Cases of acute gastroenteritis due to calicivirus in outbreaks: clinical differences by age and aetiological agent

Comparative study on epidemiological and etiological characteristics of patients with acute diarrhea with febrile or non-febrile symptoms in China

BACKGROUND

Acute diarrhea with fever can potentially represent a more severe form of the disease compared to non-febrile diarrhea. This study was to investigate the epidemiological characteristics and enteric pathogen composition of febrile-diarrheal patients, and to explore factors including pathogens associated with fever by age group.

METHODS

A nationwide surveillance study of acute diarrheal patients of all ages was conducted in 217 sentinel hospitals from 31 provinces (autonomous regions or municipalities) in China between 2011 and 2020. Seventeen diarrhea-related pathogens, including seven viruses and ten bacteria, were investigated and their association with occurrence of fever symptoms was assessed using multivariate logistic analysis.

RESULTS

A total of 146,296 patients with acute diarrhea (18.6% with fever) were tested. Th diarrheal children below 5 years had the highest frequency of fever (24.2%), and related to significantly higher prevalence of viral enteropathogens (40.2%) as compared with other age groups (P < 0.001). Within each age group, the febrile-diarrheal patients were associated with a significantly higher prevalence of bacterial pathogens than afebrile-diarrheal patients (all P < 0.01). There was discrepancy when each pathogen was compared, i.e., nontyphoidal Salmonella (NTS) was overrepresented in febrile vs non-febrile patients of all age groups, while the febrile vs non-febrile difference for diarrheagenic Escherichia coli (DEC) was only significant for adult groups. The multivariate analysis revealed significant association between fever and infection with rotavirus A among children [odds ratio (OR) = 1.60], for DEC in adult groups (OR = 1.64), for NTS in both children (OR = 2.95) and adults (OR = 3.59).

CONCLUSIONS

There are significant discrepancy of the infected enteric pathogens in patients with acute diarrhea with fever between age groups, and it is valuable for priority detection of NTS and rotavirus A in patients with children < 5 years old and NTS and DEC in adult patients. The results may be useful in identifying dominant pathogen candidates for the application of diagnostic assays and prevention control.

Atypical Viral Infections in Gastroenterology

Enteric viruses are commonly found obligate parasites in the gastrointestinal (GI) tract. These viruses usually follow a fecal-oral route of transmission and are characterized by their extraordinary stability as well as resistance in high-stress environments. Most of them cause similar symptoms including vomiting, diarrhea, and abdominal pain. In order to come in contract with mucosal surfaces, these viruses need to pass the three main lines of defense: mucus layer, innate immune defenses, and adaptive immune defenses. The following atypical gastrointestinal infections are discussed: SARS-CoV2, hantavirus, herpes simplex virus I, cytomegalovirus, and calicivirus. Dysbiosis represents any modification to the makeup of resident commensal communities from those found in healthy individuals and can cause a patient to become more susceptible to bacterial and viral infections. The interaction between bacteria, viruses, and host physiology is still not completely understood. However, with growing research on viral infections, dysbiosis, and new methods of detection, we are getting closer to understanding the nature of these viruses, their typical and atypical characteristics, long-term effects, and mechanisms of action in different organ systems.

Global molecular prevalence and genotype distribution of Sapovirus in children with gastrointestinal complications: A systematic review and meta-analysis

Sapovirus (SaV) is an emerging cause of children gastrointestinal complications such as acute gastroenteritis (AGE). The aim of the present systematic review and meta-analysis was to estimate the global prevalence of the SaV in children and association of infection with SaVs and AGE in children based on case-control studies. Four international databases (PubMed, Scopus, Web of Sciences and Google Scholar) were used to retrieve English-language studies published between January 2000 and December 2020. Comprehensive Meta-Analysis software was applied to estimate the overall prevalence, publication bias and heterogeneity index. The pooled prevalence of SaV infection among children with gastroenteritis was 3.4% [95% confidence interval (CI): 2.9%-3.9%] based on a random-effects meta-analysis. Genogroup I was the dominant genogroup of SaV in children with gastroenteritis [2.2% (95% CI: 1.6%-3.0%)], association analysis showed that SaV was associated with gastroenteritis [OR: 1.843 (95% CI: 1.27-2.66)]. Given the significant prevalence of the virus in children, it is necessary to pay more attention to this situation. Therefore, preventive health measures in children should be a priority.

Clinical Profiles of Childhood Astrovirus-, Sapovirus-, and Norovirus-Associated Acute Gastroenteritis in Pediatric Emergency Departments in Alberta, 2014-2018

BACKGROUND

Infections by previously underdiagnosed viruses astrovirus and sapovirus are poorly characterized compared with norovirus, the most common cause of acute gastroenteritis.

METHODS

Children <18 years old with acute gastroenteritis were recruited from pediatric emergency departments in Alberta, Canada between 2014 and 2018. We described and compared the clinical course of acute gastroenteritis in children with astrovirus, sapovirus, and norovirus.

RESULTS

Astrovirus was detected in 56 of 2688 (2.1%) children, sapovirus was detected in 146 of 2688 (5.4%) children, and norovirus was detected in 486 of 2688 (18.1%) children. At illness onset, ~60% of astrovirus cases experienced both diarrhea and vomiting. Among sapovirus and norovirus cases, 35% experienced diarrhea at onset and 80% of 91% (sapovirus/norovirus) vomited; however, diarrhea became more prevalent than vomiting at approximately day 4 of illness. Over the full course of illness, diarrhea was 18% (95% confidence interval [CI], 8%- 29%) more prevalent among children with astrovirus than norovirus infections and had longer duration with greater maximal events; there were a median of 4.0 fewer maximal vomiting events (95% CI, 2.0-5.0). Vomiting continued for a median of 24.8 hours longer (95% CI, 9.6-31.7) among children with sapovirus versus norovirus. Differences between these viruses were otherwise minimal.

CONCLUSIONS

Sapovirus infections attended in the emergency department are more similar to norovirus than previously reported, whereas astrovirus infections have several distinguishable characteristics.

Porcine Sapovirus-Induced Tight Junction Dissociation via Activation of RhoA/ROCK/MLC Signaling Pathway

Tight junctions (TJs) are a major barrier and also an important portal of entry for different pathogens. Porcine sapovirus (PSaV) induces early disruption of the TJ integrity of polarized LLC-PK cells, allowing it to bind to the buried occludin co-receptors hidden beneath the TJs on the basolateral surface. However, the signaling pathways involved in the PSaV-induced TJ dissociation are not yet known. Here, we found that the RhoA/ROCK/MLC signaling pathway was activated in polarized LLC-PK cells during the early infection of PSaV Cowden strain in the presence of bile acid. Specific inhibitors of RhoA, ROCK, and MLC restored PSaV-induced reduction of transepithelial resistance, increase of paracellular flux, intracellular translocation of occludin, and lateral membrane lipid diffusion. Moreover, each inhibitor significantly reduced PSaV replication, as evidenced by a reduction in viral protein synthesis, genome copy number, and progeny viruses. The PKC/MLCK and RhoA/ROCK/MYPT signaling pathways, known to dissociate TJs, were not activated during early PSaV infection. Among the above signaling pathways, the RhoA/ROCK/MLC signaling pathway was only activated by PSaV in the absence of bile acid, and specific inhibitors of this signaling pathway restored early TJ dissociation. Our findings demonstrate that PSaV binding to cell surface receptors activates the RhoA/ROCK/MLC signaling pathway, which in turn disrupts TJ integrity via the contraction of the actomyosin ring. Our study contributes to understanding how PSaV enters the cells and will aid in developing efficient and affordable therapies against PSaV and other calicivirus infections.IMPORTANCEPorcine sapovirus (PSaV), one of the most important enteric pathogens, is known to disrupt tight junction (TJ) integrity to expose its buried co-receptor occludin in polarized LLC-PK cells. However, the cellular signaling pathways that facilitate TJ dissociation are not yet completely understood. Here, we demonstrate that early infection of PSaV in polarized LLC-PK cells in either the presence or absence of bile acids activates the RhoA/ROCK/MLC signaling pathway, whose inhibitors reverse the early PSaV infection-induced early dissociation of TJs and reduce PSaV replication. However, early PSaV infection did not activate the PKC/MLCK and RhoA/ROCK/MYPT signaling pathways, which are also known to dissociate TJs. This study provides a better understanding of the mechanism involved in early PSaV infection-induced disruption of TJs, which is important for controlling or preventing PSaV and other calicivirus infections.

Epidemiological and Genetic Characterization of Sapovirus in Patients with Acute Gastroenteritis in Valencia (Spain)

Sapovirus is a common cause of acute gastroenteritis in all age groups. Sapovirus infections are seldom investigated in Spain, and its epidemiology in the country is not well known. The use of molecular diagnostic procedures has allowed a more frequent detection of sapoviruses in patients with diarrhea. A total of 2545 stool samples from patients with acute gastroenteritis attended from June 2018 to February 2020 at the Clinic University Hospital in Valencia, Spain, were analyzed by reverse transcription (RT) and real-time multiplex PCR (RT-PCR) to investigate the etiology of enteric infections. Sapovirus was the second enteric virus detected with a positive rate of 8%, behind norovirus (12.2%) and ahead of rotavirus (7.1%), astrovirus (4.9%) and enteric adenoviruses (2.9%). Most sapovirus infections occurred in infants and young children under 3 years of age (74%) with the highest prevalence in autumn and early winter. Coinfections were found in 25% of the patients with sapovirus diarrhea, mainly with other enteric viruses. Genotyping demonstrated the circulation of seven different genotypes during the study period, with a predominance of genotypes GI.1, GI.2, and GII.1. Phylogenetic analysis showed that genogroup GII strains form a cluster separated from genogroup GI and GV, being genotype GV.1 strains related to genotype GI.1 and GI.2 strains.

Genetic analysis of sapoviruses detected in outbreaks and sporadic cases of acute gastroenteritis in Miyagi Prefecture, Japan

BACKGROUND

Human sapovirus (SaV) causes sporadic and endemic acute gastroenteritis worldwide. However, little is known about the relationship between the mode of transmission and genetic characteristics of SaV.

OBJECTIVE

To investigate the molecular characteristics of SaV-associated acute gastroenteritis among sporadic cases, foodborne, and nonfoodborne outbreaks.

STUDY DESIGN

We performed a systematic review of publications and genetic analysis of SaV in fecal specimens from 98 outpatients with acute gastroenteritis, 32 stool samples from 8 foodborne outbreaks, and 63 stool samples from 23 nonfoodborne outbreaks in Miyagi Prefecture, Japan from 1993 and between 2004 and 2020. Reverse transcription polymerase chain reaction (RT-PCR) was employed for the detection of SaV, and the partial capsid gene was sequenced for genotyping and phylogenetic analysis.

RESULTS

The overall detection rate of SaV in sporadic cases, foodborne, and nonfoodborne outbreaks was 5.8, 1.7, and 4.3%, respectively. Genotypic analysis revealed GI.1 to be the predominant genotype in sporadic cases (31.5%) and nonfoodborne outbreaks (52.1%), whereas it was not detected in foodborne outbreaks. Some outbreaks occurred following sporadic cases with the same genotype.

CONCLUSIONS

The distribution of SaV genotypes was different between foodborne outbreaks and other settings. The effective SaV infection control may differ depending on the genomic characteristics.

Genetic recombination and diversity of sapovirus in pediatric patients with acute gastroenteritis in Thailand, 2010-2018

Background

Human sapovirus (SaV) is an etiologic agent of acute gastroenteritis (AGE) in all age groups worldwide. Genetic recombination of SaV has been reported from many countries. So far, none of SaV recombinant strain has been reported from Thailand. This study examined the genetic recombination and genotype diversity of SaV in children hospitalized with AGE in Chiang Mai, Thailand.

Methods

Stool samples were collected from children suffering from diarrhea who admitted to the hospitals in Chiang Mai, Thailand between 2010 and 2018. SaV was detected by RT-PCR and the polymerase and capsid gene sequences were analysed.

Results

From a total of 3,057 samples tested, 50 (1.6%) were positive for SaV. Among positive samples, SaV genotype GI.1 was the most predominant genotype (40%; 20/50), followed by GII.1 and GII.5 (each of 16%; 8/50), GI.2 (14%; 7/50), GIV.1 (4%; 2/50), and GI.5 (2%; 1/50). In addition, 4 SaV recombinant strains of GII.1/GII.4 were identified in this study (8%; 4/50).

Conclusions

The data revealed the genetic diversity of SaV circulating in children with AGE in Chiang Mai, Thailand during 2010 to 2018 and the intragenogroup SaV recombinant strains were reported for the first time in Thailand.

Al-Kasaby N. Molecular Study of Norovirus in Pediatric Patients with Gastroenteritis

Aim:

The aim of the present study was to detect the prevalence of norovirus and genotypes determination by real-time PCR among children below 18 years as an etiology of acute gastroenteritis and to compare rapid detection of norovirus by Enzyme-Linked Immunoassay (ELISA) to virus detection by real-time PCR.

Methods:

The research was a cross-sectional study conducted on children below 18 years complaining of community-acquired acute gastroenteritis. A stool sample was subjected to direct-antigen detection by ELISA for norovirus and molecular study by real-time polymerase chain reaction.

Results:

The study included 200 children with acute gastroenteritis with a mean age of 6.7±3.8 years. Norovirus antigen was detected by EIA in 34.5% and by real-time PCR in 30.5% of studied children with genotype GII, the predominant detected genotype (80.97%). Both real-time PCR and antigen detection of norovirus were positive in 43 (70.5%) of the children and negative in 113(81.3%) of the studied children. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for antigen detection by ELISA were 70.5%, 81.3%, 62.3%, 86.3% and 78%, respectively. Comparison between patients positive for norovirus and those negative for norovirus by real-time PCR revealed non-significant difference as regards age, sex, the season of occurrence and residence.

Conclusion:

The present study highlights that norovirus prevalence is common among pediatric patients with gastroenteritis above 5 years with GII genotype as the prevalent genotype. There was a significant correlation between positive and negative results of antigen detection of norovirus by ELISA and detection of RNA of norovirus by real-time PCR in stool samples. However, the screening for norovirus by ELISA has limited sensitivity and needs to be associated with a molecular method for accurate diagnosis of sporadic cases of gastroenteritis.

Characteristics of Campylobacter and Salmonella Infections and Acute Gastroenteritis in Older Adults in Australia, Canada, and the United States

BACKGROUND

The early detection of enteric infections in older adults is challenging because typical signs and symptoms of disease may be less common, absent, or overlooked. Understanding illness characteristics of enteric infections among older adults could improve the timeliness and accuracy of clinical diagnoses, thereby improving patient outcomes and increasing cases reported to surveillance.

METHODS

Here, we describe illness characteristics (percentage reporting bloody diarrhea, fever, vomiting, abdominal pain; percentage hospitalized; duration of hospitalization; and duration of illness) among older adults (≥65 years) with acute gastroenteritis and culture-confirmed Campylobacter and nontyphoidal Salmonella infections in Australia, Canada, and the United States and compare these characteristics with those among younger people (<5 years, 5-24 years, and 25-64 years).

RESULTS

A significant negative correlation was found between all symptoms and increasing age group, except for bloody diarrhea in cases of acute gastroenteritis. Adults aged ≥85 years reported bloody diarrhea in only 9% of nontyphoidal Salmonella and 4% of Campylobacter infections compared with 59% and 55% among children aged <5 years. Conversely, a greater percentage of older adults (≥65) than younger persons (<5, 5-24, 25-64) reported being hospitalized, with an increasing linear relationship in age groups 65 years and older.

CONCLUSIONS

Although older adults are more likely to have severe illness and be hospitalized, we found that the proportion of persons reporting symptoms typically associated with enteric infections decreases with age. These findings have implications for clinical recognition and treatment of gastrointestinal illness, as well as for public health research.

Phosphatidylinositol 3-Kinase/Akt and MEK/ERK Signaling Pathways Facilitate Sapovirus Trafficking and Late Endosomal Acidification for Viral Uncoating in LLC-PK Cells

Sapovirus, an important cause of acute gastroenteritis in humans and animals, travels from the early to the late endosomes and requires late endosomal acidification for viral uncoating. However, the signaling pathways responsible for these viral entry processes remain unknown. Here we demonstrate the receptor-mediated early activation of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein extracellular signal-regulated kinase/extracellular signal-regulated kinase (MEK/ERK) signaling pathways involved in sapovirus entry processes. Both signaling pathways were activated during the early stage of porcine sapovirus (PSaV) infection. However, depletion of the cell surface carbohydrate receptors by pretreatment with sodium periodate or neuraminidase reduced the PSaV-induced early activation of these signaling pathways, indicating that PSaV binding to the cell surface carbohydrate receptors triggered these cascades. Addition of bile acid, known to be essential for PSaV escape from late endosomes, was also found to exert a stiffening effect to stimulate both pathways. Inhibition of these signaling pathways by use of inhibitors specific for PI3K or MEK or small interfering RNAs (siRNAs) against PI3K or MEK resulted in entrapment of PSaV particles in early endosomes and prevented their trafficking to late endosomes. Moreover, phosphorylated PI3K and ERK coimmunoprecipitated subunit E of the V-ATPase proton pump that is important for endosomal acidification. Based on our data, we conclude that receptor binding of PSaV activates both PI3K/Akt and MEK/ERK signaling pathways, which in turn promote PSaV trafficking from early to late endosomes and acidification of late endosomes for PSaV uncoating. These signaling cascades may provide a target for potent therapeutics against infections by PSaV and other caliciviruses.IMPORTANCE Sapoviruses cause acute gastroenteritis in both humans and animals. However, the host signaling pathway(s) that facilitates host cell entry by sapoviruses remains largely unknown. Here we demonstrate that porcine sapovirus (PSaV) activates both PI3K/Akt and MEK/ERK cascades at an early stage of infection. Removal of cell surface receptors decreased PSaV-induced early activation of both cascades. Moreover, blocking of PI3K/Akt and MEK/ERK cascades entrapped PSaV particles in early endosomes and prevented their trafficking to the late endosomes. PSaV-induced early activation of PI3K and ERK molecules further mediated V-ATPase-dependent late endosomal acidification for PSaV uncoating. This work unravels a new mechanism by which receptor-mediated early activation of both cascades may facilitate PSaV trafficking from early to late endosomes and late endosomal acidification for PSaV uncoating, which in turn can be a new target for treatment of sapovirus infection.

Household transmission of acute gastroenteritis during the winter season in Japan

Objectives

Acute gastroenteritis, including illness caused by norovirus, is sometimes transmissible among susceptible persons who experience close contact, including those within a household, and it disturbs social activities of patients and their family. However, epidemiological assessment of the transmissibility and its heterogeneity has not been conducted. The present study aimed to quantify the frequency of household transmission that was likely caused by norovirus, and characterize its determinants.

Methods

A household survey was conducted, analyzing the history of suspected norovirus infection from January to March, 2017. Noro-like illness was clinically defined as a patient with either: (i) diarrhea or vomiting multiple times a day; or (ii) diarrhea or vomiting persisting for 2 or more days.

Results

Among 380 households, 132 households (34.7%) were eligible for epidemiological analysis, with an estimated secondary attack risk of 13.8% (38/276). Age-specific secondary attack risk was highest among index case patients aged 0 to 14 years (25.8%). The prevalence of vomiting in this age group was higher than in other age groups, with an odds ratio of household transmission estimated at 4.3.

Conclusions

Age-dependent heterogeneity was successfully identified, offering critical insights into future considerations for norovirus control at various social settings.

Epidemiology of Acute Gastroenteritis Outbreaks Caused by Human Calicivirus (Norovirus and Sapovirus) in Catalonia: A Two Year Prospective Study, 2010-2011

Background

The epidemiology of cases of acute gastroenteritis (AGE) of viral etiology is a relevant public health issue. Due to underreporting, the study of outbreaks is an accepted approach to investigate their epidemiology. The objective of this study was to investigate the epidemiological characteristics of AGE outbreaks due to norovirus (NoV) and sapovirus (SV) in Catalonia.

Material and Methods

Prospective study of AGE outbreaks of possible viral etiology notified during two years in Catalonia. NoV and SV were detected by real time reverse transcription polymerase (RT-PCR).

Results

A total of 101 outbreaks were registered affecting a total of 2756 persons and 12 hospitalizations (hospitalization rate: 0.8x1,000,000 persons-year); 49.5% of outbreaks were foodborne, 45.5% person to person and 5% waterborne. The distribution of outbreaks according to the setting showed a predominance of catering services (39.6%), nursing homes and long term care facilities (26.8%) and schools (11.9%). The median number of cases per outbreak was 17 (range 2–191). The total Incidence rate (IR) was 18.3 per 100,000 persons-years (95%CI: 17.6–19.0). The highest IR was in persons aged ≥65 years (43.6x100,000 (95% CI: 41.0–46.2)) (p<0.001). A total of 1065 samples were analyzed with a positivity rate of 60.8%. 98% of positive samples were NoV (GII 56.3%; GI 4.2%; GII+GI 4.2%; non- typable 33.0%). SV was identified in two person-to-person transmission outbreaks in children.

Conclusions

These results confirm the relevance of viral AGE outbreaks, both foodborne and person-to-person, especially in institutionalized persons. SV should be taken into account when investigating viral AGE outbreaks.

Three gastroenteritis outbreaks in South Korea caused by the consumption of kimchi tainted by norovirus GI.4

BACKGROUND

In April 2013, outbreaks of acute gastroenteritis were reported at three schools in Jeonju, South Korea. Epidemiological investigations were performed to characterize the outbreaks and implement appropriate control measures.

MATERIALS AND METHODS

Retrospective cohort studies were performed at these schools. Stool and environmental samples were collected for bacterial and viral assessment. A food supplier of the schools, food company X, was inspected, and samples of cabbage kimchi and groundwater were tested for norovirus by real-time reverse-transcriptase polymerase chain reaction. The relatedness of the detected norovirus strains was evaluated by phylogenetic analysis.

RESULTS

Of the 3347 questionnaires distributed, 631 (attack rate: 18.9%) met the case definition. Among the consumed food items, kimchi products (i.e., cabbage and fresh kimchi) were significantly associated with illness. The kimchi products were supplied by food company X. Among stool samples from 95 students and 34 food handlers at the 3 schools, 39 (41.1%) and 14 (41.2%) samples, respectively, were positive for norovirus. The samples of groundwater and cabbage kimchi at food company X were positive for norovirus. The predominant genotype of norovirus detected in the patient, groundwater, and cabbage kimchi samples, GI.4, shared high nucleotide identity.

CONCLUSIONS

Kimchi products tainted with norovirus GI.4 from contaminated groundwater were linked to the acute gastroenteritis outbreaks. Therefore, kimchi manufacturers in South Korea should apply chlorine disinfection when using groundwater. Moreover, more stringent sanitation requirements and strict regulations for food companies are recommended.

Economic costs of outbreaks of acute viral gastroenteritis due to norovirus in Catalonia (Spain), 2010-2011

Background

To determine the direct and indirect costs of outbreaks of acute viral gastroenteritis (AVG) due to norovirus in closed institutions (hospitals, social health centers or nursing homes) and the community in Catalonia in 2010–11.

Methods

Information on outbreaks were gathered from the reports made by epidemiological surveillance units. Direct costs (medical visits, hospital stays, drug treatment, sample processing, transport, diagnostic tests, monitoring and control of the outbreaks investigated) and indirect costs (lost productivity due to work absenteeism, caregivers time and working hours lost due to medical visits) were calculated.

Results

Twenty-seven outbreaks affecting 816 people in closed institutions and 74 outbreaks affecting 1,940 people in the community were detected. The direct and indirect costs of outbreaks were € 131,997.36 (€ 4,888.79 per outbreak) in closed institutions and € 260,557.16 (€ 3,521.04 per outbreak) in community outbreaks. The cost per case was € 161.76 in outbreaks in closed institutions and € 134.31 in community outbreaks. The main costs were surveillance unit monitoring (€ 116,652.93), laboratory diagnoses (€ 119,950.95), transport of samples (€ 69,970.90), medical visits (€ 25,250.50) and hospitalization (€ 13,400.00).

Conclusions

The cost of outbreaks of acute viral gastroenteritis due to norovirus obtained in this study was influenced by the number of people affected and the severity of the outbreak, which determined hospitalizations and work absenteeism. Urgent reporting of outbreaks would allow the implementation of control measures that could reduce the numbers affected and the duration of the illness and thus the costs derived from them.

A cost benefit analysis of the Luminex xTAG Gastrointestinal Pathogen Panel for detection of infectious gastroenteritis in hospitalised patients

OBJECTIVES

Recent advances in the laboratory detection of infectious diarrhoea allow more rapid and sensitive identification of infected patients. Several commercial multiplex molecular panels are now available and may have significant advantages over culture based techniques. Faster and more sensitive testing of hospitalised patients with suspected infectious gastroenteritis could result in significant efficiencies in the utilisation of isolation facilities, however few studies have examined this potential benefit. We studied the potential clinical and cost benefits of a commercially available molecular panel.

METHODS

An eight-month parallel diagnostic study was conducted to measure potential economic benefits of testing hospitalised patients with the Luminex xTAG Gastrointestinal Pathogen Panel (GPP) compared with conventional laboratory testing (based on a combination of culture, microscopy and enzyme immunoassay). Laboratory testing costs and patient isolation costs were measured or estimated for 800 patients.

RESULTS

Although costing an additional £22,283, use of GPP could enable a reduction in isolation time from 2202 to 1447 days, a saving of £66,765, which more than offsets the additional laboratory testing costs.

CONCLUSION

Syndromic testing of patients against a broad panel of organisms using a multiplex molecular panel can both improve detection rates and allow better laboratory workflow practices. Removing patients testing negative using this panel could result in significant patient isolation savings.

Sapovirus translation requires an interaction between VPg and the cap binding protein eIF4E

Sapoviruses of the Caliciviridae family of small RNA viruses are emerging pathogens that cause gastroenteritis in humans and animals. Molecular studies on human sapovirus have been hampered due to the lack of a cell culture system. In contrast, porcine sapovirus (PSaV) can be grown in cell culture, making it a suitable model for understanding the infectious cycle of sapoviruses and the related enteric caliciviruses. Caliciviruses are known to use a novel mechanism of protein synthesis that relies on the interaction of cellular translation initiation factors with the virus genome-encoded viral protein genome (VPg) protein, which is covalently linked to the 5′ end of the viral genome. Using PSaV as a representative member of the Sapovirus genus, we characterized the role of the viral VPg protein in sapovirus translation. As observed for other caliciviruses, the PSaV genome was found to be covalently linked to VPg, and this linkage was required for the translation and the infectivity of viral RNA. The PSaV VPg protein was associated with the 4F subunit of the eukaryotic translation initiation factor (eIF4F) complex in infected cells and bound directly to the eIF4E protein. As has been previously demonstrated for feline calicivirus, a member of the Vesivirus genus, PSaV translation required eIF4E and the interaction between eIF4E and eIF4G. Overall, our study provides new insights into the novel mechanism of sapovirus translation, suggesting that sapovirus VPg can hijack the cellular translation initiation mechanism by recruiting the eIF4F complex through a direct eIF4E interaction.

IMPORTANCE Sapoviruses, which are members of the Caliciviridae family, are one of the causative agents of viral gastroenteritis in humans. However, human sapovirus remains noncultivable in cell culture, hampering the ability to characterize the virus infectious cycle. Here, we show that the VPg protein from porcine sapovirus, the only cultivatable sapovirus, is essential for viral translation and functions via a direct interaction with the cellular translation initiation factor eIF4E. This work provides new insights into the novel protein-primed mechanism of calicivirus VPg-dependent translation initiation.