Astrovirus VA1 in patients with acute gastroenteritis

Prevalence and Clinical Manifestation of Astrovirus Gastroenteritis in Adults: A Seven-Year Study in Washington D.C., USA

Gastroenteritis is commonly caused by viral etiologies. The inclusion of astrovirus on multiplex, syndromic gastrointestinal PCR panels allows for the detection and characterization of infected patients. This retrospective, observational, clinical study examines the epidemiology and clinical characteristics of astrovirus infections in adults from our institution in Washington D.C. (USA) over a seven-year period. Chart abstraction was performed to collect patient demographics, laboratory results, clinical presentation, and management. The overall positivity rate of astrovirus was 0.6%. Peak seasons were late winter to spring (February-April). The mean age was 32 years old (range: 18-52 years). All patients presented with gastroenteritis symptoms and were immunocompetent except one. Symptoms varied among diarrhea, abdominal pain, vomiting, and fever, but patients in age group 30-39 years experienced less vomiting (p = 0.01). Infected patients had an increase in monocytes and neutrophils and a decrease in lymphocytes (p < 0.001). Gastrointestinal co-infections were seen in 24% of our patients. In all patients, clinicians acknowledged the detection of astrovirus and discharged patients without further treatment. The median length of stay was 6 h, and no patients were admitted into the intensive care unit. We show that astrovirus infections in immunocompetent adults were associated with mild disease associated with specific cell counts and different symptoms correlated with age.

Assessing the prevalence of human enteric viruses in hospital wastewater to evaluate the effectiveness of wastewater treatment systems

In this experiment, we employed Real-time PCR(RT-PCR) and metagenomic Next-Generation Sequencing (mNGS) techniques to detect the presence of Norovirus, Rotavirus Group A, Adenovirus Group F, and Astrovirus in untreated sewage from three major hospitals. A comparison with clinical lab test outcomes revealed Norovirus as having the highest infection rate, followed by Adenovirus Group F and Rotavirus Group A. Despite not testing for Astrovirus in clinical labs, its sewage detection rate was surpassed only by Norovirus, suggesting a potentially high clinical infection rate. Further analysis of these viruses in treated sewage revealed that chlorination failed to eliminate the virus, maintaining viral concentrations in the treated sewage between 10^2 and 10^3 copies/ml. Even though nucleic acid testing methods fail to detect viral actions, the possible danger they present to public safety should not be ignored. During this experiment, viral nucleic acid was extracted directly from the samples without prior concentration. This method, unlike conventional virus detection post-concentration, bypasses concerns such as recovery efficiency, offering a clearer representation of virus concentrations in water samples and facilitating easier operation.

Mamastrovirus spike protein: Sequence and structural characterization as a basis for understanding cross-species transmission

Astroviruses (AstVs) are notable for their propensity for cross-species transmission; however, the molecular determinants underlying this phenomenon remain poorly understood. The spike protein, which is responsible for host cell entry and is a major antigenic determinant, is hypothesized to play a pivotal role. In this study, we observed high sequence variability in the spike region of AstV. Structural analyses have revealed variability, arising from diverse evolutionary relationships, among AstVs of the same host origin. AstV spike proteins can be categorized into six groups, each of which encompasses AstVs from diverse hosts that exhibit high degrees of structural similarity. These six groups correspond to branches observed in the phylogenetic tree. Notably, the spike surface-exposed loops emerged as focal hotspots for B-cell epitopes across groups, with sequence variability that may contribute to immune evasion upon host switching. Differences in the spike structures of AstVs infecting the same host raise the possibility of distinct tissue tropisms and corresponding clinical manifestations. Collectively, our findings provide insights into the roles of spike protein similarities and immune epitope diversity in driving AstV cross-species transmission. Understanding these molecular mechanisms is crucial to predicting and mitigating the emergence of novel AstV strains.

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.

In Vitro Models for Investigating Intestinal Host-Pathogen Interactions

Infectious diseases are increasingly recognized as a major threat worldwide due to the rise of antimicrobial resistance and the emergence of novel pathogens. In vitro models that can adequately mimic in vivo gastrointestinal physiology are in high demand to elucidate mechanisms behind pathogen infectivity, and to aid the design of effective preventive and therapeutic interventions. There exists a trade-off between simple and high throughput models and those that are more complex and physiologically relevant. The complexity of the model used shall be guided by the biological question to be addressed. This review provides an overview of the structure and function of the intestine and the models that are developed to emulate this. Conventional models are discussed in addition to emerging models which employ engineering principles to equip them with necessary advanced monitoring capabilities for intestinal host-pathogen interrogation. Limitations of current models and future perspectives on the field are presented.

Structure of the divergent human astrovirus MLB capsid spike

Despite their worldwide prevalence and association with human disease, the molecular bases of human astrovirus (HAstV) infection and evolution remain poorly characterized. Here, we report the structure of the capsid protein spike of the divergent HAstV MLB clade (HAstV MLB). While the structure shares a similar folding topology with that of classical-clade HAstV spikes, it is otherwise strikingly different. We find no evidence of a conserved receptor-binding site between the MLB and classical HAstV spikes, suggesting that MLB and classical HAstVs utilize different receptors for host-cell attachment. We provide evidence for this hypothesis using a novel HAstV infection competition assay. Comparisons of the HAstV MLB spike structure with structures predicted from its sequence reveal poor matches, but template-based predictions were surprisingly accurate relative to machine-learning-based predictions. Our data provide a foundation for understanding the mechanisms of infection by diverse HAstVs and can support structure determination in similarly unstudied systems.