A Study to Evaluate the Efficacy, Safety, and Tolerability of Using an Oral Once-daily 2 Drug Regimen Compared to an Oral Once-daily 3 Drug Regimen for the Treatment of Human Immunodeficiency Virus (HIV)-1 in Adults Who Have Not Previously Taken Antiretroviral Therapy

Engineered Cross-Linked Silane with Urea Polymer Thin Durable Coatings onto Polymeric Films for Controlled Antiviral Release of Activated Chlorine and Essential Oils.

In March 2020, the World Health Organization announced a pandemic attributed to SARS-CoV-2, a novel beta-coronavirus, which spread widely from China. As a result, the need for antiviral surfaces has increased significantly. Here, the preparation and characterization of new antiviral coatings on polycarbonate (PC) for controlled release of activated chlorine (Cl+) and thymol separately and combined are described. Thin coatings were prepared by polymerization of 1-[3-(trimethoxysilyl)propyl] urea (TMSPU) in ethanol/water basic solution by modified Stöber polymerization, followed by spreading the formed dispersion onto surface-oxidized PC film using a Mayer rod with appropriate thickness. Activated Cl-releasing coating was prepared by chlorination of the PC/SiO2-urea film with NaOCl through the urea amide groups to form a Cl-amine derivatized coating. Thymol releasing coating was prepared by linking thymol to TMSPU or its polymer via hydrogen bonds between thymol hydroxyl and urea amide groups. The activity towards T4 bacteriophage and canine coronavirus (CCV) was measured. PC/SiO2-urea-thymol enhanced bacteriophage persistence, while PC/SiO2-urea-Cl reduced its amount by 84%. Temperature-dependent release is presented. Surprisingly, the combination of thymol and chlorine had an improved antiviral activity, reducing the amount of both viruses by four orders of magnitude, indicating synergistic activity. For CCV, coating with only thymol was inactive, while SiO2-urea-Cl reduced it below a detectable level.

New Conditions in Heart Transplantation in Persistence of SARS-CoV-2 (preprint)

Heart transplantation is a treatment of choice for patients with severe heart failure. Infection transmission from a donor to a recipient remains a prominent problem in organ transplantation. However, the risk of SARS-CoV-2 transmission through nonlung organ transplantation is still unclear. In the article we present a case of a 28-year-old pregnant woman who developed heart failure soon after recovery from SARS-CoV-2 infection in the third trimester of gestation. In the postpartum period the disease worsened and the patient required cardiac transplantation. We examined the recipient's heart and diagnosed left ventricular noncompaction cardiomyopathy. Immunohistochemical analysis showed the SARS-CoV-2 antigen expression in the donor’s heart before transplantation and after the surgery the endomyocardial biopsy was taken. Moreover, an ultrastructural assessment of the endomyocardial specimen revealed endothelial and pericyte injury and single particles on the surface of endothelium consistent with SARS-CoV-2. Recent findings were associated these damages with SARS-CoV-2 infection. The present study describes the rare case of SARS-CoV-2 transmission from donor to recipient through a heart transplant and resulting in endothelial cell and pericyte activation and humoral immune response activation.

Recent development in antiviral surfaces: Impact of topography and environmental conditions.

The transmission of viruses is largely dependent on contact with contaminated virus-laden communal surfaces. While frequent surface disinfection and antiviral coating techniques are put forth by researchers as a plan of action to tackle transmission in dire situations like the Covid-19 pandemic caused by SARS-CoV-2 virus, these procedures are often laborious, time-consuming, cost-intensive, and toxic. Hence, surface topography-mediated antiviral surfaces have been gaining more attention in recent times. Although bioinspired hydrophobic antibacterial nanopatterned surfaces mimicking the natural sources is a very prevalent and successful strategy, the antiviral prospect of these surfaces is yet to be explored. Few recent studies have explored the potential of nanopatterned antiviral surfaces. In this review, we highlighted surface properties that have an impact on virus attachment and persistence, particularly focusing and emphasizing on the prospect of the nanotextured surface with enhanced properties to be used as antiviral surface. In addition, recent developments in surface nanopatterning techniques depending on the nano-scaled dimensions have been discussed. The impacts of environments and surface topology on virus inactivation have also been reviewed.

A Narrative Review of the Survival of the Coronavirus Family in Feces, Urine, and Wastewater

Wastewater is one of the most important ways of transmitting viral and bacterial pathogens that can cause nosocomial and clinical infections in humans. Although previous studies show that there is no current evidence that active coronaviruses are present in surface or ground waters or are transmitted through contaminated drinking water, there is an urgent need for more effective preventive measures to limit the spread of infection, which depends on understanding their routes of transmission and persistence in different environments. Here is a narrative review of the survival of the coronavirus family in feces, urine, and wastewater. Articles related to the presence of SARS-CoV-1 and SARS-CoV-2 in feces, urine, and wastewater and their survival time were searched in the literature. Articles published in the last decade (2000–2021) were selected based on the PRISMA method. The literature review showed that due to the high concentration of RNA virus in blood and urine samples with positive oral and anal swabs, no positive case has been reported using respiratory tests. The main findings of this review show that the maximum survival time of the SARS-CoV-2 in feces and urine was 33 and 31 days, respectively. Moreover, environmental conditions (temperature and pH) are the most important factors in the survival of SRRS-CoV in feces, urine, and wastewater. This study provides researchers with basic and useful information for future research orientations in relation to wastewater treatment plant systems to eliminate and manage emerging viral contaminants. © 2022 The Author(s);.

IMPACT OF SARS-CoV-2-MEDIATED CD4 T CELL ACTIVATION AND HIV DNA PERSISTANCE IN VIVO

Background: Antigen-driven CD4+ T cell proliferation is a proposed mechanism of HIV-1 reservoir persistence. We previously reported that SARSCoV- 2 infection leads to increased detectable low-level HIV-1 plasm RNA blips months after COVID-19, but the impact of SARS-CoV-2-mediated T cell activation on expansion of HIV-1 reservoirs is not known. We sought to identify if SARSCoV- 2 infection leads to expansion of preferentially HIV-infected CD4+ T cells in people with HIV (PWH) on ART. Method(s): Five PWH with samples collected prior to and approximately two months after SARS-CoV-2 infection were identified. We performed a surface activation induced marker (AIM) assay using a CD4-optimized overlapping SARS-CoV-2 peptide pool to measure OX40/CD137 expression following peptide stimulation and sorted CD4+ T cells based on surface marker expression. ddPCR quantification of genomic HIV-1 DNA was performed on sorted subsets. Result(s): We observed an increase in the frequency of SARS-CoV-2 AIM+ non-naive CD4+ T cells following COVID-19 in samples from 4 of 5 participants (mean AIM+ % 0.13 pre- vs 0.31 post). A large percentage of non-naive AIM+ CD4+ T cells expressed PD1 compared with total non-naive cells before (76% vs 36%) and after (65% vs 19%) COVID-19;PD1 expression was lower following SARS-CoV-2 in both AIM+ and AIM- CD4+ T cell subsets (although very few cells were AIM+ prior to COVID-19). HIV-1 DNA levels in non-naive AIM- CD4+ T cells prior to COVID-19 unexpectedly decreased following infection (mean 3,522 to 766 copies/106 cells). The numbers of AIM+ cells obtained by cell sorting were overall low ( 3,863 mean) and only one participant had detectable DNA in post-COVID AIM+ CD4+ T cells. However, a large majority of this participant's post-COVID AIM+ cells harbored HIV-1 DNA (0.89 copies per cell) whereas HIV DNA in their AIM- cells decreased from 8,387 to not detected following SARSCoV- 2 infection. No HIV-1 DNA was detected in the small number of AIM+ cells obtained prior to COVID-19 in this participant. Conclusion(s): COVID-19 in PWH led to a modest SARS-CoV-2-specific CD4+ cell response approximately two months following acute presentation. One participant may have preferentially expanded HIV-1-infected, SARS-CoV-2- specific CD4+ T cells following COVID-19 but studies involving larger numbers of participants and larger numbers of cells will be needed to fully understand the impact of SARS-CoV-2 on clonal expansion and HIV persistence.

Genomics, metagenomics, and pan-genomics approaches in COVID-19

The coronavirus outbreak, which initially started in Wuhan China, has rapidly led to numerous morbidities and mortalities worldwide. Although potential antiviral and antiinflammatory medicines are available, several individuals are dying daily. In order to thoroughly tackle this deadly virus, the knowledge of genomics, metagenomics, and pan genomics is required, not only to devise new treatment regimens but also to improve the present approaches. Understanding the genomic organization, diversity and structural complexity of this virus can help to figure out several previously unanswered questions. SARS-CoV-2 corona virus comprises of four major structural proteins, namely, the spike surface glycoprotein, tiny envelope protein, matrix protein, and nucleocapsid protein along with accessory proteins that contribute to pathogenesis and persistence of the virus in one way or the other. This chapter covers genomics, metagenomics, and pan-genomics-based strategies that can facilitate to figure the possible mutational recombination and trace the phylogenetic background of the species. Sequencing has been performed and the hence derived viral sequences have been deposited into exclusive repositories to speed up research and explore targeted treatment options. Moreover, immunoinformatics approaches and reverse vaccinology have been applied to speed up the process of formulating reliable, safe, and specific therapeutic options, rapidly. © 2023 Elsevier Inc. All rights reserved.

Epidemiological and etiological analysis of a case cluster caused by norovirus in a nursing home in Lanzhou

Objective: To understand the epidemiology and etiology of a cluster of cases with gastroenteritis in a nursing home in Anning district of Lanzhou, and to provide a scientific evidence for the prevention and control of norovirus diarrhea in community nursing centers. Methods: From January 28 to February 4 2021, an epidemiological investigation was conducted on all diarrhea cases, nursing staff and chefs in a nursing home in Anning district, Lanzhou city. Samples of patients' anal swabs, feces, vomitus were collected for norovirus detection by real-time fluorescent PCR. ORF1/ORF2 junction region of norovirus in some selected positive samples(Ct value 25) was sequenced. MEGA-X software was used to construct a phylogenetic tree for genetic evolution analysis using the neighboring method. Results: The first case was confirmed on January20,2021, and the number of cases peaked during January 25and 29.A total of 58 clinically diagnosed cases were reported,57were older people, with an incidence of(57/360,15.83%). Diarrhea(50/58,86.21%),vomiting(35/58,60.34%),nausea(13/58,22.41%)and abdominal pain(6/58,10.34%)were common symptoms, all cases were mild. Fifty-three asymptomatic cases were detected among chefs, housekeepers and nurses.A total of 163specimens were tested, the positive rate of norovirus GII was 49.08%(80/163). The positive rate of fecal samples collected from nurses, chefs and housekeepers was 48.62%(53/109), and was11.11%(2/18)in environmental surface swabs. The possibility of other pathogenic infections such as SARS-CoV-2was ruled out by further tests. Thirteen positive samples were selected for sequencing, and 9were successfully sequenced, they were all recombinant GII.4Sydney_2012 [P16]genotypes, forming an independent cluster, while in a large evolutionary branch with the 2020GII.10 [P16]and 2019GII.2 [P16]virus strains in Lanzhou city, showing a relative close genetic connection. Conclusions: GII .4Sydney_2012[P16]genotype of norovirus is found to be causative pathogen of this outbreak, and close contact is the main reason of the outbreak and persistence of the infection,so asymptomatic infections of norovirus play an important role in the disease spreading. Therefore, public health management in nursing homes and other centralized nursing facilities should be strengthened especially for asymptomatic workers in order to prevent virus transmission.

Transfer of Phi6 bacteriophage between human skin and surfaces common to consumer-facing environments.

AIMS: This study aimed to determine the extent of Phi6 (Φ6) transfer between skin and surfaces relevant to consumer-facing environments based on inoculum matrix, surface type and contact time. METHODS AND RESULTS: Φ6 transfer rates were determined from skin-to-fomite and fomite-to-skin influenced by inoculum matrix (artificial saliva and tripartite), surface type (aluminium, plastic, stainless steel, touchscreen, vinyl and wood) and contact time (5 and 10 s). Significant differences in estimated means were observed based on surface type (both transfer directions), inoculum matrix (skin-to-fomite) and contact time (both transfer directions). During a sequential transfer experiment from fomite-to-skin, the maximum number of consecutive transfer events observed was 3.33 ± 1.19, 2.33 ± 1.20 and 1.67 ± 1.21 for plastic, touchscreen and vinyl, respectively. CONCLUSIONS: Contact time significantly impacted Φ6 transfer rates, which may be attributed to skin absorption dynamics. Surface type should be considered for assessing Φ6 transfer rates. SIGNIFICANCE AND IMPACT OF THE STUDY: Although the persistence of Φ6 on fomites has been characterized, limited data are available regarding the transfer of Φ6 among skin and fomites. Determining Φ6 transfer rates for surfaces in consumer-facing environments based on these factors is needed to better inform future virus transmission mitigation strategies.

The Environmental Stability of SARS-CoV-2 Variants Omicron BA.1 and BA.5 on the Surfaces of Widely Used Transport Packaging Materials.

The increased transmissibility of SARS-CoV-2 variants of concern (VOCs) has raised questions regarding the environmental stability of these viruses. Although a prolonged survival time has been reported for SARS-CoV-2, how long new variants can persist on contaminated surfaces and how environmental factors affect the persistence time are not fully characterized. The present study provides a comprehensive assessment of the stability of Omicron variants BA.1 and BA.5, which are currently circulating strains, on the surfaces of widely used transport packaging materials. By monitoring viable virus detection over a 7-day period under different environmental conditions, it was found that the environmental stability of SARS-CoV-2 Omicron variants depended heavily on the surface type, temperature, and virus concentration. In addition, virus nucleic acid exhibited high stability on the material surface independent of whether viable virus was detected. These findings provide useful information for logistics practitioners and the general public to appropriately deal with transport items under different conditions to minimize the risk of epidemic transmission. IMPORTANCE This study shows the environmental stability of SARS-CoV-2 Variants Omicron BA.1 and BA.5 on surfaces of widely used transport packaging materials. The findings demonstrate that the environmental stability of the SARS-CoV-2 Omicron variants varies based on material type. The viability of SARS-CoV-2 on material surfaces depends heavily on temperature and viral titer. Low temperatures and high viral titers promote virus survival. Moreover, in contrast to virus viability, virus nucleic acid exhibits high stability on the surfaces of widely used materials, making the detection of virus nucleic acid unsuitable for evaluating the risk of epidemic transmission.

Stability of SARS-CoV-2 variants of concern (Delta and Omicron) on surfaces at room temperature.

Surfaces contaminated with infectious SARS-CoV-2 particles have the potential to cause human infection and any increase in surface survivability of a SARS-CoV-2 variant may increase its prevalence over other variants. This study investigated whether there were differences in surface persistence between Delta and Omicron variants leading to Omicron's dominance globally. Stainless steel coupons were inoculated with suspensions of either Delta or Omicron variant and exposed to typical environmental conditions within a containment level 3 laboratory. Coupons were recovered at different timepoints and enumerated using plaque assay. Both variants were recoverable for >48 h on the coupons. Omicron showed a greater reduction of viability after 48 h compared to Delta with a 20-fold decrease versus 15-fold respectively, but this difference was not statistically significant (p = 0.424). These results indicate that Omicron's surface persistence is unlikely to contribute to it becoming the dominant variant over Delta.

Plasmids and their role in human diseases

Plasmids are DNA molecules that may replicate independently of chromosomal DNA and are found in a variety of prokaryotes and eukaryotes. Even though they aren't a part of the bacterial genome, their presence is critical for bacterial survival and stability in adverse settings. The capacity of broad host range (BHR) plasmids to disseminate favourable genetic features among species as well as among taxonomically distant species is of great interest. The presence of genes that code for antibiotics and antibiotic hydrolyzing enzymes, toxic heavy metal resistance, radiation resistance, xenobiotic-compound degradation, virulence determinants, and bacteriocin production can all be ascribed to the calibre of plasmids. Plasmids can also carry the genetic information for a type IV secretion system, such as the tumour inducing (Ti) plasmid in virulent Agrobacterium tumefaciens, which is involved in gene transfer. Plasmids acquire mobile genetic elements (insertion sequences, transposons) that mobilise antimicrobial resistance genes and promote horizontal resistance determinant transfer among bacteria of various species and genera, depending on their host range, conjugative properties, and conjugation efficiency. In bacteria like Escherichia coli, Yersinia spp., and Shigella spp., plasmids encode virulence factors that are responsible for pathogenicity. The existence of virulence plasmids in pathogenic bacteria is ubiquitous, albeit the genetic composition and involvement at different stages of the disease vary by species. Virulence plasmids have a low copy number (10 per cell) but are big (>40 kb) and work similarly to episomal PAIs (Pathogenicity Islands) by undergoing internal remodelling and horizontal gene transfer. Certain virulence plasmids can also exchange virulence components with the genome or integrate with it, resulting in a genomic PAI. Viruses that cause African swine fever, such as the iridovirus, have structures that are similar to plasmids. Borrelia species cause Lyme disease and relapsing fever via their linear plasmids, which appear to encode both hemolysins, which harm blood cells, and surface proteins, which protect the bacteria from the host immune system. Restriction/anti-restriction mechanisms and partitioning systems are frequently encoded by promiscuous broad-range plasmids, ensuring sustained inheritance during bacterial cell division. These strategies encourage the persistence of plasmids while providing no advantage to the bacterial host. Purified plasmid DNA (pDNA) vaccines, on the other hand, have opened up new ways to treat emerging infectious pathogens like HIV (human immunodeficiency virus), SARS coronavirus (severe acute respiratory syndrome virus), and highly pathogenic avian influenza (H5N1) viruses that have evolved strategies to rapidly change their genetic compositions and for which other conventional vaccines have failed. A gene encoding an antigen of the target pathogen is included in a plasmid used in DNA vaccination (immunogen gene). A promoter "turns on" protein antigen expression in the host cell, and a terminator "turns it off" (a polyadenylation signal sequence). In our ever-changing microbial environment, plasmid DNA vaccines have the potential to improve human health by preventing diseases through immunization. Apart from all of these aspects, the current review will shed light on how plasmids contribute to pathogen virulence, the fitness cost they impose on their hosts, and how their coevolution with the host resolves the plasmid paradox, as well as how temperature affects the genetic plasticity of virulence plasmids. © 2023 Nova Science Publishers, Inc. All rights reserved.

Peculiarities of Periodontal Pocket Microbiome in Patients with Generalized Periodontitis in the Post-Covid Period

The oral cavity, like the lungs, is often referred to as the <<ecological niche of commensal, symbiotic, and pathogenic or-ganisms,>> and the emigration and elimination of microbes between them are constant, ensuring a healthy distribution of saprophytic microorganisms that maintains organ, tissue, and immune homeostasis. The prolonged hospital stays due to COVID-19 complications, cross-infection, oxygenation therapy through the mask or incubation, and long-term intravenous infusions limit the patient's ability to care about the oral cavity, regularly clean teeth, floss interdental, etc., which creates extremely favorable conditions for colonization by aerobic and anaerobic pathogens of the oral cavity and periodontal pockets and leads to the rapid progression of chronic generalized periodontitis in this category of patients in the future. The goal of the study was to assess the state of the microbiome of the periodontal pockets of dental patients in the post-covid period. Methods. The object of the study was 140 patients with generalized periodontitis of the I and II stages of development in the chronic course (GP), among which 80 patients had coronavirus disease in the closest past. The patients were randomized by age, sex, and stage of GP development. The diagnosis of periodontal disease was established according to the classification by Danilevskyi. The bacteriological material for aerobic and facultative anaerobic microflora and yeast-like fungi was collected from periodontal pockets with a calibrated bacteriological loop and immediately seeded on blood agar. Results. Significant qualitative and quantitative changes in the nature of the oral microbiocenosis were observed in patients with GP after the recent coronavirus disease, compared with similar patients who did not suffer from COVID-19. We have noticed almost complete disappearance of bacteria that belong to the transient representatives of the oral microflora such as Neisseria, corynebacteria (diphtheria), micrococci, and lac-tobacilli. The main resident representatives of the oral microflora, i.e., alpha-hemolytic Streptococci of the mitis group, were found in all healthy individuals and patients of groups A and C, but in 30.0 +/- 4.58% of patients in group B, alpha-hemolytic streptococci in the contents of periodontal pockets are present in quantities not available for detection by the applied method (<2.7 lg CCU/mL). In terms of species, Streptococcus oralis and Streptococcus salivarius are more characteris-tic in gingival crevicular fluid in healthy individuals (93.8% of selected strains). In 68.4 +/- 3.32% of patients in group A, 64.0 +/- 3.43% of patients in group B, and 67.5 +/- 3.76% of patients in group C, the dominant species were Streptococcus gordonii and Streptococcus sanguinis (p<0.01), which increased pathogenic potential as they produce streptolysin-O, inhibit complement activation, bind to fibronectine, actively form biofilms on the surface of tooth enamel and gum epithelial surface, and can act as an initiator of adhesion of periodontal pathogens. The other representatives of the resident microflora of the oral cavity - Stomatococcus mucilaginosus and Veillonella parvula for the patients of group C are also found in periodontal pockets with a significantly lower index of persistence and minimal population level. In the post-covid period, both the population level and the frequency of colonization of periodontal pockets by Staphylo-cocci and beta-hemolytic Streptococci decreases rapidly. For these patient groups, unlike for those that did not suffer from COVID-19, we did not find any case of colonization with Staphylococcus aureus, as well as beta-hemolytic Streptococci and Epidermal staphylococcus were also absent. The most characteristic in the post-covid period is a decrease in the proportion of alpha-hemolytic Streptococci, an increase in the proportion of yeast-like fungi of Candida species, as well as the appearance of a significant number of gram-negative rod-shaped bacteria (Enterobacteria and Pseudomonads). In periodontal patien s, the microbial count is approximately 2 orders of magnitude lower than in those with GP who did not suffer from COVID-19 (p<0.05). Conclusions. The overpassed coronavirus disease due to intensive antibiotic therapy leads to a marked decrease in the number of viable saprophytic microorganisms in the periodontal pockets of patients with GP. In the post-covid period for the patients with GP, there is a decrease in the level of colonization of periodontal pockets by species of resident oral microflora - alpha-hemolytic Streptococci, reduction of resident micro-organism's species, and almost complete disappearance of transient microflora. On the other hand, the frequency of colonization of periodontal pockets by fungi species, enterobacteria, and pseudomonads significantly increases. There are more expressed disorders in the periodontal pocket's microbiome for the patients with a severe and complicated course of coronavirus disease, such as post-covid pulmonary fibrosis, which requires reconsideration of approaches to therapeutic and pharmacological treatment in this category of patients.Copyright © 2022, Zabolotny Institute of Microbiology and Virology, NAS of Ukraine. All rights reserved.

An Investigation into the Presence of Pathogens on Inanimate Surfaces in the Hospital Environment

Background The hospital environment is understood to play an important role in the transmission of nosocomial pathogens, with inanimate surfaces facilitating pathogen movement and persistence in the environment. The majority of studies of surface contamination have been carried out in outbreak conditions or on high-dependency wards. Current surface cleaning guidance only requires surfaces to be visually clean. Microbiological standards for cleanliness have been proposed however they are not widely adopted and little implementation guidance is available. Evidence-based surface sampling protocols are required for the transmission risk surfaces pose to be adequately quantified and addressed. Methods Environmental surface samples will be collected in a number of in- and outpatient settings staff and public areas, such as waiting rooms. This will be done before and after cleaning. Pathogens associated with nosocomial infection (e.g., ESKAPE pathogens Clostridioides difficile and Candida auris) will be identified through culture methods and MALDI-ToF mass spectrometry. Antimicrobial susceptibility profiles of isolates will be determined following EUCAST protocols. Realtime PCR will be utilized to identify viral pathogens (including norovirus adenovirus influenza and SARS-CoV-2) present. Following this samples will be collected for community composition sequencing allowing for non-culturable microorganisms to be identified. Whole genome sequencing will be performed on any pathogens of interest isolated during this investigation. Results and Conclusion Fewer microorganisms are expected to be isolated after cleaning than prior and samples from inpatient environments will have higher proportions of pathogens. The hospital microbiome has rarely been investigated outside of outbreak conditions. This study presents a novel, systematic approach to assess the microorganisms present in the hospital environment and how they are impacted by current cleaning measures. This will build a comprehensive picture of the hospital microflora and provide an evidence base for the development of surface sampling protocols helping inform clinical risk assessments and subsequently improving patient outcomes.

Inhibition of major histocompatibility complex-I antigen presentation by sarbecovirus ORF7a proteins.

Viruses employ a variety of strategies to escape or counteract immune responses, including depletion of cell surface major histocompatibility complex class I (MHC-I), that would ordinarily present viral peptides to CD8+ cytotoxic T cells. As part of a screen to elucidate biological activities associated with individual severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) viral proteins, we found that ORF7a reduced cell surface MHC-I levels by approximately fivefold. Nevertheless, in cells infected with SARS-CoV-2, surface MHC-I levels were reduced even in the absence of ORF7a, suggesting additional mechanisms of MHC-I down-regulation. ORF7a proteins from a sample of sarbecoviruses varied in their ability to induce MHC-I down-regulation and, unlike SARS-CoV-2, the ORF7a protein from SARS-CoV lacked MHC-I downregulating activity. A single amino acid at position 59 (T/F) that is variable among sarbecovirus ORF7a proteins governed the difference in MHC-I downregulating activity. SARS-CoV-2 ORF7a physically associated with the MHC-I heavy chain and inhibited the presentation of expressed antigen to CD8+ T cells. Specifically, ORF7a prevented the assembly of the MHC-I peptide loading complex and caused retention of MHC-I in the endoplasmic reticulum. The differential ability of ORF7a proteins to function in this way might affect sarbecovirus dissemination and persistence in human populations, particularly those with infection- or vaccine-elicited immunity.

Evaluation of coronavirus decay in French coastal water and application to SARS-CoV-2 risk evaluation using Porcine Epidemic Diarrhea Virus as surrogate. (preprint)

SARS-CoV-2 in infected patient mainly display pulmonary and oronasal tropism however, the presence of the virus has also been demonstrated in stools of patients and consequently in wastewater treatment plant effluents, questioning the potential risk of environmental contamination (such as seawater contamination) through inadequately treated wastewater spill-over into surface or coastal waters. The environmental detection of RNA alone does not substantiate risk of infection, and evidence of an effective transmission is not clear where empirical observations are lacking. Therefore, here, we decided to experimentally evaluate the persistence and infectious capacity of the Porcine epidemic diarrhea virus (PEDv), considered as a coronavirus representative model and SARS-CoV-2 surrogate, in the coastal environment of France. Coastal seawater was collected, sterile-filtered, and inoculated with PEDv before incubation for 0-4 weeks at four temperatures representative of those measured along the French coasts throughout the year (4, 8, 15, and 24{degrees}C). The decay rate of PEDv was determined using mathematical modeling and was used to determine the half-life of the virus along the French coast in accordance with temperatures from 2000 to 2021. We experimentally observed an inverse correlation between seawater temperature and the persistence of infectious viruses in seawater and confirm that the risk of transmission of infectious viruses from contaminated stool in wastewater to seawater during recreational practices is very limited. The present work represents a good model to assess the risk of transmission of not only SARS-CoV-2 but may also be used to model the risk of other coronaviruses, specifically enteric coronaviruses. ImportanceThis present work is a follow up addressing the question of the persistence of coronavirus in marine environment owing to the fact that SARS-CoV-2 is regularly detected in wastewater treating plan and the coastal environment is particularly at risk since it is subjected to increasing anthropogenic pressure and is the final receiver of surface waters and treated or sometimes insufficiently depurated waste waters. Our findings are of interest to researchers and authorities seeking to monitor SARS-CoV-2 and also enteric coronaviruses in the environment, either in tourist areas or in regions of the world, where centralized systems for wastewater treatment are not implemented, and more broadly, to the scientific community involved in "One Health" approaches.

Persistence of SARS-CoV-2 and its surrogate, bacteriophage Phi6, on surfaces and in water (preprint)

The COVID-19 pandemic has motivated research on the persistence of infectious SARS-CoV-2 in environmental reservoirs such as surfaces and water. Viral persistence data has been collected for SARS-CoV-2 and its surrogates, including bacteriophage Phi6. Despite its wide use, no side-by-side comparisons between Phi6 and SARS-CoV-2 exist. Here, we quantified the persistence of SARS-CoV-2 and Phi6 on surfaces (plastic and metal) and in water and evaluated the influence that the deposition solution has on viral persistence by using four commonly used deposition solutions: two culture media (DMEM and Tryptone Soya Broth (TSB)), Phosphate Buffered Saline (PBS), and human saliva. Phi6 remained infectious in water significantly longer than SARS-CoV-2, having a half-life of 27 hours as compared with 15 hours for SARS-CoV-2. The persistence of viruses on surfaces was significantly influenced by the virus used and the deposition solution, but not by the surface material. Phi6 remained infectious significantly longer than SARS-CoV-2 when the inoculation solution was culture media (DMEM, TSB) and saliva. Using culture media and saliva led to half-lives between 9 hours and 2 weeks for Phi6, as compared to 0.5 to 2 hours for SARS-CoV-2. Using PBS as a deposition solution led to half-lives shorter than 4 hours for both viruses on all surfaces. Our results showed that, although it has been frequently used as a surrogate for coronaviruses, bacteriophage Phi6 is not an adequate surrogate for studies quantifying SARS-CoV-2 persistence, as it over-estimates infectiousness. Additionally, our findings reveal the need of using adequate deposition solutions when evaluating viral persistence on surfaces.

Conformational stability of SARS-CoV-2 glycoprotein spike variants.

The severe acute respiratory syndrome spread worldwide, causing a pandemic. SARS-CoV-2 mutations have arisen in the spike, a glycoprotein at the viral envelope and an antigenic candidate for vaccines against COVID-19. Here, we present comparative data of the glycosylated full-length ancestral and D614G spike together with three other transmissible strains classified by the World Health Organization as variants of concern: beta, gamma, and delta. By showing that D614G has less hydrophobic surface exposure and trimer persistence, we place D614G with features that support a model of temporary fitness advantage for virus spillover. Further, during the SARS-CoV-2 adaptation, the spike accumulates alterations leading to less structural stability for some variants. The decreased trimer stability of the ancestral and gamma and the presence of D614G uncoupled conformations mean higher ACE-2 affinities compared to the beta and delta strains. Mapping the energetics and flexibility of variants is necessary to improve vaccine development.

SARS-CoV-2 persistence on common food covering materials: plastic wrap, fruit wax, and cardboard takeout containers.

AIMS: Assess the persistence of infectious SARS-CoV-2 virus and virus genomic material on three common food coverings. METHODS AND RESULTS: The stability of infectious virus and genomic material on plastic wrap, fruit wax, and cardboard takeout containers was measured. SARS-CoV-2 in simulated saliva was applied to the surface of these materials and allowed to dry. Samples were stored at 4°C or 20°C and a relative humidity of 30%, 50%, 65%, or 70% for up to 7 days. Viability was measured by TCID50 and the half-life for infectious virus was determined to be ~24 hours and ~8 hours at 4°C and 20°C, respectively, on all surfaces and RH tested. There was no loss of virus genomic material as measured by qRT-PCR at all conditions evaluated. CONCLUSIONS: SARS-CoV-2 virus remains infectious on food coverings for hours to days. It is estimated that a 99.9% reduction in titer requires 10 days at 4°C and 3 days at 20°C for all RH tested. SARS-CoV-2 genomic material showed no loss when assayed by qRT-PCR. Significance and Impact of Study: SARS-CoV-2 virus on food coverings loses infectivity over a certain period, but PCR assays can still detect virus genomic material throughout the same time. Thus, testing and controls may need to consider the fact that virus genomic material may still be detected when no infectious virus is present.

Safety and Impact of Dasatinib on Viral Persistence and Inflammation in People With HIV Under Antiretroviral Treatment