SARS-CoV-2 transmission modes: Why and how contamination occurs around shared meals and drinks?

In spite of prevention measures enacted all over the world to control the COVID-19 pandemic outbreak, including mask wearing, social distancing, hand hygiene, vaccination, and other precautions, the SARS-CoV-2 virus continues to spread globally at an unabated rate of about 1 million cases per day. The specificities of superspreading events as well as evidence of human-to-human, human-to-animal and animal-to-human transmission, indoors or outdoors, raise questions about a possibly neglected viral transmission route. In addition to inhaled aerosols, which are already recognized as key contributors to transmission, the oral route represents a strong candidate, in particular when meals and drinks are shared.

[Covid-19: is the oral transmission route during shared meals and drinks credible?].

Epidemiological and observational studies converge to suspect today a risk of contracting Covid-19 around shared meals and drinks. Contamination of table objects (plates, cutlery, glasses) or food and beverages put in the mouth is possible through droplets projected during speech or through direct contacts by dirty hands. This contamination could involve employees in the food chain, restaurant or bar staff and diners among themselves.

Full-length G glycoprotein directly extracted from rabies virus with detergent and then stabilized by amphipols in liquid and freeze-dried forms.

Pathogen surface antigens are at the forefront of the viral strategy when invading host organisms. These antigens, including membrane proteins (MPs), are broadly targeted by the host immune response. Obtaining these MPs in a soluble and stable form constitutes a real challenge, regardless of the application purposes (e.

Shared Food, Meals and Drinks: 10 Arguments Suggesting an Oral Transmission Route of SARS-CoV-2.

Numerous observational, epidemiologic data have suggested that the risk of COVID19 is related to shared meals or drinks. The presence of ACE2 receptors in the gastrointestinal tract supports this hypothesis. Furthermore, several patients experience gastrointestinal symptoms without any respiratory disease.

Biophysical virus particle specific characterization to sharpen the definition of virus stability.

Vaccine thermostability is key to successful global immunization programs as it may have a significant impact on the continuous cold-chain maintenance logistics, as well as affect vaccine potency. Modern biological and biophysical techniques were combined to in-depth characterize the thermostability of a formulated rabies virus (RABV) in terms of antigenic and genomic titer, virus particle count and aggregation state. Tunable resistive pulse sensing (TRPS) and nanoparticle tracking analysis (NTA) were used to count virus particles while simultaneously determining their size distribution.

Characterization of recombinant yellow fever-dengue vaccine viruses with human monoclonal antibodies targeting key conformational epitopes.

The recombinant yellow fever-17D-dengue virus, live, attenuated, tetravalent dengue vaccine (CYD-TDV) is licensed in several dengue-endemic countries. Although the vaccine provides protection against dengue, the level of protection differs by serotype and warrants further investigation. We characterized the antigenic properties of each vaccine virus serotype using highly neutralizing human monoclonal antibodies (hmAbs) that bind quaternary structure-dependent epitopes.

Innovative in cellulo method as an alternative to in vivo neurovirulence test for the characterization and quality control of human live Yellow Fever virus vaccines: A pilot study.

Live attenuated vaccines have proved to be mostly valuable in the prevention of infectious diseases in humans, especially in developing countries. The safety and potency of vaccine, and the consistency of vaccine batch-to-batch manufacturing, must be proven before being administrated to humans. For now, the tests used to control vaccine safety largely involve animal testing.

[Phages and vaccination: towards new opportunities?].

Bacteriophages, or phages, are ubiquitous microorganisms that only infect bacteria. They were briefly used, mainly in the West, in the early 20th century to treat human bacterial infections, before being replaced by antibiotics in the 1940s. In the 1970s, the phage display technology, which consists of presenting multiple copies of small polypeptides at the surface of the phage, led to consider phages as vaccine antigen producers.

Robust real-time cell analysis method for determining viral infectious titers during development of a viral vaccine production process.

The classical cell-culture methods, such as cell culture infectious dose 50% (CCID) assays, are time-consuming, end-point assays currently used during the development of a viral vaccine production process to measure viral infectious titers. However, they are not suitable for handling the large number of tests required for high-throughput and large-scale screening analyses. Impedance-based bio-sensing techniques used in real-time cell analysis (RTCA) to assess cell layer biological status in vitro, provide real-time data.

Determinants Involved in Hepatitis C Virus and GB Virus B Primate Host Restriction.

Unlabelled: Hepatitis C virus (HCV) only infects humans and chimpanzees, while GB virus B (GBV-B), another hepatotropic hepacivirus, infects small New World primates (tamarins and marmosets). In an effort to develop an immunocompetent small primate model for HCV infection to study HCV pathogenesis and vaccine approaches, we investigated the HCV life cycle step(s) that may be restricted in small primate hepatocytes. First, we found that replication-competent, genome-length chimeric HCV RNAs encoding GBV-B structural proteins in place of equivalent HCV sequences designed to allow entry into simian hepatocytes failed to induce viremia in tamarins following intrahepatic inoculation, nor did they lead to progeny virus in permissive, transfected human Huh7.

Influenza A(H1N1)pdm09 virus in pigs, Réunion Island.

During 2009, pandemic influenza A(H1N1)pdm09 virus affected humans on Réunion Island. Since then, the virus has sustained circulation among local swine herds, raising concerns about the potential for genetic evolution of the virus and possible retransmission back to humans of variants with increased virulence. Continuous surveillance of A(H1N1)pdm09 infection in pigs is recommended.

Enhanced gene silencing in cells cured of persistent virus infection by RNA interference.

We compared HEp-2-derived cells cured of persistent poliovirus infection by RNA interference (RNAi) with parental cells, to investigate possible changes in the efficiency of RNAi. Lower levels of poliovirus replication were observed in cured cells, possibly facilitating virus silencing by antiviral small interfering RNAs (siRNAs). However, green fluorescent protein (GFP) produced from a measles virus vector and also GFP and luciferase produced from plasmids that do not replicate in human cells were more effectively silenced by specific siRNAs in cured than in control cells.

The disulfide bonds in glycoprotein E2 of hepatitis C virus reveal the tertiary organization of the molecule.

Hepatitis C virus (HCV), a major cause of chronic liver disease in humans, is the focus of intense research efforts worldwide. Yet structural data on the viral envelope glycoproteins E1 and E2 are scarce, in spite of their essential role in the viral life cycle. To obtain more information, we developed an efficient production system of recombinant E2 ectodomain (E2e), truncated immediately upstream its trans-membrane (TM) region, using Drosophila melanogaster cells.

Inhibition of hepatitis C virus infection in cell culture by small interfering RNAs.

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and hepatocellular carcinoma, yet fully efficacious treatments are missing. In this study, we investigated RNA interference (RNAi), a specific gene silencing process mediated by small interfering RNA (siRNA) duplexes, as an antiviral strategy against HCV. Synthetic siRNAs were designed to target conserved sequences of the HCV 5' nontranslated region (NTR) located in a functional, stem-loop structured domain of the HCV internal ribosome entry site (IRES), which is crucial for initiation of polyprotein translation.

Reduced apoptosis in human intestinal cells cured of persistent poliovirus infection.

Cells cured of persistent virus infection can be used to investigate cellular pathways of resistance to viral cytopathic effects. Persistent poliovirus (PV) infections were established in human intestinal Caco-2 cells, and spontaneously cured cell cultures were obtained. Two cell clones, cl6 and b13, cured of type 3 PV mutant infection and their parental Caco-2 cells were compared for susceptibility to PV infection, PV receptor CD155 expression, capacity to differentiate into polarized enterocytes, and PV-, staurosporine-, and actinomycin D-induced apoptosis.

Complete cure of persistent virus infections by antiviral siRNAs.

Small interfering RNAs (siRNAs) have been developed as antiviral agents for mammalian cells. The capacity of specific siRNAs to prevent virus infections has been demonstrated, and there is evidence that these new antiviral agents could have a partial therapeutic effect a few days after infection. We investigated the possibility of curing a persistent infection, several months after becoming established, using an in vitro model of persistent poliovirus (PV) infection in HEp-2 cells.

Silencing viruses by RNA interference.

Post-transcriptional gene silencing (PTGS) makes possible new approaches for studying the various steps of the viral cycle. Plus-strand RNA viruses appear to be attractive targets for small interfering RNAs (siRNAs), as their genome functions as both mRNA and replication template. PTGS creates an alternative to classic reverse genetics for viruses with either negative-strand or double-stranded RNA genomes and for those with a large genome.

Poliovirus mutants excreted by a chronically infected hypogammaglobulinemic patient establish persistent infections in human intestinal cells.

Immunodeficient patients whose gut is chronically infected by vaccine-derived poliovirus (VDPV) may excrete large amounts of virus for years. To investigate how poliovirus (PV) establishes chronic infections in the gut, we tested whether it is possible to establish persistent VDPV infections in human intestinal Caco-2 cells. Four type 3 VDPV mutants, representative of the viral evolution in the gut of a hypogammaglobulinemic patient over almost 2 years [J.