Search

Human norovirus was discovered more than five decades ago and is a widespread cause of outbreaks of acute gastroenteritis. There are no approved vaccines or antivirals currently available. However, norovirus inhibitors, including capsid-specific monoclonal antibodies (Mabs) and nanobodies, have recently shown promising results. Several Mabs and nanobodies were found to inhibit norovirus replication using a human intestinal enteroid (HIE) culture system and/or could block norovirus attachment to histo-blood group antigen (HBGA) co-factors. In our pursuit to develop a single broad-spectrum norovirus therapeutic, we continued our analysis and development of a cross-reactive and HBGA interfering nanobody (NB26). To improve NB26 binding capacity and therapeutic potential, we conjugated NB26 onto a human IgG Fc domain (Fc-NB26). We confirmed that Fc-NB26 cross-reacts with genetically diverse GII genotype capsid protruding (P) domains (GII.8, GII.14, GII.17, GII.24, GII.26, and GII.NA1) using a direct enzyme-linked immunosorbent assay. Furthermore, X-ray crystallography structures of these P domains and structures of other GII genotypes reveal that the NB26 binding site is largely conserved, validating its broad reactivity. We showed that Fc-NB26 has ~100-fold higher affinity toward the norovirus P domain compared to native NB26. We also found that both NB26 and Fc-NB26 neutralize human norovirus replication in the HIE culture system. Furthermore, the mode of inhibition confirmed that like NB26, Fc-NB26 caused norovirus particle disassembly and aggregation. Overall, these new findings demonstrate that structural modifications to nanobodies can improve their therapeutic potential.IMPORTANCEDeveloping vaccines and antivirals against norovirus remains a challenge, mainly due to the constant genetic and antigenic evolution. Moreover, re-infection with genetically related and/or antigenic variants is not uncommon. We further developed our leading norovirus nanobody (NB26) that indirectly interfered with norovirus binding to HBGAs, by converting NB26 into a dimeric Fc-linked Nanobody (Fc-NB26). We found that Fc-NB26 had improved binding affinity and neutralization capacity compared with native NB26. Using X-ray crystallography, we showed this nanobody engaged highly conserved capsid residues among genetically diverse noroviruses. Development of such broadly reactive potent therapeutic nanobodies delivered as a slow-releasing prophylactic could be of exceptional value for norovirus outbreaks, especially for the prevention or treatment of severe acute gastroenteritis in high-risk groups such as the young, elderly, and immunocompromised., Competing Interests: The authors declare no conflict of interest.

Purpose of Review: Viruses are the most common etiological agents of diarrhea in children. Despite rotavirus vaccine introduction, rotavirus remains as the leading cause of death globally, followed by norovirus, which represents a diagnostic challenge. Here, we describe new advances in the diagnosis and management of viral diarrheas., Recent Findings: Although immunoassays are widely used for their fast turnaround time and low cost, molecular techniques have become the most reliable diagnostic method due to their high sensitivity and capacity to analyze multiple pathogens in gastrointestinal panels. Isothermal nucleic acid amplification assays (LAMP and RPA) are promising techniques since they do not require sophisticated equipment and can be used as point-of-care testing. CRISPR/Cas nucleic acid detection systems are new diagnostic methods with great potential. Several recent published articles describe the role of human intestinal enteroids to characterize norovirus infection, to test new drugs, and for vaccine development. The interaction between the human gut microbiota and gastrointestinal viral infections has been extensively reviewed and offers some innovative mechanisms for therapeutic and preventive measures., Summary: Although important advances have been made, more research is needed to address remaining challenges and further improve diagnostic capabilities and better management strategies for this critical infectious disease., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Rabbit hemorrhagic disease virus (RHDV) can cause fatal fulminant hepatitis, which is very similar to human acute liver failure. The aim of this study was to investigate whether adipose-derived stem cells (ADSCs) could alleviate RHDV2-induced liver injury in rabbits. Twenty 50-day-old rabbits were divided randomly into two groups (RHDV2 group, ADSCs + RHDV2 group). Starting from the 1st day, two groups of rabbits were given 0.5 ml of viral suspensions by subcutaneous injection in the neck. Meanwhile, the ADSCs + RHDV2 group was injected with ADSCs cell suspension (1.5 × 10 7 cells/ml) via a marginal ear vein, and the RHDV2 group was injected with an equal amount of saline via a marginal ear vein. At the end of the 48 h experiment, the animals were euthanized and gross hepatic changes were observed before liver specimens were collected. Histopathological analysis was performed using hematoxylin-eosin (HE), periodic acid schiff (PAS) and Masson's trichrome staining. For RHDV2 affected rabbits, HE staining demonstrated disorganized hepatic cords, loss of cellular detail, and severe cytoplasmic vacuolation within hepatocytes. Glycogen was not observed with PAS staining, and Masson's Trichrome staining showed increased hepatic collagen deposition. For rabbits treated with ADSCs at the time of inoculation, hepatic pathological changes were significantly less severe, liver glycogen synthesis was increased, and collagen fiber deposition was decreased. For RHDV2 affected rabbits, Tunel and immunofluorescence staining showed that the number of apoptotic cells, TGF-β, and MMP-9 protein expression increased. And that in the ADSC treated group there was less hepatocyte apoptosis. In addition, RHDV2 induces liver inflammation and promotes the expression of IL-1β, IL-6, and TNF-α. In rabbits administered ADSCs at time of inoculation, the expression of inflammatory factors in liver tissue decreased significantly. Our experiments show that ADSCs can protect rabbits from liver injury by RHDV2 and reduce the pathological and inflammatory response of liver. However, the specific protective mechanism needs further study., Competing Interests: Declaration of competing interest Authors have no conflict of interest to declare., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Acute liver failure (ALF) is a rare and severe disease, which, despite continuous advances in medicine, is still characterized by high mortality (65-85%). Very often, a liver transplant is the only effective treatment for ALF. Despite the implementation of prophylactic vaccinations in the world, the viral background of ALF is still a problem and leads to many deaths. Depending on the cause of ALF, it is sometimes possible to reverse this condition with appropriate therapies, which is why the search for effective antiviral agents seems to be a very desirable direction of research. Defensins, which are our natural antimicrobial peptides, have a very high potential to be used as therapeutic agents for infectious liver diseases. Previous studies on the expression of human defensins have shown that increased expression of human α and β-defensins in HCV and HBV infections is associated with a better response to treatment. Unfortunately, conducting clinical trials for ALF is very difficult due to the severity of the disease and the low incidence, therefore animal models are important for the development of new therapeutic strategies. One of the best animal models that has real reference to research on acute liver failure (ALF) is rabbit hemorrhagic disease in rabbits caused by the Lagovirus europaeus virus. So far, there have been no studies on the potential of defensins in rabbits infected with Lagovirus europaeus virus., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Hrynkiewicz and Niedźwiedzka-Rystwej.)

Norovirus is generally an acute infection causing symptoms such as diarrhea, nausea, and vomiting lasting for 24-48 hours. However, for immunocompromised patients, norovirus gastroenteritis can last for several years and result in villous atrophy and lead to severe malnutrition, dehydration, electrolyte imbalance and continuous viral shedding. Several treatment strategies have been suggested in case reports: nitazoxanide, ribavirin and enterally administered immunoglobulin with varying results. Favipiravir is also suggested but not tested on humans, highlighting the need for further research.

Knowledge of the epidemiology of sporadic acute gastroenteritis (AGE) in the United States is limited. During September 2016-September 2017, we surveyed Kaiser Permanente Northwest members in Oregon and Washington, USA, to collect data on the 30-day prevalence of dually defined AGE and diarrhea disease and related health-seeking behavior; from a subset of participants, we obtained a stool specimen. Using the iterative proportional fitting algorithm with raked weights, we generated AGE prevalence and annualized rate estimates. We detected norovirus, rotavirus, astrovirus, and sapovirus from submitted stool specimens through real-time quantitative reverse transcription PCR (qRT-PCR). We estimated a 30-day prevalence of 10.4% for AGE and 7.6% for diarrhea only; annual rates were 1.27 cases/person/year for AGE and 0.92 cases/person/year for diarrhea only. Of those with AGE, 19% sought medical care. Almost one quarter (22.4%) of stool specimens from those reporting AGE tested positive for ≥1 viral pathogen, compared with 8.2% from those without AGE.

Since the first clinical description in 1952, immunoglobulin replacement therapy remains the mainstay of treatment of patients with X-linked agammaglobulinemia (XLA). However, this therapy only replaces IgG isotype and does not compensate for the loss of Bruton tyrosine kinase in non-B-lymphocytes. Patients may still therefore develop complications despite current standard of care. Here, we describe an XLA patient with persistent chronic norovirus infection, refractory to treatment and causing intestinal failure. The patient underwent haematopoietic stem cell transplantation, curing XLA and allowed clearance of norovirus prior to humoral immunoreconstitution, suggesting non-humoral immunodeficiency in these patients., (© 2021. The Author(s).)

Human sapoviruses (HuSaVs) cause acute gastroenteritis similar to human noroviruses. Although HuSaVs were discovered four decades ago, no HuSaV has been grown in vitro, which has significantly impeded the understanding of viral biology and the development of antiviral strategies. In this study, we identified two susceptible human cell lines, that originated from testis and duodenum, that support HuSaV replication and found that replication requires bile acids. HuSaVs replicated more efficiently in the duodenum cell line, and viral RNA levels increased up to ∼6 log 10 -fold. We also detected double-stranded RNA, viral nonstructural and structural proteins in the cell cultures, and intact HuSaV particles. We confirmed the infectivity of progeny viruses released into the cell culture supernatants by passaging. These results indicate the successful growth of HuSaVs in vitro. Additionally, we determined the minimum infectious dose and tested the sensitivities of HuSaV GI.1 and GII.3 to heat and ultraviolet treatments. This system is inexpensive, scalable, and reproducible in different laboratories, and can be used to investigate mechanisms of HuSaV replication and to evaluate antivirals and/or disinfection methods for HuSaVs., Competing Interests: The authors declare no competing interest.

Human noroviruses (HuNoVs) are a main cause of acute gastroenteritis worldwide. They are frequently involved in foodborne and waterborne outbreaks. Environmental transmission of the virus depends on two main factors: the ability of viral particles to remain infectious and their adhesion capacity onto different surfaces. Until recently, adhesion of viral particles to food matrices was mainly investigated by considering non-specific interactions (e.g. electrostatic, hydrophobic) and there was only limited information about infectious HuNoVs because of the absence of a reliable in vitro HuNoV cultivation system. Many HuNoV strains have now been described as having specific binding interactions with human Histo-Blood Group Antigens (HBGAs) and non-HBGA ligands found in food and the environment. Relevant approaches to the in vitro replication of HuNoVs were also proposed recently. On the basis of the available literature data, this review discusses the opportunities to use this new knowledge to obtain a better understanding of HuNoV transmission to human populations and better evaluate the hazard posed by HuNoVs in foodstuffs and the environment., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Human norovirus frequently causes outbreaks of acute gastroenteritis. Although discovered more than five decades ago, antiviral development has, until recently, been hampered by the lack of a reliable human norovirus cell culture system. Nevertheless, a lot of pathogenesis studies were accomplished using murine norovirus (MNV), which can be grown routinely in cell culture. In this study, we analyzed a sizeable library of nanobodies that were raised against the murine norovirus virion with the main purpose of developing nanobody-based inhibitors. We discovered two types of neutralizing nanobodies and analyzed the inhibition mechanisms using X-ray crystallography, cryo-electron microscopy (cryo-EM), and cell culture techniques. The first type bound on the top region of the protruding (P) domain. Interestingly, this nanobody binding region closely overlapped the MNV receptor-binding site and collectively shared numerous P domain-binding residues. In addition, we showed that these nanobodies competed with the soluble receptor, and this action blocked virion attachment to cultured cells. The second type bound at a dimeric interface on the lower side of the P dimer. We discovered that these nanobodies disrupted a structural change in the capsid associated with binding cofactors (i.e., metal cations/bile acid). Indeed, we found that capsids underwent major conformational changes following addition of Mg 2+ or Ca 2+ Ultimately, these nanobodies directly obstructed a structural modification reserved for a postreceptor attachment stage. Altogether, our new data show that nanobody-based inhibition could occur by blocking functional and structural capsid properties. IMPORTANCE This research discovered and analyzed two different types of MNV-neutralizing nanobodies. The top-binding nanobodies sterically inhibited the receptor-binding site, whereas the dimeric-binding nanobodies interfered with a structural modification associated with cofactor binding. Moreover, we found that the capsid contained a number of vulnerable regions that were essential for viral replication. In fact, the capsid appeared to be organized in a state of flux, which could be important for cofactor/receptor-binding functions. Blocking these capsid-binding events with nanobodies directly inhibited essential capsid functions. Moreover, a number of MNV-specific nanobody binding epitopes were comparable to human norovirus-specific nanobody inhibitors. Therefore, this additional structural and inhibition information could be further exploited in the development of human norovirus antivirals., (Copyright © 2020 American Society for Microbiology.)

Background: Chronic norovirus infection in immunocompromised patients can be severe, and presently there is no effective treatment. Adoptive transfer of virus-specific T cells has proven to be safe and effective for the treatment of many viral infections, and this could represent a novel treatment approach for chronic norovirus infection. Hence, we sought to generate human norovirus-specific T cells (NSTs) that can recognize different viral sequences., Methods: Norovirus-specific T cells were generated from peripheral blood of healthy donors by stimulation with overlapping peptide libraries spanning the entire coding sequence of the norovirus genome., Results: We successfully generated T cells targeting multiple norovirus antigens with a mean 4.2 ± 0.5-fold expansion after 10 days. Norovirus-specific T cells comprised both CD4+ and CD8+ T cells that expressed markers for central memory and effector memory phenotype with minimal expression of coinhibitory molecules, and they were polyfunctional based on cytokine production. We identified novel CD4- and CD8-restricted immunodominant epitopes within NS6 and VP1 antigens. Furthermore, NSTs showed a high degree of cross-reactivity to multiple variant epitopes from clinical isolates., Conclusions: Our findings identify immunodominant human norovirus T-cell epitopes and demonstrate that it is feasible to generate potent NSTs from third-party donors for use in antiviral immunotherapy., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: After the introduction of rotavirus vaccines into immunization schedules, noroviruses account for the majority of acute gastrointestinal infections. The aim of the study was to assess the clinical presentation in immunocompromised and immunocompetent children with hospital- and community-acquired norovirus gastroenteritis., Material and Methods: We retrospectively reviewed clinical records of children with noroviral gastroenteritis, hospitalized in the Pediatric Hospital, Medical University of Warsaw, between 2015 and 2018. Acute gastrointestinal tract symptoms and confirmed etiology of noroviral infection were inclusion criteria. The analysis was performed in the subgroups of immunocompetent and immunocompromised patients, during community-acquired and nosocomial infections., Results: A total of 57 children with median age 1.5 year (IQR: 0.7-4.0) were recruited. The majority of patients were immunocompetent (87.7%), and nosocomial infections were predominant (56.1%). Gastrointestinal symptoms included nausea, vomiting and diarrhoea (in approximately 85%), while systemic manifestations such as fever and malaise where observed in only ¼. Routine laboratory tests were normal in most of the patients. An analysis in the subgroups revealed statistically significant differences in blood pH and serum electrolyte levels - acidosis and electrolyte disturbances were statistically significantly more common in immunocompromised vs immunocompetent patients (p<0.05)., Conclusions: More frequently the clinical presentation includes gastrointestinal symptoms with no differences between immunocompromised and immunocompetent hosts. The median laboratory values were normal in generally healthy children; disturbances were observed only in children with immunodeficiencies. Therefore, prophylactic measures are of particular importance in the latter group, which is especially sensitive to severe and nosocomial infections., (© National Institute of Public Health – National Institute of Hygiene.)

Feline calicivirus (FCV) causes upper respiratory tract infections in felines and threatens the health of wild and domestic felines. Clinically, specific drugs to treat FCV have not yet been developed. Here, IgG was extracted from inactivated FCV-immunized horse sera. Equine F(ab') 2 fragments were obtained from pepsin-digested IgG and then purified by protein-G column chromatography. In our study, equine immunoglobulin F(ab') 2 fragments showed efficient neutralizing activity in vitro against FCV and had therapeutic and prophylactic effects in FCV-infected cats. The anti-FCV-specific F(ab') 2 fragment can significantly alleviate the clinical symptoms of FCV-infected cats and reduce the viral loads of the trachea, lung and spleen. These results indicate that the F(ab') 2 fragment prepared from inactivated FCV-immunized horses may be used as a prophylactic and therapeutic agent for diseases caused by FCV., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Neutropenic diets were adopted as a way to decrease the infection risks in immunocompromised individuals, but these diets result in significant restrictions in the variety and types of foods an individual may consume. We used a controlled before-and-after study design in consecutive pediatric and young adult patients who underwent hematopoietic stem cell transplant at our center between January 1, 2014, and December 31, 2014. From January through June, all patients were placed on a traditional neutropenic diet; on July 1, we liberalized the bone marrow transplant (BMT) diet to a modified BMT diet. We compared the incidence of bloodstream infections in the first 100 days post-transplant, incidence of norovirus in the first 100 days, total parenteral nutrition days through day 100, incidence of grade 3 to 4 graft-versus-host disease at day 100, gastrointestinal graft-versus-host disease (any stage), and 100-day overall survival. In addition, we administered an investigator-created survey to evaluate food cravings, nausea, diet limitations, and subjective quality of life. In total, 102 patients underwent hematopoietic stem cell transplant during the study period. Forty-nine (48%) received the neutropenic diet and 53 (52%) the BMT diet. Other than more males receiving the neutropenic diet (67% versus 47%, P = 0.05), there were no statistical demographic and outcome differences between the 2 groups. Additionally, 46 subjects (45%) completed the investigator-created questionnaire. There was no difference in the perceived food cravings, nausea, diet limitations, and subjective quality of life between the 2 cohorts. These data demonstrate noninferiority of the modified BMT diet over the traditional neutropenic diet. We believe the food safety-based diet offers a greater variety of food, which may assist in the transition to a normal diet., (Copyright © 2019. Published by Elsevier Inc.)

The main causative agents of feline upper respiratory tract disease (FURTD) are feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV). These viral infections are common, especially in multiple cat households. Severely affected cats often need to be hospitalized. Intensive symptomatic therapy is important in the management of cats with FURTD. The use of antiviral drugs is limited in cats, as they are often ineffective or toxic when given systemically. Antiviral drugs are, therefore, mainly used locally for the treatment of FHV-1-associated eye changes. Famciclovir, however, is an effective drug for systemic therapy in cats with FHV-1-related clinical signs. For FCV, only few antiviral drugs are available. In a controlled study, the use of immunoglobulins in cats with FHV-1 and/or FCV infection reduced clinical signs of FURTD significantly faster., Competing Interests: Die Autoren bestätigen, dass kein Interessenkonflikt besteht., (© Georg Thieme Verlag KG Stuttgart · New York.)

Acute Viral Gastroenteritis: Viruses Other Than Norovirus Abstract. Norovirus is the leading cause of acute viral gastroenteritis. Norovirus is highly contagious, thus outbreaks of norovirus in hospitals and long-term care facilities are feared. Usually, stool samples of patients with a potentially viral gastroenteritis are first checked for the presence of norovirus. In recent years, sapovirus and astrovirus were increasingly reported as cause of acute gastroenteritis. Outbreaks of acute viral gastroenteritis caused by sapovirus or astrovirus are hardly distinguishable from those caused by norovirus because of a similar clinical presentation. Molecular analyses of stool specimen are needed for accurate diagnosis of the viral cause of acute gastroenteritis. It is worth to further investigate stool samples of patients suspected of acute viral gastroenteritis not only for norovirus, but also for sapovirus and astrovirus.

Discovered in the 1970s, human noroviruses (NoV) are the leading cause of foodborne disease and gastroenteritis outbreaks worldwide. NoV affect people of all ages. In children less than 5 years old, despite rotavirus remains the main enteropathogen responsible for viral gastroenteritis, NoV become the first etiological virus in countries where the rotavirus vaccine was introduced. Treatment of viral gastroenteritis is symptomatic. The key element in front of NoV infection is limiting their transmission. A rapid NoV detection during outbreak is important in the aim to rapidly implement hygiene measures to limit the size of the outbreak. Prevention of NoV infections relies on the use of adequate hand hygiene measures and disinfection of contaminated environmental surfaces. In face of an acute gastroenteritis outbreak, the early NoV identification with rapid laboratory tests or molecular biology methods is needed in the aim to implement as soon as possible hygiene measures to limit the size of the NoV outbreak. Due to antigenically diverse NoV strains and the lack of long term immunity, the development of an effective vaccine is difficult.

The host microbiota has emerged a third player in interactions between hosts and viral pathogens. This opens new possibilities to use different tools to modulate the intestinal microbial composition, aimed at reducing the risk of or treating viral enteric infections., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The diagnosis, treatment, and prevention of infectious diseases in older adults in long-term care facilities (LTCFs), particularly nursing facilities, remains a challenge for all health providers who care for this population. This review provides updated information on the currently most important challenges of infectious diseases in LTCFs. With the increasing prescribing of antibiotics in older adults, particularly in LTCFs, the topic of antibiotic stewardship is presented in this review. Following this discussion, salient points on clinical relevance, clinical presentation, diagnostic approach, therapy, and prevention are discussed for skin and soft tissue infections, infectious diarrhea (Clostridium difficile and norovirus infections), bacterial pneumonia, and urinary tract infection, as well as some of the newer approaches to preventive interventions in the LTCF setting., (© 2018, Copyright the Authors Journal compilation © 2018, The American Geriatrics Society.)

Background: The burden of medically-attended acute gastro-enteritis (MA-AGE) that can be attributed to norovirus is not well established in Japan. Using a nationwide database of medical care insurance claims, we estimated the incidence of medically-attended norovirus-attributable gastroenteritis (MA-NGE) in Japan., Methods: The incidences of MA-NGE outpatient consultations or hospitalization in Japan were modelled on seasonal patterns of MA-AGE for unspecified causes derived from the Japan Medical Data Center (JMDC) database for the period July 2007 to June 2015., Results: Mean age-adjusted annual incidence rates (per 10,000 person-years) of MA-NGE associated with outpatient care or hospitalization were 389 (95% CI 269-558) and 13 (95% CI 9-20), respectively. Highest rates were in children under 5 years of age: 1,569 (95% CI 1,325-1,792) for outpatient consultations and 48 (95% CI 39-56) for hospitalizations. Of all gastroenteritis episodes associated with outpatient care or hospitalization, 29% and 31% were attributed to norovirus, respectively. Norovirus was estimated to be responsible for 4,964,000 outpatient visits (95% CI 3,435,000-7,123,000) and 171,000 hospitalizations (95% CI 110,000-251,000) per year across Japan., Conclusions: Incidence rates of MA-AGE are high in Japan, and norovirus-attributable disease is at least as high as in some other developed countries.

Possible mechanisms that lead to inactivation of feline calicivirus (FCV) by cold atmospheric-pressure plasma (CAP) generated in 99% argon-1% O2 admixture were studied. We evaluated the impact of CAP exposure on the FCV viral capsid protein and RNA employing several cultural, molecular, proteomic and morphologic characteristics techniques. In the case of long exposure (2 min) to CAP, the reactive species of CAP strongly oxidized the major domains of the viral capsid protein (VP1) leading to disintegration of a majority of viral capsids. In the case of short exposure (15 s), some of the virus particles retained their capsid structure undamaged but failed to infect the host cells in vitro. In the latter virus particles, CAP exposure led to the oxidation of specific amino acids located in functional peptide residues in the P2 subdomain of the protrusion (P) domain, the dimeric interface region of VP1 dimers, and the movable hinge region linking the S and P domains. These regions of the capsid are known to play an essential role in the attachment and entry of the virus to the host cell. These observations suggest that the oxidative effect of CAP species inactivates the virus by hindering virus attachment and entry into the host cell. Furthermore, we found that the oxidative impact of plasma species led to oxidation and damage of viral RNA once it becomes unpacked due to capsid destruction. The latter effect most likely plays a secondary role in virus inactivation since the intact FCV genome is infectious even after damage to the capsid.

In immunocompromised patients, the NoV infection is prolonged and severe. We retrospectively studied the severity of the NoV infection in children after an ITx, the treatment, and the long-term evolution. Norovirus PCR in stools was positive for 19 children in 21 separate episodes. The infection was symptomatic in 18 cases. At diagnosis, the median weight loss was 5% (0-11) and the creatinine clearance was 75 mL/min/1.73 m 2 (19-142). On 14 digestive biopsies, the pathological findings were non-specific with a constant mononuclear infiltration, showing signs of rejection in one case. Fifteen children in 17 cases were hospitalized for a median duration of 41 days (0-119) with IV infusions for 33 days (0-120). The viral shedding lasted 78 days (20-360). Nine children with severe or prolonged diarrhea received intravenous IGs and four of them additional NTZ. On follow-up, five other children developed a rejection 12 months (1-33) after NoV infection. Four uncontrolled rejections led to graft removal. Children mostly needed hospital admission and IV rehydration, but the symptoms upon presentation were moderate. Symptoms and shedding durations are prolonged as expected. The treatment efficacy cannot be assessed. The rejection induction by the NoV cannot be excluded., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Norovirus has become increasingly recognized as causing viral gastroenteritis in children. Few data are available on the characteristics of children admitted to pediatric emergency departments with norovirus gastroenteritis and accompanying seizures. Our aim in this study was to describe the clinical features of, and risk factors for, seizures accompanying norovirus gastroenteritis. We collected 6359 stool samples from patients with gastroenteritis, of whom 1444 (22.71%) had laboratory-confirmed norovirus gastroenteritis. Of all patients, 108 (7.48%) children exhibited norovirus gastroenteritis and seizures; 49 (45.4%) were febrile, and 59 (54.6%) afebrile. The mean patient age was 2.31 ± 2.12 years; most were <5 years of age (92.6%). The afebrile group had a significantly higher incidence of 2 or more seizures than the febrile subjects ( P = .004). Early recognition and prompt treatment of convulsions associated with norovirus gastroenteritis in children are important. Future studies might explore the long-term prognoses of these patients.

Aims: The aim of these guidelines is to update and extend evidence-based recommendations for the diagnosis and management of children with acute gastroenteritis (AGE) in Israel, based on new data and the recently published European update., Methods: The recommendations, which are based on a systematic review of the literature, were graded by the level of evidence. The guidelines were endorsed by the Israeli societies for Pediatric Gastroenterology, Pediatric Infectious Diseases and the Israeli Association of Pediatrics., Results: Gastroenteritis severity is mainly linked to etiology, and rotavirus is most frequently associated with dehydration. Dehydration reflects severity and should be monitored by established score systems. Laboratory tests are generally not needed. Oral rehydration with hypo-osmolar solution is the major treatment and should start as soon as possible. Breast-feeding should not be interrupted; regular feeding should usually be continued with no dietary changes including milk. Data suggest that in the hospital setting, in non-breast-fed infants and young children, lactose-free feeds can be considered in the management of gastroenteritis. Antimicrobial therapy should be given in exceptional cases. Hospitalization should generally be reserved for children requiring enteral/parenteral rehydration, and most cases may be managed in an outpatients setting. Enteral rehydration is superior to intravenous rehydration., Conclusions: Implementation of the scientifically-based guidelines in clinical practice may improve the standard of care of pediatric AGE in Israel.

Photodynamic inactivation (PDI) is extensively used to inactivate different type of pathogens through the use of photosensitizers (PS). Curcumin has been identified as an excellent natural photosensitizer with some potential applications in the food industry. The aim of this study was to assess the antiviral activity of photoactivated curcumin on norovirus surrogates, feline calicivirus (FCV), and murine norovirus (MNV). Initially, different concentrations of curcumin (13.5-1358 µM) were individually mixed with each virus at titers of ca. 6-7 log TCID 50 /ml and photoactivated by LED blue light with light dose of 3 J/cm 2 . Results showed that photoactivated curcumin at 50 µg/mL reduced FCV titers by almost 5 log after incubation at 37 °C for 30 min. Lower antiviral activity (0.73 log TCID 50 /mL reduction) was reported for MNV. At room temperature, curcumin at 5 µg/mL reduced FCV titers by 1.75 log TCID 50 /mL. These results represent a step forward in improving food safety using photoactivated curcumin as an alternative natural additive to reduce viral contamination.

Transplant patients are at increased risk for developing severe norovirus (NoV) infections with secondary complications such as rejection episodes and acute transplant failure. This single-center retrospective study included all kidney transplant patients tested positive for NoV RNA between January 2007 and December 2011. Data were compared to a control group of 528 kidney transplant patients without NoV infection. Sixty-five kidney transplant patients were recorded NoV RNA positive. Of these, 26 patients (40%) presented with acute transplant failure (AKI). In 43 patients (66.2%), dose reduction in immunosuppression was performed, and of 22 patients receiving tacrolimus, four patients (18.2%) showed toxic trough levels above 15 ng/mL at time of diagnosis. In three patients (4.6%), indicated therapeutic procedures had to be postponed due to prolonged severe diarrhea. Ten patients (15.4%) developed chronic NoV infection. One-year patient and graft survival in NoV patients and controls was 92.3% and 96.4%, respectively (n.s.). Compared to controls, eGFR was already significantly lower before NoV infection and loss of eGFR relative to baseline over 12 and 36 months was significantly higher in NoV-infected patients. In particular, patients initially presenting with AKI experienced a long-term loss of transplant function. Risk factors for NoV infection were immunosuppression containing steroids and antirejection therapy., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Noroviruses have emerged as one of the leading causes of viral gastroenteritis worldwide, affecting community-dwelling and institutionalized older adults. Recent global epidemics present a growing challenge to the healthcare system and to long-term care facilities. Noroviruses spread readily and rapidly through multiple routes (e.g., person-to-person contact, contact with contaminated surfaces, airborne dissemination of vomitus) and thus are able to sustain an epidemic efficiently and successfully. Although norovirus gastroenteritis is a short self-limited illness in healthy immunocompetent individuals, it can result in significant morbidity and mortality in vulnerable compromised persons such as frail elderly persons and older residents of nursing homes. Diagnosis is made by clinical assessment and confirmed primarily by stool evaluation using polymerase chain reaction. Treatment is confined to supportive measures. Public health prevention and control strategies provide guidance regarding surveillance and the necessary steps to curb the clinical effect and spread of norovirus infections in various settings, including long-term care., (© 2016, Copyright the Authors Journal compilation © 2016, The American Geriatrics Society.)

The protein 3D8 single-chain variable fragment (3D8 scFv) has potential anti-viral activity due to its ability to penetrate into cells and hydrolyze nucleic acids. Probiotic Lactobacillus paracasei engineered to secrete 3D8 scFv for oral administration was used to test the anti-viral effects of 3D8 scFv against gastrointestinal virus infections. We found that injection of 3D8 scFv into the intestinal lumen resulted in the penetration of 3D8 scFv into the intestinal villi and lamina propria. 3D8 scFv secreted from engineered L. paracasei retained its cell-penetrating and nucleic acid-hydrolyzing activities, which were previously shown with 3D8 scFv expressed in Escherichia coli. Pretreatment of RAW264.7 cells with 3D8 scFv purified from L. paracasei prevented apoptosis induction by murine norovirus infection and decreased messenger RNA (mRNA) expression of the viral capsid protein VP1. In a mouse model, oral administration of the engineered L. paracasei prior to murine norovirus infection reduced the expression level of mRNA encoding viral polymerase. Taken together, these results suggest that L. paracasei secreting 3D8 scFv provides a basis for the development of ingestible anti-viral probiotics active against gastrointestinal viral infection.

Norovirus, an RNA virus of the family Caliciviridae, is a human enteric pathogen that causes substantial morbidity across both health care and community settings. Several factors enhance the transmissibility of norovirus, including the small inoculum required to produce infection (<100 viral particles), prolonged viral shedding, and its ability to survive in the environment. In this review, we describe the basic virology and immunology of noroviruses, the clinical disease resulting from infection and its diagnosis and management, as well as host and pathogen factors that complicate vaccine development. Additionally, we discuss overall epidemiology, infection control strategies, and global reporting efforts aimed at controlling this worldwide cause of acute gastroenteritis. Prompt implementation of infection control measures remains the mainstay of norovirus outbreak management., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

A commercial hyperimmune serum, containing antibodies against feline calicivirus (FCV), feline herpesvirus 1 (FHV-1), and feline panleukopenia virus, is available for treatment of cats with feline upper respiratory tract disease (FURTD), but its efficacy has not been rigorously evaluated in scientific studies. The aim of this randomised, placebo-controlled, double-blind clinical trial was to evaluate the efficacy of passive immunisation in cats with acute viral FURTD caused by FCV and/or FHV-1 infection. All cats received symptomatic treatment during the study period. Hyperimmune serum was administered to one group (n = 22) and an equivalent amount of saline was administered to the control group (n = 20) as placebo, for 3 consecutive days. In the treatment group, cats ≤12 weeks old received 2 mL, cats >12 weeks old received 4 mL, subcutaneously once daily and topically into eyes, nostrils, and mouth every 8 h. Clinical signs, including a 'FURTD score' and general health status, were recorded daily for 8 days and again on day 21. FCV shedding was determined by quantitative PCR on days 0 and 21. Clinical signs and health status in both groups improved significantly over time (P < 0.001). Cats receiving hyperimmune serum significantly improved in terms of 'FURTD score' (P = 0.046) and general health status (P = 0.032) by day 3, while cats in the placebo group only improved significantly by day 7. There was no significant difference in the number of cats shedding FCV between the two groups. Thus, administration of hyperimmune serum led to a more rapid improvement of clinical signs in cats with acute viral FURTD, but by day 7, clinical signs had improved equally in both groups., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Noroviruses (NoVs) are among the most frequent causes of acute pediatric gastroenteritis. Although the disease is often self-limiting and recovery is the rule, it constitutes an important health problem because of its highly contagious nature and the high rate of morbidity. NoVs are responsible for 47-96 % of outbreaks of acute pediatric gastroenteritis, and 5-36 % of sporadic cases. NoV-induced gastroenteritis is a frequent cause of hospitalization, and severe and sometimes fatal cases have been reported in immunocompromised children. The increasing recognition of NoVs as the cause of pediatric disease and the limited success in preventing outbreaks have led to consideration of vaccines. However, while awaiting the development of a vaccine, there is an urgent need for more epidemiological data concerning childhood NoV infection, including the impact of NoVs on different age groups, the possible etiological role of NoVs in infections other than gastroenteritis, and the socioeconomic impact of NoVs on households.

Norovirus are the most frequent causes of epidemic gastroenteritis. Infections generally resolve spontaneously, but may lead to severe complications including death, or become chronic in immunocompromised hosts. Complications preferentially occur in immunocompromised hosts and their consequences are sometimes severe in vulnerable individuals living in confined spaces, such as healthcare settings. Norovirus have a high capacity to mutate. This and their capacity to persist in the water and on everyday objects of our surroundings favor the occurrence of epidemics. As a vaccination protective against most relevant strains is currently not available and in view of their high contagiousness, the prevention and control of the norovirus gastroenteritis remains a major clinical challenge.

Norovirus infection causes a significant burden of morbidity and (in the developing world) mortality. In immunocompromised hosts, norovirus infection can become chronic, with devastating consequences. Unfortunately, therapeutic options for chronic disease are unproven, and treatment is largely supportive. We report a case of norovirus infection causing debilitating chronic gastroenteritis in a transplant patient that responded to a short course of enterally administered human immune globulin., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Passive immunoprophylaxis or immunotherapy with norovirus-neutralizing monoclonal antibodies (MAbs) could be a useful treatment for high-risk populations, including infants and young children, the elderly, and certain patients who are debilitated or immunocompromised. In order to obtain antinorovirus MAbs with therapeutic potential, we stimulated a strong adaptive immune response in chimpanzees to the prototype norovirus strain Norwalk virus (NV) (genogroup I.1). A combinatorial phage Fab display library derived from mRNA of the chimpanzees' bone marrow was prepared, and four distinct Fabs reactive with Norwalk recombinant virus-like particles (rVLPs) were recovered, with estimated binding affinities in the subnanomolar range. Mapping studies showed that the four Fabs recognized three different conformational epitopes in the protruding (P) domain of NV VP1, the major capsid protein. The epitope of one of the Fabs, G4, was further mapped to a specific site involving a key amino acid residue, Gly365. One additional specific Fab (F11) was recovered months later from immortalized memory B cells and partially characterized. The anti-NV Fabs were converted into full-length IgG (MAbs) with human γ1 heavy chain constant regions. The anti-NV MAbs were tested in the two available surrogate assays for Norwalk virus neutralization, which showed that the MAbs could block carbohydrate binding and inhibit hemagglutination by NV rVLP. By mixing a single MAb with live Norwalk virus prior to challenge, MAbs D8 and B7 neutralized the virus and prevented infection in a chimpanzee. Because chimpanzee immunoglobulins are virtually identical to human immunoglobulins, these chimpanzee anticapsid MAbs may have a clinical application.

Although recognized as the leading cause of epidemic acute gastroenteritis across all age groups, norovirus has remained poorly characterized with respect to its endemic disease incidence. Use of different methods, including attributable proportion extrapolation, population-based surveillance, and indirect modeling, in several recent studies has considerably improved norovirus disease incidence estimates for the United States. Norovirus causes an average of 570-800 deaths, 56,000-71,000 hospitalizations, 400,000 emergency department visits, 1.7-1.9 million outpatient visits, and 19-21 million total illnesses per year. Persons >65 years of age are at greatest risk for norovirus-associated death, and children <5 years of age have the highest rates of norovirus-associated medical care visits. Endemic norovirus disease occurs year round but exhibits a pronounced winter peak and increases by ≤ 50% during years in which pandemic strains emerge. These findings support continued development and targeting of appropriate interventions, including vaccines, for norovirus disease.

Viral gastroenteritis is extremely common, causing millions of cases of diarrhea in all age groups worldwide. Norovirus has been identified as the leading cause of viral gastroenteritis in the adult population. The combination of a low infectious dose, viral shedding before and for weeks after illness, and resistance to temperatures from freezing to 60°C and to many common household cleaners makes norovirus a winter peril. Mild disease requires symptomatic treatment alone. Complicated cases develop severe dehydration and hypovolemia, requiring the skills of critical care nurses to meet the challenges of care. This article addresses diagnosis and prevention strategies., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Aim: Noroviruses are considered as a major cause of acute gastroenteritis in childhood worldwide. This prospective study was undertaken to investigate the frequency and clinical features of norovirus infections in children aged less than 5 years with acute gastroenteritis in Greece., Methods: Routine stool samples were obtained from 227 children, 119 boys and 108 girls, with acute gastroenteritis, who attended a tertiary paediatric hospital in Athens during the period November 2008 - October 2009. All specimens were tested for the presence of norovirus, rotavirus and adenovirus antigens using validated enzyme-linked immunoassays., Results: Norovirus was detected in 8 (7.9%) out of 101 children during the period November 2008 to April 2009, while the respective rate during the period May 2009 to October 2009 was 1/126 (0.8%). In the total sample, rotavirus was detected in 56 (24.7%) children and adenovirus in 5 (2.2%) children. Three (1.3%) samples grew Campylobacter jejuni, while 6 (2.6%) samples grew Salmonella. In all cases, norovirus was detected as a unique viral pathogen. Among norovirus-positive children, who required hospitalization, the median duration of intravenous fluid administration was 3.5 days. The median duration of hospitalization was 4 days (range 3 days to 5 days) and did not differ from the duration of hospitalization of rotavirus-positive children., Conclusion: Our results suggest norovirus as the second most common cause of community-acquired acute gastroenteritis in children in Greece, following rotavirus. We highlight the need to implement norovirus detection assays for the clinical diagnosis and the prevention of viral gastroenteritis in paediatric departments.

Feline calicivirus (FCV) is a pathogenic microorganism that causes upper respiratory diseases in cats. Recently, an FCV infection with a high mortality rate has been confirmed, and there is need to develop a treatment for cases of acute infection. We evaluated whether the replication of FCV could be prevented by RNA interference. For this study, we designed an siRNA targeted to the polymerase region of the strain FCV-B isolated from a cat that died after exhibiting neurological symptoms. Cells transfected with siR-pol dose-dependently suppressed the replication of FCV-B. siR-pol suppressed its replication by suppressing the target viral RNA.

Diarrhea is a frequent complication among hospitalized patients. Nosocomial diarrhea is generally diagnosed as increased frequency and decreased consistency of stools developing after 72 hours of hospitalization. The causes of nosocomial diarrhea may be infectious or noninfectious. Noninfectious etiologies occur most commonly, and are often adverse effects of medications or enteral nutrition therapies. Infectious etiologies are most concerning and include Clostridium difficile and norovirus. Patients with nosocomial diarrhea should be placed in isolation with contact precautions in place until the presence of C difficile infection is determined. Irrespective of etiology, diarrhea can cause serious complications in hospitalized patients, including malnutrition, hemodynamic instability, metabolic acidosis, and potentially fatal pseudomembranous colitis. This article reviews nosocomial diarrhea, including its pathophysiology, infectious and noninfectious causes, and treatment strategies based on identified cause.