibited good specificity with no cross-reaction with clinically similar pathogens. The coefficient of variation of Ct values for both inter-batch and intra-batch reproducibility was less than 5%, indicating good reproducibility. In testing 53 clinical samples, the detection results showed high consistency and concordance with the reference reagent, with a positive concordance rate of up to 98.11%.Conclusions:The developed integrated RSV genotyping POCT reagent incorporates nucleic acid extraction, purification, and detection into a single process, achieving a "sample in, result out" workflow. It is simple to operate and provides accurate, reliable, and stable detection results. This product can be used for the genotyping of RSV A and B in POCT, offering support for the prevention, control, and diagnosis of RSV.

Objective:To understand the relationship between the RNA shedding time of SARS-CoV-2 infected persons and the single nucleotide mutation of the virus, the population of infected persons, underlying diseases and other factors, so as to provide more clues for the study of SARS-CoV-2 infection dynamics.Methods:The data of epidemiology, clinical manifestations, and underlying diseases of infected persons in a cluster epidemic of COVID-19 in Jiangsu province from July to September 2021 were collected. Nasopharyngeal swab samples of cases were collected, and the whole genome of the virus was sequenced by second-generation sequencing technology. The online analysis platform was used to judge the virus type and analyze the mutation site, and Cox proportional risk model was used to analyze the relationship between the RNA shedding time of SARS-CoV-2 and various research factors.Results:There were 350 persons who finally obtained the whole genome sequence of the virus in this COVID-19 outbreak, of which 60.3% were female, the median age was 49 years old (interquartile range, IQR: 37-65 years old)), and the median time of virus shedding was 33 days ( IQR, 26-44 days). The whole-genome sequencing analysis showed that compared with the Wuhan reference strain sequence, the infected persons’ sequence had 34~41 nucleotide mutation sites, belonging to VOC/Delta variant (B.1.617.2 evolutionary branch), and C346T, C1060T, T2803C, T7513C, A29681C were the main single nucleotide polymorphisms (SNPs) of this epidemic. Cox regression analysis showed that age, underlying disease, clinical classification, vaccination, SNP T2803C and T7513C had an impact on the RNA shedding time of SARS-CoV-2. The adjusted multivariate Cox regression result showed that age [ HR=0.73, 95% CI (0.55, 0.95)] and T7513C [ HR=0.37, 95% CI (0.18, 0.77)] were still the risk factors for the extension of SARS-CoV-2 RNA shedding time. Conclusions:This study analyzed the effects of the individual factors and viral single nucleotide variations on the time of viral RNA shedding. Those who were older, suffered from hypertension, had more severe clinical symptoms, were not vaccinated or incompletely vaccinated, and had T7513C mutation in the infected virus, had a risk of a long RNA shedding time of SARS-CoV-2, which should be given special attention and follow-up after rehabilitation.

Objective:To analyze the epidemiological and clinical characteristics of respiratory syncytial virus (RSV) infection in children in Jiangsu Province from 2014 to 2023.Methods:The acute respiratory infection cases in children aged 0-14 years were selected from outpatient/emergency or inpatient departments in 2 surveillance sentinel hospitals, respectively, in Nanjing, Suzhou and Taizhou of Jiangsu from 1 July 2014 to 31 December 2023, and RSV nucleic acid test was conducted and the intensity of the RSV infection was accessed by WHO influenza epidemiological threshold method, and case information and clinical data were collected. χ2 test was used to compare the differences between groups, and the Bonferroni method was used for pairwise comparisons between groups. Results:In 4 946 cases of acute respiratory infections, the RSV positive rate was 8.21% (406/4 946), and the age M( Q1, Q3) of the cases was 1 (0, 3) years. The RSV positive rate was 10.92% (258/2 362) during 2014-2019 and 6.06% (118/1 948) during 2019-2023, the difference was significant ( χ2=31.74, P<0.001). RSV infection mainly occurred from October to March during 2014-2019, with the incidence peak in December and moderate or higher intensity. The seasonality of RSV infection was not obvious during 2019-2023, with low intensity. The RSV positive rate was highest in children in age group 0- years (17.85%, 151/846), and the positive rate declined gradually with age ( χ2=184.51, P<0.001). The RSV positive rate was higher in inpatient cases (9.84%, 244/2 480) than in outpatient/emergency cases (6.57%, 162/2 466) ( χ2=17.54, P<0.001). In the 155 RSV infection cases with complete clinical data, the clinical symptoms mainly included cough (99.35%, 154/155), fever (55.48%, 86/155), and shortness of breath (45.16%, 70/155). In the cases aged <6 months, the proportion of those with fever was low, but the proportion of those with shortness of breath, transferred to intensive care units, and receiving oxygen therapy were higher (all P<0.05). Children aged <6 months and those with underlying diseases were more likely to have severe RSV infection (all P<0.05). Conclusions:RSV infection in children in Jiangsu Province showed seasonal prevalence in winter from 2014 to 2019. Since 2020, the seasonal characteristics of the epidemic have changed, the epidemic period has been dispersed and the epidemic intensity has decreased. Infants <1 year old were at high risk for RSV infection, and those <6 months old and with underlying diseases might have severe infection.