Norovirus: Facts and Reflections from Past, Present, and Future

Human Norovirus is currently the main viral cause of acute gastroenteritis (AGEs) in most countries worldwide. Nearly 50 years after the discovery of the “Norwalk virus” by Kapikian and colleagues, the scientific and medical community continue to generate new knowledge on the full biological and disease spectrum of Norovirus infection. Nevertheless, several areas remain incompletely understood due to the serious constraints to effectively replicate and propagate the virus. Here, we present a narrated historic perspective and summarize our current knowledge, including insights and reflections on current points of interest for a broad medical community, including clinical and molecular epidemiology, viral–host–microbiota interactions, antivirals, and vaccine prototypes. We also include a reflection on the present and future impacts of the COVID-19 pandemic on Norovirus infection and disease.

A comprehensive approach for microbiota and health monitoring in mouse colonies using metagenomic shotgun sequencing

Background Health surveillance of murine colonies employed for scientific purposes aim at detecting unwanted infection that can affect the well-being of animals and personnel, and potentially undermine scientific results. In this study, we investigated the use of a next-generation sequencing (NGS) metagenomic approach for monitoring the microbiota composition and uncovering the possible presence of pathogens in mice housed in specific pathogen-free (SPF) or conventional (non-SPF) facilities. Results Analysis of metagenomic NGS assay through public and free algorithms and databases allowed to precisely assess the composition of mouse gut microbiome and quantify the contribution of the different microorganisms at the species level. Sequence analysis allowed the uncovering of pathogens or the presence of imbalances in the microbiota composition. In several cases, fecal pellets taken from conventional facilities were found to carry gene sequences from bacterial pathogens (Helicobacter hepaticus, Helicobacter typhlonius, Chlamydia muridarum, Streptococcus pyogenes, Rodentibacter pneumotropicus, Citrobacter rodentium, Staphylococcus aureus), intestinal protozoa (Entamoeba muris, Tritrichomonas muris, Spironucleus muris) nematoda (Aspiculuris tetraptera, Syphacia obvelata), eukaryotic parasites (Myocoptes musculinus) and RNA virus (Norwalk virus). Thus, the use of NGS metagenomics can reduce the number of tests required for the detection of pathogens and avoid the use of sentinel mice. Conclusions In summary, in comparison with standard approaches, which require multiple types of test, NGS assay can detect bacteria, fungi, DNA and RNA viruses, and eukaryotic parasites from fecal pellets in a single test. Considering the need to protect animal well-being and to improve the success and reproducibility of preclinical studies, this work provides the proof-of-concept that the use of NGS metagenomics for health monitoring of laboratory mice is a feasible and dependable approach, that is able to broaden the current concept of health monitoring of laboratory mice from “pathogen surveillance” to a more inclusive “microbiota surveillance”.

Thin-Film Freeze-Drying of a Norovirus Vaccine Candidate

A bivalent Norovirus vaccine candidate has been developed that contains Norovirus strain GI.1 Norwalk-virus like particles (VLP) and strain GII.4 Consensus VLP adsorbed onto aluminum (oxy)hydroxide. In the present study, we tested the feasibility of converting the vaccine from a liquid suspension into dry powder by thin-film freeze-drying (TFFD). With the proper amount of trehalose and/or sucrose as cryoprotectant, TFFD can be applied to transform the Norovirus vaccine candidate into dry powders without causing antigen loss or particle aggregation, while maintaining the potency of the antigens within a specified acceptable range. In an accelerated stability study, the potency of the antigens was also maintained in the specified acceptable range after the dry powders were stored for eight weeks at 40 oC, 75% relative humidity. The dry powder Norovirus vaccine offers the potential to eliminate the cold chain requirement for transport and/or storage of the vaccine.

Prediction of norovirus using Internet search data in the US (Preprint)

BACKGROUND Norovirus is a contagious disease leading to vomiting and diarrhea. The transmission of norovirus spreads quickly and easily in various ways. Because effective methods to prevent or treat norovirus have not been discovered, it is important to rapidly recognize and report norovirus outbreaks in the early phase. Internet search has been a useful method for people to access information immediately. With the precise record of Internet search trends, Internet search has been a useful tool to manifest infectious disease outbreaks. OBJECTIVE In this study, we tried to discover the correlation between Internet search terms and norovirus infection. METHODS The Internet search trend data of norovirus were obtained from Google Trends. We used cross-correlation analysis to discover the temporal correlation between norovirus and other terms. We also used multiple linear regression with the stepwise method to recognize the most important predictors of Internet search trends and norovirus. In addition, we evaluated the temporal correlation between actual norovirus cases and Internet search terms in New York, California, and USA. RESULTS Some Google search terms such as gastroenteritis, vomiting, and watery diarrhea were coincided with norovirus Google Trends. Some Google search terms such as contagious, Norwalk virus, travel presented earlier than norovirus Google Trends. Some Google search terms such as dehydration, bar, and restaurant presented several months later than norovirus Google Trends. We found that the symptoms of gastroenteritis, including vomiting and watery diarrhea, were important factors that were significantly correlated with norovirus Google Trends. In actual norovirus cases of New York, California, and USA, some Google search terms presented coincided, earlier, or later than actual norovirus cases. CONCLUSIONS Our study provides novel strategy-based Internet search evidence regarding the epidemiology of norovirus.

Outbreaks of infectious diseases in healthcare facilities: Issues of epidemiological diagnostics and preanalytical stage

Background. The issue of outbreaks of infectious diseases in healthcare facilities is not often discussed in the scientific community. Several years ago, the primary etiological agents of outbreaks in hospitals were bacteria, whereas in most cases under modern conditions, outbreak incidence is caused by viruses. Aim. Based on the analysis of research materials on outbreaks of infectious diseases in healthcare facilities of Ural and Siberian Federal Districts, this work aimed to characterize infectious diseases under contemporary conditions and identify problematic issues of the preanalytical stage of epidemiological diagnostics and the organization of preventive and anti-epidemic measures. Methods. The data of federal statistical monitoring form No. 23 Information on outbreaks of infectious diseases (18 units of information) and the copy of the Acts of an epidemiological investigation of foci of infectious (parasitic) diseases with the establishment of a causal relationship (14 units of information) were analyzed. The work used epidemiological and statistical methods of information processing. The significance of differences between the indices of independent samples was evaluated using Fishers exact test. Results. In 2018, 14 outbreaks of infectious diseases were recorded in healthcare facilities in 7 out of 18 subjects in Ural and Siberian Federal Districts. The total number of victims was 183 people (97 (53.0%) children and 86 (47.0%) adults). Most of the outbreaks (12 of 14; 85.7%) were of viral etiology. One outbreak was of bacterial, and one was of fungal origin. Discussion. Viruses played a key role in the formation of foci with multiple diseases in the healthcare facilities of Ural and Siberian Federal Districts in 2018. Most of the foci of infection with an aerogenic transmission mechanism were caused by varicella-zoster virus, and those with fecaloral transmission mechanism were etiologically associated with Norwalk virus. Children were the most vulnerable contingents in outbreaks in the healthcare facilities. In all the situations analyzed, the prerequisites for an outbreak include the untimely isolation of the source of infection, hospital overload, and inadequate financial and logistical support. Anti-epidemic measures were conducted to the fullest extent during outbreaks of acute intestinal infections in comparison with outbreaks of a different etiology. Conclusion. Most outbreaks registered in the hospitals could be prevented by vaccination of the related population.

Production and Clinical Evaluation of Norwalk GI.1 Virus Lot 001-09NV in Norovirus Vaccine Development

Background Human noroviruses (HuNoV) are the leading cause of gastroenteritis. No vaccine is currently available to prevent norovirus illness or infection. Safe, infectious challenge strains are needed to assess vaccine efficacy in the controlled human infection model (CHIM). Methods A stock of HuNoV strain Norwalk virus ([NV] GI.1) was prepared. Healthy, genetically susceptible adults were inoculated with NV Lot 001-09NV and monitored for infection, gastroenteritis symptoms, and immune responses. Results Lot 001-09NV induced gastroenteritis in 9 (56%) and infection in 11 (69%) of 16 genetically susceptible subjects. All infected subjects developed strong immune responses to GI.1 with a 30-fold (geometric mean titer) increase in blocking titers (BT50) and a 161-fold increase in GI.1-specific immunoglobulin (Ig)G titers when compared with baseline. GI.1-specific cellular responses in peripheral blood were observed 9 days postchallenge with an average of 3253 IgA and 1227 IgG antibody-secreting cells per million peripheral blood mononuclear cells. Conclusions GI.1 Lot 001-09NV appears to be similar in virulence to previous passages of NV strain 8fIIa. The safety profile, attack rate, and duration of illness make GI.1 Lot 001-09NV a useful challenge strain for future vaccine studies aimed at establishing immune correlates.