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From January 2015 to December 2018, 213 norovirus outbreaks with 3,951 patients were reported in Jiangsu, China. Based on viral RdRp and VP1 genes, eight genotypes, GII.2[P16] (144, 67.6%), GII.3[P12] (21, 9.9%), GII.6[P7] (5, 2.3%), GII.14[P7] (4, 1.9%), GII.4 Sydney[P31] (3, 1.4%), GII.1[P33] (1, 0.5%), GII.2[P2] (3, 1.4%), and GII.17[P17] (16, 7.5%) were identified throughout the study period. These genotypes were further regrouped as GII.R (Recombinant) and GII.Non-R (Non-recombinant) strains. In this report we showed that GII.R strains were responsible for at least 178 (83.6%) of 213 norovirus-positive outbreaks with a peak in 2017 and 2018. Most norovirus outbreaks occurred in primary schools and 94 of 109 (86.2%) outbreaks in primary schools were caused by GII.R, while GII.Non-R and GII.NT (not typed) strains accounted for 6 (5.5%) and 9 (8.3%) norovirus outbreaks, respectively. The SimPlot analysis showed recombination breakpoints near the ORF1/2 junction for all six recombinant strains. The recombination breakpoints were detected at positions varying from nucleotides 5009 to 5111, localized in the ORF1 region for four strains (GII.2[P16], GII.3[P12], GII.6[P7], and GII.14[P7]) and in the ORF2 region for the other (GII.4 Sydney[P31] and GII.1[P33]). We identified four clusters, Cluster I through IV, in the GII.P7 RdRp gene by phylogenetic analysis and the GII.14[P7] variants reported here belonged to Cluster IV in the RdRp tree. The HBGA binding site of all known GII.14 strains remained conserved with several point mutations found in the predicted conformational epitopes. In conclusion, gastroenteritis outbreaks caused by noroviruses increased rapidly in the last years and these viruses were classified into eight genotypes. Emerging recombinant noroviral strains have become a major concern and challenge to public health.

Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in infants and young children worldwide. To elucidate the molecular epidemiology of G2P[4] rotavirus in China and the protective effects of vaccines, whole-genome analysis of 13 G2P[4] RVA strains collected from China in 2022 was performed. Twelve strains possessed the typical DS-1-like genome constellation G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Only GS2265 possessed the genome constellation G2-P[4]-12-R2-C2-M2-A2-N2-T2-E1-H2. With the exception of the NSP4 segment of GS2265, all other sequences of the 13 G2P[4] RVA strains clustered within the same lineage on phylogenetic analysis. However, QD2210 and SX2205 were grouped into different branches compared to the other strains. In the VP7 antigenic epitopes, four residues differed from the RotaTeq G2 strain; specifically, A87T and D96N in the 7-1a region and S213D and S242N in the 7-1b region. Comparison of the current G2P[4] RVA strains circulating in China with those circulating globally revealed a high degree of sequence identity. High genetic variability among the newly characterized G2P[4] RVA strains suggest the strains evolve fast. Finally, our data suggest that the multivalent RotaTeq vaccine could have provided better protection than the monovalent Rotarix and LLR.

CaliciNet China, a network of provincial, county, and city laboratories coordinated by the Chinese Centers for Disease Control and Prevention, was launched in October 2016 to monitor the epidemiology and genotype distribution of norovirus outbreaks in China. During October 2016-September 2018, a total of 556 norovirus outbreaks were reported, and positive fecal samples from 470 (84.5%) outbreaks were genotyped. Most of these outbreaks were associated with person-to-person transmission (95.1%), occurred in childcare centers or schools (78.2%), and were reported during November-March of each year (63.5%). During the 2-year study period, 81.2% of all norovirus outbreaks were typed as GII.2[P16]. In China, most norovirus outbreaks are reported by childcare centers or schools; GII.2[P16] is the predominant genotype. Ongoing surveillance by CaliciNet China will provide information about the evolving norovirus genotype distribution and outbreak characteristics important for the development of effective interventions, including vaccines.

Objectives Norovirus genotype GII.3[P12] strains have been an important pathogen for sporadic gastroenteritis infection. In previous studies of GII.3[P12], the number of specimens and time span are relatively small, which is difficult to truly reflect the infection and evolution of this type of norovirus. Here we report a molecular epidemiological study of the NoVs prevalent in Jiangsu between 2010 and 2019 to investigate the evolution of the GII.3[P12] strains in China. Methods In this study 60 GII.3[P12] norovirus strains were sequenced and analyzed for evolution, recombination, and selection pressure using bioanalysis software. Results The GII.3[P12] strains were continuously detected during the study period, which showed a high constituent ratio in males, in winter and among children aged 0–11 months, respectively. A time-scaled evolutionary tree showed that both GII.P12 RdRp and GII.3 VP1 sequences were grouped into three major clusters (Cluster I–III). Most GII.3[P12] strains were mainly located in sub-cluster (SC) II of Cluster III. A SimPlot analysis identified GII.3[P12] strain to be as an ORF1-intragenic recombinant of GII.4[P12] and GII.3[P21]. The RdRp genes of the GII.3[P12] showed a higher mean substitution rate than those of all GII.P12, while the VP1 genes of the GII.3[P12] showed a lower mean substitution rate than those of all GII.3. Alignment of the GII.3 capsid sequences revealed that three HBGA binding sites of all known GII.3 strains remained conserved, while several amino acid mutations in the predicted antibody binding sites were detected. The mutation at 385 was within predicted antibody binding regions, close to host attachment factor binding sites. Positive and negative selection sites were estimated. Two common positively selected sites (sites 385 and 406) were located on the surface of the protruding domain. Moreover, an amino acid substitution (aa204) was estimated to be near the active site of the RdRp protein. Conclusions We conducted a comprehensive analysis on the epidemic and evolution of GII.3[P12] noroviruses and the results suggested that evolution was possibly driven by intergenic recombination and mutations in some key amino acid sites.

Human adenovirus (HAdV) is common pathogens that cause various respiratory diseases. The genetic diversity of viruses caused by recombination is considered to be the main source of emerging outbreaks. The aim of this study is to explore the evolutionary relationship and recombination events of HAdV genome in respiratory tract infections in Jiangsu Province. Whole-genome sequencing (WGS) technology was used to sequence 66 patients with HAdV infection (37 patients with influenza-like illness (ILI) and 29 hospitalized patients with pneumonia) from Jiangsu Province. Epidemiological analysis was performed on hospitalized pneumonia and ILI patients infected with HAdV. Subsequently, phylogenetic, recombination, and nucleotide and amino acid identity analyses were performed. Epidemiological analysis of patients undergoing WGS showed that 75.7% of ILI patients were infected with the HAdVB strain and 69.0% of hospitalized pneumonia patients were infected with the HAdVC strain. Moreover, the hospitalized pneumonia and ILI patients infected with HAdV were different in region and time. The strains of HAdVB3 and HAdVB7 genotypes were mainly infected in 2015 and 2017, and the strains of HAdVC1 and HAdVC2 genotypes were mainly infected in 2020. The results of histogram analysis showed that the HAdV strain mainly infected children under 5 years old. In addition, 36 novel recombinant strains were identified. The discovery of these recombinant strains may contribute to understanding the epidemiology of HAdV and research on related vaccines. Furthermore, the percentage of nucleotide and amino acid identities revealed a high level of genetic conservation within isolates from HAdVB3, HAdVB7, HAdVC1, HAdVC2 and HAdVC5 genotypes. The WGS analysis reveals the evolutionary relationships and recombination events of HAdV strains in Jiangsu Province, which is helpful to deepen the understanding of HAdV epidemiology and evolution. In addition, it provides a basis for the formulation of public health strategies in Jiangsu Province.

Introduction: China implemented a dynamic zero-COVID strategy to curb viral transmission in response to the coronavirus disease 2019 (COVID-19) pandemic. This strategy was designed to inhibit mutation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19. This study explores the dynamics of viral evolution under stringent non-pharmaceutical interventions (NPIs) through real-world observations. Methodology: Our analysis encompassed all polymerase chain reaction (PCR)-confirmed COVID-19 cases (n = 780) from two consecutive outbreaks occurring in July to August 2021. Epidemiological investigations and in-depth viral genome analyses were conducted to determine the sources of infection and the inter-outbreak linkages. Results: The outbreaks likely originated via contaminated objects from an imported COVID-19 case to local airport cleaners. Most patients presented clinically mild symptoms. All viral genomes clustered into a single clade, with genomes from the subsequent Yangzhou outbreak forming a distinct branch, diverging from those of the initial Nanjing outbreak. Compared to the Wuhan-Hu-1 strain, the Delta variants isolated from the imported case and early local cases in Nanjing had 35 nucleotide mutations and three deletions. Various single nucleotide variant (SNV) combinations were observed in subsequent transmissions, with NPIs accounting for the termination of 67.2% (92/137) of SNV combinations. Stringent implementation of NPIs resulted in a greater number of terminated SNV combinations than emerging ones. Additionally, vaccination of cases was associated with SNV combination termination. Conclusions: This study underscores the significant role of NPIs in preventing the accumulation of SARS-CoV-2 mutations.

Objective: To describe the epidemiological characteristics of norovirus outbreaks in Jiangsu Province, utilize the total attack rate ( TAR ) and transmissibility ( R unc ) as the measurement indicators of the outbreak, and a statistical difference in risk factors associated with TAR and transmissibility was compared. Ultimately, this study aimed to provide scientific suggestions to develop the most appropriate prevention and control measures. Method: We collected epidemiological data from investigation reports of all norovirus outbreaks in Jiangsu Province from 2012 to 2018 and performed epidemiological descriptions, sequenced the genes of the positive specimens collected that were eligible for sequencing, created a database and calculated the TAR , constructed SEIAR and SEIARW transmission dynamic models to calculate R unc , and performed statistical analyses of risk factors associated with the TAR and R unc . Results: We collected a total of 206 reported outbreaks, of which 145 could be used to calculate transmissibility. The mean TAR in was 2.6% and the mean R unc was 12.2. The epidemiological characteristics of norovirus outbreaks showed an overall increasing trend in the number of norovirus outbreaks from 2012 to 2018; more outbreaks in southern Jiangsu than northern Jiangsu; more outbreaks in urban areas than in rural areas; outbreaks occurred mostly in autumn and winter. Most of the sites where outbreaks occurred were schools, especially primary schools. Interpersonal transmission accounted for the majority. Analysis of the genotypes of noroviruses revealed that the major genotypes of the viruses changed every 3 years, with the GII.2 [P16] type of norovirus dominating from 2016 to 2018. Statistical analysis of TAR associated with risk factors found statistical differences in all risk factors, including time (year, month, season), location (geographic location, type of settlement, type of premises), population (total number of susceptible people at the outbreak site), transmission route, and genotype ( P < 0.05). Statistical analysis of transmissibility associated with risk factors revealed that only transmissibility was statistically different between sites. Conclusions: The number of norovirus outbreaks in Jiangsu Province continues to increase during the follow-up period. Our findings highlight the impact of different factors on norovirus outbreaks and identify the key points of prevention and control in Jiangsu Province.

Background The major etiology of hand, foot and mouth disease (HFMD) is infection with human enterovirus A (HEV-A). Among subtypes of HEV-A, coxsackievirusA16 (CoxA16) and enterovirus 71 (EV71) are major causes for recurrent HFMD among infants and children in Jiangsu Province, mainland China. Here, we analyzed maternal antibodies between prenatal women and their neonates, to determine age-specific seroprevalence of human EV71 and CoxA16 infections in infants and children aged 0 to 15 years. The results may facilitate the development of immunization against HFMD. Methods This study used cross-section of 40 pairs of pregnant women and neonates and 800 subjects aged 1 month to 15 years old. Micro-dose cytopathogenic effects measured neutralizing antibodies against EV71 and CoxA16. Chi-square test compared seroprevalence rates between age groups and McNemar test, paired-Samples t-test and independent-samples t-test analyzed differences of geometric mean titers. Results A strong correlation between titers of neutralizing antibody against EV71 and CoxA16 in prenatal women and neonates was observed (r EV71  = 0.67, r CoxA16  = 0.56, respectively, p  < 0.05). Seroprevalence rates of anti-EV71 antibody gradually decreased with age between 0 to 6 months old, remained low between 7 to 11 months (5.0–10.0%), and increased between 1 and 4 years (22.5–87.5%). Age-specific seroprevalence rates of anti-EV71 antibody stabilized in >80% of children between 5 to 15 years of age. However, seroprevalence rates of anti-CoxA16 antibody were very low (0.0–13.0%) between 0 to 6 months of age, gradually increased between 7 months to 4 years (15.0–70.0%), and stabilized at 54.0% (108/200) between 5 to 15 years. Seroprevalence rates against EV71 and CoxA16 were low under 1 year (0.0–10.0%), and showed an age dependent increase with high seroprevalence (52.5–62.5%) between 4 and10 years of age. Conclusions Concomitant infection of EV71 and CoxA16 was common in Jiangsu Province. Therefore, development of bivalent vaccine against both EV71 and CoxA16 is critical. The optimal schedule for vaccination may be 4 to11 months of age.

We investigated the seropositive rates and persistence of antibody against pandemic (H1N1) 2009 virus (pH1N1) in pregnant women and voluntary blood donors after the second wave of the pandemic in Nanjing, China. Serum samples of unvaccinated pregnant women (n = 720) and voluntary blood donors (n = 320) were collected after the second wave of 2009 pandemic in Nanjing. All samples were tested against pH1N1 strain (A/California/7/2009) with hemagglutination inhibition assay. A significant decline in seropositive rates, from above 50% to about 20%, was observed in pregnant women and voluntary blood donors fifteen weeks after the second wave of the pandemic. A quarter of the samples were tested against a seasonal H1N1 strain (A/Brisbane/59/2007). The antibody titers against pH1N1 strain were found to correlate positively with those against seasonal H1N1 strain. The correlation was modest but statistically significant. The high seropositive rates in both pregnant women and voluntary blood donors suggested that the pH1N1 virus had widely spread in these two populations. Immunity derived from natural infection seemed not to be persistent well.

Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in infants and young children worldwide. To elucidate the molecular epidemiology of G2P[4] rotavirus in China and the protective effects of vaccines, whole-genome analysis of 13 G2P[4] RVA strains collected from China in 2022 was performed. Twelve strains possessed the typical DS-1-like genome constellation G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Only GS2265 possessed the genome constellation G2-P[4]-12-R2-C2-M2-A2-N2-T2-E1-H2. With the exception of the NSP4 segment of GS2265, all other sequences of the 13 G2P[4] RVA strains clustered within the same lineage on phylogenetic analysis. However, QD2210 and SX2205 were grouped into different branches compared to the other strains. In the VP7 antigenic epitopes, four residues differed from the RotaTeq G2 strain; specifically, A87T and D96N in the 7-1a region and S213D and S242N in the 7-1b region. Comparison of the current G2P[4] RVA strains circulating in China with those circulating globally revealed a high degree of sequence identity. High genetic variability among the newly characterized G2P[4] RVA strains suggest the strains evolve fast. Finally, our data suggest that the multivalent RotaTeq vaccine could have provided better protection than the monovalent Rotarix and LLR.Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in infants and young children worldwide. To elucidate the molecular epidemiology of G2P[4] rotavirus in China and the protective effects of vaccines, whole-genome analysis of 13 G2P[4] RVA strains collected from China in 2022 was performed. Twelve strains possessed the typical DS-1-like genome constellation G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Only GS2265 possessed the genome constellation G2-P[4]-12-R2-C2-M2-A2-N2-T2-E1-H2. With the exception of the NSP4 segment of GS2265, all other sequences of the 13 G2P[4] RVA strains clustered within the same lineage on phylogenetic analysis. However, QD2210 and SX2205 were grouped into different branches compared to the other strains. In the VP7 antigenic epitopes, four residues differed from the RotaTeq G2 strain; specifically, A87T and D96N in the 7-1a region and S213D and S242N in the 7-1b region. Comparison of the current G2P[4] RVA strains circulating in China with those circulating globally revealed a high degree of sequence identity. High genetic variability among the newly characterized G2P[4] RVA strains suggest the strains evolve fast. Finally, our data suggest that the multivalent RotaTeq vaccine could have provided better protection than the monovalent Rotarix and LLR.