Salivirus in Children and Its Association with Childhood Acute Gastroenteritis: A Paired Case-Control Study

Ten different viral agents infecting and co-infecting children with acute gastroenteritis in Southern Italy: Role of known pathogens and emerging viruses during and after COVID-19 pandemic

Acute gastroenteritis (AGE) represents a world public health relevant problem especially in children. Enteric viruses are the pathogens mainly involved in the episodes of AGE, causing about 70.00% of the cases. Apart from well-known rotavirus (RVA), adenovirus (AdV) and norovirus (NoV), there are various emerging viral pathogens potentially associated with AGE episodes. In this study, the presence of ten different enteric viruses was investigated in 152 fecal samples collected from children hospitalized for gastroenteritis. Real time PCR results showed that 49.3% of them were positive for viral detection with the following prevalence: norovirus GII 19.7%, AdV 15.8%, RVA 10.5%, human parechovirus (HPeV) 5.3%, enterovirus (EV) 3.3%, sapovirus (SaV) 2.6%. Salivirus (SalV), norovirus GI and astrovirus (AstV) 1.3% each, aichivirus (AiV) found in only one patient. In 38.2% of feces only one virus was detected, while co-infections were identified in 11.8% of the cases. Among young patients, 105 were ≤5 years old and 56.0% tested positive for viral detection, while 47 were >5 years old with 40.0% of them infected. Results obtained confirm a complex plethora of viruses potentially implicated in gastroenteritis in children, with some of them previously known for other etiologies but detectable in fecal samples. Subsequent studies should investigate the role of these viruses in causing gastroenteritis and explore the possibility that other symptoms may be ascribed to multiple infections.

Wastewater-based epidemiology applied at the building-level reveals distinct virome profiles based on the age of the contributing individuals

BACKGROUND

Human viruses released into the environment can be detected and characterized in wastewater. The study of wastewater virome offers a consolidated perspective on the circulation of viruses within a population. Because the occurrence and severity of viral infections can vary across a person's lifetime, studying the virome in wastewater samples contributed by various demographic segments can provide valuable insights into the prevalence of viral infections within these segments. In our study, targeted enrichment sequencing was employed to characterize the human virome in wastewater at a building-level scale. This was accomplished through passive sampling of wastewater in schools, university settings, and nursing homes in two cities in Catalonia. Additionally, sewage from a large urban wastewater treatment plant was analysed to serve as a reference for examining the collective excreted human virome.

RESULTS

The virome obtained from influent wastewater treatment plant samples showcased the combined viral presence from individuals of varying ages, with astroviruses and human bocaviruses being the most prevalent, followed by human adenoviruses, polyomaviruses, and papillomaviruses. Significant variations in the viral profiles were observed among the different types of buildings studied. Mamastrovirus 1 was predominant in school samples, salivirus and human polyomaviruses JC and BK in the university settings while nursing homes showed a more balanced distribution of viral families presenting papillomavirus and picornaviruses and, interestingly, some viruses linked to immunosuppression.

CONCLUSIONS

This study shows the utility of building-level wastewater-based epidemiology as an effective tool for monitoring the presence of viruses circulating within specific age groups. It provides valuable insights for public health monitoring and epidemiological studies.

Study of Cosavirus, Salivirus, and Bufavirus viruses in children with acute gastroenteritis

Background

Acute gastroenteritis (AGE) in children represents a health problem. Besides common enteric viruses such as rotavirus and adenovirus, new viruses such as cosavirus, salivirus, and bufavirus may be associated with AGE. The objective of the study was to detect cosavirus, salivirus, and bufavirus viruses in children below 5 years with acute gastroenteritis by the use of real-time polymerase chain reaction (PCR) besides detection of rotavirus and adenovirus by enzyme-linked immunosorbent assay (ELISA).

Method

The study included 150 children ≤ 5 years with community-acquired diarrhea. Stool samples from children were subjected for the detection of rotavirus and adenovirus antigens by ELISA and for detection of buvavirus, salivirus, and cosavirus by real-time PCR.

Results

The commonest virus detected in the stool samples of children with AGE was rotavirus 31.3% followed by adenovirus 24%. Among the new viruses studied, salivirus was detected in six samples (4.0%), buvavirus was detected in four samples (2.7%), and cosavirus was detected in two samples (1.3%). The mixed rotavirus detection with studied viruses was 23.4% for adenovirus, 4.3% for calicivirus, and 2.1% for bocavirus, and none of the detected cosavirus was associated with rotavirus. In the studied children, at least one of the new viruses was detected in ten children (6.7%). Buvavirus, salivirus, and cosavirus were detected as a single virus (0.7%) in the children with acute gastroenteritis and buvavirus was detected with cosavirus without other viruses in one sample (0.7%).

Conclusion

The study reports the occurrence of buvavirus, cosavirus, and salivirus in the pediatric patients with community-acquired acute gastroenteritis. There was a high prevalence of rotavirus and adenovirus antigens in those patients with low positivity for buvavirus, cosavirus, and salivirus viruses. There is a need for a large cohort study to study the prevalence of buvavirus, cosavirus, and salivirus in pediatrics with acute gastroenteritis and to validate their association with the disease.

RNA-Seq Virus Fraction in Lake Baikal and Treated Wastewaters

In this study, we analyzed the transcriptomes of RNA and DNA viruses from the oligotrophic water of Lake Baikal and the effluent from wastewater treatment plants (WWTPs) discharged into the lake from the towns of Severobaikalsk and Slyudyanka located on the lake shores. Given the uniqueness and importance of Lake Baikal, the issues of biodiversity conservation and the monitoring of potential virological hazards to hydrobionts and humans are important. Wastewater treatment plants discharge treated effluent directly into the lake. In this context, the identification and monitoring of allochthonous microorganisms entering the lake play an important role. Using high-throughput sequencing methods, we found that dsDNA-containing viruses of the class Caudoviricetes were the most abundant in all samples, while Leviviricetes (ssRNA(+) viruses) dominated the treated water samples. RNA viruses of the families Nodaviridae, Tombusviridae, Dicitroviridae, Picobirnaviridae, Botourmiaviridae, Marnaviridae, Solemoviridae, and Endornavirida were found in the pelagic zone of three lake basins. Complete or nearly complete genomes of RNA viruses belonging to such families as Dicistroviridae, Marnaviridae, Blumeviridae, Virgaviridae, Solspiviridae, Nodaviridae, and Fiersviridae and the unassigned genus Chimpavirus, as well as unclassified picorna-like viruses, were identified. In general, the data of sanitary/microbiological and genetic analyses showed that WWTPs inadequately purify the discharged water, but, at the same time, we did not observe viruses pathogenic to humans in the pelagic zone of the lake.

Diversity of picornaviruses detected in diarrheal samples from children in Belém, Brazilian Amazon (1982-2019)

In this investigation, fecal specimens from children with diarrhea were collected from four community studies conducted between 1982 and 2019 in Belém, Brazilian Amazon. A total of 234 samples were tested by quantitative reverse transcription polymerase chain reaction (RT-qPCR) to detect infections by picornaviruses of the Enterovirus (EV), Parechovirus (HPeV), Cosavirus (HCoSV), Kobuvirus (Aichivirus - AiV) and Salivirus (SalV) genera. The positive samples were subjected to different amplification protocols of the VP1 region of the genome, such as nested PCR or snPCR, and were subsequently genotyped by sequencing VP1 and VP3 of the viral genome. Positivity was observed in 76.5% (179/234) of the samples tested using RT-qPCR for at least one virus, and co-infection was observed in 37.4% (67/179) of the cases. EV was detected in 50.8% (119/234), HPeV in 29.9% (70/234), HCoSV in 27.3% (64/234), and AiV/SalV in 2.1% (5/234) of the specimens tested by RT-qPCR. Using nested PCR and/or snPCR techniques, the positivity rates were 94.11% (112/119) for EV, 72.85% (51/70) for HPeV, and 20.31% (13/64) for HCoSV. It was not possible to amplify the samples that were positive for AiV/SalV. Sequencing revealed 67.2% (80/119) EV, 51.4% (36/70) HPeV, and 20.31% (13/64) HCoSV. Forty-five different types of EV were found among species A, B, and C; HCoSV identified five species, including a possible recombinant strain; all HPeV were identified as belonging to species A, in two samples a possible recombination involving three different strains was verified. This study demonstrated the high circulation and diversity of different types of picornaviruses in fecal samples, including those collected more than 30 years ago. This endorsed the evaluation of important points in the epidemiology of these viruses, such as the presence of co-infection and the possibility of knowing more about these agents, considering that some were recently described; therefore, their detection in older samples can provide more data about their ancestry.

Candida albicans-enteric viral interactions-The prostaglandin E2 connection and host immune responses

The human microbiome comprises trillions of microorganisms residing within different mucosal cavities and across the body surface. The gut microbiota modulates host susceptibility to viral infections in several ways, and microbial interkingdom interactions increase viral infectivity within the gut. Candida albicans, a frequently encountered fungal species in the gut, produces highly structured biofilms and eicosanoids such as prostaglandin E₂ (PGE₂), which aid in viral protection and replication. These biofilms encompass viruses and provide a shield from antiviral drugs or the immune system. PGE₂ is a key modulator of active inflammation with the potential to regulate interferon signaling upon microbial invasion or viral infections. In this review, we raise the perspective of gut interkingdom interactions involving C. albicans and enteric viruses, with a special focus on biofilms, PGE₂, and viral replication. Ultimately, we discuss the possible implications of C. albicans-enteric virus associations on host immune responses, particularly the interferon signaling pathway.

Viruses associated with ill health in wild chimpanzees

Viral infection is a major cause of ill health in wild chimpanzees (Pan troglodytes), but most evidence to date has come from conspicuous disease outbreaks with high morbidity and mortality. To examine the relationship between viral infection and ill health during periods not associated with disease outbreaks, we conducted a longitudinal study of wild eastern chimpanzees (P. t. schweinfurthii) in the Kanyawara and Ngogo communities of Kibale National Park, Uganda. We collected standardized, observational health data for 4 years and then used metagenomics to characterize gastrointestinal viromes (i.e., all viruses recovered from fecal samples) in individual chimpanzees before and during episodes of clinical disease. We restricted our analyses to viruses thought to infect mammals or primarily associated with mammals, discarding viruses associated with nonmammalian hosts. We found 18 viruses (nine of which were previously identified in this population) from at least five viral families. Viral richness (number of viruses per sample) did not vary by health status. By contrast, total viral load (normalized proportion of sequences mapping to viruses) was significantly higher in ill individuals compared with healthy individuals. Furthermore, when ill, Kanyawara chimpanzees exhibited higher viral loads than Ngogo chimpanzees, and males, but not females, exhibited higher infection rates with certain viruses and higher total viral loads as they aged. Post-hoc analyses, including the use of a machine-learning classification method, indicated that one virus, salivirus (Picornaviridae), was the main contributor to health-related and community-level variation in viral loads. Another virus, chimpanzee stool-associated virus (chisavirus; unclassified Picornavirales), was associated with ill health at Ngogo but not at Kanyawara. Chisavirus, chimpanzee adenovirus (Adenoviridae), and bufavirus (Parvoviridae) were also associated with increased age in males. Associations with sex and age are consistent with the hypothesis that nonlethal viral infections cumulatively reflect or contribute to senescence in long-lived species such as chimpanzees.

Salivirus infection: Systematic review and meta-analysis of association with gastrointestinal symptoms in children

Salivirus (SaV) is a newly described member of the family Picornaviridae that has been associated with gastrointestinal (GI) symptoms, particularly in children. The aim of the present study was to evaluate the prevalence of SaV in symptomatic children and its potential association with GI complications. A systematic search was conducted from 01 December 2009 to 10 December 2020, in three major English databases, including Scopus, PubMed and Web of Science as well as Google scholar search engine. Random effect model-based overall prevalence and odds ratio (OR) were assessed in cross-sectional and case-control studies by STATA 14.1. The random effect model-based pooled prevalence of SaV was 1.6% (95% CI, 0.010-0.022%) and overall OR for all eight case-control studies indicated an association (3.19 with 95% confidence interval 1.35-7.57) that was not statistically significant, due to the small number of studies available. More comprehensive case-control studies in multiple geographies should be conducted on the prevalence of SaV in children.

From a case-control survey to a diagnostic viral gastroenteritis panel for testing of general practitioners' patients

OBJECTIVE

To evaluate the pathogenicity of a broad range of 11 possible gastroenteritis viruses, by means of statistical relationships with cases vs. controls, or Ct-values, in order to establish the most appropriate diagnostic panel for our general practitioner (GP) patients in the Netherlands (2010-2012).

METHODS

Archived stool samples from 1340 cases and 1100 controls were retested using internally controlled multiplex real-time PCRs for putative pathogenic gastroenteritis viruses: adenovirus, astrovirus, bocavirus, enterovirus, norovirus GI and GII, human parechovirus, rotavirus, salivirus, sapovirus, and torovirus.

RESULTS

The prevalence of any virus in symptomatic cases and asymptomatic controls was 16.6% (223/1340) and 10.2% (112/1100), respectively. Prevalence of astrovirus (adjusted odds ratio (aOR) 10.37; 95% confidence interval (CI) 1.34-80.06) and norovirus GII (aOR 3.10; CI 1.62-5.92) was significantly higher in cases versus controls. Rotavirus was encountered only in cases. We did not find torovirus and there was no statistically significant relationship with cases for salivirus (aOR 1,67; (CI) 0.43-6.54)), adenovirus non-group F (aOR 1.20; CI 0.75-1.91), bocavirus (aOR 0.85; CI 0.05-13.64), enterovirus (aOR 0.83; CI 0.50-1.37), human parechovirus (aOR 1.61; CI 0.54-4.77) and sapovirus (aOR 1.15; CI 0.67-1.98). Though adenovirus group F (aOR 6.37; CI 0.80-50.92) and norovirus GI (aOR 2.22, CI: 0.79-6.23) are known enteropathogenic viruses and were more prevalent in cases than in controls, this did not reach significance in this study. The Ct value did not discriminate between carriage and disease in PCR-positive subjects.

CONCLUSIONS

In our population, diagnostic gastroenteritis tests should screen for adenovirus group F, astrovirus, noroviruses GI and GII, and rotavirus. Case-control studies as ours are lacking and should also be carried out in populations from other epidemiological backgrounds.

Bufavirus, Cosavirus, and Salivirus in Diarrheal Italian Infants

Three newly discovered viruses have been recently described in diarrheal patients: Cosavirus (CosV) and Salivirus (SalV), 2 picornaviruses, and bufavirus (BuV), a parvovirus. The detection rate and the role of these viruses remain to be established in acute gastroenteritis (AGE) in diarrheal Italian infants. From November 2016 to November 2017, stool samples were collected from 160 children <5 years old suffering from AGE and attending the Children's Hospital in Turin, Italy. During the study period, 1 (0.5%) sample was positive for 1 of the 3 investigated viruses: 0 (0%) CosV, 1 (0.5%) SalV, and 0 (0%) BuV, whereas 42 (26.0%) children were infected with rotavirus and 2 (1%) with adenovirus. No mixed infections involving the 3 viruses were found. Although these viruses are suspected to be responsible for AGE in children, our data showed that this association was uncertain. Therefore, further studies with large cohorts of healthy and diarrheal children will be needed to evaluate their clinical role in AGE.

Molecular Detection of Human Salivirus in Italy Through Monitoring of Urban Sewages

Salivirus (SalV) is a newly discovered virus associated to acute gastroenteritis in humans. In Italy, its prevalence and genetic diversity is unknown. To reduce this knowledge gap, 124 sewage samples collected throughout the country were analyzed for SalV by two nested RT-PCRs targeting the 5'UTR and the 3D regions and by real-time RT-qPCR. Virus RNA was detected in 37 (29.8%) samples; of these, 24 could be characterized and all belonged to genotype A1. Viral concentrations ranged between 2.8 × 10³ and 1.9 × 10⁵ genome copies per liter. This is the first report of SalV occurrence in water environments in Italy, suggesting that SalV infection is not uncommon in this country.

Occurrence of Salivirus in Sewage and River Water Samples in Karaj, Iran

Salivirus is a newly discovered virus which seems to be related to acute gastroenteritis in children. Salivirus may infect susceptible children by fecal-oral route after exposure to contaminated water. The present study aims to evaluate the occurrence and quantity of Salivirus in treated and untreated sewage water and river water samples collected in the city of Karaj, Iran by reverse transcription-quantitative PCR assay. A total of 50 samples were collected from environmental waters containing 22 treated and untreated sewage water in volume of 1 l and 28 river water samples in volume of 5 l were included in this study. After viral RNA extraction, the Real-time PCR was performed to amplify the 5'UTR sequence of Salivirus genome and viral load was assessed. Out of the 50 samples tested, the Salivirus genomic RNA was identified in 5/12 (41.6%) of treated and 3/10 (30%) of untreated sewage samples and in 8/28 (28.5%) of river water samples. The maximum viral load was 4.8 × 10⁶ copies/l in treated sewage water sample in September and the lower viral load was 4 × 10⁵ copies/l related to treated sewage water taken in December. This is the first report of Salivirus occurrence in the environmental waters in Iran. The viral prevalence of Salivirus in each of the three sets of tested samples was within low to moderate in range.

Metagenomic analysis of viruses in toilet waste from long distance flights-A new procedure for global infectious disease surveillance

Human viral pathogens are a major public health threat. Reliable information that accurately describes and characterizes the global occurrence and transmission of human viruses is essential to support national and global priority setting, public health actions, and treatment decisions. However, large areas of the globe are currently without surveillance due to limited health care infrastructure and lack of international cooperation. We propose a novel surveillance strategy, using metagenomic analysis of toilet material from international air flights as a method for worldwide viral disease surveillance. The aim of this study was to design, implement, and evaluate a method for viral analysis of airplane toilet waste enabling simultaneous detection and quantification of a wide range of human viral pathogens. Toilet waste from 19 international airplanes was analyzed for viral content, using viral capture probes followed by high-throughput sequencing. Numerous human pathogens were detected including enteric and respiratory viruses. Several geographic trends were observed with samples originating from South Asia having significantly higher viral species richness as well as higher abundances of salivirus A, aichivirus A and enterovirus B, compared to samples originating from North Asia and North America. In addition, certain city specific trends were observed, including high numbers of rotaviruses in airplanes departing from Islamabad. Based on this study we believe that central sampling and analysis at international airports could be a useful supplement for global viral surveillance, valuable for outbreak detection and for guiding public health resources.

Complex virome in feces from Amerindian children in isolated Amazonian villages

The number of viruses circulating in small isolated human populations may be reduced by viral extinctions and rare introductions. Here we used viral metagenomics to characterize the eukaryotic virome in feces from healthy children from a large urban center and from three Amerindian villages with minimal outside contact. Numerous human enteric viruses, mainly from the Picornaviridae and Caliciviridae families, were sequenced from each of the sites. Multiple children from the same villages shed closely related viruses reflecting frequent transmission clusters. Feces of isolated villagers also contained multiple viral genomes of unknown cellular origin from the Picornavirales order and CRESS-DNA group and higher levels of nematode and protozoan DNA. Despite cultural and geographic isolation, the diversity of enteric human viruses was therefore not reduced in these Amazonian villages. Frequent viral introductions and/or increased susceptibility to enteric infections may account for the complex fecal virome of Amerindian children in isolated villages.

Overview of Trends in the Application of Metagenomic Techniques in the Analysis of Human Enteric Viral Diversity in Africa's Environmental Regimes

There has been an increase in the quest for metagenomics as an approach for the identification and study of the diversity of human viruses found in aquatic systems, both for their role as waterborne pathogens and as water quality indicators. In the last few years, environmental viral metagenomics has grown significantly and has enabled the identification, diversity and entire genome sequencing of viruses in environmental and clinical samples extensively. Prior to the arrival of metagenomics, traditional molecular procedures such as the polymerase chain reaction (PCR) and sequencing, were mostly used to identify and classify enteric viral species in different environmental milieu. After the advent of metagenomics, more detailed reports have emerged about the important waterborne viruses identified in wastewater treatment plant effluents and surface water. This paper provides a review of methods that have been used for the concentration, detection and identification of viral species from different environmental matrices. The review also takes into consideration where metagenomics has been explored in different African countries, as well as the limitations and challenges facing the approach. Procedures including sample processing, experimental design, sequencing technology, and bioinformatics analysis are discussed. The review concludes by summarising the current thinking and practices in the field and lays bare key issues that those venturing into this field need to consider and address.

Presence of Human Enteric Viruses, Protozoa, and Indicators of Pathogens in the Bagmati River, Nepal

Quantification of waterborne pathogens in water sources is essential for alerting the community about health hazards. This study determined the presence of human enteric viruses and protozoa in the Bagmati River, Nepal, and detected fecal indicator bacteria (total coliforms, Escherichia coli, and Enterococcus spp.), human-fecal markers (human Bacteroidales and JC and BK polyomaviruses), and index viruses (tobacco mosaic virus and pepper mild mottle virus). During a one-year period between October 2015 and September 2016, a total of 18 surface water samples were collected periodically from three sites along the river. Using quantitative polymerase chain reaction, all eight types of human enteric viruses tested—including adenoviruses, noroviruses, and enteroviruses, were detected frequently at the midstream and downstream sites, with concentrations of 4.4–8.3 log copies/L. Enteroviruses and saliviruses were the most frequently detected enteric viruses, which were present in 72% (13/18) of the tested samples. Giardia spp. were detected by fluorescence microscopy in 78% (14/18) of the samples, with a lower detection ratio at the upstream site. Cryptosporidium spp. were detected only at the midstream and downstream sites, with a positive ratio of 39% (7/18). The high concentrations of enteric viruses suggest that the midstream and downstream regions are heavily contaminated with human feces and that there are alarming possibilities of waterborne diseases. The concentrations of enteric viruses were significantly higher in the dry season than the wet season (p < 0.05). There was a significant positive correlation between the concentrations of human enteric viruses and the tested indicators for the presence of pathogens (IPP) (p < 0.05), suggesting that these IPP can be used to estimate the presence of enteric viruses in the Bagmati River water.

Salivirus infection in children with diarrhea, Thailand

A new member of the Picornaviridae family named salivirus, and also known as klassevirus, was identified recently from the feces of children with gastroenteritis. At present, it remains unclear whether salivirus is associated with gastroenteritis in humans and epidemiological data are very limited. To investigate the prevalence of salivirus in Thailand, we performed molecular screening of fecal samples from children hospitalized with acute gastroenteritis in Chiang Mai, Thailand during 2015-2016 through the application of RT-nested PCR. Salivirus was detected in 1 out of 229 (0.44%) fecal samples tested and it belonged to genotype A1, based on nucleotide sequences of the 5'UTR, VP1, and 3D regions. This is the first report of salivirus infection in young children with acute diarrhea in Thailand.

A cluster of salivirus A1 (Picornaviridae) infections in newborn babies with acute gastroenteritis in a neonatal hospital unit in Hungary

Salivirus (family Picornaviridae) may be associated with acute gastroenteritis in humans, but there have been no reports of salivirus outbreaks. Salivirus A1 infection with faecal virus concentrations of 2.1-2.6 × 10(9)/g were identified retrospectively in newborn babies, between the ages of 1.5 and 5 days, with apparent clinical symptoms of diarrhea (100 %), fever (40 %), vomiting (40 %), and loss of appetite (40 %) in a neonatal hospital unit in Hungary in July 2013. The complete genome sequence of the salivirus (including the 5'-terminal end) was determined. Salivirus mono-infection may be associated with gastroenteritis in babies who are a few days old. Salivirus testing should be done in public health laboratories in gastroenteritis outbreaks with unknown etiology.

Characterization of a Salivirus (Picornaviridae) from a Diarrheal Child in Guatemala

The complete genome sequence of a salivirus was identified in a stool sample from a Guatemalan child with acute gastroenteritis during a 2009 norovirus outbreak. This genome (genotype A1 strain GUT/2009/A-1746) shares 82% to 94% genome-wide nucleotide identity with saliviruses from the United States, China, Germany, and Nigeria, representing the first salivirus sequence from Central America.

Viruses Causing Gastroenteritis: The Known, The New and Those Beyond

The list of recently discovered gastrointestinal viruses is expanding rapidly. Whether these agents are actually involved in a disease such as diarrhea is the essential question, yet difficult to answer. In this review a summary of all viruses found in diarrhea is presented, together with the current knowledge about their connection to disease.