Saccharomyces cerevisiae cells that display norovirus P induce both systemic and mucosal neutralizing antibodies

The human norovirus (HuNov) is the leading cause of acute gastroenteritis (AGE) worldwide. Mucosal secretory IgA (sIgA) in the gastrointestinal tract interrupts the interaction between host cells and HuNov, thus inhibiting viral infection. In this study, we constructed a recombinant Saccharomyces cerevisiae (S. cerevisiae) expressing the HuNov P protein (GII. 4) and evaluated its immunogenicity in mice after oral delivery. First, the recombinant S. cerevisiae (EBY100/pYD1-P) efficiently expressed P, as evidenced by western blotting and indirect fluorescent assay. Second, after oral administration, EBY100/pYD1-P, especially the high-dose group (5 × 109 clone formation units), elicited systemic and mucosal immune responses characterized by significant sera IgG, IgA, and mucosal sIgA. More importantly, these antibodies showed a substantial neutralization effect against P. Lastly, EBY100/pYD1-P induced significant P-specific IFN-γ-secreting T cells and IL4-secreting T cells. Collectively, the recombinant S. cerevisiae expressing HuNov P is a promising mucosal vaccine candidate against HuNov.

Interactions between human norovirus and intestinal microbiota/microbes: A scoping review

Human norovirus (HuNoV) is an important foodborne virus, which causes non-bacterial acute gastroenteritis and is associated with a high disease burden. Recently, researchers have focus on the interaction between HuNoV and intestinal microbiota/microbes and engaged in studies investigating the implications of this interaction on HuNoV infection. However, the interaction mechanism and the implication of this interaction on host remain obscure. Current scoping review aimed to systematically investigate the interaction between HuNoV and intestinal microbiota, as well as their implication on HuNoV or HuNoV related symptoms. We found that HuNoV could bind to intestinal microbes and affect the intestinal microbial composition, diversity, and microbial gene expression. In reverse, intestinal microbes could affect HuNoV infectivity, although demonstrating contradictory effects (i.e., promote or inhibit HuNoV replication). These contradictory effects existed among microbes, in part, could be attributed to the differences among microbes (histo-blood group antigens and/or other small molecule substances). Results of current scoping review could assist in the selection and isolation of potential microbial candidates to prevent and/or alleviate HuNoV related symptoms.

Virulence, antibiotic resistance phenotypes and molecular characterisation of Vibrio furnissii isolates from patients with diarrhoea

BACKGROUND

Vibrio furnissii is an emerging human pathogen closely related to V. fluvialis that causes acute gastroenteritis. V. furnissii infection has been reported to be rarer than V. fluvialis, but a multi-drug resistance plasmid has recently been discovered in V. furnissii.

METHODS

During daily monitoring at a general hospital in Beijing, China, seven V. furnissii strains were collected from patients aged over 14 years who presented with acute diarrhoea between April and October 2018. Genome analysis and comparison were performed for virulence and antimicrobial resistance genes, plasmids and transposon islands, together with phylogenetic analysis. Antimicrobial resistance to 19 antibiotics was investigated using the microbroth dilution method. Virulence phenotypes were investigated based on type VI secretion system (T6SS) expression and using a bacterial killing assay and a haemolysin assay.

RESULTS

Phylogenetic analysis based on single-nucleotide polymorphisms revealed a closer relationship between V. furnissii and V. fluvialis than between other Vibrio spp. The seven V. furnissii isolates were in different monophyletic clades in the phylogenetic tree, suggesting that the seven cases of gastroenteritis were independent. High resistance to cefazolin, tetracycline and streptomycin was found in the V. furnissii isolates at respective rates of 100.0%, 57.1% and 42.9%, and intermediate resistance to ampicillin/sulbactam and imipenem was observed at respective rates of 85.7% and 85.7%. Of the tested strains, VFBJ02 was resistant to both imipenem and meropenem, while VFBJ01, VFBJ02, VFBJ05 and VFBJ07 were multi-drug resistant. Transposon islands containing antibiotic resistance genes were found on the multi-drug resistance plasmid in VFBJ05. Such transposon islands also occurred in VFBJ07 but were located on the chromosome. The virulence-related genes T6SS, vfh, hupO, vfp and ilpA were widespread in V. furnissii. The results of the virulence phenotype assays demonstrated that our isolated V. furnissii strains encoded an activated T6SS and grew in large colonies with strong beta-haemolysis on blood agar.

CONCLUSION

This study showed that diarrhoea associated with V. furnissii occurred sporadically and was more common than expected in the summer in Beijing, China. The antibiotic resistance of V. furnissii has unique characteristics compared with that of V. fluvialis. Fluoroquinolones and third-generation cephalosporins, such as ceftazidime and doxycycline, were effective at treating V. furnissii infection. Continua laboratory-based surveillance is needed for the prevention and control of V. furnissii infection, especially the dissemination of the antibiotic resistance genes in this pathogen.

Human norovirus cultivation systems and their use in antiviral research

Human norovirus (HuNoV) is a major cause of acute gastroenteritis and foodborne diseases, affecting all age groups. Despite its clinical needs, no approved antiviral therapies are available. Since the discovery of HuNoV in 1972, studies on anti-norovirals, mechanism of HuNoV infection, viral inactivation, etc., have been hampered by the lack of a robust laboratory-based cultivation system for HuNoV. A recent breakthrough in the development of HuNoV cultivation systems has opened opportunities for researchers to investigate HuNoV biology in the context of de novo HuNoV infections. A tissue stem cell-derived human intestinal organoid/enteroid (HIO) culture system is one of those that supports HuNoV replication reproducibly and, to our knowledge, is most widely distributed to laboratories worldwide to study HuNoV and develop therapeutic strategies. This review summarizes recently developed HuNoV cultivation systems, including HIO, and their use in antiviral studies.

Effects of Salmonella Outer Membrane Vesicles on Intestinal Microbiota and Intestinal Barrier Function

Salmonella enterica is one of the most important zoonotic pathogens causing foodborne gastroenteritis worldwide. Outer membrane vesicles (OMVs) are lipid-bilayer vesicles produced by Gram-negative bacteria, which contain biologically active components. We hypothesized that OMVs are an important weapon of S. enterica to initiate enteric diseases pathologies. In this study, the effects of S. enterica OMVs (SeOMVs) on intestinal microbiota and intestinal barrier function were investigated. In vitro fecal culture experiments showed that alpha diversity indexes and microbiota composition were altered by SeOMV supplementation. SeOMV supplementation showed an increase of pH, a decrease of OD630 and total short chain fatty acid (SCFA) concentrations. In vitro IPEC-J2 cells culture experiments showed that SeOMV supplementation did not affect the IPEC-J2 cell viability and the indicated genes expression. In vivo experiments in mice showed that SeOMVs had adverse effects on average daily gain (p < 0.05) and feed:gain ratio (p < 0.05), and had a tendency to decrease the final body weight (p = 0.073) in mice. SeOMV administration decreased serum interleukin-10 level (p < 0.05), decreased the relative abundance of bacteria belonging to the genera BacC-u-018 and Akkermansia (p < 0.05). Furthermore, SeOMV administration damaged the ileum mucosa (p < 0.05). These findings suggest that SeOMVs play an important role in the activation of intestinal inflammatory response induced by S. enterica, and downregulation of SCFA-producing bacteria is a possible mechanism.

Current trends and new approaches for human norovirus replication in cell culture: a literature review

Human norovirus (HuNoV) is one of the world's leading causes of acute gastroenteritis. At present, effective reproduction of the virus in cell cultures remains a challenge for virologists, as there is a lack of a permissive cell line that allows the entire viral life cycle to be reproduced. This is a barrier to the study of the HuNoV life cycle, its tropism, and virus-host interactions. It is also a major hurdle for the development of viral detection platforms, and ultimately for the development of therapeutics. The lack of an inexpensive, technically simple, and easily implemented cultivation method also negatively affects our ability to evaluate the efficacy of a variety of control measures (disinfectants, food processes) for human norovirus. In the process of monitoring this pathogen, it is necessary to detect infectious viral particles in water, food, and other environmental samples. Therefore, improvement of in vitro replication of HuNoV is still needed. In this review, we discuss current trends and new approaches to HuNoV replication in cell culture. We highlight ways in which previous research on HuNoV and other noroviruses has guided and influenced the development of new HuNoV culture systems and discuss the improvement of in vitro replication of HuNoV.

A systematic review and meta-analysis indicates a high risk of human noroviruses contamination in vegetable worldwide, with GI being the predominant genogroup

Human noroviruses (HuNoVs) are the most predominant viral agents of acute gastroenteritis. Vegetables are important vehicles of HuNoVs transmission. This study aimed to assess the HuNoVs prevalence in vegetables. We searched the Web of Science, Excerpta Medica Database, PubMed, and Cochrane databases until June 1, 2023. A total of 27 studies were included for the meta-analysis. Statistical analysis was conducted using Stata 14.0 software. This analysis showed that the pooled HuNoVs prevalence in vegetables was 7 % (95 % confidence interval (CI): 3-13) worldwide. The continent with largest number of studies was Europe, and the highest number of samples was lettuce. As revealed by the results of the subgroup meta-analysis, the prevalence of GI genogroup was the highest (3 %, 95 % CI: 1-7). A higher prevalence was seen in vegetables from farms (18 %, 95 % CI: 5-37), while only 4 % (95 % CI: 1-8) in retail. The HuNoVs prevalence of ready-to-eat vegetables and non-ready-to-eat vegetables was 2 % (95 % CI: 0-8) and 9 % (95 % CI: 3-16), respectively. The prevalence by quantitative real time RT-PCR was 8 % (95 % CI: 3-15) compared to 3 % (95 % CI: 0-13) by conventional RT-PCR. Furthermore, the HuNoVs prevalence in vegetables was 6 % (95 % CI: 1-14) in ISO pretreatment method and 8 % (95 % CI: 1-19) in non-ISO method, respectively. This study is helpful in comprehensively understanding the prevalence of HuNoVs contamination in vegetables worldwide.

Physician-directed microbiological testing versus syndromic multiplex PCR in gastroenteritis

INTRODUCTION

Syndromic multiplex PCR testing is an alternative to conventional stool testing based on physician-directed request forms. The objective of this study was to compare the etiologic yield of conventional microbiological testing based on physician-directed request forms with that of rapid syndromic testing. In addition, the adequacy of the clinician ordering, which is an important piece of the diagnostic stewardship, was evaluated.

MATERIALS AND METHODS

Physician-directed conventional microbiological testing and extensive molecular syndromic testing with the Fast Track Diagnostics Gastroenteritis Kit were performed in parallel on 1238 samples to evaluate the contribution of a multiplex panel to the diagnostic process of gastroenteritis.

RESULTS

A potential causative pathogen was identified in 18.4% of stool samples by standard microbiological testing and in 41.3% of stool samples tested using the syndromic panel. Only 15.1% of the request forms could be considered successful of which 88.2% were labeled inadequate. Conventional physician-directed based testing missed the etiologic diagnosis in 32.3% of the specimens (excluding sapovirus and astrovirus). Bacterial infections were theoretically not missed as bacterial stool culture was requested on all stool samples, but in 28.6% of the cases, no isolate could be recovered. In 36.9% of the samples testing positive for a viral pathogen, no viral testing was requested. In addition, 72.5% of all samples positive for a parasite were clinically suspected by the physician.

CONCLUSION

This study suggests that syndromic multiplex PCR assays are a better strategy for pathogen detection in patients with gastroenteritis than physician-directed laboratory testing based on the clinical presentation.

Genomic analysis of clinical Aeromonas isolates reveals genetic diversity but little evidence of genetic determinants for diarrhoeal disease

Aeromonas spp. are associated with a number of infectious syndromes in humans including gastroenteritis and dysentery. Our understanding of the genetic diversity, population structure, virulence determinants and antimicrobial resistance of the genus has been limited by a lack of sequenced genomes linked to metadata. We performed a comprehensive analysis of the whole genome sequences of 447 Aeromonas isolates from children in Karachi, Pakistan, with moderate-to-severe diarrhoea (MSD) and from matched controls without diarrhoea that were collected as part of the Global Enteric Multicenter Study (GEMS). Human-associated Aeromonas isolates exhibited high species diversity and extensive antimicrobial and virulence gene content. Aeromonas caviae, A. dhankensis, A. veronii and A. enteropelogenes were all significantly associated with MSD in at least one cohort group. The maf2 and lafT genes that encode components of polar and lateral flagella, respectively, exhibited a weak association with isolates originating from cases of gastroenteritis.

Retention of Virus Versus Surrogate, by Ultrafiltration in Seawater: Case Study of Norovirus Versus Tulane

In the field of chemical engineering and water treatment, the study of viruses, included surrogates, is well documented. Often, surrogates are used to study viruses and their behavior because they can be produced in larger quantities in safer conditions and are easier to handle. In fact, surrogates allow studying microorganisms which are non-infectious to humans but share some properties similar to pathogenic viruses: structure, composition, morphology, and size. Human noroviruses, recognized as the leading cause of epidemics and sporadic cases of gastroenteritis across all age groups, may be mimicked by the Tulane virus. The objectives of this work were to study (i) the ultrafiltration of Tulane virus and norovirus to validate that Tulane virus can be used as a surrogate for norovirus in water treatment process and (ii) the retention of norovirus and the surrogate as a function of water quality to better understand the use of the latter pathogenic viruses. Ultrafiltration tests showed significant logarithmic reduction values (LRV) in viral RNA: around 2.5 for global LRV (i.e., based on the initial and permeate average concentrations) and between 2 and 6 for average LRV (i.e., retention rate considering the increase of viral concentration in the retentate), both for norovirus and the surrogate Tulane virus. Higher reduction rates (from 2 to 6 log genome copies) are obtained for higher initial concentrations (from 101 to 107 genome copies per mL) due to virus aggregation in membrane lumen. Tulane virus appears to be a good surrogate for norovirus retention by membrane processes.

Detection of Rotavirus in Respiratory Specimens From Bangladeshi Children Aged <2 Years Hospitalized for Acute Gastroenteritis

To examine the potential for respiratory transmission of rotavirus, we systematically assessed if rotavirus RNA is detectable by real-time quantitative reverse transcription-polymerase chain reaction from nasal and oropharyngeal swab specimens of Bangladeshi children with acute rotavirus gastroenteritis. Forehead swabs were collected to assess skin contamination. Among 399 children aged <2 years hospitalized for gastroenteritis during peak rotavirus season, rotavirus RNA was detected in stool, oral, nasal and forehead swab specimens of 354 (89%). A subset was genotyped; genotype was concordant within a child's specimen set and several different genotypes were detected across children. These findings support possible respiratory transmission of rotavirus and warrant further investigation.

Etiologies of Mild and Moderate Diarrheal Illness among Children in Consuelo, Dominican Republic

Since the rotavirus vaccine was included in the Dominican Republic's national immunization schedule in 2012, the microbiologic etiologies of acute gastroenteritis have not been described. This study aimed to determine the contribution of rotavirus as an etiology of acute gastroenteritis over a 12-month period in children under 5 years of age in both an inpatient and an outpatient setting in Consuelo, Dominican Republic. All children who were seen at Niños Primeros en Salud clinic or admitted to Hospital Municipal Dr. Angel Ponce Pinedo for acute gastroenteritis during January 2021-April 2022 were enrolled in the study. Stools were evaluated for rotavirus, enteric parasites, and pathogenic bacteria. Pathogen detection was compared between outpatients and inpatients and on the basis of child's vaccination status. From 181 children enrolled, 170 stool samples were collected, 28 (16.5%) from inpatients and 142 (83.5%) from outpatients. Rotavirus was the most commonly detected pathogen and was proportionately more common among hospitalized children, with nine (32.1%) cases among hospitalized children and 16 (11.3%) among outpatient children. (Pearson χ2 = 8.1, P = 0.004). Among patients with a positive rotavirus result, vaccination rate was lower among moderate (hospitalized) (three of six; 50%) compared with mild (outpatient) diarrhea patients (12 of 15; 80%). Giardia lamblia (10%) was the next most prevalent pathogen detected in both inpatients and outpatients using standard laboratory measures. Despite the availability of rotavirus vaccination, rotavirus remains a common cause of gastrointestinal illness among children under 5 years of age in our cohort. Incomplete vaccination status was associated with hospitalization for gastrointestinal illness.

Campylobacter species and genotype distribution in Finnish beef liver - Retail liver juice ideal for isolation and quantification

Campylobacteriosis, primarily caused by Campylobacter jejuni and C. coli, is the main bacterial zoonosis worldwide. While poultry is recognized as the main reservoir, bovines are considered another important reservoir for Campylobacter spp. found in human infections. In contrast to chicken, retail beef is seldom contaminated by Campylobacter species. However, beef liver is recognized to be frequently contaminated and has been linked to human infections via epidemiological investigations. Our aims were to evaluate the prevalence of Campylobacter spp. inside and on the surface of beef liver pieces at retail in Finland and to analyse the population in more detail using whole genome sequencing (WGS) to assess the public health relevance. A total of 90 retail beef livers were studied using both enrichment of the external peptone-saline rinse of the liver piece and direct culture from the inside after surface sterilization. Furthermore, 46 of the livers were also studied using direct culture of retail beef liver juice collected from the bottom of the consumer package to estimate the concentration of Campylobacter species. Overall, 44 (49 %) of the samples were positive for Campylobacter species, C. jejuni, C. fetus and C. lari being identified in 42 %, 8.9 % and 1.1 % of the samples, respectively. Direct culture of retail liver juice was a sensitive and convenient method for Campylobacter spp. detection, resulting in 48 % prevalence and a mean concentration of 49 cfu/ml (maximum 335 cfu/ml). Two samples (2.2 %), containing large hepatic ducts, were positive for C. jejuni internally, representing multilocus sequence typing (MLST) sequence type ST-19 and ST-21. WGS, core genome phylogeny and core genome MLST revealed that in most cases only one clearly distinct clone of clinically relevant C. jejuni or C. fetus was isolated from a single lot of samples. However, in some cases several distinct clones were identified simultaneously even from a single liver piece. In epidemiological investigations, it is thus highly advisable to genotype multiple isolates to capture the whole diversity of Campylobacter spp. from suspected food sources. Good kitchen hygiene, avoidance of cross-contamination and thorough cooking are important for limiting the transmission of campylobacteriosis.

Aerosol Transmission of Norovirus

Norovirus (NoV) is a major cause of acute gastroenteritis outbreaks worldwide. A comprehensive understanding of the transmission mode is of great significance for the prevention and control of the NoV infection. Currently, the transmission modes of NoV include contact, food-borne, water-borne and aerosol transmission. The first three modes are more common, while aerosol transmission is seldom reported. In this paper, the source, generation mechanism, infectivity, sampling and related outbreaks of NoV aerosol are summarized and discussed.

Molecular Signature of Monocytes Shaped by the Shigella sonnei 1790-Generalized Modules for Membrane Antigens Vaccine

Shigellosis, an acute gastroenteritis infection caused by Shigella species, remains a public health burden in developing countries. Recently, many outbreaks due to Shigella sonnei multidrug-resistant strains have been reported in high-income countries, and the lack of an effective vaccine represents a major hurdle to counteract this bacterial pathogen. Vaccine candidates against Shigella sonnei are under clinical development, including a Generalized Modules for Membrane Antigens (GMMA)-based vaccine. The mechanisms by which GMMA-based vaccines interact and activate human immune cells remain elusive. Our previous study provided the first evidence that both adaptive and innate immune cells are targeted and functionally shaped by the GMMA-based vaccine. Here, flow cytometry and confocal microscopy analysis allowed us to identify monocytes as the main target population interacting with the S. sonnei 1790-GMMA vaccine on human peripheral blood. In addition, transcriptomic analysis of this cell population revealed a molecular signature induced by 1790-GMMA mostly correlated with the inflammatory response and cytokine-induced processes. This also impacts the expression of genes associated with macrophages' differentiation and T cell regulation, suggesting a dual function for this vaccine platform both as an antigen carrier and as a regulator of immune cell activation and differentiation.

The effect of changing diagnostic method from culture to PCR on the number of episodes of human campylobacteriosis in Denmark: a retrospective study (2015-2022)

IMPORTANCE

This study is important because it shows the potential epidemiological silence associated with the use of culture as the primary diagnostic method for the laboratory identification of human campylobacteriosis. Also, we show how polymerase chain reaction methods are associated with a systematic increase in the number of human campylobacteriosis episodes as reported by routine disease surveillance. These findings are operationally relevant and have public health implications because they tell how crucial it is to consider changes in diagnostic methods, e.g., in the epidemiological analysis of historical data and in the interpretation of future data in light of the past. We also believe that this study highlights how the synergy between microbiology and epidemiology is essential for disease surveillance.

End-point rapid detection of total and pathogenic Vibrio parahaemolyticus (tdh+ and/or trh1+ and/or trh2+) in raw seafood using a colorimetric loop-mediated isothermal amplification-xylenol orange technique

Background

Vibrio parahaemolyticus is the leading cause of bacterial seafood-borne gastroenteritis in humans worldwide. To ensure seafood safety and to minimize the occurrence of seafood-borne diseases, early detection of total V. parahaemolyticus (pathogenic and non-pathogenic strains) and pathogenic V. parahaemolyticus (tdh+ and/or trh1+ and/or trh2+) is required. This study further improved a loop-mediated isothermal amplification (LAMP) assay using xylenol orange (XO), a pH sensitive dye, to transform conventional LAMP into a one-step colorimetric assay giving visible results to the naked eye. LAMP-XO targeted rpoD for species specificity and tdh, trh1, and trh2 for pathogenic strains. Multiple hybrid inner primers (MHP) of LAMP primers for rpoD detection to complement the main primer set previously reported were designed by our group to maximize sensitivity and speed.

Methods

Following the standard LAMP protocol, LAMP reaction temperature for rpoD, tdh, trh1, and trh2 detection was first determined using a turbidimeter. The acquired optimal temperature was subjected to optimize six parameters including dNTP mix, betaine, MgSO4, Bst 2.0 WarmStart DNA polymerase, reaction time and XO dye. The last parameter was done using a heat block. The color change of the LAMP-XO result from purple (negative) to yellow (positive) was monitored visually. The detection limits (DLs) of LAMP-XO using a 10-fold serial dilution of gDNA and spiked seafood samples were determined and compared with standard LAMP, PCR, and quantitative PCR (qPCR) assays. Subsequently, the LAMP-XO assay was validated with 102 raw seafood samples and the results were compared with PCR and qPCR assays.

Results

Under optimal conditions (65 °C for 75 min), rpoD-LAMP-XO and tdh-LAMP-XO showed detection sensitivity at 102 copies of gDNA/reaction, or 10 folds greater than trh1-LAMP-XO and trh2-LAMP-XO. This level of sensitivity was similar to that of standard LAMP, comparable to that of the gold standard qPCR, and 10-100 times higher than that of PCR. In spiked samples, rpoD-LAMP-XO, tdh-LAMP-XO, and trh2-LAMP-XO could detect V. parahaemolyticus at 1 CFU/2.5 g spiked shrimp. Of 102 seafood samples, LAMP-XO was significantly more sensitive than PCR (P < 0.05) for tdh and trh2 detection and not significantly different from qPCR for all genes determined. The reliability of tdh-LAMP-XO and trh2-LAMP-XO to detect pathogenic V. parahaemolyticus was at 94.4% and 100%, respectively.

Conclusions

To detect total and pathogenic V. parahaemolyticus, at least rpoD-LAMP-XO and trh2-LAMP-XO should be used, as both showed 100% sensitivity, specificity, and accuracy. With short turnaround time, ease, and reliability, LAMP-XO serves as a better alternative to PCR and qPCR for routine detection of V. parahaemolyticus in seafood. The concept of using a one-step LAMP-XO and MHP-LAMP to enhance efficiency of diagnostic performance of LAMP-based assays can be generally applied for detecting any gene of interest.

Effective Approaches to Diagnostic Stewardship of Syndromic Molecular Panels

BACKGROUND

Syndromic molecular panels for the diagnosis of gastroenteritis, meningitis/encephalitis, and pneumonia are becoming routinely used for patient care throughout the world.

CONTENT

These rapid, sample-to-answer assays have great potential to improve patient care, infection control, and antimicrobial stewardship. However, diagnostic stewardship is essential for their optimal use and accuracy, and interventions can be applied at all phases of the diagnostic process.

SUMMARY

The aim of this review article is to describe effective approaches to diagnostic stewardship for syndromic molecular panels to ensure appropriate test utilization and quality assured results.

Recovery of Recombinant Rotaviruses by Reverse Genetics

Rotaviruses are the primary cause of severe gastroenteritis in infants and young children throughout the world. To combat rotavirus illness, several live oral vaccines have been developed, or are under development, that are formulated from attenuated human or human-animal reassortant strains of rotavirus. While the effectiveness of these vaccines is generally high in developed countries, the same vaccines are significantly less effective in many developing countries, where the need for rotavirus vaccines is greatest. Recently, reverse genetics systems have been developed that allow modification of the segmented double-stranded (ds)RNA genome of rotavirus, including reprogramming the genome to allow expression of additional proteins that may stimulate expanded neutralizing antibody responses in vaccinated children. The use of reverse genetics systems may not only lead to the development of more potent classes of vaccines but can be used to better explore the intricacies of rotavirus molecular biology and pathogenesis. In this article, we share protocols that can be used to generate recombinant rotaviruses, including modified strains that express foreign proteins.

Vosoritide therapy in children with achondroplasia aged 3-59 months: a multinational, randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Vosoritide is a recombinant C-type natriuretic peptide analogue that increases annualised growth velocity in children with achondroplasia aged 5-18 years. We aimed to assess the safety and efficacy of vosoritide in infants and children younger than 5 years.

METHODS

This double-blind, randomised, placebo-controlled, phase 2 trial was done in 16 hospitals across Australia, Japan, the UK, and the USA. Children younger than 60 months with a clinical diagnosis of achondroplasia confirmed by genetic testing and who had completed a baseline growth study or observation period were enrolled into one of three sequential cohorts based on age at screening: 24-59 months (cohort 1); 6-23 months (cohort 2); and 0-5 months (cohort 3). Each cohort included sentinels who received vosoritide to determine appropriate daily drug dose, with the remainder randomly assigned (1:1) within each age stratum (except in Japan, where participants were randomly assigned within each cohort) to receive daily subcutaneous injections of vosoritide (30·0 μg/kg for infants aged 0-23 months; 15·0 μg/kg for children aged 24-59 months) or placebo for 52 weeks. Participants, caregivers, investigators, and the sponsor were masked to treatment assignment. The first primary outcome was safety and tolerability, assessed in all participants who received at least one study dose. The second primary outcome was change in height Z score at 52 weeks from baseline, analysed in all randomly assigned participants. This trial is registered with EudraCT, 2016-003826-18, and ClinicalTrials.gov, NCT03583697.

FINDINGS

Between May 13, 2018, and March 1, 2021, 75 participants were recruited (37 [49%] females). 11 were assigned as sentinels, whereas 32 were randomly assigned to receive vosoritide and 32 placebo. Two participants discontinued treatment and the study: one in the vosoritide group (death) and one in the placebo group (withdrawal). Adverse events occurred in all 75 (100%) participants (annual rate 204·5 adverse events per patient in the vosoritide group and 73·6 per patient in the placebo group), most of which were transient injection-site reactions and injection-site erythema. Serious adverse events occurred in three (7%) participants in the vosoritide group (decreased oxygen saturation, respiratory syncytial virus bronchiolitis and sudden infant death syndrome, and pneumonia) and six (19%) participants in the placebo group (petit mal epilepsy, autism, gastroenteritis, vomiting and parainfluenza virus infection, respiratory distress, and skull fracture and otitis media). The least-squares mean difference for change from baseline in height Z score between the vosoritide and placebo groups was 0·25 (95% CI -0·02 to 0·53).

INTERPRETATION

Children with achondroplasia aged 3-59 months receiving vosoritide for 52 weeks had a mild adverse event profile and gain in the change in height Z score from baseline.

FUNDING

BioMarin Pharmaceutical.

Genomic and clinical characteristics of campylobacteriosis in Australia

Campylobacter spp. are a common cause of bacterial gastroenteritis in Australia, primarily acquired from contaminated meat. We investigated the relationship between genomic virulence characteristics and the severity of campylobacteriosis, hospitalisation, and other host factors.We recruited 571 campylobacteriosis cases from three Australian states and territories (2018-2019). We collected demographic, health status, risk factors, and self-reported disease data. We whole genome sequenced 422 C. jejuni and 84 C. coli case isolates along with 616 retail meat isolates. We classified case illness severity using a modified Vesikari scoring system, performed phylogenomic analysis, and explored risk factors for hospitalisation and illness severity.On average, cases experienced a 7.5 day diarrhoeal illness with additional symptoms including stomach cramps (87.1 %), fever (75.6 %), and nausea (72.0 %). Cases aged ≥75 years had milder symptoms, lower Vesikari scores, and higher odds of hospitalisation compared to younger cases. Chronic gastrointestinal illnesses also increased odds of hospitalisation. We observed significant diversity among isolates, with 65 C. jejuni and 21 C. coli sequence types. Antimicrobial resistance genes were detected in 20.4 % of isolates, but multidrug resistance was rare (0.04 %). Key virulence genes such as cdtABC (C. jejuni) and cadF were prevalent (>90 % presence) but did not correlate with disease severity or hospitalisation. However, certain genes (e.g. fliK, Cj1136, and Cj1138) appeared to distinguish human C. jejuni cases from food source isolates.Campylobacteriosis generally presents similarly across cases, though some are more severe. Genotypic virulence factors identified in the literature to-date do not predict disease severity but may differentiate human C. jejuni cases from food source isolates. Host factors like age and comorbidities have a greater influence on health outcomes than virulence factors.

Cytolethal distending toxin B inoculation leads to distinct gut microtypes and IBS-D-like microRNA-mediated gene expression changes in a rodent model

Diarrhea-predominant irritable bowel syndrome (IBS-D), associated with increased intestinal permeability, inflammation, and small intestinal bacterial overgrowth, can be triggered by acute gastroenteritis. Cytolethal distending toxin B (CdtB) is produced by gastroenteritis-causing pathogens and may underlie IBS-D development, through molecular mimicry with vinculin. Here, we examine the effects of exposure to CdtB alone on gut microbiome composition, host intestinal gene expression, and IBS-D-like phenotypes in a rat model. CdtB-inoculated rats exhibited increased anti-CdtB levels, which correlated with increased stool wet weights, pro-inflammatory cytokines (TNFα, IL2) and predicted microbial metabolic pathways including inflammatory responses, TNF responses, and diarrhea. Three distinct ileal microbiome profiles (microtypes) were identified in CdtB-inoculated rats. The first microtype (most like controls) had altered relative abundance (RA) of genera Bifidobacterium, Lactococcus, and Rothia. The second had lower microbial diversity, higher Escherichia-Shigella RA, higher absolute E. coli abundance, and altered host ileal tissue expression of immune-response and TNF-response genes compared to controls. The third microtype had higher microbial diversity, higher RA of hydrogen sulfide (H2S)-producer Desulfovibrio, and increased expression of H2S-associated pain/serotonin response genes. All CdtB-inoculated rats exhibited decreased ileal expression of cell junction component mRNAs, including vinculin-associated proteins. Significantly, cluster-specific microRNA-mRNA interactions controlling intestinal permeability, visceral hypersensitivity/pain, and gastrointestinal motility genes, including several previously associated with IBS were seen. These findings demonstrate that exposure to CdtB toxin alone results in IBS-like phenotypes including inflammation and diarrhea-like stool, decreased expression of intestinal barrier components, and altered ileal microtypes that influenced changes in microRNA-modulated gene expression and predicted metabolic pathways consistent with specific IBS-D symptoms.

A mathematical, classical stratification modeling approach to disentangling the impact of weather on infectious diseases: A case study using spatio-temporally disaggregated Campylobacter surveillance data for England and Wales

Disentangling the impact of the weather on transmission of infectious diseases is crucial for health protection, preparedness and prevention. Because weather factors are co-incidental and partly correlated, we have used geography to separate out the impact of individual weather parameters on other seasonal variables using campylobacteriosis as a case study. Campylobacter infections are found worldwide and are the most common bacterial food-borne disease in developed countries, where they exhibit consistent but country specific seasonality. We developed a novel conditional incidence method, based on classical stratification, exploiting the long term, high-resolution, linkage of approximately one-million campylobacteriosis cases over 20 years in England and Wales with local meteorological datasets from diagnostic laboratory locations. The predicted incidence of campylobacteriosis increased by 1 case per million people for every 5° (Celsius) increase in temperature within the range of 8°-15°. Limited association was observed outside that range. There were strong associations with day-length. Cases tended to increase with relative humidity in the region of 75-80%, while the associations with rainfall and wind-speed were weaker. The approach is able to examine multiple factors and model how complex trends arise, e.g. the consistent steep increase in campylobacteriosis in England and Wales in May-June and its spatial variability. This transparent and straightforward approach leads to accurate predictions without relying on regression models and/or postulating specific parameterisations. A key output of the analysis is a thoroughly phenomenological description of the incidence of the disease conditional on specific local weather factors. The study can be crucially important to infer the elusive mechanism of transmission of campylobacteriosis; for instance, by simulating the conditional incidence for a postulated mechanism and compare it with the phenomenological patterns as benchmark. The findings challenge the assumption, commonly made in statistical models, that the transformed mean rate of infection for diseases like campylobacteriosis is a mere additive and combination of the environmental variables.

Nonsecretor Phenotype Is Associated With Less Risk of Rotavirus-Associated Acute Gastroenteritis in a Vaccinated Nicaraguan Birth Cohort

BACKGROUND

Histo-blood group antigens (HBGAs) have been associated with rotavirus vaccine take; but the effect of these HBGAs on rotavirus incidence and risk remains poorly explored in vaccinated populations.

METHODS

Rotavirus-associated acute gastroenteritis (AGE) was assessed in 444 Nicaraguan children followed from birth until 3 years of age. AGE episodes were tested for rotavirus by reverse-transcription quantitative polymerase chain reaction, and saliva or blood was used to determine HBGA phenotypes. Cox proportional hazards models were used to estimate the relative hazard of rotavirus AGE by HBGA phenotypes.

RESULTS

Rotavirus was detected in 109 (7%) stool samples from 1689 AGE episodes over 36 months of observation between June 2017 and July 2021. Forty-six samples were successfully genotyped. Of these, 15 (35%) were rotavirus vaccine strain G1P[8], followed by G8P[8] or G8P[nt] (11 [24%]) and equine-like G3P[8] (11 [24%]). The overall incidence of rotavirus-associated AGE was 9.2 per 100 child-years, and was significantly higher in secretor than nonsecretor children (9.8 vs 3.5/100 child-years, P = .002).

CONCLUSIONS

The nonsecretor phenotype was associated with decreased risk of clinical rotavirus vaccine failure in a vaccinated Nicaraguan birth cohort. These results show the importance of secretor status on rotavirus risk, even in vaccinated children.

Rotavirus-mediated DGAT1 degradation: A pathophysiological mechanism of viral-induced malabsorptive diarrhea

Gastroenteritis is among the leading causes of mortality globally in infants and young children, with rotavirus (RV) causing ~258 million episodes of diarrhea and ~128,000 deaths annually in infants and children. RV-induced mechanisms that result in diarrhea are not completely understood, but malabsorption is a contributing factor. RV alters cellular lipid metabolism by inducing lipid droplet (LD) formation as a platform for replication factories named viroplasms. A link between LD formation and gastroenteritis has not been identified. We found that diacylglycerol O-acyltransferase 1 (DGAT1), the terminal step in triacylglycerol synthesis required for LD biogenesis, is degraded in RV-infected cells by a proteasome-mediated mechanism. RV-infected DGAT1-silenced cells show earlier and increased numbers of LD-associated viroplasms per cell that translate into a fourfold-to-fivefold increase in viral yield (P < 0.05). Interestingly, DGAT1 deficiency in children is associated with diarrhea due to altered trafficking of key ion transporters to the apical brush border of enterocytes. Confocal microscopy and immunoblot analyses of RV-infected cells and DGAT1-/- human intestinal enteroids (HIEs) show a decrease in expression of nutrient transporters, ion transporters, tight junctional proteins, and cytoskeletal proteins. Increased phospho-eIF2α (eukaryotic initiation factor 2 alpha) in DGAT1-/- HIEs, and RV-infected cells, indicates a mechanism for malabsorptive diarrhea, namely inhibition of translation of cellular proteins critical for nutrient digestion and intestinal absorption. Our study elucidates a pathophysiological mechanism of RV-induced DGAT1 deficiency by protein degradation that mediates malabsorptive diarrhea, as well as a role for lipid metabolism, in the pathogenesis of gastroenteritis.

The impact of COVID-19 pandemic on the incidence of acute gastroenteritis outbreaks in Catalonia (Spain)

We carried out a retrospective study of acute gastroenteritis (AGE) outbreaks reported between 1 January 2015 and 31 December 2021 in Catalonia (Spain) to compare the incidence from 2015 to 2019 with that observed from 2020 to 2021. We observed a higher incidence rate of outbreaks during the prepandemic period (16.89 outbreaks/1,000,000 person-years) than during the pandemic period (6.96 outbreaks/1,000,000 person-years) (rate ratio (RR) 0.41; 95% confidence interval (CI) 0.34 to 0.51). According to the aetiology of the outbreak, those of viral aetiology decreased from 7.82 to 3.38 outbreaks/1,000,000 person-years (RR 2.31; 95% CI 1.72 to 3.12), and those of bacterial aetiology decreased from 5.01 to 2.78 outbreaks/1,000,000 person-years (RR 1.80; 95% CI 1.29 to 2.52). There was a great reduction in AGE outbreaks in Catalonia. This reduction may have been due to the effect of the nonpharmaceutical measures applied to reduce the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the collapse of the healthcare system and epidemiological surveillance services may also have had a strong influence.

Culture of Human Rotaviruses in Relevant Models Shows Differences in Culture-Adapted and Nonculture-Adapted Strains

Rotavirus (RV) is the leading cause of acute gastroenteritis (AGE) in children under 5 years old worldwide, and several studies have demonstrated that histo-blood group antigens (HBGAs) play a role in its infection process. In the present study, human stool filtrates from patients diagnosed with RV diarrhea (genotyped as P[8]) were used to infect differentiated Caco-2 cells (dCaco-2) to determine whether such viral strains of clinical origin had the ability to replicate in cell cultures displaying HBGAs. The cell culture-adapted human RV Wa model strain (P[8] genotype) was used as a control. A time-course analysis of infection was conducted in dCaco-2 at 1, 24, 48, 72, and 96 h. The replication of two selected clinical isolates and Wa was further assayed in MA104, undifferentiated Caco-2 (uCaco-2), HT29, and HT29-M6 cells, as well as in monolayers of differentiated human intestinal enteroids (HIEs). The results showed that the culture-adapted Wa strain replicated more efficiently in MA104 cells than other utilized cell types. In contrast, clinical virus isolates replicated more efficiently in dCaco-2 cells and HIEs. Furthermore, through surface plasmon resonance analysis of the interaction between the RV spike protein (VP8*) and its glycan receptor (the H antigen), the V7 RV clinical isolate showed 45 times better affinity compared to VP8* from the Wa strain. These findings support the hypothesis that the differences in virus tropism between clinical virus isolates and RV Wa could be a consequence of the different HBGA contents on the surface of the cell lines employed. dCaco-2, HT29, and HT29M6 cells and HIEs display HBGAs on their surfaces, whereas MA104 and uCaco-2 cells do not. These results indicate the relevance of using non-cell culture-adapted human RV to investigate the replication of rotavirus in relevant infection models.

Source attribution of campylobacteriosis in Australia, 2017-2019

Campylobacter jejuni and Campylobacter coli infections are the leading cause of foodborne gastroenteritis in high-income countries. Campylobacter colonizes a variety of warm-blooded hosts that are reservoirs for human campylobacteriosis. The proportions of Australian cases attributable to different animal reservoirs are unknown but can be estimated by comparing the frequency of different sequence types in cases and reservoirs. Campylobacter isolates were obtained from notified human cases and raw meat and offal from the major livestock in Australia between 2017 and 2019. Isolates were typed using multi-locus sequence genotyping. We used Bayesian source attribution models including the asymmetric island model, the modified Hald model, and their generalizations. Some models included an "unsampled" source to estimate the proportion of cases attributable to wild, feral, or domestic animal reservoirs not sampled in our study. Model fits were compared using the Watanabe-Akaike information criterion. We included 612 food and 710 human case isolates. The best fitting models attributed >80% of Campylobacter cases to chickens, with a greater proportion of C. coli (>84%) than C. jejuni (>77%). The best fitting model that included an unsampled source attributed 14% (95% credible interval [CrI]: 0.3%-32%) to the unsampled source and only 2% to ruminants (95% CrI: 0.3%-12%) and 2% to pigs (95% CrI: 0.2%-11%) The best fitting model that did not include an unsampled source attributed 12% to ruminants (95% CrI: 1.3%-33%) and 6% to pigs (95% CrI: 1.1%-19%). Chickens were the leading source of human Campylobacter infections in Australia in 2017-2019 and should remain the focus of interventions to reduce burden.

An ecological study of the spatiotemporal dynamics and drivers of domestically acquired campylobacteriosis in Ireland, 2011-2018

In 2021, Campylobacteriosis was the main gastrointestinal disease in the European Union since 2007 according to the European Centre for Disease Prevention and Control. In the Republic of Ireland, the incidence of the disease is particularly high with approximately 3,000 cases per annum, raising significant concerns for national health authorities with an expected increase in the number of cases in the light of climate change. The current study sought to assess the spatio-temporal patterns of campylobacteriosis in the Republic of Ireland using 20,391 cases from January 2011 to December 2018. An ensemble of spatial statistics techniques including seasonal decomposition, spatial clustering and space-time scanning, were used to elucidate the main individual and spatio-temporal characteristics of the disease in the country. Findings revealed that cases from the paediatric age group (i.e., under 5 years old) were more likely to occur in rural areas (aOR: 1.1.27, CI 95% 1.14-1.41) while cases from the intermediate age group (i.e., >5 & <65 years old) were associated with urban living (aOR: 1.30, CI 95% 1.21-1.4). The disease exhibited a peak during Irish summer, with a stronger seasonal signal reported in counties located on the Western part of the country. Infection hotspots were more likely to occur in urban areas, and more particularly on the Southern part of the island and around the main metropolitan areas. Overall, research findings pointed out the influence of local and spatio-temporally specific socio-demographic and environmental risk factors (i.e., cooking habits, local weather, dietary types) therefore highlighting the need for initiating spatio-temporally targeted health management and surveillance strategies.

Retrospective Analysis of the Clinical Features and Pregnancy Outcomes in 124 Pregnant Patients with Non-Obstetric Acute Abdomen

Objective

To retrospectively analyze the clinical characteristics and pregnancy outcomes of patients with the non-obstetric acute abdomen (AAD) during pregnancy.

Methods

A total of 124 patients with non-obstetric AAD during pregnancy were selected, including acute gastroenteritis (n = 42), acute appendicitis (n = 24), pedicle torsion of ovarian tumor (n = 21), acute pancreatitis (n = 10), urinary stones (n = 8), acute cholecystitis (n = 5), ruptured ovarian cyst (n = 6), red degeneration of hysteromyoma (n = 4), pedicle torsion of subserosal hysteromyoma (n = 3) and intestinal obstruction (n = 1). The clinical data of included patients were collected, and their clinical manifestations, clinical diagnosis, treatment modalities, and pregnancy outcomes were analyzed.

Results

Common clinical manifestations included abdominal pain, nausea, vomiting, fever, elevated leukocytes, and neutrophil count. Clinical diagnosis analysis revealed acute gastroenteritis (n = 42), acute appendicitis (n = 24), pedicle torsion of ovarian tumor (n = 21), acute pancreatitis (n = 10), urinary stones (n = 8), acute cholecystitis (n = 5), ruptured ovarian cyst (n = 6), red degeneration of hysteromyoma (n = 4), pedicle torsion of subserosal hysteromyoma (n = 3) and intestinal obstruction (n = 1) in patients. Surgery was performed for conditions such as acute appendicitis and ovarian tumor torsion, while conservative treatment was preferred for cases of acute gastroenteritis. 65 patients received surgery and 59 patients received conservative treatment. The pregnancy outcomes indicated 113 patients with full-term delivery, 5 with premature delivery, 6 with miscarriage and 1 with fetal death. Pregnancy outcomes varied, with 113 patients achieving full-term delivery, 5 experiencing premature delivery, 6 undergoing miscarriage, and 1 case of fetal death.

Conclusion

Non-obstetric AAD during pregnancy manifests clinically as nausea and vomiting, abdominal pain, elevated body temperature, and leukocytes, all of which have pregnancy outcomes. Pregnant patients with non-obstetric AAD should be diagnosed according to their clinical manifestations, physical examinations, and relevant imaging examinations, and appropriate treatment modalities should be selected to achieve a better pregnancy outcome and ensure the safety of the mother and baby during the clinical diagnosis and treatment process. This study underscores the need for prompt and accurate diagnosis in pregnant patients with non-obstetric AAD, to optimize pregnancy outcomes and ensure maternal-fetal safety.

Acute gastroenteritis outbreak associated with multiple and rare norovirus genotypes after storm events in Santa Catarina, Brazil

Norovirus is a major cause of acute diarrheal disease (ADD) outbreaks worldwide. In the present study, we investigated an ADD outbreak caused by norovirus in several municipalities of Santa Catarina state during the summer season, southern Brazil in 2023. As of the 10th epidemiological week of 2023, approximately 87 000 ADD cases were reported, with the capital, Florianópolis, recording the highest number of cases throughout the weeks. By using RT-qPCR and sequencing, we detected 10 different genotypes, from both genogroups (G) I and II. Some rare genotypes were also identified. Additionally, rotavirus and human adenovirus were sporadically detected among the ADD cases. Several features of the outbreak suggest that sewage-contaminated water could played a role in the surge of ADD cases. Storm events in Santa Catarina state that preceded the outbreak likely increased the discharge of contaminated wastewater and stormwater into water bodies, such as rivers and beaches during a high touristic season in the state. Climate change-induced extreme weather events, including intensified rainfall and frequent floods, can disturb healthcare and sanitation systems. Implementing public policies for effective sanitation, particularly during peak times, is crucial to maintain environmental equilibrium and counter marine pollution.

Acetylation of K188 and K192 inhibits the DNA-binding ability of NarL to regulate Salmonella virulence

Salmonella infection significantly increases nitrate levels in the intestine, immune cells, and immune organs of the host, and it can exploit nitrate as an electron acceptor to enhance its growth. In the presence of nitrate or nitrite, NarL, a regulatory protein of the Nar two-component system, is activated and regulates a number of genes involved in nitrate metabolism. However, research on NarL at the post-translational level is limited. In this study, we demonstrate that the DNA-binding sites K188 and 192 of NarL can be acetylated by bacterial metabolite acetyl phosphate and that the degree of acetylation has a considerable influence on the regulatory function of NarL. Specifically, acetylation of NarL negatively regulates the transcription of narG, narK, and napF, which affects the utilization of nitrate in Salmonella. Besides, both cell and mouse models show that acetylated K188 and K192 result in attenuated replication in RAW 264.7 cells, as well as impaired virulence in mouse model. Together, this research identifies a novel NarL acetylation mechanism that regulates Salmonella virulence, providing a new insight and target for salmonellosis treatment.IMPORTANCESalmonella is an important intracellular pathogen that can cause limited gastroenteritis and self-limiting gastroenteritis in immunocompetent humans. Nitrate, the highest oxidation state form of nitrogen, is critical in the formation of systemic infection in Salmonella. It functions as a signaling molecule that influences Salmonella chemotaxis, in addition to acting as a reduced external electron acceptor for Salmonella anaerobic respiration. NarL is an essential regulatory protein involved in nitrate metabolism in Salmonella, and comprehending its regulatory mechanism is necessary. Previous research has linked NarL phosphorylation to the formation of its dimer, which is required for NarL to perform its regulatory functions. Our research demonstrated that acetylation also affects the regulatory function of NarL. We found that acetylation affects Salmonella pathogenicity by weakening the ability of NarL to bind to the target sequence, further refining the mechanism of the anaerobic nitrate respiration pathway.

Differential transcriptome response following infection of porcine ileal enteroids with species A and C rotaviruses

BACKGROUND

Rotavirus C (RVC) is the major causative agent of acute gastroenteritis in suckling piglets, while most RVAs mostly affect weaned animals. Besides, while most RVA strains can be propagated in MA-104 and other continuous cell lines, attempts to isolate and culture RVC strains remain largely unsuccessful. The host factors associated with these unique RVC characteristics remain unknown.

METHODS

In this study, we have comparatively evaluated transcriptome responses of porcine ileal enteroids infected with RVC G1P[1] and two RVA strains (G9P[13] and G5P[7]) with a focus on innate immunity and virus-host receptor interactions.

RESULTS

The analysis of differentially expressed genes regulating antiviral immune response indicated that in contrast to RVA, RVC infection resulted in robust upregulation of expression of the genes encoding pattern recognition receptors including RIG1-like receptors and melanoma differentiation-associated gene-5. RVC infection was associated with a prominent upregulation of the most of glycosyltransferase-encoding genes except for the sialyltransferase-encoding genes which were downregulated similar to the effects observed for G9P[13].

CONCLUSIONS

Our results provide novel data highlighting the unique aspects of the RVC-associated host cellular signalling and suggest that increased upregulation of the key antiviral factors maybe one of the mechanisms responsible for RVC age-specific characteristics and its inability to replicate in most cell cultures.

Interference Between Enteric Viruses and Live-Attenuated Rotavirus Vaccine Virus in a Healthy Australian Birth Cohort

BACKGROUND

Rotavirus vaccines have reduced effectiveness in high-mortality settings. Interference between enteric viruses and live-attenuated oral vaccine strains may be a factor.

METHODS

In a birth cohort of healthy Australian infants, parents collected weekly stool samples. Three hundred eighty-one paired swabs collected within 10-days of RotaTeq vaccination from 140 infants were tested for 10 enteric viruses and RotaTeq strains.

RESULTS

Collectively, both ribonucleic acid and deoxyribonucleic acid viruses were negatively associated with RotaTeq shedding (adjusted odds ratio = 0.29, 95% confidence interval = 0.14-0.58 and adjusted odds ratio = 0.30, 95% confidence interval = 0.11-0.78, respectively).

CONCLUSIONS

Enteric viruses may interfere with RotaTeq replication in the gut and thus RotaTeq stool shedding.

When the implementation of water safety plans fail: rethinking the approach to water safety planning following a serious waterborne outbreak and implications for subsequent water sector reforms

Water suppliers in New Zealand have been preparing the water safety plans (WSPs) since 2005; large drinking water-associated outbreaks of campylobacteriosis occurred in Darfield in 2012 and in Havelock North in 2016. This paper reviews the WSP that was in place for Havelock North, and analyses why it failed to prevent this outbreak. The risk assessment team completing the WSP underestimated the risks to human health of contamination events, while overestimating the security of the groundwater and bore heads. Historical Escherichia coli transgressions were dismissed as likely despite sampler or testing errors, rather than important warning signals. The outbreak was a consequence of multiple factors including an untreated supply, a local animal faecal source, limitations to the aquifer integrity and bore head protection, and a failure to proactively respond to a flooding event. The overarching issue was a focus on narrow compliance with the Health Act rather than the use of the WSP as a valuable tool to proactively understand and manage public health risks. New Zealand plans to focus on the ability of an organisation to manage risk, with the emphasis on promoting conversations with water suppliers about integrated risk management rather than focusing solely on the preparation of a WSP.

Whole genome sequencing and genomic characterization of a DS-1-like G2P[4] group A rotavirus in Japan

After rotavirus was discovered in 1973, it became the leading pathogen in causing acute gastroenteritis in humans worldwide. In this study, we performed whole genome sequencing and genomic characterization of a DS-1-like G2P[4] group A rotavirus in feces of a Japanese child with acute gastroenteritis who was fully Rotarix® vaccinated. The genomic investigation determined a genomic constellation G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 of this rotavirus strain. Its antigenic epitopes of the VP7 and VP4 proteins had significant mismatches compared with the vaccine strains. Our study is the latest attempt to investigate the evolution of the VP7 and VP4 genes of emerging G2P[4] rotavirus in Japan.

Genotypic investigation of a rotavirus cluster at a quaternary-care pediatric hospital

Rotavirus (RV) was a common healthcare-associated infection prior to the introduction of the RV vaccine. Following widespread RV vaccination, healthcare-associated rotavirus cases are rare. We describe an investigation of a cluster of rotavirus infections in a pediatric hospital in which an uncommon genotype not typically circulating in the United States was detected.

FlgM is required to evade NLRC4-mediated host protection against flagellated Salmonella

Salmonella enterica serovar Typhimurium is a leading cause of gastroenteritis worldwide and a deadly pathogen in children, immunocompromised patients, and the elderly. Salmonella induces innate immune responses through the NLRC4 inflammasome, which has been demonstrated to have distinct roles during systemic and mucosal detections of flagellin and non-flagellin molecules. We hypothesized that NLRC4 recognition of Salmonella flagellin is the dominant protective pathway during infection. To test this hypothesis, we used wild-type, flagellin-deficient, and flagellin-overproducing Salmonella to establish the role of flagellin in mediating NLRC4-dependent host resistance during systemic and mucosal infections in mice. We observed that during the systemic phase of infection, Salmonella efficiently evades NLRC4-mediated innate immunity. During mucosal Salmonella infection, flagellin recognition by the NLRC4 inflammasome pathway is the dominant mediator of protective innate immunity. Deletion of flgM results in constitutive expression of flagellin and severely limits systemic and mucosal Salmonella infections in an NLRC4 inflammasome-dependent manner. These data establish that recognition of Salmonella's flagellin by the NLRC4 inflammasome during mucosal infection is the dominant innate protective pathway for host resistance against the enteric pathogen and that FlgM-mediated evasion of the NLRC4 inflammasome enhances virulence and intestinal tissue destruction.

Engineering conjugative CRISPR-Cas9 systems for the targeted control of enteric pathogens and antibiotic resistance

Pathogenic Escherichia coli and Salmonella enterica pose serious public health threats due to their ability to cause severe gastroenteritis and life-threatening sequela, particularly in young children. Moreover, the emergence and dissemination of antibiotic resistance in these bacteria have complicated control of infections. Alternative strategies that effectively target these enteric pathogens and negate or reduce the need of antibiotics are urgently needed. Such an alternative is the CRISPR-Cas9 system because it can generate sequence-specific lethal double stranded DNA breaks. In this study, two self-transmissible broad host range conjugative plasmids, pRK24 and pBP136, were engineered to deliver multiplexed CRSIPR-Cas9 systems that specifically target Enterohemorrhagic and Enteropathogenic strains of E. coli (EHEC and EPEC), S. enterica, and blaCMY-2 antibiotic resistance plasmids. Using in vitro mating assays, we show that the conjugative delivery of pRK24-CRISPR-Cas9 carrying guide RNAs to the EPEC/EHEC eae (intimin) gene can selectively kill enterohemorrhagic E. coli O157 eae+ cells (3 log kill at 6 h) but does not kill the isogenic Δeae mutant (P<0.001). Similar results were also obtained with a pBP136 derivative, pTF16, carrying multiplexed guide RNAs targeting E. coli eae and the S. enterica ssaN gene coding for the type III secretion ATPase. Another pBP136 derivative, TF18, carries guide RNAs targeting S. enterica ssaN and the antibiotic resistance gene, blaCMY-2, carried on the multi-drug resistant pAR06302. Introduction of pTF18 into bacteria harboring pAR06302 showed plasmids were cured at an efficiency of 53% (P<0.05). Using a murine neonate EPEC infection model, pTF16 was delivered by a murine derived E. coli strain to EPEC infected mice and showed significant reductions of intestinal EPEC (P<0.05). These results suggest that establishing conjugative CRISPR-Cas9 antimicrobials in the intestinal microbiome may provide protection from enteric pathogens and reduce antibiotic resistance without disrupting the normal microbiota.

Entry and egress of human astroviruses

Astroviruses encapsidate a positive-sense, single-stranded RNA genome into ∼30nm icosahedral particles that infect a wide range of mammalian and avian species, but their biology is not well understood. Human astroviruses (HAstV) are divided into three clades: classical HAstV serotypes 1-8, and novel or non-classical HAstV of the MLB and VA clades. These viruses are part of two genogroups and phylogenetically cluster with other mammalian astroviruses, highlighting their zoonotic potential. HAstV are a highly prevalent cause of nonbacterial gastroenteritis, primarily in children, the elderly and immunocompromised. Additionally, asymptomatic infections and extraintestinal disease (e.g., encephalitis), are also observed, mostly in immunocompetent or immunocompromised individuals, respectively. While these viruses are highly prevalent, no approved vaccines or antivirals are available to prevent or treat infections. This is in large part due to their understudied nature and the limited understanding of even very basic features of their life cycle and pathogenesis at the cellular and organismal level. This review will summarize molecular features of human astrovirus biology, pathogenesis, and tropism, and then focus on two stages of the viral life cycle, namely entry and egress, since these are proven targets for therapeutic interventions. We will further highlight gaps in knowledge in hopes of stimulating future research into these understudied viruses.

Identification of a GII.6 norovirus blockade antibody epitope

Noroviruses (NoVs) are the leading agent that causes acute viral gastroenteritis worldwide. Sporadic cases of GII.6 NoV have been reported primarily in addition to occasional outbreaks. Using the major capsid protein VP1 of GII.6 NoV derived from three distinct clusters, we demonstrated three blockade monoclonal antibodies (mAbs, 1F7, 1F11, and 2B6) generated previously exhibited cluster-specific binding effects. Combining sequence alignment and blocking immune epitopes, we sequentially designed a total of 18 mutant proteins containing one, two, or three mutations, or swapped regions. Indirect enzyme-linked immunosorbent assay (ELISA) demonstrated that the three blocking mAbs lost or showed significantly reduced binding for H383Y, D387N, V390D, and T391D mutant proteins. Combining data from mutant proteins with swapping regions and point mutations, the binding region of the three mAbs was mapped to residues 380-395. Sequence alignment of this region showed within-cluster conservation and between-cluster variations, further strengthening the idea of blockade epitope-mediated evolution of NoV.

Prospective study of an amino acid-based elemental diet in an eosinophilic gastritis and gastroenteritis nutrition trial

BACKGROUND

Eosinophilic gastritis/gastroenteritis (EoG/EoGE) are rare disorders with pathologic gastric and/or small intestinal eosinophilia lacking an approved therapy. An allergic mechanism is postulated but underexplored mechanistically and therapeutically.

OBJECTIVE

We evaluated the effectiveness of a food allergen-free diet (elemental formula) in controlling gastrointestinal eosinophilia in adult EoG/EoGE.

METHODS

Adults aged 18 to 65 years with histologically active EoG/EoGE (≥30 eosinophils per high-power field) in the stomach and/or duodenum and gastrointestinal symptoms within the month preceding enrollment were prospectively enrolled onto a single-arm clinical trial to receive elemental formula for 6 consecutive weeks. The primary end point was percentage of participants with complete histologic remission (<30 eosinophils per high-power field in both stomach and duodenum). Exploratory outcomes were improvement in symptoms, endoscopy results, blood eosinophilia, quality of life, Physician Global Assessment score, and EoG-relevant gastric transcriptome and microbiome.

RESULTS

Fifteen adults (47% male, average age 37.7 years, average symptom duration 8.8 years) completed the trial. Multi-gastrointestinal segment involvement affected 87%. All subjects had complete histologic remission in the stomach (P = .002) and duodenum (P = .001). Scores improved in overall PhGA (P = .002); EGREFS (P = .003); EGDP (P = .002); SODA pain intensity (P = .044), non-pain (P = .039), and satisfaction (P = .0024); and PROMIS depression (P = .0078) and fatigue (P = .04). Food reintroduction reversed these improvements. The intervention was well tolerated in 14 subjects, with 1 serious adverse event reported in 1 subject.

CONCLUSION

An amino acid-based elemental diet improves histologic, endoscopic, symptomatic, quality-of-life, and molecular parameters of EoG/EoGE; these findings and disease recurrence with food trigger reintroduction support a dominant role for food allergens in disease pathogenesis.

CLINICALTRIALS

gov Identifier: NCT03320369.

The quality of diagnostic guidelines for children in primary care: A meta-epidemiological study

AIM

To determine the quality of paediatric guidelines relevant to diagnosis of three of the most common conditions in primary care: fever, gastroenteritis and constipation.

METHODS

We undertook a meta-epidemiological study of paediatric guidelines for fever, gastroenteritis and gastroenteritis. We systematically searched MEDLINE, Embase, Trip Database, Guidelines International Network, the National Guideline Clearinghouse and WHO from February 2011 to September 2022 for guidelines from high-income settings containing diagnostic recommendations. We assessed the quality of guideline reporting for included guidelines using the AGREE II tool.

RESULTS

We included 16 guidelines: fever (n = 7); constipation (n = 4) and gastroenteritis (n = 5). The overall quality across the three conditions was graded moderate (median AGREE II score 4.5/7, range 2.5-6.5) with constipation guidelines rated the highest (median 6/7), and fever rated the lowest (median 3.8/7). Major methodological weaknesses included consideration of guideline applicability. Half of the guidelines did not report involving parent representatives, and 56% did not adequately declare or address their competing interests.

CONCLUSIONS

Substantial variations exist in the quality of paediatric guidelines related to the diagnosis of primary care presentations. Better quality guidance is needed for general practitioners to improve diagnosis for children in primary care.

Human astrovirus capsid protein releases a membrane lytic peptide upon trypsin maturation

The human astrovirus (HAstV) is a non-enveloped, single-stranded RNA virus that is a common cause of gastroenteritis. Most non-enveloped viruses use membrane disruption to deliver the viral genome into a host cell after virus uptake. The virus-host factors that allow for HAstV cell entry are currently unknown but thought to be associated with the host-protease-mediated viral maturation. Using in vitro liposome disruption analysis, we identified a trypsin-dependent lipid disruption activity in the capsid protein of HAstV serotype 8. This function was further localized to the P1 domain of the viral capsid core, which was both necessary and sufficient for membrane disruption. Site-directed mutagenesis identified a cluster of four trypsin cleavage sites necessary to retain the lipid disruption activity, which is likely attributed to a short stretch of sequence ending at arginine 313 based on mass spectrometry of liposome-associated peptides. The membrane disruption activity was conserved across several other HAstVs, including the emerging VA2 strain, and effective against a wide range of lipid identities. This work provides key functional insight into the protease maturation process essential to HAstV infectivity and presents a method to investigate membrane penetration by non-enveloped viruses in vitro. IMPORTANCE Human astroviruses (HAstVs) are an understudied family of viruses that cause mild gastroenteritis but have recent cases associated with a more severe neural pathogenesis. Many important elements of the HAstV life cycle are not well understood, and further elucidating them can help understand the various forms of HAstV pathogenesis. In this study, we utilized an in vitro liposome-based assay to describe and characterize a previously unreported lipid disruption activity. This activity is dependent on the protease cleavage of key sites in HAstV capsid core and can be controlled by site-directed mutagenesis. Our group observed this activity in multiple strains of HAstV and in multiple lipid conditions, indicating this may be a conserved activity across the AstV family. The discovery of this function provides insight into HAstV cellular entry, pathogenesis, and a possible target for future therapeutics.

Bioactivity of Fucoidan-Rich Extracts from Fucus vesiculosus against Rotavirus and Foodborne Pathogens

Marine algae are sources of bioactive components with defensive properties of great value against microbial infections. This study investigated the bioactivity of extracts from brown algae Fucus vesiculosus against rotavirus, the worldwide leading cause of acute gastroenteritis in infants and young children. Moreover, one of the extracts was tested against four foodborne bacteria: Campylobacter jejuni, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes, and the non-pathogenic: E. coli K12. In vitro tests using MA104 cells revealed that both whole algae extracts and crude fucoidan precipitates neutralized rotavirus in a dose-responsive manner. The maximum neutralization activity was observed when the rotavirus was incubated with 100 μg mL-1 of the hydrochloric acid-obtained crude fucoidan (91.8%), although crude fucoidan extracted using citric acid also demonstrated high values (89.5%) at the same concentration. Furthermore, molecular weight fractionation of extracts decreased their antirotaviral activity and high molecular weight fractions exhibited higher activity compared to those of lower molecular weight. A seaweed extract with high antirotaviral activity was also found to inhibit the growth of C. jejuni, S. Typhimurium, and L. monocytogenes at a concentration of 0.2 mg mL-1. Overall, this study expands the current knowledge regarding the antimicrobial mechanisms of action of extracts from F. vesiculosus.

A Campylobacteriosis Outbreak Caused by One Asymptomatic Food Handler Carrier

In August 2021, three students with diarrhea from the same school visited a local hospital in the S district of Beijing. An epidemic investigation showed that there were more students with diarrhea in the same school and they had one meal together. Campylobacter jejuni was isolated from both patients with diarrhea and asymptomatic food handlers; however, the latter also carried Campylobacter coli. Phylogenomic analysis showed that there was a campylobacteriosis outbreak among the students, and the asymptomatic food handler may have been the source of the infection. Routine inspection and surveillance for Campylobacter is needed for the food producing staff, particularly those cooking in the cafeteria in schools or other public food services.

[Correlation between serum zinc and brain injury in infants with mild gastroenteritis complicated with benign infantile convulsion and febrile convulsion]

OBJECTIVE

To investigate the association between serum zinc levels and convulsive brain injury in infants with mild gastroenteritis complicated with benign infantile seizures (BICE) and febrile seizures (FC).

METHODS

A case-control study method was conducted. 120 children with mild gastroenteritis and convulsion admitted to the First Affiliated Hospital of Hebei North University from January 2020 to January 2022 were enrolled as the research subjects. They were divided into BICE group and FC group according to the type of convulsion. The serum zinc level, the frequency and duration of convulsion, and the occurrence of convulsive brain injury in the two groups were recorded. Multivariate Logistic regression analysis was used to screen the risk factors for convulsive brain injury. The Spearman correlation method was used to analyze the association between serum zinc levels, clinical characteristics of convulsion and convulsive brain injury.

RESULTS

A total of 120 children were enrolled, of which 81 developed to BICE and 39 developed to FC during hospitalization. The serum zinc level of children in the FC group was significantly lower than that in the BICE group (μmol/L: 39.24±6.50 vs. 48.65±7.21, P < 0.01). In the BICE group and FC group, the serum zinc level in children with more than 2 convulsions was significantly lower than that in the children with one convulsion (μmol/L: 37.65±6.50 vs. 53.17±7.55 in the BICE group, and 30.27±5.58 vs. 44.16±7.57 in the FC group, both P < 0.01). Serum zinc level in children with convulsion duration ≥ 5 minutes was significantly lower than that in the children with convulsion duration < 5 minutes (μmol/L: 38.75±6.74 vs. 51.21±7.58 in the BICE group, and 31.08±5.46 vs. 45.19±7.25 in the FC group, both P < 0.01). Moreover, the serum zinc level of children with different convulsion frequency and duration in the FC group was significantly lower than that in the BICE group (all P < 0.01). Among the 120 children, 9 cases of convulsive brain injury occurred, and the incidence rate was 7.50%. The incidence of convulsive brain injury in the BICE group was 1.23% (1/81), which was significantly lower than 20.51% in the FC group (8/39, P < 0.01). The serum zinc level of children with convulsive brain injury was significantly lower than that of children with non-brain injury (μmol/L: 28.50±5.00 vs. 60.22±7.31, P < 0.01), and the number of convulsion was significantly higher than that of non-cerebral injury (≥ 2 convulsions: 100.00% vs. 1.80%, P < 0.01), and the duration of convulsion in children with brain injury was significantly longer than that of non-brain-injured children (convulsion duration ≥ 5 minutes: 100.00% vs. 11.71%, P < 0.01). Multivariate Logistic regression analysis showed that decreased serum zinc level [odds ratio (OR) = 2.147, 95% confidence interval (95%CI) was 1.354-3.403], increased number of convulsion (OR = 3.452, 95%CI was 1.266-9.417), and prolonged convulsion duration (OR = 3.117, 95%CI was 1.326-7.327) were independent risk factor for convulsive brain injury in children with mild gastroenteritis and convulsion (all P < 0.05). Spearman correlation analysis showed that serum zinc level, convulsion ≥ 2 times, duration of convulsion ≥ 5 minutes and convulsion ≥ 2 times + convulsion duration ≥ 5 minutes were significantly negatively correlated with the occurrence of convulsive brain injury in FC children (r values were -0.546, -0.517, -0.522, and -0.528, all P < 0.01). There was no significant correlation between serum zinc level, convulsion ≥ 2 times, convulsion duration ≥ 5 minutes and convulsion ≥ 2 times+convulsion duration ≥ 5 minutes and convulsive brain injury in BICE children (r values were -0.281, -0.129, -0.201, -0.243, all P > 0.05).

CONCLUSIONS

Serum zinc level is related to the characteristics of convulsive symptoms in children with mild gastroenteritis complicated with FC, and has a strong negative correlation with the occurrence of convulsive brain injury. Active targeted intervention and treatment may help reduce the incidence of brain injury in children.

Genomic Characterization of Campylobacter jejuni Associated with Perimyocarditis: A Family Case Report

Campylobacter spp. is the leading cause of foodborne gastrointestinal infections in humans worldwide. This study reports the first case of four family members who had contact with the same source of Campylobacter jejuni contamination with different results. Only the little siblings were infected by the same C. jejuni strain, but with different symptoms. Whereas the daughter was slightly affected with mild enteritis, the son suffered a longer campylobacteriosis followed with a perimyocarditis. This is the first case of the youngest patient affected by C. jejuni-related perimyocarditis published to date. The genomes of both strains were characterized by whole-genome sequencing and compared with the C. jejuni NCTC 11168 genome to gain insights into the molecular features that may be associated with perimyocarditis. Various comparison tools were used for the comparative genomics analysis, including the identification of virulence and antimicrobial resistance genes, phase variable (PV) genes, and single nucleotide polymorphisms (SNPs) identification. Comparisons of the strains identified 16 SNPs between them, which constituted small but significant changes mainly affecting the ON/OFF state of PV genes after passing through both hosts. These results suggest that PV occurs during human colonization, which modulates bacteria virulence through human host adaptation, which ultimately is related to complications after a campylobacteriosis episode depending on the host status. The findings highlight the importance of the relation between host and pathogen in severe complications of Campylobacter infections.