Application of a novel lytic phage vB_EcoM_SQ17 for the biocontrol of Enterohemorrhagic Escherichia coli O157:H7 and Enterotoxigenic E. coli in food matrices.

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 and Enterotoxigenic E. coli (ETEC) are important foodborne pathogens, causing serious food poisoning outbreaks worldwide. Bacteriophages, as novel antibacterial agents, have been increasingly exploited to control foodborne pathogens. In this study, a novel broad-host range lytic phage vB_EcoM_SQ17 (SQ17), was isolated, characterized, and evaluated for its potential to control bacterial counts in vitro and in three different food matrices (milk, raw beef, and fresh lettuce). Phage SQ17 was capable of infecting EHEC O157:H7, ETEC, and other E. coli strains. Morphology, one-step growth, and stability assay showed that phage SQ17 belongs to the Caudovirales order, Myoviridae family, and Mosigvirus genus. It has a short latent period of 10 min, a burst size of 71 PFU/infected cell, high stability between pH 4 to 12 as well as thermostability between 30°C and 60°C for 60 min. Genome sequencing analysis revealed that the genome of SQ17 does not contain any genes associated with antibiotic resistance, toxins, lysogeny, or virulence factors, indicating the potential safe application of phage SQ17 in the food industry. In Luria-Bertani (LB) medium, phage SQ17 significantly decreased the viable counts of EHEC O157:H7 by more than 2.40 log CFU/ml (p < 0.05) after 6 h of incubation at 37°C. Phage SQ17 showed great potential to be applied for biocontrol of EHEC O157:H7 in milk and raw beef. In fresh lettuce, treatment with SQ17 also resulted in significant reduction of viable cell counts of EHEC O157:H7 and ETEC at both 4°C and 25°C. Our results demonstrate that SQ17 is a good candidate for application as an EHEC O157:H7 and ETEC biocontrol agent in the processing stages of food production and food preservation.

Burden of whooping cough in China (PertussisChina): study protocol of a prospective, population-based case-control study.

INTRODUCTION: Pertussis is one of the top 10 diseases of children under 10 years of age, and the few vaccine-preventable diseases who is on a rise in China in recent years; however, the true burden of pertussis, including age-stratified incidence and risk factors of severe sequelae, are under-recognised. We aim to estimate the health burden of laboratory-confirmed pertussis by age groups, considering the setting of illness onset (ie, in community, outpatient and inpatient), in a Chinese population (~2.23 million in total) at two sites. METHODS AND ANALYSIS: This paper describes the study design of a 1-year, prospective, age-stratified and population-based case-control study, including site selection, study population, case registry, ascertainment and enrolment, control recruitment, follow-up of case, microbiological methods, data collection, quality control activities and statistical methods used to generate incidence estimates. During June 2021 through May 2022, registry of suspected pertussis cases (namely chronic/persistent cough) will be conducted in several participating hospitals (SHs) at the two sites, which are selected based on Healthcare Utilisation and Attitudes Surveys (HUAS) carried out before study initiation. A case-control study will be conducted in the SHs and we aim to enrol a total of 1000 suspected pertussis cases (ie, all hospital admissions and the first 1-3 outpatient visits each week each hospital) and 2000 frequency matched healthy controls in community. Our primary study outcome, the laboratory-confirmed Bordetella pertussis infection, will be determined by a comprehensive laboratory methods and procedures (ie, culture, PCR and serological tests) in both cases and controls at enrolment and during 60-day's follow-up visits. Finally, data from HUAS (ie, population size), case registry (ie, the total number of suspected pertussis cases) and case-control study (ie, the prevalence or population attributable fraction of Bordetella pertussis) will be combined to calculate incidence and its 95% CI through bootstrap method. Epidemiological analyses will be conducted to determine the risk factors associated with severe sequelae of pertussis. ETHICS AND DISSEMINATION: This study has been approved by Chinese Centre for Disease Control and Prevention's Institutional Review Board (no. ICDC-202110). Results will be disseminated via academic presentations and publication in peer-reviewed journals, and will provide valuable scientific data and some new insights into the incidence, aetiology and risk factors for severe sequelae of pertussis to academic societies and the public health authorities who is currently struggling and fighting against this burdensome disease worldwide.

A rapid performance evaluation approach for lower mobility hybrid robot based on gravity-center position.

This article develops a rapid performance evaluation approach for lower mobility hybrid robot, which provides guidance for manipulator evaluation, design, and optimization. First, a general position vector model of gravity center for the lower mobility hybrid robot in the whole workspace is constructed based on a general inverse kinematic model. A performance evaluation index based on gravity-center position is then proposed, where the coordinates pointing to the supporting direction are selected as the evaluation index of the robot performance. Furthermore, the credibility of the evaluation approach is verified from a 5-DOF hybrid robot (TriMule) by comparing with the condition number and the first natural frequency. Analysis results demonstrate that the evaluation index can not only reflect the performance spatial distribution in the whole workspace but also is sensitive to the performance difference caused by mass distribution. The proposed performance evaluation approach provides a new index for the rapid design and optimization of the cantilever robot.

The impact of universal live attenuated hepatitis A vaccines in Henan, China, 2005-2018.

OBJECTIVES: To analyze the effects of one dose of live attenuated hepatitis A vaccine in a developing country. METHODS: The reported cases of hepatitis A virus (HAV) infection from 2005 to 2018 in Henan province, China, were analyzed. Data of vaccinated children were assessed on the childhood immunization information management system. Questionnaire survey and blood sample collection were randomly conducted in six counties and districts of Henan province to analyze the prevalence of HAV lgG among the population aged 0-70 years. RESULTS: In 2008, Henan province began to expand its program on immunization, and children aged 18 months were given one dose of live attenuated hepatitis A vaccine (HepA-L). From 2005 to 2007, the HAV incidence remained steady at above 5000 cases per year and increased to 7489 in 2007. Since 2008, the HAV incidence decreased cumulatively from 4576 to 237 in 2018, indicating a 94.8% decrease, which was particularly pronounced among adolescents (98.2%). The proportion of hepatitis A cases in patients younger than 10 years continually decreased from 41.6% in 2012 to 3.8% in 2018. The reduction of reported cases older than 40 years was slower than that of children. In 2012, the proportion of hepatitis A cases older than 40 years was 27.6%, and continually increased to 69.2% (164/237) in 2018. The results of serological investigation showed that the 0-1.5-year age group had the lowest anti-HAV IgG prevalence (38.6%), which increased to 75.0% in the 4-6-year age group, covered by this immunization program. CONCLUSIONS: The data indicated a large decrease in HAV infections in Henan province from 2008 onward in response to the introduction of a planned immunization program of HepA-L.

Analysis on Genotype Distribution and Mutation of Major Hydroponic Region of Hepatitis B Virus in Henan Province.

To understand the genotype and the mutation of amino acid (aa) in the major hydrophilic region (MHR) of hepatitis B virus(HBV). The serum samples were collected from the surveillance of HBV among population in Henan in 2012. The S gene of HBV was amplified and sequenced. The acid amino sequences were analyzed with Mega6. 0 software. A total of 50 sequences of HBV S gene were contained, including 8 sequences of genotype B(16. 0%) and 42 sequences of genotype C (84. 0%). The main serotype of HBV among Henan population was adrq+ (84. 0%) . The mutation rate of T1261 was the highest (14. 0%). The overall prevalence of mutant strain of MHR was 24. 0% (12/50), and it was 37. 5% (3/8) for genotype B,21. 4% (9/42) for genotype C. HBV genotype C was predominant in Henan,followed by genotype B. The adrq+ serotype was predominant followed by adw2. The mutation of amino acid in,MHR of HBV was detected in this study. It is necessary to strengthen the surveillance for HBV mutation to provide accurate information during immunization process and HBIG therapy.

[Effects of Coastal Organic Pollution on Bacterioplankton Community in Sanmen Bay].

Coastal organic pollution has become a serious problem, thus it is imperative to assess the potential effects on the marine environment. The microbes are generally the first responders to environmental perturbation, which may serve as biological indicators for pollution levels. In this study, we collected surface seawater samples from Sanmen Bay and adjacent Yushan Reserve. Using an Illumina sequencing based analysis of bacterial 16S rRNA gene, we explored the effect of organic pollution on the bacterioplankton community compositions (BCCs). The results showed that the organic pollution (A) was 4.57±2.41 at Sanmen Bay, which was significantly higher (P<0.001) than that in Yushan Reserve (0.43±0.74). The bacterial diversity and community compositions differed significantly between the two locations. Specifically, the relative abundance of Actinobacteria, α-Proteobacteria, ß-Proteobacteria, SAR406 in Sanmen Bay was significantly higher than that in Yushan Reserve, while Bacteroidetes, Cyanobacteria, Planctomycetes exhibited an opposite change pattern. A multivariate regression tree analysis showed that the bacterial diversity was primarily affected by water pH, organic pollution and chlorophyll a levels, which respectively explained 27.7%, 15.6% and 6.7% variance in bacterial diversity. A redundancy analysis (RDA) revealed that the bacterioplankton community was significantly controlled by pH, salinity and organic pollution, which cumulatively explained 14.8% of the variation in BCCs. In addition, the geographic distance was significantly (P <0.001) correlated with BCCs, accounting for 4.42% variance, which suggested that the spatial distribution of bacterioplankton community was non-random. Moreover, this study screened 23 sensitive bacterial families, whose relative abundances were significantly associated the organic pollution. For a given bacterial family, the change pattern of relative abundance was consistent with its known function, thus holding the potential for indicating organic pollution levels. To conclude, this study showed that the increasing coastal organic pollution had altered BCCs, and enriched the relative abundances of potential pathogens. Furthermore, the sensitive bio-indicators were screened for evaluating the increasing organic pollution level.

[Sero-prevalence and associated risk factors on hepatitis C in Maqiao township, Henan province of China].

OBJECTIVE: To describe the prevalence and risk factors of hepatitis C virus (HCV) occurred in Henan province, at the end of 2011. METHODS: Five villages round Maqiao township, including 5187 residents, were selected for the study. Five-milliliter-blood was drawn from every one of the interviewee. Clinical data including age, gender and anti-HCV antibody was recorded. Patients with positive antibodies against HCV were tested for HCV RNA. RESULTS: A total number of 5187 people from five villages were studied, with age span from 1 to 97. The average age was 48 years and the sex ratio was 1:1.34. The anti-HCV result showed that the prevalence was 2.27%, with 1-9 age group the lowest (1.55%) and the ≥ 50 year-olds the highest (4.93%). Different villages seemed to have significant differences on the prevalence of HCV, with the highest as 8.68% and the lowest as 0.55%. Under risk factors analysis and distance-infection rates linear regression analysis, data showed that the prevalence might have correlated to the behavior of a certain family-run clinic. RESULTS: from multivariate analysis indicated that factors as intravenous dropping, intravenous injection and the use of surgery/endoscope were associated with the HCV infection in this village. CONCLUSION: Although the public health care system had been developed for more than ten years, iatrogenic infection was yet responsible for the infection of HCV patients in the rural areas of China that called for further attention paid to the system.

Characterization and function analysis of a Halo-alkaline-adaptable Trk K+ uptake system in Alkalimonas amylolytica strain N10.

By functional complementation of Escherichia coli mutants defective in potassium (K(+)) uptake, two genes that are required for K(+) uptake in halo-alkaliphilic Alkalimonas amylolytica strain N10 were cloned. These two genes, Aa-trkA (1337 bp) and Aa-trkH (1452 bp), were adjacent on the A. amylolytica N10 chromosome and transcribed in opposite directions. Complementation experiments revealed that Aa-TrkA and Aa-TrkH from A. amylolytica strain N10 restored the ability to grow at low K(+) concentration in E. coli DeltatrkA and DeltatrkG DeltatrkH strains, respectively. In addition, Aa-TrkAH supported the growth of an E. coli DeltasapD strain, indicating that the ATP-binding protein TrkE was dispensable for the Trk system of A. amylolytica strain N10. The net K(+) uptake was detected at different pH levels and the critical NaCl concentration indicated that Aa-TrkAH is an alkaline-adaptable and partially halo-adaptable K(+) transporter. Kinetics determined by heterogeneous K(+) transport experiments with an E. coli DeltatrkA strain revealed that Aa-TrkAH has an alkaline pH optimum close to 8.5 or higher. Site-directed mutagenesis of Aa-TrkH showed that Phe103 and Ser229 play certain key roles in K(+) selection and transportation. The molecular chaperones groES-groEL and tig promoted Aa-TrkH and Aa-TrkA overexpression in vitro.

Exploring membrane and cytoplasm proteomic responses of Alkalimonas amylolytica N10 to different external pHs with combination strategy of de novo peptide sequencing.

Identification of differentially proteomic responses to external pHs would pave an access for understanding of survival mechanisms of bacteria living at extreme pH environment. We cultured Alkalimonas amylolytica N10 (N10), a novel alkaliphilic bacterium found in Lake Chahannor, in media with three different pHs and extracted the correspondent membrane and cytoplasm proteins for proteomic analysis through 2-DE. The differential 2-DE spots corresponding to the altered pHs were delivered to MALDI TOF/TOF MS for protein identification. Since the genomic data of strain N10 was unavailable, we encountered a problem at low rate of protein identification with 18.1%. We employed, therefore, a combined strategy of de novo sequencing to analyze MS/MS signals generated from MALDI TOF/TOF MS. A significantly improved rate of protein identification was thus achieved at over than 70.0%. Furthermore, we extensively investigated the expression of these pH-dependent N10 genes using Western blot and real-time PCR. The conclusions drawn from immunoblot and mRNA measurements were mostly in agreement with the proteomic observations. We conducted the bioinformatic analysis to all the pH-dependent N10 proteins and found that some membrane proteins participated in iron transport were differentially expressed as external pH elevated and most of differential proteins with increased or bell-shape mode of pH-dependence were involved in bioenergetic process and metabolism of carbohydrates, fatty acid, amino acids, and nucleotides. Our data thus provide a functional profile of the pH-responsive proteins in alkaliphiles, leading to elucidation of alkaliphilic-adaptive mechanism.