A Single-Dose Intranasal ChAd Vaccine Protects Upper and Lower Respiratory Tracts against SARS-CoV-2

The COVID-19 Menace

Coronavirus disease 2019 (COVID-19) is caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which binds to ectoenzyme angiotensin-converting enzyme 2. It is very contagious and is spreading rapidly around the world. Until now, coronaviruses have mainly been associated with the aerodigestive tract due to the presence of a monobasic cleavage site for the resident transmembrane serine protease 2. Notably, SARS-CoV-2 is equipped with a second, polybasic cleavage site for the ubiquitous furin protease, which may determine the widespread tissue tropism. Furthermore, the terminal sequence of the furin-cleaved spike protein also binds to neuropilin receptors. Clinically, there is enormous variability in the severity of the disease. Severe consequences are seen in a relatively small number of patients, most show moderate symptoms, but asymptomatic cases, especially among young people, drive disease spread. Unfortunately, the number of local infections can quickly build up, causing disease outbreaks suddenly exhausting health services' capacity. Therefore, COVID-19 is dangerous and unpredictable and has become the most serious threat for generations. Here, the latest research on COVID-19 is summarized, including its spread, testing methods, organ-specific complications, the role of comorbidities, long-term consequences, mortality, as well as a new hope for immunity, drugs, and vaccines.

IgA Nephropathy After SARS-CoV-2 Vaccination

Here we present the first case of newly diagnosed IgA nephropathy (IgAN) after a SARS-CoV-2 vaccination. A 30-year-old man with no known past medical history presented with gross hematuria and subnephrotic proteinuria 24 hours after the second dose of the mRNA-1273 SARS-CoV-2 vaccine. A kidney biopsy showed IgAN. He was started on an angiotensin receptor blocker, resulting in proteinuria reduction. Similar to natural infection of SARS-CoV-2, persons who receive 2 mRNA-based vaccines demonstrate robust antibodies against the receptor-binding domain (RBD) of the S1 protein. Given the uniqueness of glycosylation of RBD and potent stimulation of immune response from mRNA-based vaccine compared to other vaccines, we hypothesize that our patient developed de novo antibodies, leading to IgA-containing immune-complex deposits. This case highlights the urgency of understanding the immunological responses to novel mRNA-based SARS-CoV-2 vaccines in more diverse populations. Despite the lack of clear causality, nephrologists should be alerted if any new-onset hematuria or proteinuria is observed.

An Update on mRNA-Based Viral Vaccines

With the success of COVID-19 vaccines, newly created mRNA vaccines against other infectious diseases are beginning to emerge. Here, we review the structural elements required for designing mRNA vaccine constructs for effective in vitro synthetic transcription reactions. The unprecedently speedy development of mRNA vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was enabled with previous innovations in nucleoside modifications during in vitro transcription and lipid nanoparticle delivery materials of mRNA. Recent updates are briefly described in the status of mRNA vaccines against SARS-CoV-2, influenza virus, and other viral pathogens. Unique features of mRNA vaccine platforms and future perspectives are discussed.

Inhaled vaccine delivery in the combat against respiratory viruses: a 2021 overview of recent developments and implications for COVID-19

INTRODUCTION

As underlined by the late 2019 outbreak of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), vaccination remains the cornerstone of global health-care. Although vaccines for SARS-CoV-2 are being developed at a record-breaking pace, the majority of those that are licensed or currently registered in clinical trials are formulated as an injectable product, requiring a tightly regulated cold-chain infrastructure, and primarily inducing systemic immune responses.

AREAS COVERED

Here, we shed light on the status of inhaled vaccines against viral pathogens, providing background to the role of the mucosal immune system and elucidating what factors determine an inhalable vaccine's efficacy. We also discuss whether the development of an inhalable powder vaccine formulation against SARS-CoV-2 could be feasible. The review was conducted using relevant studies from PubMed, Web of Science and Google Scholar.

EXPERT OPINION

We believe that the scope of vaccine research should be broadened toward inhalable dry powder formulations since dry vaccines bear several advantages. Firstly, their dry state can tremendously increase vaccine stability and shelf-life. Secondly, they can be inhaled using disposable inhalers, omitting the need for trained health-care personnel and, therefore, facilitating mass-vaccination campaigns. Thirdly, inhalable vaccines may provide improved protection since they can induce an IgA-mediated mucosal immune response.

Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces viral shedding after SARS-CoV-2 D614G challenge in preclinical models

ChAdOx1 nCoV-19/AZD1222 is an approved adenovirus-based vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently being deployed globally. Previous studies in rhesus macaques revealed that intramuscular vaccination with ChAdOx1 nCoV-19/AZD1222 provided protection against pneumonia but did not reduce shedding of SARS-CoV-2 from the upper respiratory tract. Here, we investigated whether intranasally administered ChAdOx1 nCoV-19 reduces detection of virus in nasal swabs after challenging vaccinated macaques and hamsters with SARS-CoV-2 carrying a D614G mutation in the spike protein. Viral loads in swabs obtained from intranasally vaccinated hamsters were decreased compared to control hamsters, and no viral RNA or infectious virus was found in lung tissue after a direct challenge or after direct contact with infected hamsters. Intranasal vaccination of rhesus macaques resulted in reduced virus concentrations in nasal swabs and a reduction in viral loads in bronchoalveolar lavage and lower respiratory tract tissue. Intranasal vaccination with ChAdOx1 nCoV-19/AZD1222 reduced virus concentrations in nasal swabs in two different SARS-CoV-2 animal models, warranting further investigation as a potential vaccination route for COVID-19 vaccines.

Intranasal vaccine from whole Leishmania donovani antigens provides protection and induces specific immune response against visceral leishmaniasis

Visceral leishmaniasis is a protozoan disease associated with high fatality rate in developing countries. Although the drug pipeline is constantly improving, available treatments are costly and live-threatening side effects are not uncommon. Moreover, an approved vaccine against human leishmaniasis does not exist yet. Using whole antigens from Leishmania donovani promastigotes (LdAg), we investigated the protective potential of a novel adjuvant-free vaccine strategy. Immunization of mice with LdAg via the intradermal or the intranasal route prior to infection decreases the parasitic burden in primary affected internal organs, including the liver, spleen, and bone marrow. Interestingly, the intranasal route is more efficient than the intradermal route, leading to better parasite clearance and remarkable induction of adaptive immune cells, notably the helper and cytotoxic T cells. In vitro restimulation experiments with Leishmania antigens led to significant IFN-γ secretion by splenocytes; therefore, exemplifying specificity of the adaptive immune response. To improve mucosal delivery and the immunogenic aspects of our vaccine strategy, we used polysaccharide-based nanoparticles (NP) that carry the antigens. The NP-LdAg formulation is remarkably taken up by dendritic cells and induces their maturation in vitro, as revealed by the increased expression of CD80, CD86 and MHC II. Intranasal immunization with NP-LdAg does not improve the parasite clearance in our experimental timeline; however, it does increase the percentage of effector and memory T helper cells in the spleen, suggesting a potential induction of long-term memory. Altogether, this study provides a simple and cost-effective vaccine strategy against visceral leishmaniasis based on LdAg administration via the intranasal route, which could be applicable to other parasitic diseases.

Visceral leishmaniasis is a neglected tropical disease caused by specific species of Leishmania parasites that affect internal organs including spleen, liver, and bone marrow. The infective stage called promastigote, is transmitted into the host skin via sandfly bites. Visceral leishmaniasis is usually associated with high mortality rate in poor and developing countries, lacking proper health assistance. Moreover, treatments are expensive while no approved vaccines exist to prevent infection and avoid disease outbreaks. This study suggests an affordable and adjuvant-free vaccine formulation made from the total lysate of promastigotes. Vaccine administration via the intranasal route, ensures a remarkable clearance of Leishmania parasites from the internal organs of infected experimental mice. In particular, intranasal route known to be not invasive, is efficient in inducing adequate immune response against the infective form of the parasite. Further studies are now required to improve this prophylactic vaccine and provide therefore the basis for a promising translational approach.

Effect of SARS-CoV-2 Mutations on the Efficacy of Antibody Therapy and Response to Vaccines

SARS-CoV-2 causes severe acute respiratory syndrome, which has led to significant morbidity and mortality around the world. Since its emergence, extensive prophylactic and therapeutic countermeasures have been employed to successfully prevent the spread of COVID-19. Extensive work has been undertaken on using monoclonal antibody therapies, mass vaccination programs, and antiviral drugs to prevent and treat COVID-19. However, since antiviral drugs could take years to become widely available, immunotherapy and vaccines currently appear to be the most feasible option. In December 2020, the first vaccine against SARS-CoV-2 was approved by the World Health Organization (WHO) and, subsequently, many other vaccines were approved for use by different international regulators in different countries. Most monoclonal antibodies (mAbs) and vaccines target the SARS-CoV-2 surface spike (S) protein. Recently, mutant (or variant) SARS-CoV-2 strains with increased infectivity and virulence that evade protective host antibodies present either due to infection, antibody therapy, or vaccine administration have emerged. In this manuscript, we discuss the different monoclonal antibody and vaccine therapies available against COVID-19 and how the efficacy of these therapies is affected by the emergence of variants of SARS-CoV-2. We also discuss strategies that might help society cope with variants that could neutralize the effects of immunotherapy and escape the protective immunity conferred by vaccines.

Single-Dose Intranasal Administration of AdCOVID Elicits Systemic and Mucosal Immunity against SARS-CoV-2 and Fully Protects Mice from Lethal Challenge

The coronavirus disease 2019 (COVID-19) pandemic has highlighted the urgent need for effective prophylactic vaccination to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Intranasal vaccination is an attractive strategy to prevent COVID-19 as the nasal mucosa represents the first-line barrier to SARS-CoV-2 entry. The current intramuscular vaccines elicit systemic immunity but not necessarily high-level mucosal immunity. Here, we tested a single intranasal dose of our candidate adenovirus type 5-vectored vaccine encoding the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein (AdCOVID) in inbred, outbred, and transgenic mice. A single intranasal vaccination with AdCOVID elicited a strong and focused immune response against RBD through the induction of mucosal IgA in the respiratory tract, serum neutralizing antibodies, and CD4+ and CD8+ T cells with a Th1-like cytokine expression profile. A single AdCOVID dose resulted in immunity that was sustained for over six months. Moreover, a single intranasal dose completely protected K18-hACE2 mice from lethal SARS-CoV-2 challenge, preventing weight loss and mortality. These data show that AdCOVID promotes concomitant systemic and mucosal immunity and represents a promising vaccine candidate.

Adenoviral vector vaccine platforms in the SARS-CoV-2 pandemic

Adenoviral vectors have been explored as vaccine agents for a range of infectious diseases, and their ability to induce a potent and balanced immune response made them logical candidates to apply to the COVID-19 pandemic. The unique molecular characteristics of these vectors enabled the rapid development of vaccines with advanced designs capable of overcoming the biological challenges faced by early adenoviral vector systems. These successes and the urgency of the COVID-19 situation have resulted in a flurry of candidate adenoviral vector vaccines for COVID-19 from both academia and industry. These vaccines represent some of the lead candidates currently supported by Operation Warp Speed and other government agencies for rapid translational development. This review details adenoviral vector COVID-19 vaccines currently in human clinical trials and provides an overview of the new technologies employed in their design. As these vaccines have formed a cornerstone of the COVID-19 global vaccination campaign, this review provides a full consideration of the impact and development of this emerging platform.

Engineering of the current nucleoside-modified mRNA-LNP vaccines against SARS-CoV-2

Currently, there are over 230 different COVID-19 vaccines under development around the world. At least three decades of scientific development in RNA biology, immunology, structural biology, genetic engineering, chemical modification, and nanoparticle technologies allowed the accelerated development of fully synthetic messenger RNA (mRNA)-based vaccines within less than a year since the first report of a SARS-CoV-2 infection. mRNA-based vaccines have been shown to elicit broadly protective immune responses, with the added advantage of being amenable to rapid and flexible manufacturing processes. This review recapitulates current advances in engineering the first two SARS-CoV-2-spike-encoding nucleoside-modified mRNA vaccines, highlighting the strategies followed to potentiate their effectiveness and safety, thus facilitating an agile response to the current COVID-19 pandemic.

Immunogenicity and protective efficacy of an intranasal live-attenuated vaccine against SARS-CoV-2

Global deployment of an effective and safe vaccine is necessary to curtail the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we evaluated a Newcastle disease virus (NDV)-based vectored-vaccine in mice and hamsters for its immunogenicity, safety, and protective efficacy against SARS-CoV-2. Intranasal administration of recombinant (r)NDV-S vaccine expressing spike (S) protein of SARS-CoV-2 to mice induced high levels of SARS-CoV-2-specific neutralizing immunoglobulin A (IgA) and IgG2a antibodies and T-cell-mediated immunity. Hamsters immunized with two doses of vaccine showed complete protection from lung infection, inflammation, and pathological lesions following SARS-CoV-2 challenge. Importantly, administration of two doses of intranasal rNDV-S vaccine significantly reduced the SARS-CoV-2 shedding in nasal turbinate and lungs in hamsters. Collectively, intranasal vaccination has the potential to control infection at the site of inoculation, which should prevent both clinical disease and virus transmission to halt the spread of the COVID-19 pandemic.

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Vaccine induces high levels of neutralizing Abs and T-cell-mediated immunity

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Vaccine ameliorates lung inflammation and pathology in hamster induced by SARS-CoV-2

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The SARS-CoV-2 remains undetectable in lungs and nasal turbinates of vaccinated hamster

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Two doses of intranasal vaccine show complete protection against SARS-CoV-2 challenge

Risk for COVID-19 infection in patients with tobacco smoke-associated cancers of the upper and lower airway

PURPOSE

Cancer patients are regarded as a group at risk for both COVID-19 infection and severe clinical course because of advanced age, comorbidities and iatrogenic immune impairment. Among them, patients with cancer of the upper and lower airways share other risk factors, mostly related to tobacco-smoke exposure, including male gender, airway epithelial damages, chronic obstructive respiratory disease (COPD), cardiovascular and cerebrovascular diseases. Clinical and pathophysiological factors shared by these conditions are reviewed.

METHODS

Review of the published literature since the beginning of 2020.

RESULTS

COVID-19 is a respiratory infectious disease and SARS-CoV-2 replication and shedding occurs in nasal and bronchial epithelial respiratory cells through the interaction with ACE2 and TMPRSS2 receptors, both overexpressed in smokers and former smokers. Tobacco-smoke airway exposure is also characterized by a chronic inflammation with activation of inflammatory cells and cytokine release including interleukin-6 (IL-6). A high release of cytokine in response to viral infection is documented in COVID-19 patients with adverse clinical outcomes and IL-6 is a key element of the cytokine storm syndrome leading to multi-organ damage.

CONCLUSIONS

Patients with cancers of the upper and lower airways might be at increased risk of infection, morbidity and mortality from COVID-19 also because of tobacco exposure, a key factor in triggering inflammation, immunity and cancer.

Nonhuman Adenoviral Vector-Based Platforms and Their Utility in Designing Next Generation of Vaccines for Infectious Diseases

Several human adenoviral (Ad) vectors have been developed for vaccine delivery owing to their numerous advantages, including the feasibility of different vector designs, the robustness of elicited immune responses, safety, and scalability. To expand the repertoire of Ad vectors for receptor usage and circumvention of Ad vector immunity, the use of less prevalent human Ad types or nonhuman Ads were explored for vector design. Notably, many nonhuman Ad vectors have shown great promise in preclinical and clinical studies as vectors for vaccine delivery. This review describes the key features of several nonhuman Ad vector platforms and their implications in developing effective vaccines against infectious diseases.

An intranasal vaccine durably protects against SARS-CoV-2 variants in mice

SARS-CoV-2 variants that attenuate antibody neutralization could jeopardize vaccine efficacy. We recently reported the protective activity of an intranasally administered spike protein-based chimpanzee adenovirus-vectored vaccine (ChAd-SARS-CoV-2-S) in animals, which has advanced to human trials. Here, we assessed its durability, dose response, and cross-protective activity in mice. A single intranasal dose of ChAd-SARS-CoV-2-S induced durably high neutralizing and Fc effector antibody responses in serum and S-specific IgG and IgA secreting long-lived plasma cells in the bone marrow. Protection against a historical SARS-CoV-2 strain was observed across a 100-fold vaccine dose range and over a 200-day period. At 6 weeks or 9 months after vaccination, serum antibodies neutralized SARS-CoV-2 strains with B.1.351, B.1.1.28, and B.1.617.1 spike proteins and conferred almost complete protection in the upper and lower respiratory tracts after challenge with variant viruses. Thus, in mice, intranasal immunization with ChAd-SARS-CoV-2-S provides durable protection against historical and emerging SARS-CoV-2 strains.

Design and proof of concept for targeted phage-based COVID-19 vaccination strategies with a streamlined cold-free supply chain

Development of effective vaccines against coronavirus disease 2019 (COVID-19) is a global imperative. Rapid immunization of the entire human population against a widespread, continually evolving, and highly pathogenic virus is an unprecedented challenge, and different vaccine approaches are being pursued. Engineered filamentous bacteriophage (phage) particles have unique potential in vaccine development due to their inherent immunogenicity, genetic plasticity, stability, cost-effectiveness for large-scale production, and proven safety profile in humans. Herein we report the development and initial evaluation of two targeted phage-based vaccination approaches against SARS-CoV-2: dual ligand peptide-targeted phage and adeno-associated virus/phage (AAVP) particles. For peptide-targeted phage, we performed structure-guided antigen design to select six solvent-exposed epitopes of the SARS-CoV-2 spike (S) protein. One of these epitopes displayed on the major capsid protein pVIII of phage induced a specific and sustained humoral response when injected in mice. These phage were further engineered to simultaneously display the peptide CAKSMGDIVC on the minor capsid protein pIII to enable their transport from the lung epithelium into the systemic circulation. Aerosolization of these "dual-display" phage into the lungs of mice generated a systemic and specific antibody response. In the second approach, targeted AAVP particles were engineered to deliver the entire S protein gene under the control of a constitutive CMV promoter. This induced tissue-specific transgene expression, stimulating a systemic S protein-specific antibody response in mice. With these proof-of-concept preclinical experiments, we show that both targeted phage- and AAVP-based particles serve as robust yet versatile platforms that can promptly yield COVID-19 vaccine prototypes for translational development.

Mucosal vaccines - fortifying the frontiers

Mucosal vaccines offer the potential to trigger robust protective immune responses at the predominant sites of pathogen infection. In principle, the induction of adaptive immunity at mucosal sites, involving secretory antibody responses and tissue-resident T cells, has the capacity to prevent an infection from becoming established in the first place, rather than only curtailing infection and protecting against the development of disease symptoms. Although numerous effective mucosal vaccines are in use, the major advances seen with injectable vaccines (including adjuvanted subunit antigens, RNA and DNA vaccines) have not yet been translated into licensed mucosal vaccines, which currently comprise solely live attenuated and inactivated whole-cell preparations. The identification of safe and effective mucosal adjuvants allied to innovative antigen discovery and delivery strategies is key to advancing mucosal vaccines. Significant progress has been made in resolving the mechanisms that regulate innate and adaptive mucosal immunity and in understanding the crosstalk between mucosal sites, and this provides valuable pointers to inform mucosal adjuvant design. In particular, increased knowledge on mucosal antigen-presenting cells, innate lymphoid cell populations and resident memory cells at mucosal sites highlights attractive targets for vaccine design. Exploiting these insights will allow new vaccine technologies to be leveraged to facilitate rational mucosal vaccine design for pathogens including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and for cancer.

Safety, tolerability, and immunogenicity of an aerosolised adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) in adults: preliminary report of an open-label and randomised phase 1 clinical trial

Background

SARS-CoV-2 has caused millions of deaths, and, since Aug 11, 2020, 20 intramuscular COVID-19 vaccines have been approved for use. We aimed to evaluate the safety and immunogenicity of an aerosolised adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) in adults without COVID-19 from China.

Method

This was a randomised, single-centre, open-label, phase 1 trial done in Zhongnan Hospital (Wuhan, China), to evaluate the safety and immunogenicity of the Ad5-nCoV vaccine by aerosol inhalation in adults (≥18 years) seronegative for SARS-CoV-2. Breastfeeding or pregnant women and people with major chronic illnesses or history of allergies were excluded. Participants were enrolled and randomly assigned (1:1:1:1:1) into five groups to be vaccinated via intramuscular injection, aerosol inhalation, or both. Randomisation was stratified by sex and age (18–55 years or ≥56 years) using computer-generated randomisation sequences (block sizes of five). Only laboratory staff were masked to group assignment. The participants in the two aerosol groups received an initial high dose (2 × 10¹⁰ viral particles; HDmu group) or low dose (1 × 10¹⁰ viral particles; LDmu group) of Ad5-nCoV vaccine on day 0, followed by a booster on day 28. The mixed vaccination group received an initial intramuscular (5 × 10¹⁰ viral particles) vaccine on day 0, followed by an aerosolised booster (2 × 10¹⁰ viral particles) vaccine on day 28 (MIX group). The intramuscular groups received one dose (5 × 10¹⁰ viral particles; 1Dim group) or two doses (10 × 10¹⁰ viral particles; 2Dim group) of Ad5-nCoV on day 0. The primary safety outcome was adverse events 7 days after each vaccination, and the primary immunogenicity outcome was anti-SARS-CoV-2 spike receptor IgG antibody and SARS-CoV-2 neutralising antibody geometric mean titres at day 28 after last vaccination. This trial is registered with ClinicalTrials.gov, number NCT04552366.

Findings

Between Sept 28, 2020, and Sept 30, 2020, 230 individuals were screened for inclusion, of whom 130 (56%) participants were enrolled into the trial and randomly assigned into one of the five groups (26 participants per group). Within 7 days after vaccination, adverse events occurred in 18 (69%) in the HDmu group, 19 (73%) in the LDmu group, 19 (73%) in the MIX group, 19 (73%) in the 1Dim group, and 15 (58%) in the 2Dim group. The most common adverse events reported 7 days after the first or booster vaccine were fever (62 [48%] of 130 participants), fatigue (40 [31%] participants), and headache (46 [35%] participants). More adverse events were reported in participants who received intramuscular vaccination, including participants in the MIX group (49 [63%] of 78 participants), than those who received aerosol vaccine (13 [25%] of 52 participants) after the first vaccine vaccination. No serious adverse events were noted within 56 days after the first vaccine. At days 28 after last vaccination, geometric mean titres of SARS-CoV-2 neutralising antibody was 107 (95% CI 47–245) in the HDmu group, 105 (47–232) in the LDmu group, 396 (207–758) in the MIX group, 95 (61–147) in the 1Dim group, and 180 (113–288) in the 2Dim group. The geometric mean concentrations of receptor binding domain-binding IgG was 261 EU/mL (95% CI 121–563) in the HDmu group, 289 EU/mL (138–606) in the LDmu group, 2013 EU/mL (1180–3435) in the MIX group, 915 EU/mL (588–1423) in the 1Dim group, and 1190 EU/mL (776–1824) in the 2Dim group.

Interpretation

Aerosolised Ad5-nCoV is well tolerated, and two doses of aerosolised Ad5-nCoV elicited neutralising antibody responses, similar to one dose of intramuscular injection. An aerosolised booster vaccination at 28 days after first intramuscular injection induced strong IgG and neutralising antibody responses. The efficacy and cost-effectiveness of aerosol vaccination should be evaluated in future studies.

Funding

National Key Research and Development Programme of China and National Science and Technology Major Project.

Translation

For the Chinese translation of the Summary see Supplementary Material.

A single intranasal or intramuscular immunization with chimpanzee adenovirus-vectored SARS-CoV-2 vaccine protects against pneumonia in hamsters

The development of an effective vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of coronavirus disease 2019 (COVID-19), is a global priority. Here, we compare the protective capacity of intranasal and intramuscular delivery of a chimpanzee adenovirus-vectored vaccine encoding a prefusion stabilized spike protein (chimpanzee adenovirus [ChAd]-SARS-CoV-2-S) in Golden Syrian hamsters. Although immunization with ChAd-SARS-CoV-2-S induces robust spike-protein-specific antibodies capable of neutralizing the virus, antibody levels in serum are higher in hamsters vaccinated by an intranasal compared to intramuscular route. Accordingly, against challenge with SARS-CoV-2, ChAd-SARS-CoV-2-S-immunized hamsters are protected against less weight loss and have reduced viral infection in nasal swabs and lungs, and reduced pathology and inflammatory gene expression in the lungs, compared to ChAd-control immunized hamsters. Intranasal immunization with ChAd-SARS-CoV-2-S provides superior protection against SARS-CoV-2 infection and inflammation in the upper respiratory tract. These findings support intranasal administration of the ChAd-SARS-CoV-2-S candidate vaccine to prevent SARS-CoV-2 infection, disease, and possibly transmission.

Age-dependent appearance of SARS-CoV-2 entry sites in mouse chemosensory systems reflects COVID-19 anosmia-ageusia symptoms

COVID-19 pandemic has given rise to a collective scientific effort to study its viral causing agent SARS-CoV-2. Research is focusing in particular on its infection mechanisms and on the associated-disease symptoms. Interestingly, this environmental pathogen directly affects the human chemosensory systems leading to anosmia and ageusia. Evidence for the presence of the cellular entry sites of the virus, the ACE2/TMPRSS2 proteins, has been reported in non-chemosensory cells in the rodent’s nose and mouth, missing a direct correlation between the symptoms reported in patients and the observed direct viral infection in human sensory cells. Here, mapping the gene and protein expression of ACE2/TMPRSS2 in the mouse olfactory and gustatory cells, we precisely identify the virus target cells to be of basal and sensory origin and reveal the age-dependent appearance of viral entry-sites. Our results propose an alternative interpretation of the human viral-induced sensory symptoms and give investigative perspectives on animal models.

Brechbühl et al characterise the gene and protein expression of ACE2/TMPRSS2 in the mouse olfactory and gustatory cells, which reveals that SARS-CoV-2 target cells are of basal and sensory origin. They also demonstrate an age-dependent appearance of viral entry-sites, which could inform the use of mouse models in the investigation of SARS-CoV-2 effects on olfaction.

Inhalation Delivery for the Treatment and Prevention of COVID-19 Infection

Coronavirus disease-2019 (COVID-19) is caused by coronavirus-2 (SARS-CoV-2) and has produced a global pandemic. As of 22 June 2021, 178 million people have been affected worldwide, and 3.87 million people have died from COVID-19. According to the Centers for Disease Control and Prevention (CDC) of the United States, COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes. Since the location of initial infection and disease progression is primarily through the lungs, the inhalation delivery of drugs directly to the lungs may be the most appropriate route of administration for treating COVID-19. This review article aims to present possible inhalation therapeutics and vaccines for the treatment of COVID-19 symptoms. This review covers the comparison between SARS-CoV-2 and other coronaviruses such as SARS-CoV/MERS, inhalation therapeutics for the treatment of COVID-19 symptoms, and vaccines for preventing infection, as well as the current clinical status of inhaled therapeutics and vaccines.

Intranasal Administration of RBD Nanoparticles Confers Induction of Mucosal and Systemic Immunity against SARS-CoV-2

Mucosal immunity plays a significant role in host defense against viruses in the respiratory tract. Because the upper respiratory airway is a primary site of SARS-CoV-2 entry, immunization at the mucosa via the intranasal route could potentially lead to induction of local sterilizing immunity that protects against SARS-CoV-2 infection. In this study, we evaluated the immunogenicity of a receptor-binding domain (RBD) of SARS-CoV-2 spike glycoprotein loaded into N,N,N-trimethyl chitosan nanoparticles (RBD-TMC NPs). We showed that intranasal delivery of RBD-TMC NPs into mice induced robust local mucosal immunity, as evidenced by the presence of IgG and IgA responses in BALs and the lungs of immunized mice. Furthermore, mice intranasally administered with this platform of immunogens developed robust systemic antibody responses including serum IgG, IgG1, IgG2a, IgA and neutralizing antibodies. In addition, these immunized mice had significantly higher levels of activated splenic CD4⁺ and CD8⁺ cells compared with those that were administered with soluble RBD immunogen. Collectively, these findings shed light on an alternative route of vaccination that mimics the natural route of SARS-CoV-2 infection. This route of administration stimulated not only local mucosal responses but also the systemic compartment of the immune system.

COVID-19: vaccine's progress

Under the pressure of the COVID-19 pandemic, vaccines were developed and rolled out into mass vaccination campaigns at incredible speed. What normally takes a decade was worked out within a year. Vaccines were produced along many different platforms ranging from inactivated whole virus vaccines over adenovirus-vectored vaccines, recombinant protein vaccines and nanoparticles to mRNA vaccines. Several vaccines went through preclinical testing and completed successful phase 1 to phase 3 clinical trials. The first evaluations of national vaccination campaigns document astonishing high levels of protection against disease. The present article summarizes the published reports leading to these striking achievements with vaccines based on different concepts.

Low Innate Immunity and Lagged Adaptive Immune Response in the Re-Tested Viral RNA Positivity of a COVID-19 Patient

Recent studies have highlighted observations regarding re-tested positivity (RP) of SARS-CoV-2 RNA in discharged COVID-19 patients, however, the immune mechanisms underlying SARS-CoV-2 RNA RP in immunocompetent patients remain elusive. Herein, we describe the case of an immunocompetent COVID-19 patient with moderate symptoms who was twice re-tested as positive for SARS-CoV-2 RNA, and the period between first and third viral RNA positivity was 95 days, longer than previously reported (18–25 days). The chest computed tomography findings, plasma anti-SARS-CoV-2 antibody, neutralizing antibodies (NAbs) titer, and whole blood transcriptic characteristics in the viral RNA RP patient and other COVID-19 patients were analyzed. During the SARS-CoV-2 RNA RP period, new lung lesions were observed. The COVID-19 patient with viral RNA RP had delayed seroconversion of anti-spike/receptor-binding domain (RBD) IgA antibody and NAbs and were accompanied with disappearance of the lung lesions. Further experimental data validated that NAbs titer was significantly associated with anti-RBD IgA and IgG, and anti-spike IgG. The RP patient had lower interferon-, T cells- and B cell-related genes expression than non-RP patients with mild-to-moderate symptoms, and displayed lower cytokines and chemokines gene expression than severe patients. Interestingly, the RP patient had low expression of antigen presentation-related genes and low B cell counts which might have contributed to the delayed anti-RBD specific antibody and low CD8+ cell response. Collectively, delayed antigen presentation-related gene expression was found related to delayed adaptive immune response and contributed to the SARS-CoV-2 RNA RP in this described immunocompetent patient.

Two-tiered SARS-CoV-2 seroconversion screening in the Netherlands and stability of nucleocapsid, spike protein domain 1 and neutralizing antibodies

BACKGROUND

Serological testing in the COVID-19 pandemic is mainly implemented to gain sero-epidemiological data, but can also retrospectively inform about suspected SARS-CoV-2 infection.

METHOD

We verified and applied a two-tiered testing strategy combining a SARS-CoV-2 receptor-binding domain (RBD)-specific lateral flow assay (LFA) with a nucleocapsid protein (NCP) IgG ELISA to assess seroconversion in n = 7241 individuals. The majority had experienced symptoms consistent with COVID-19, but had no access to RT-PCR testing. Longitudinal follow-up in n = 97 LFA + individuals was performed up to 20 weeks after initial infection using NCP and spike protein S1 domain (S1) IgG ELISAs and a surrogate virus neutralization test (sVNT).

RESULTS

Individuals reporting symptoms from January 2020 onwards showed seroconversion, as did a considerable proportion of asymptomatic individuals. Seroconversion for symptomatic and asymptomatic individuals was higher in an area with a known infection cluster compared to a low incidence area. Overall, 94% of individuals with a positive IgG result by LFA were confirmed by NCP ELISA. The proportion of ELISA-confirmed LFA results declined over time, in line with contracting NCP IgG titres during longitudinal follow-up. Neutralizing antibody activity was considerably more stable than S1 and NCP IgG titres, and both reach a plateau after approximately 100 d. The sVNT proved to be not only highly specific, but also more sensitive than the specificity-focussed two-tiered serology approach.

CONCLUSIONS

Our results demonstrate the high specificity of two-tiered serology testing and highlight the sVNT used as a valuable tool to support modelling of SARS-CoV-2 transmission dynamics, complement molecular testing and provide relevant information to individuals.

Emerging Advances of Nanotechnology in Drug and Vaccine Delivery against Viral Associated Respiratory Infectious Diseases (VARID)

Viral-associated respiratory infectious diseases are one of the most prominent subsets of respiratory failures, known as viral respiratory infections (VRI). VRIs are proceeded by an infection caused by viruses infecting the respiratory system. For the past 100 years, viral associated respiratory epidemics have been the most common cause of infectious disease worldwide. Due to several drawbacks of the current anti-viral treatments, such as drug resistance generation and non-targeting of viral proteins, the development of novel nanotherapeutic or nano-vaccine strategies can be considered essential. Due to their specific physical and biological properties, nanoparticles hold promising opportunities for both anti-viral treatments and vaccines against viral infections. Besides the specific physiological properties of the respiratory system, there is a significant demand for utilizing nano-designs in the production of vaccines or antiviral agents for airway-localized administration. SARS-CoV-2, as an immediate example of respiratory viruses, is an enveloped, positive-sense, single-stranded RNA virus belonging to the coronaviridae family. COVID-19 can lead to acute respiratory distress syndrome, similarly to other members of the coronaviridae. Hence, reviewing the current and past emerging nanotechnology-based medications on similar respiratory viral diseases can identify pathways towards generating novel SARS-CoV-2 nanotherapeutics and/or nano-vaccines.

Immunologically relevant aspects of the new COVID-19 vaccines-an ÖGAI (Austrian Society for Allergology and Immunology) and AeDA (German Society for Applied Allergology) position paper

BACKGROUND

The vaccines against the coronavirus disease 2019 (COVID-19) approved in the European Union represent a decisive step in the fight against the pandemic. The application of these available vaccines to patients with pre-existing immunological conditions leads to a multitude of questions regarding efficacy, side effects and the necessary patient information.

RESULTS

This review article provides insight into mechanisms of action of the currently available severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines and summarises the current state of science as well as expert recommendations regarding tolerability of the vaccines. In addition, the potential to develop protective immune responses is determined. A special focus is given on patients under immunosuppression or in treatment with immunomodulatory drugs. Special groups of the population such as children, pregnant women and the elderly are also considered.

CONCLUSION

Despite the need for a patient-specific risk-benefit assessment, the consensus among experts is that patients with immunological diseases in particular benefit from the induced immune protection after COVID-19 vaccination and do not have an increased risk of side effects.

Nasal vaccination against SARS-CoV-2: Synergistic or alternative to intramuscular vaccines?

It is striking that all marketed SARS-CoV-2 vaccines are developed for intramuscular administration designed to produce humoral and cell mediated immune responses, preventing viremia and the COVID-19 syndrome. They have a high degree of efficacy in humans (70-95%) depending on the type of vaccine. However, little protection is provided against viral replication and shedding in the upper airways due to the lack of a local sIgA immune response, indicating a risk of transmission of virus from vaccinated individuals. A range of novel nasal COVID-19 vaccines are in development and preclinical results in non-human primates have shown a promising prevention of replication and shedding of virus due to the induction of mucosal immune response (sIgA) in upper and lower respiratory tracts as well as robust systemic and humoral immune responses. Whether these results will translate to humans remains to be clarified. An IM prime followed by an IN booster vaccination would likely result in a better well-rounded immune response, including prevention (or strong reduction) in viral replication in the upper and lower respiratory tracts.

Development of SARS-CoV-2 vaccines: challenges, risks, and the way forward

The COVID-19 pandemic mandates the development of a safe and effective Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) vaccine. This review analyzes the complexities, challenges, and other vital issues associated with the development of the SARS-CoV-2 vaccine. A brief review of the immune responses (innate, antibody, and T-cell) to SARS-CoV-2, including immune targets, correlates of protection, and duration of immunity is presented. Approaches to vaccine development including different vaccine platforms, critical attributes of novel vaccine candidates, the status of the ongoing clinical trials, and the ways to speed up vaccine development are also reviewed. Despite a historical average success rate of only 6%, and a usual gestation period of 10-12 years for the development of a new vaccine, the world is on the verge of developing COVID-19 vaccines in an extraordinary short time span.

Recent updates in COVID-19 with emphasis on inhalation therapeutics: Nanostructured and targeting systems

The current world health threat posed by the novel coronavirus disease of 2019 (COVID-19) calls for the urgent development of effective therapeutic options. COVID-19 needs daunting routes such as nano-antivirals. Hence, the role of nanotechnology is very critical in combating this nano-enemy "virus." Although substantial resources are under ongoing attention for prevention and care, we would like to start sharing with readers our vision of the role of inhaled nanomaterials and targeting systems that can play an important role in the fight against the COVID-19. In this review, we underline the genomic structure of COVID-19, recent modes of virus transmission with measures to control the infection, pathogenesis, clinical presentation of SARS-CoV-2, and how much the virus affects the lung. Additionally, the recent therapeutic approaches for managing COVID-19 with emphasis on the value of nanomaterial-based technical approaches are discussed in this review. This review also focuses on the safe and efficient delivery of useable targeted therapies using designed nanocarriers. Moreover, the effectiveness and availability of active targeting of certain specific receptors expressed on the coronavirus surfaces via tailored ligand nanoparticles are manipulated. It was also highlighted in this review the role of inhaled medicines including antivirals and repurposed drugs for fighting the associated lung disorders and efficiency of developed vaccines. Moreover, the inhalation delivery safety techniques were also highlighted.

The Cellular and Chemical Biology of Endocytic Trafficking and Intracellular Delivery-The GL-Lect Hypothesis

Lipid membranes are common to all forms of life. While being stable barriers that delimitate the cell as the fundamental organismal unit, biological membranes are highly dynamic by allowing for lateral diffusion, transbilayer passage via selective channels, and in eukaryotic cells for endocytic uptake through the formation of membrane bound vesicular or tubular carriers. Two of the most abundant fundamental fabrics of membranes-lipids and complex sugars-are produced through elaborate chains of biosynthetic enzymes, which makes it difficult to study them by conventional reverse genetics. This review illustrates how organic synthesis provides access to uncharted areas of membrane glycobiology research and its application to biomedicine. For this Special Issue on Chemical Biology Research in France, focus will be placed on synthetic approaches (i) to study endocytic functions of glycosylated proteins and lipids according to the GlycoLipid-Lectin (GL-Lect) hypothesis, notably that of Shiga toxin; (ii) to mechanistically dissect its endocytosis and intracellular trafficking with small molecule; and (iii) to devise intracellular delivery strategies for immunotherapy and tumor targeting. It will be pointed out how the chemical biologist's view on lipids, sugars, and proteins synergizes with biophysics and modeling to "look" into the membrane for atomistic scale insights on molecular rearrangements that drive the biogenesis of endocytic carriers in processes of clathrin-independent endocytosis.

Delivery Routes for COVID-19 Vaccines

The novel coronavirus, SARS-CoV-2, which causes COVID-19, has resulted in a pandemic with millions of deaths. To eradicate SARS-CoV-2 and prevent further infections, many vaccine candidates have been developed. These vaccines include not only traditional subunit vaccines and attenuated or inactivated viral vaccines but also nucleic acid and viral vector vaccines. In contrast to the diversity in the platform technology, the delivery of vaccines is limited to intramuscular vaccination. Although intramuscular vaccination is safe and effective, mucosal vaccination could improve the local immune responses that block the spread of pathogens. However, a lack of understanding of mucosal immunity combined with the urgent need for a COVID-19 vaccine has resulted in only intramuscular vaccinations. In this review, we summarize the history of vaccines, current progress in COVID-19 vaccine technology, and the status of intranasal COVID-19 vaccines. Future research should determine the most effective route for vaccine delivery based on the platform and determine the mechanisms that underlie the efficacy of different delivery routes.

An Intramuscular DNA Vaccine for SARS-CoV-2 Decreases Viral Lung Load but Not Lung Pathology in Syrian Hamsters

The 2019 novel coronavirus, SARS-CoV-2, first reported in December 2019, has infected over 102 million people around the world as of February 2021 and thus calls for rapid development of safe and effective interventions, namely vaccines. In our study, we evaluated a DNA vaccine against SARS-CoV-2 in the Syrian hamster model. Hamsters were vaccinated with a DNA-plasmid encoding the SARS-CoV-2 full length spike open reading frame (ORF) to induce host cells to produce spike protein and protective immune responses before exposure to infectious virus. We tested this vaccine candidate by both intranasal (IN) and intramuscular (IM) routes of administration and complexing with and without an in vivo delivery reagent. Hamsters receiving prime-boost-boost IM-only vaccinations recovered body weight quicker, had decreased lung viral loads, and increased SARS-CoV-2-specific antibody titers compared to control vaccinated animals but, surprisingly, lung pathology was as severe as sham vaccinated controls. The IM/IN combination group showed no efficacy in reducing lung virus titers or pathology. With increasing public health need for rapid and effective interventions, our data demonstrate that in some vaccine contexts, significant antibody responses and decreased viral loads may not be sufficient to prevent lung pathology.

Biomaterials-Based Opportunities to Engineer the Pulmonary Host Immune Response in COVID-19

The COVID-19 pandemic caused by the global spread of the SARS-CoV-2 virus has led to a staggering number of deaths worldwide and significantly increased burden on healthcare as nations scramble to find mitigation strategies. While significant progress has been made in COVID-19 diagnostics and therapeutics, effective prevention and treatment options remain scarce. Because of the potential for the SARS-CoV-2 infections to cause systemic inflammation and multiple organ failure, it is imperative for the scientific community to evaluate therapeutic options aimed at modulating the causative host immune responses to prevent subsequent systemic complications. Harnessing decades of expertise in the use of natural and synthetic materials for biomedical applications, the biomaterials community has the potential to play an especially instrumental role in developing new strategies or repurposing existing tools to prevent or treat complications resulting from the COVID-19 pathology. Leveraging microparticle- and nanoparticle-based technology, especially in pulmonary delivery, biomaterials have demonstrated the ability to effectively modulate inflammation and may be well-suited for resolving SARS-CoV-2-induced effects. Here, we provide an overview of the SARS-CoV-2 virus infection and highlight current understanding of the host's pulmonary immune response and its contributions to disease severity and systemic inflammation. Comparing to frontline COVID-19 therapeutic options, we highlight the most significant untapped opportunities in immune engineering of the host response using biomaterials and particle technology, which have the potential to improve outcomes for COVID-19 patients, and identify areas needed for future investigations. We hope that this work will prompt preclinical and clinical investigations of promising biomaterials-based treatments to introduce new options for COVID-19 patients.

SARS-CoV-2 B.1.1.7 and B.1.351 variants of concern induce lethal disease in K18-hACE2 transgenic mice despite convalescent plasma therapy

SARS-CoV-2 variants of concern (VoCs) are impacting responses to the COVID-19 pandemic. Here we present a comparison of the SARS-CoV-2 USA-WA1/2020 (WA-1) strain with B.1.1.7 and B.1.351 VoCs and identify significant differences in viral propagation in vitro and pathogenicity in vivo using K18-hACE2 transgenic mice. Passive immunization with plasma from an early pandemic SARS-CoV-2 patient resulted in significant differences in the outcome of VoC-infected mice. WA-1-infected mice were protected by plasma, B.1.1.7-infected mice were partially protected, and B.1.351-infected mice were not protected. Serological correlates of disease were different between VoC-infected mice, with B.1.351 triggering significantly altered cytokine profiles than other strains. In this study, we defined infectivity and immune responses triggered by VoCs and observed that early 2020 SARS-CoV-2 human immune plasma was insufficient to protect against challenge with B.1.1.7 and B.1.351 in the mouse model.

SARS-CoV-2 vaccines in advanced clinical trials: Where do we stand?

The ongoing SARS-CoV-2 pandemic has led to the focused application of resources and scientific expertise toward the goal of developing investigational vaccines to prevent COVID-19. The highly collaborative global efforts by private industry, governments and non-governmental organizations have resulted in a number of SARS-CoV-2 vaccine candidates moving to Phase III trials in a period of only months since the start of the pandemic. In this review, we provide an overview of the preclinical and clinical data on SARS-CoV-2 vaccines that are currently in Phase III clinical trials and in few cases authorized for emergency use. We further discuss relevant vaccine platforms and provide a discussion of SARS-CoV-2 antigens that may be targeted to increase the breadth and durability of vaccine responses.

N-terminal domain antigenic mapping reveals a site of vulnerability for SARS-CoV-2

The SARS-CoV-2 spike (S) glycoprotein contains an immunodominant receptor-binding domain (RBD) targeted by most neutralizing antibodies (Abs) in COVID-19 patient plasma. Little is known about neutralizing Abs binding to epitopes outside the RBD and their contribution to protection. Here, we describe 41 human monoclonal Abs (mAbs) derived from memory B cells, which recognize the SARS-CoV-2 S N-terminal domain (NTD) and show that a subset of them neutralize SARS-CoV-2 ultrapotently. We define an antigenic map of the SARS-CoV-2 NTD and identify a supersite (designated site i) recognized by all known NTD-specific neutralizing mAbs. These mAbs inhibit cell-to-cell fusion, activate effector functions, and protect Syrian hamsters from SARS-CoV-2 challenge, albeit selecting escape mutants in some animals. Indeed, several SARS-CoV-2 variants, including the B.1.1.7, B.1.351, and P.1 lineages, harbor frequent mutations within the NTD supersite, suggesting ongoing selective pressure and the importance of NTD-specific neutralizing mAbs for protective immunity and vaccine design.

Protection against SARS-CoV-2 infection by a mucosal vaccine in rhesus macaques

Effective SARS-CoV-2 vaccines are urgently needed. Although most vaccine strategies have focused on systemic immunization, here we compared the protective efficacy of 2 adjuvanted subunit vaccines with spike protein S1: an intramuscularly primed/boosted vaccine and an intramuscularly primed/intranasally boosted mucosal vaccine in rhesus macaques. The intramuscular-alum–only vaccine induced robust binding and neutralizing antibody and persistent cellular immunity systemically and mucosally, whereas intranasal boosting with nanoparticles, including IL-15 and TLR agonists, elicited weaker T cell and Ab responses but higher dimeric IgA and IFN-α. Nevertheless, following SARS-CoV-2 challenge, neither group showed detectable subgenomic RNA in upper or lower respiratory tracts versus naive controls, indicating full protection against viral replication. Although mucosal and systemic protective mechanisms may differ, results demonstrate both vaccines can protect against respiratory SARS-CoV-2 exposure. In summary, we have demonstrated that the mucosal vaccine was safe after multiple doses and cleared the input virus more efficiently in the nasal cavity and thus may act as a potent complementary reinforcing boost for conventional systemic vaccines to provide overall better protection.

In vitro cell culture model of human nasal-associated lymphoid tissue (NALT) to evaluate the humoral immune response to SARS-CoV-2 spike proteins

To date, coronavirus disease 2019 (COVID-19) continues to be considered a pandemic worldwide, with a mild to severe disease presentation that is sometimes associated with serious complications that are concerning to global health authorities. Scientists are working hard to understand the pathogenicity of this novel virus, and a great deal of attention and effort has been focused on identifying therapeutics and vaccines to control this pandemic.

Methods

This study used tonsils removed from twelve patients who underwent an elective tonsillectomy in the ear, nose, and throat (ENT) department at Saudi Germany Hospital, Madinah, Saudi Arabia. Tonsillar mononuclear cells (MNCs) were separated and co-cultured in RPMI complete medium in the presence and absence of viral spike (S) proteins (the full-length S, S1 subunit, and S2 subunit proteins). Enzyme-linked immunosorbent assay (ELISA) was used to measure secreted antibody concentrations following stimulation.

Results

The in vitro human nasal-associated lymphoid tissue (NALT) cell culture model was successfully used to evaluate the humoral immune response against SARS-CoV-2- S protein. Significant (p < 0.0001, n = 12) levels of specific, anti-S IgG, IgM, and IgA antibody responses were detected in cells culture supernatanat folloeing stimulation with the full-length S protein compared with unstimulated cells. In contrast, S1 and S2 subunit proteins alone failed to induce a mucosal humoral immune response following tonsillar MNC stimulation.

Conclusion

We demonstrated a successful human NALT in vitro cell culture model that was used to study the mucosal humoral immune response to the SARS-CoV-2 S protein. This model could be advantageous for the in-depth study of cellular immune responses to the S protein and other viral antigens, such as nucleocapsid and matrix antigen. The S protein appears to be the important viral protein that may be able to mimic the natural infection process intranasally and should be studied as a component of a candidate vaccine.

In vivo monoclonal antibody efficacy against SARS-CoV-2 variant strains

Rapidly-emerging variants jeopardize antibody-based countermeasures against SARS-CoV-2. While recent cell culture experiments have demonstrated loss of potency of several anti-spike neutralizing antibodies against SARS-CoV-2 variant strains1-3, the in vivo significance of these results remains uncertain. Here, using a panel of monoclonal antibodies (mAbs) corresponding to many in advanced clinical development by Vir Biotechnology, AbbVie, AstraZeneca, Regeneron, and Lilly we report the impact on protection in animals against authentic SARS-CoV-2 variants including WA1/2020 strains, a B.1.1.7 isolate, and chimeric strains with South African (B.1.351) or Brazilian (B.1.1.28) spike genes. Although some individual mAbs showed reduced or abrogated neutralizing activity against B.1.351 and B.1.1.28 viruses with E484K spike protein mutations in cell culture, low prophylactic doses of mAb combinations protected against infection in K18-hACE2 transgenic mice, 129S2 immunocompetent mice, and hamsters without emergence of resistance. Two exceptions were mAb LY-CoV555 monotherapy which lost all protective activity in vivo, and AbbVie 2B04/47D11, which showed partial loss of activity. When administered after infection as therapy, higher doses of mAb cocktails protected in vivo against viruses displaying a B.1.351 spike gene. Thus, many, but not all, of the antibody products with Emergency Use Authorization should retain substantial efficacy against the prevailing SARS-CoV-2 variant strains.

A single intranasal dose of chimpanzee adenovirus-vectored vaccine protects against SARS-CoV-2 infection in rhesus macaques

The deployment of a vaccine that limits transmission and disease likely will be required to end the coronavirus disease 2019 (COVID-19) pandemic. We recently described the protective activity of an intranasally administered chimpanzee adenovirus-vectored vaccine encoding a pre-fusion stabilized spike (S) protein (ChAd-SARS-CoV-2-S [chimpanzee adenovirus-severe acute respiratory syndrome-coronavirus-2-S]) in the upper and lower respiratory tracts of mice expressing the human angiotensin-converting enzyme 2 (ACE2) receptor. Here, we show the immunogenicity and protective efficacy of this vaccine in non-human primates. Rhesus macaques were immunized with ChAd-Control or ChAd-SARS-CoV-2-S and challenged 1 month later by combined intranasal and intrabronchial routes with SARS-CoV-2. A single intranasal dose of ChAd-SARS-CoV-2-S induces neutralizing antibodies and T cell responses and limits or prevents infection in the upper and lower respiratory tracts after SARS-CoV-2 challenge. As ChAd-SARS-CoV-2-S confers protection in non-human primates, it is a promising candidate for limiting SARS-CoV-2 infection and transmission in humans.

Longitudinal profiling of respiratory and systemic immune responses reveals myeloid cell-driven lung inflammation in severe COVID-19

Immune response dynamics in coronavirus disease 2019 (COVID-19) and their severe manifestations have largely been studied in circulation. Here, we examined the relationship between immune processes in the respiratory tract and circulation through longitudinal phenotypic, transcriptomic, and cytokine profiling of paired airway and blood samples from patients with severe COVID-19 relative to heathy controls. In COVID-19 airways, T cells exhibited activated, tissue-resident, and protective profiles; higher T cell frequencies correlated with survival and younger age. Myeloid cells in COVID-19 airways featured hyperinflammatory signatures, and higher frequencies of these cells correlated with mortality and older age. In COVID-19 blood, aberrant CD163+ monocytes predominated over conventional monocytes, and were found in corresponding airway samples and in damaged alveoli. High levels of myeloid chemoattractants in airways suggest recruitment of these cells through a CCL2-CCR2 chemokine axis. Our findings provide insights into immune processes driving COVID-19 lung pathology with therapeutic implications for targeting inflammation in the respiratory tract.

Saliva: What Dental Practitioners Should Know about the Role of This Biofluid in the Transmission and Diagnostic of SARS-CoV-2

A novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has become a global ongoing pandemic. This pandemic represents a great work risk for all health professionals, it includes dental professionals who are in constant contact with saliva, which represents one of the main routes of transmission of the disease. This is due to the fact that a wide variety of oral tissues and cells are susceptible to infection by SARS-CoV-2 and that they express the ACE2 receptor, which is the main route of entry of the virus into cells, as well as the proteins TMPRSS and furin that contributes to the binding of the virus to the host cells. According to recent studies, some of the oral cells most susceptible to infection by SARS-CoV-2 are the epithelial cells of the salivary glands. This explains the presence of the virus in the saliva of infected patients and provides scientific evidence that supports the use of saliva as a biofluid that offers the opportunity to develop new detection and diagnostic techniques. This is because saliva is much easier to collect compared to nasopharyngeal swab. However, the presence of the virus in saliva, also represents a great source of transmission, since the main form of infection is through microscopic drops that are generated when infected people cough or sneeze. Likewise, health professionals, such as dentists are exposed to contagion through saliva. The objective of this review article is to provide a perspective on the main cells and tissues that can be affected by the virus, the risk of contagion that the presence of the virus in saliva represents for dentists; and the new techniques developed from saliva samples for the diagnosis and surveillance of SARS-CoV-2 infection. This review is expected to contribute to the knowledge of oral health professionals about the risk of saliva in the spread of SARS-CoV-2, but also its advantages as a diagnostic tool for pandemic control. In conclusion, the authors can mention that information that provides more scientific evidence of the mechanisms of infection of the coronavirus in oral cells and tissues is being published continually. This also explains the presence of the virus in the saliva of infected people and the risk of contagion that this means. It also provides scientific evidence of the use of saliva as a biofluid for the detection, diagnosis, monitoring, and control of the spread of the virus.

INFECTION-ACQUIRED VERSUS VACCINE-INDUCED IMMUNITY AGAINST COVID-19

The course of COVID-19 depends on a dynamic interplay between SARS-CoV-2 and the host's immune system. Although it is an emerging global health issue, little is known about the specificity, safety, and duration of the immunity elicited by the virus. This hypothesis article explores the benefits of infection-acquired and vaccine-induced immunity against COVID-19, suggesting that the latter outweighs the former. Comparative studies are proposed to explain and reveal all aspects of the immune responses. Although vaccine development relies on studies of naturally acquired immune responses, there are still no comparative analyses of the natural and vaccine immunity against SARS-CoV-2. Moreover, there are scarce reports on the characteristics of both types of responses. The scientific facts about the virulence of SARS-CoV-2 affecting the immune system are of great importance for proposed comparative analyses. Various immunological methods can be employed to elucidate infection-acquired and vaccine-induced immunity against SARS-CoV-2. The safe vaccination of subjects with and without COVID-19 history may disrupt the virus spreading and end the pandemic.

Bridging animal and clinical research during SARS-CoV-2 pandemic: A new-old challenge

Many milestones in medical history rest on animal modeling of human diseases. The SARS-CoV-2 pandemic has evoked a tremendous investigative effort primarily centered on clinical studies. However, several animal SARS-CoV-2/COVID-19 models have been developed and pre-clinical findings aimed at supporting clinical evidence rapidly emerge. In this review, we characterize the existing animal models exposing their relevance and limitations as well as outline their utility in COVID-19 drug and vaccine development. Concurrently, we summarize the status of clinical trial research and discuss the novel tactics utilized in the largest multi-center trials aiming to accelerate generation of reliable results that may subsequently shape COVID-19 clinical treatment practices. We also highlight areas of improvement for animal studies in order to elevate their translational utility. In pandemics, to optimize the use of strained resources in a short time-frame, optimizing and strengthening the synergy between the preclinical and clinical domains is pivotal.

Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global COVID-19 pandemic. Rapidly spreading SARS-CoV-2 variants may jeopardize newly introduced antibody and vaccine countermeasures. Here, using monoclonal antibodies (mAbs), animal immune sera, human convalescent sera and human sera from recipients of the BNT162b2 mRNA vaccine, we report the impact on antibody neutralization of a panel of authentic SARS-CoV-2 variants including a B.1.1.7 isolate, chimeric strains with South African or Brazilian spike genes and isogenic recombinant viral variants. Many highly neutralizing mAbs engaging the receptor-binding domain or N-terminal domain and most convalescent sera and mRNA vaccine-induced immune sera showed reduced inhibitory activity against viruses containing an E484K spike mutation. As antibodies binding to spike receptor-binding domain and N-terminal domain demonstrate diminished neutralization potency in vitro against some emerging variants, updated mAb cocktails targeting highly conserved regions, enhancement of mAb potency or adjustments to the spike sequences of vaccines may be needed to prevent loss of protection in vivo.