Pathogenic characteristics of an aggregated diarrhea event caused by Plesiomonas shigelloides from stream.

This study aimed to investigate the cause of a foodborne disease outbreak in Huzhou on August 14, 2023. Multiple enteropathogens were detected using FilmArray, and the pathogen was subsequently isolated and cultured from anal swabs of the cases and stream water. The isolated strains were identified using VITEK MS, and antimicrobial susceptibility test, pulsed field gel electrophoresis (PFGE) molecular typing, and whole genome sequencing (WGS) were performed on the isolates of Plesiomonas shigelloides. Gene annotation and sequence alignment were used to analyze the virulence genes and drug resistance genes of the strains. A phylogenetic tree was constructed based on single nucleotide polymorphism (SNP), and homology analysis was conducted to trace the origin of P. shigelloides. A total of 7 strains of P.shigelloides were isolated, with 3 from stream water and 4 from anal swabs. All 7 strains exhibited the same PFGE pattern and showed resistance to amikacin, trimethoprim-sulfamethoxazole, chloramphenicol, tetracycline, cefazolin, streptomycin, and florfenicol. The isolated strains carried the same resistance genes and virulence factors. In the sequences of the isolated strains from this outbreak, 11 mutation sites were detected. The phylogenetic tree based on SNP sites showed that these strains were homologous. This foodborne disease outbreak caused by P.shigelloides was the first reported in Huzhou. WGS can be used as a complementary method to PFGE for epidemiological investigations of disease outbreaks.

Prevalence and Serotyping of Salmonella in Retail Food in Huzhou China.

Salmonella is one of the most common foodborne pathogens. A total of 70-80% of bacterial food poisoning is caused by Salmonella in China. From 2015 to 2023, a total of 1945 samples in 6 food categories were collected in Huzhou for monitoring of Salmonella. Epidemiological analysis, serotyping, and antibiotic sensitivity testing were conducted on isolated Salmonella. Ninety Salmonella strains were detected from 1945 samples, and the total detection rate was 4.63%. Among all kinds of food, the detection rate of Salmonella in raw animal meat (8.93%) and raw poultry meat (8.54%) was the highest. Salmonella had also been detected in ready-to-eat foods (bulk cooked meat, Chinese cold dishes) and emerging food categories (seasoned raw meat and premade dishes). A total of 24 serotypes of Salmonella were detected, of which the dominant serotype was Salmonella Typhimurium. The serotypes of Salmonella detected in different types of food were different. The results showed that the isolates had strong resistance to ampicillin (AMP) and tetracycline (TET).

Genomic characterization of Campylobacter isolates in Huzhou, China.

Campylobacter is a major foodborne pathogen that causes outbreaks and sporadic gastrointestinal disease, creating a serious disease burden. Campylobacter strains isolated from diarrhea cases (n = 11) and raw poultry meat products (n = 2) in Huzhou, including 11 Campylobacter jejuni and 2 Campylobacter coli strains, were subjected to virulence gene, drug resistance gene, genetic correlation, antibiotic resistance, and multilocus sequence typing (MLST) analyses. The 13 Campylobacter isolates were divided into 12 sequence types (STs), one of which was a new ST. The isolated strains contain multiple virulence-related genes. Drug sensitivity analysis showed that the resistance rate of the 13 isolates to nalidixic acid, ciprofloxacin, and tetracycline was 92.3%. Genome sequencing indicated that all 11 strains of C. jejuni carried the tet(O) and blaOXA resistance genes, and 2 strains of C. coli carried multiple drug resistance genes. Phylogenetic analysis based on core-genome single-nucleotide polymorphisms indicated that the 11 C. jejuni isolates from diarrhea patients and food sources are not closely phylogenetically related.

Early evolution and transmission of GII.P16-GII.2 norovirus in China.

Norovirus is the most common cause of acute gastroenteritis worldwide. During 2016-2017, a novel recombinant GII.P16-GII.2 genotype of norovirus suddenly appeared and over the next several years became the predominant strain in both China and worldwide. To better understand the origin and diffusion of the GII.P16-GII.2 genotype in China, we conducted molecular evolutionary analyses, including phylodynamics and phylogeography. Moreover, to trace person-to-person transmission of GII.P16-GII.2 norovirus, we applied the novel method, TransPhylo, to a historical phylogeny using sequences obtained from a publicly available database. A time-scaled phylogenetic tree indicated that the time to the most recent common ancestor of the GII.P16-GII.2 major capsid protein (VP1) gene diverged from the GII.P2-GII.2 VP1 gene at 2,001.03 with an evolutionary rate of 3.32 × 10-3 substitutions/site/year. The time to the most recent common ancestor of the GII.P16-GII.2 RNA-dependent RNA polymerase region diverged from the GII.P16-GII.4 RNA-dependent RNA polymerase region at 2,013.28 with an evolutionary rate of 9.44 × 10-3 substitutions/site/year. Of these 2 genomic regions, VP1 gene sequence variations were the most influenced by selective pressure. A phylogeographic analysis showed that GII.P16-GII.2 strains in China communicated most frequently with those in the United States, Australia, Thailand, and Russia, suggesting import from Australia to Taiwan and from the United States to Guangdong. TransPhylo analyses indicated that the basic reproductive number (R0) and sampling proportion (pi) of GII.P16-GII.2 norovirus were 1.99 (95% confidence interval: 1.58-2.44) and 0.76 (95% confidence interval: 0.63-0.88), respectively. Strains from the United States and Australia were responsible for large spread during the evolution and transmission of the virus. Coastal cities and places with high population densities should be closely monitored for norovirus.

Characterization of Clinical Salmonella entericas Trains in Huzhou, China.

Background: Salmonella enterica subspecies enterica causes salmonellosis in humans and animals and is an important antecedent of food infections worldwide. This study collected 105 clinical S. enterica isolates from diarrhoea samples from six sentinel hospitals for active surveillance of foodborne diseases in Huzhou, China, between 2018 and 2020. These represented all the Salmonella isolates collected in Huzhou during that period. Methods: The isolates were characterized by serovar determination, antimicrobial susceptibility tests, and pulse-field gel electrophoresis (PFGE) typing. Results: The 105 Salmonella strains were mainly S. typhimurium (35.24%, 95% CI from 25.95 to 44.53%) and S. enteritidis (18.10%, 95% CI from 10.61 to 25.58%). Testing indicated that the resistance rate of the Salmonella strains ranged from 0.00% to 70.48%, and the highest resistance rate was for ampicillin (70.48%; 74/105), followed by tetracycline (67.62%; 71/105) and doxycycline (65.71%; 69/105). Following XbaI digestion, the 105 strains yielded 93 PFGE patterns, and 15 clones had similarity values >85.00%. Conclusions: Our analyses revealed the serovar distribution of isolates recovered from diarrhoea patients and the characteristics of resistant strains in Huzhou from 2018 to 2020. Our results highlight a serovar shift and a concerning number of multidrug-resistant (MDR) strains. Continued surveillance of Salmonella and their MDR profiles and efforts to control the rapid increase in antimicrobial resistance among Salmonella in Huzhou are needed.

Emergence and predominance of a new serotype of Vibrio parahaemolyticus in Huzhou, China.

BACKGROUND: During our surveillance period, we found a new type of Vibrio parahaemolyticus (V. parahaemolyticus) with serotype O10:K4, which had increased over the past 2 years in Huzhou and became the second most common serotype after O3:K6. METHODS: Strains were isolated from stool samples of diarrhea patients in the First People's Hospital in Huzhou. The serotypes, virulence-associated genes, antimicrobial susceptibility, and pulsed field gel electrophoresis (PFGE) of these strains were analyzed. RESULTS: Between January 2017 and December 2021, there were 598 (5.36%) V. parahaemolyticus-positive samples of 11,166 stool specimens. The V. parahaemolyticus detection rate was high in summer months. The O3:K6 was the dominant serotype in 2017-2020 and a new serotype, O10:K4, was the predominant serotype in 2021. The majority of isolates tested were resistant to ampicillin (86.8%). We randomly chose the strains with serotype O3:K6 and O10:K4 for PFGE to compare the genetic relationship between these two serotypes. The results showed that the PFGE profiles of V. parahaemolyticus O3:K6 and O10:K4 were genetically similar. The strains showed a tendency to cluster on the basis of their serotype profiles. However, some O3:K6 strains showed 100% similarity with O10:K4 strains. CONCLUSION: A new serotype with pandemic potential of V. parahaemolyticus, O10:K4, was detected in 2020 and became dominant in 2021 in Huzhou.

Molecular typing and epidemiology profiles of human adenovirus infection among hospitalized patients with severe acute respiratory infection in Huzhou, China.

BACKGROUND: Severe acute respiratory infections (SARI) threaten human health and cause a large number of hospitalizations every year. However, as one of the most common pathogen that cause acute respiratory tract infection, the molecular epidemiological information relating to human adenoviruses (HAdVs) among patients with SARI is limited. Here, we evaluate the epidemiological and molecular characteristics of HAdV infections among hospitalized patients with SARI from January 2017 to December 2019 in Huzhou, China. METHODS: From January 2017 to December 2019, a total of 657 nasopharyngeal swabs collected from inpatients with SARI were screened for HAdV and other common respiratory viruses by multiplex real-time PCR. All samples that tested positive for HAdV were further typed by sequencing partial sequences of hexon gene. Genotypes of HAdV were confirmed by phylogenetic analysis. Epidemiological data were analyzed using Microsoft Excel 2010 and service solutions (SPSS) 21.0 software. RESULTS: 251 (38.20%) samples were positive for at least one respiratory virus. HAdV was the second common viral pathogen detected, with a detection rate of 7.08%. Infection with HAdV was found in all age groups tested (0<2, 2<5, 5<15, 15<50, 50<65, ≥65). Children under 15 years old accounted for 84.62% (44/52) of the infections. Higher activity of HAdV infection could be seen in spring-early autumn season. Seven different types of HAdV belonging to 4 species (HAdV-A, B, C, E) were identified in hospitalized SARI cases, with HAdV-B3 as the most prevalent HAdV types, followed by HAdV-B7 and HAdV-E4. HAdV-B3 was the most frequently detected genotype in 2017 and 2019, accounting for 75.00% (9/12) and 63.64% (7/11) of typed HAdV infections in 2017 and 2019, respectively. No predominant strain was responsible for HAdV infections in 2018, although HAdV-B7 (28.57%, 2/7) and HAdV-C1 (28.57%, 2/7) were the major causative genotypes. CONCLUSIONS: This study revealed the prevalence and the molecular epidemiological characteristics of HAdV infections among hospitalized patients with SARI in Huzhou from January 2017 to December 2019. The HAdV prevalence is related to age and season. As the most prevalent HAdV types, HAdV-B3 was co-circulating with other types and presented an alternate prevalence pattern.

Molecular typing and epidemiologic profiles of human metapneumovirus infection among children with severe acute respiratory infection in Huzhou, China.

BACKGROUND: Human metapneumovirus (hMPV) is one of the important pathogens in infant respiratory tract infection. However, the molecular epidemiology of hMPV among children < 14 years of age hospitalized with severe acute respiratory infection (SARI) is unclear. We investigated the hMPV infection status and genotypes of children hospitalized with SARI from January 2016 to December 2020 in Huzhou, China. METHODS: A nasopharyngeal flocked swab, nasal wash, or nasopharyngeal swab/or opharyngeal swab combination sample was collected from children with SARI in Huzhou from January 2016 to December 2020. Quantitative reverse transcription-polymerase chain reaction was performed to detect hMPV RNA. The hMPV F gene was amplified and sequenced, followed by analysis using MEGA software (ver. 7.0). Epidemiological data were analyzed using Microsoft Excel 2010 and SPSS (ver. 22.0) software. RESULTS: A total of 1133 children with SARI were recruited from 2016 to 2020. Among them, 56 (4.94%) were positive for hMPV-RNA. Children < 5 years of age accounted for 85.71% of the positive cases. The hMPV incidence was high in spring and winter, especially in December and January to March. Phylogenetic analysis of the F-gene sequences of 28 hMPV strains showed that the A1, B1, and B2 genotypes were prevalent in Huzhou, and the dominant hMPV genotype varied according to surveillance year. CONCLUSIONS: HMPV is an important respiratory pathogen in children in Huzhou, with a high incidence in winter and spring in children < 5 years of age. In this study, genotypes A1, B1, and B2 were the most prevalent.

Molecular characterization of clinical and environmental Vibrio parahaemolyticus isolates in Huzhou, China.

Vibrio parahaemolyticus is responsible for seafood-borne gastroenteritis worldwide. Isolates of V. parahaemolyticus from clinical samples (n = 54) and environmental samples (n = 38) in Huzhou were analyzed by serological typing, virulence gene detection, antibiotic resistance testing, and pulsed-field gel electrophoresis (PFGE) for molecular typing. O3:K6 was the main serotype and tlh+tdh+trh- was the most frequently detected virulence genotype in clinical strains. O2:Kut was the main serotype and tlh+tdh-trh- was the most frequently detected virulence genotype in environmental strains. Antibiotic resistance testing indicated that the isolates were highly resistant to ampicillin (90.76%), followed by gentamicin and tetracycline. Following the restriction enzyme NotI digestion, the 91 strains yielded 81 PFGE patterns, and 16 clones had similarity values of > 85.00%, indicating a high level of diversity. Finally, there may be cross-contamination between freshwater and seawater products, so it is necessary to strengthen supervision of food processing.

Molecular epidemiology and changes in genotype diversity of norovirus infections in acute gastroenteritis patients in Huzhou, China, 2018.

Norovirus is an important causative agent of acute gastroenteritis worldwide, affecting people of all ages. Stool samples collected from patients with clinical symptoms of acute gastroenteritis in all age groups at the diarrhea outpatient department of the First People's Hospital in Huzhou were analyzed to gain insight into the prevalence and genetic characteristics of norovirus. From January to December 2018, a total of 551 specimens were screened for norovirus by real-time reverse transcription-polymerase chain reaction (RT-PCR). RT-PCR was used for genomic amplification and sequencing of the RNA-dependent RNA polymerase and capsid gene of the positive samples. Genotypes of norovirus were assigned using the norovirus Noronet typing tool and phylogenetic analysis. About 100 (18.1%) specimens were identified as norovirus positive. GII genogroup was the main genogroup identified (83.0%; 83/100). About 42 (42.0%) samples were successfully sequenced and genotyped by RT-PCR. Since one of the samples was dual infection, so we got 43 virus finally. Nine norovirus GII genotypes and four norovirus GI genotypes were detected in Huzhou during our research period. The main two norovirus GII genotypes were GII.2[P16] (54.8%; 23/43) and GII.17[P17] (11.9%; 5/43). We characterized the molecular epidemiology of norovirus infection in acute gastroenteritis patients during 2018. GII genogroup was the main genogroup identified. The dominance norovirus genotype circulating in the population of Huzhou was GII.2[P16] in 2018.

An increasing prevalence of non-GII.4 norovirus genotypes in acute gastroenteritis outbreaks in Huzhou, China, 2014-2018.

Since 2014, novel non-GII.4 norovirus (NoV) genotypes continue to be reported as the main cause of outbreaks worldwide. In this study, we analyzed the epidemiological and genetic features of NoV outbreaks from July 2014 to June 2018 in Huzhou, China. A total of 450 stool samples collected from 51 AGE outbreaks were tested for NoVs by real-time RT PCR. Partial polymerase and capsid sequences of NoV-positive samples were amplified and sequenced for phylogenetic analysis. NoVs were found to be responsible of 84.3% of AGE outbreaks in Huzhou over the past 5 years. Most NoV outbreaks were reported in the cool months (November-March) and occurred in primary schools and kindergartens. Changes in the diversity of genotypes and the distribution of predominant types were observed in recent years. At least eight genotypes were identified, and 91.9% of the genotyped outbreaks were caused by non-GII.4 strains. The top three circulating genotypes during the study period were GII.2[P16], GII.3[P12], and GII.17[P17]. The predominant NoV genotypes in outbreaks have changed from GII.4 variants to GII.17[P17] in 2014-2015, GII.3[P12] in 2015-2016, and then GII.2[P16] in 2016-2018. Non-GII.4 NoVs play an increasingly important role in outbreaks in Huzhou. Continuous surveillance is needed to monitor the emergence of novel NoV strains and help control NoV outbreaks in the next epidemic season.

Identification of Chicken-Derived Ingredients as Adulterants Using Loop-Mediated Isothermal Amplification.

ABSTRACT: Meat adulteration has recently become an issue of increasing public concern. In addition to posing a health risk to consumers with metabolic disorders or allergies, meat adulteration has triggered many economic and religious problems. Chicken meat is a common adulterant in nonchicken products because of its low cost and ready availability. A loop-mediated isothermal amplification assay coupled with a lateral flow dipstick was developed to identify chicken in nonchicken products. We optimized the amplification time and temperature to obtain the best result. This assay is performed at a constant temperature in a water bath and can be completed in 1 h. No precision instruments or equipment are needed. With a one-step reaction and easy operation, the testing cost is low. This method is highly sensitive and specific and is a valuable method for identifying chicken in nonchicken products to meets the requirements of on-site inspection and detection.

Emergence of norovirus GII.P16-GII.2 strains in patients with acute gastroenteritis in Huzhou, China, 2016-2017.

BACKGROUND: In late 2016, an uncommon recombinant NoV genotype called GII.P16-GII.2 caused a sharp increase in outbreaks of acute gastroenteritis in different countries of Asia and Europe, including China. However, we did not observe a drastic increase in sporadic norovirus cases in the winter of 2016 in Huzhou. Therefore, we investigate the prevalence and genetic diversity of NoVs in the sporadic acute gastroenteritis (AGE) cases from January 2016 to December 2017 in Huzhou City, Zhejiang, China. METHODS: From January 2016 to December 2017, a total of 1001 specimens collected from patients with AGE were screened for NoV by real-time RT-PCR. Partial sequences of the RNA-dependent RNA polymerase (RdRp) and capsid gene of the positive samples were amplified by RT-PCR and sequenced. Genotypes of NoV were confirmed by online NoV typing tool and phylogenetic analysis. Complete VP1 sequences of GII.P16-GII.2 strains detected in this study were further obtained and subjected into sequence analysis. RESULTS: In total, 204 (20.4%) specimens were identified as NoV-positive. GII genogroup accounted for most of the NoV-infected cases (98.0%, 200/204). NoV infection was found in all age groups tested (< 5, 5-15, 16-20, 21-30, 31-40, 41-50, 51-60, and >60 years), with the 5-15 year age group having the highest detection rate (17/49, 34.7%). Higher activity of NoV infection could be seen in winter-spring season. The predominant NoV genotypes have changed from GII.Pe-GII.4 Sydney2012 and GII.P17-GII.17 in 2016 to GII.P16-GII.2, GII.Pe-GII.4 Sydney2012 and GII.P17-GII.17 in 2017. Phylogenetic analyses revealed that 2016-2017 GII.P16-GII.2 strains were most closely related to Japan 2010-2012 cluster in VP1 region and no common mutations were found in the amino acids of the HBGA-binding sites and the predicted epitopes. CONCLUSIONS: We report the emergence of GII.P16-GII.2 strains and characterize the molecular epidemiological patterns NoV infection between January 2016 and December 2017 in Huzhou. The predominant genotypes of NoV during our study period are diverse. VP1 amino acid sequences of 2016-2017 GII.P16-GII.2 strains remain static after one year of circulation.

Nearly complete genome sequence of one GII.17 Norovirus identified by direct sequencing from HuZhou, China.

BACKGROUND: Human norovirus is the leading cause of acute gastroenteritis worldwide. However, in vitro culture system is complicated for human norovirus. Sequence analysis became more useful for norovirus research, particularly when using complete genomic sequences. METHODS: Real-time RT-PCR (qPCR) was performed for norovirus detection. Three modified paris of PCR primes were designed based on the alignment of the novel GII.17 norovirus complete sequence available in Genbank., which could amplify three overlapping fragments cover the whole genome. The PCR fragments were sequencing by Sanger sequence with Primer walking methods. Genogroup and genotype were assigned using the Norovirus Noronet typing tool and the strains were named according to the time of isolation. The phylogenetic analysis was conducted using MEGA software (ver. 6.06). RESULTS: One nearly complete genome sequence were obtained from sample collected from Huzhou, China. The partial genome sequence of the HuzhouNS2014603 strain is composed of 7556 nucleotides (nt).The strain was classified as GII.17 genotype both in ORF1 and ORF2, and was most closely related to the LC037415.1/Hu/GII.17/Kawasaki308 strain. Within the GII.17 cluster, the 2013/14 season strains were grouped separately from the GII.17 strains detected in 2014/15. HuzhouNS2014603 was clustered with the 2014/15 season strains. Compared with other strains selected, there are 98 variable residues across the VP1 domain. Among the 98 variable amino acids, 13 (13.3%) were observed in the shell domain and 22 (22.4%) in the P1domain; most of the substitutions and insertions were located in the P2 domain, account for 63 (64.3%). CONCLUSIONS: This is the first report of the nearly complete genome of the novel GII.17 by direct sequencing method in the Huzhou area. The results of this study could be helpful for the study of the genetic evolution of the virus, the development of rapid diagnostic reagents and the design of vaccine.

Detection and differentiation of Vibrio parahaemolyticus by multiplexed real-time PCR.

Vibrio parahaemolyticus is a common and important pathogen that causes human gastroenteritis worldwide. A rapid, sensitive, and specific assay is urgently required for detection and differentiation of V. parahaemolyticus strains. We designed three sets of primers and probes using groEL and two virulence genes (tdh and trh) from V. parahaemolyticus, and developed a multiplex real-time PCR protocol. The sensitivity and specificity of the multiplex assay was evaluated by environmental and clinical specimens of V. parahaemolyticus. The multiplex PCR response system and annealing temperature were optimized. The detection limits of the multiplex real-time PCR were 104 and 105 CFU/mL (or CFU/g) in pure cultures and spiked oysters, respectively. The multiplex real-time PCR specifically detected and differentiated V. parahaemolyticus from 35 Vibrio strains and 11 other bacterial strains. Moreover, this method can detect and distinguish virulent from nonvirulent strains, with no cross-reactivity observed in the bacteria tested. This newly established multiplex real-time PCR assay offers rapid, specific, and reliable detection of the total and pathogenic V. parahaemolyticus strains, which is very useful during outbreaks and sporadic cases caused by V. parahaemolyticus infection.

Clinical and molecular analyses of norovirus-associated sporadic acute gastroenteritis: the emergence of GII.17 over GII.4, Huzhou, China, 2015.

BACKGROUND: Noroviruses (NoVs) are the most common cause of non-bacterial acute gastroenteritis (AGE) in all age groups worldwide. The NoVs circulating in Huzhou over the past 7 years were predominantly GII.4 genotypes. In the winter of 2014-2015, a novel variant of NoV GII.17 emerged and became predominant. We report the epidemiological patterns and genetic characteristics of NoV after the appearance of GII.17 in Huzhou City, Zhejiang, China. METHODS: Between January and December 2015, 746 stool specimens collected from patients with acute gastroenteritis were screened for NoV. Real-time RT-PCR (qPCR) was performed for NoV detection. RT-PCR was used for genomic amplification and sequencing. Genogroups and genotypes were assigned using an online NoV typing tool ( http://www.rivm.nl/mpf/norovirus/typingtool ). Phylogenetic analyses were conducted using MEGA (ver. 6.06). RESULTS: In total, 196 (26.3%) specimens were identified as NoV-positive. NoV infection was found in all age groups tested (≤5, 6-15, 16-40, 41-60, and ≥60 years), with the 16-40-year age group having the highest detection rate (117/196, 59.7%). Of the 196 NoV-positive specimens, 191 (97.5%) viruses belonged to GII, and 4 (2.0%) to GI; one sample showed GI and GII co-infection. Overall, 117 (59.7%) viruses were sequenced, and new GII.P17/GII.17 variants were the dominant genotype, accounting for 75.2%, followed by GII.Pe/GII.4 Sydney 2012 strains (11.11%). AGE patients infected with the GII.P17/GII.17 genotypes almost all had abdominal pain and watery stools. CONCLUSIONS: We report the epidemiological patterns and genetic characteristics of the emergence GII.17 over the GII.4 in Huzhou between January and December 2015. After the emergence of GII.17 in October 2014, it steadily replaced the previously circulating GII.4 Sydney 2012 strain, and continued to be dominant in 2015.

[Complete Genome Analysis of a Recombinant GI Norovirus Identified in Huzhou,China].

To study the genotype and genomic and molecular organization of a GI norovirus isolate from Huzhou, China, the genomic sequence of 2008/Huzhou/N11 was amplified by RT-PCR, then the PCR product was purified,sequenced, and input into phylogenetic and Simplot analyses. The complete genomic sequence of the 2008/Huzhou/N11 strain was 7691nucleotides (nt) long. It contained three open reading frames(ORFs):ORF1,ORF2,and ORF3,with lengths of 5367,1623,and 630 nt, respectively. Phylogenetic analysis revealed that the RdRp region of 2008/Huzhou/N11 belonged to genotype GI.2,and the VP1 and VP2regions belonged to genotype GI.6.The SimPlot analysis indicated that potential recombination points in 2008/Huzhou/N11 were located upstream of the ORF1/ORF2 overlap. The complete genomic sequence of this recombinant GI.2/GI.6 strain can serve as a reference sequence for the phylogenetic analysis of norovirus evolution.

Emergence and predominance of norovirus GII.17 in Huzhou, China, 2014-2015.

BACKGROUND: Norovirus (NoV) has been recognized as the leading cause of both outbreaks and sporadic cases of acute gastroenteritis in children and adults worldwide. Stool samples collected from outpatients with clinical symptoms of acute gastroenteritis in all age groups at the First People's Hospital in Huzhou, Huzhou, China between March 2014 and February 2015 were analyzed to gain insight into the epidemiology and genetic variation in NoV strains circulating in China. METHOD: Real-time RT-PCR (qPCR) was performed for Norovirus detection. RT-PCR were used for genomic amplification and sequencing. Genogroup and genotype were assigned using the NoV Noronet typing tool and the strains were named according to the time of isolation. The phylogenetic analysis was conducted using MEGA 5. RESULTS: Of the 809 specimens, 193 (23.9 %) were positive for NoV, with GII.4 and GII.17 the most commonly identified strains. Phylogenetic analysis confirmed the presence of five recombinant strains in Huzhou. Recombinants GII.P13/GII.17 and GII.P12/GII.4 were newly detected in China. The GII.P13/GII.17 recombinant was first identified in October 2014 and steadily replaced GII.Pe/GII.4 (GII.4 Sydney 2012) as the predominant circulating NoV genotype. CONCLUSION: This is the first report of the detection of GII.17 in the Huzhou area and of a NoV genotype being detected in greater numbers than GII.4. Furthermore, our results indicated that following the emergence of GII.17 in October 2014, it steadily replaced the previous circulating GII.4 Sydney2012 strain, which was the dominant circulating genotype for the past 2 years. As norovirus are the important cause of nonbacterial gastroenteritis, continuous and comprehensive study of the norovirus strains involved in large and cost-effective acute gastroenteritis would help understanding the molecular epidemiology of norovirus infections and development of improved prevention and control measures.

A cross-priming amplification assay coupled with vertical flow visualization for detection of Vibrio parahaemolyticus.

Vibrio parahaemolyticus is a marine seafood-borne pathogen that causes gastrointestinal disorders in humans. In this study, we developed a cross-priming amplification (CPA) assay coupled with vertical flow (VF) visualization for rapid and sensitive detection of V. parahaemolyticus. This assay correctly detected all target strains (n = 13) and none of the non-target strains (n = 27). Small concentrations of V. parahaemolyticus (1.8 CFU/mL for pure cultures and 18 CFU/g for reconstituted samples) were detected within 1 h. CPA-VF can be applied at a large scale and can be used to detect V. parahaemolyticus strains rapidly in seafood and environmental samples, being especially useful in the field.