Intranasal Inoculation Research Articles

Beta Spike-Presenting SARS-CoV-2 Virus-like Particle Vaccine Confers Broad Protection against Other VOCs in Mice.

Virus-like particles (VLPs) are non-infectious and serve as promising vaccine platforms because they mimic the membrane-embedded conformations of fusion glycoproteins on native viruses. Here, we employed SARS-CoV-2 VLPs (SMEN) presenting ancestral, Beta, or Omicron spikes to identify the variant spike that elicits potent and cross-protective immune responses in the highly sensitive K18-hACE2 challenge mouse model. A combined intranasal and intramuscular SMEN vaccine regimen generated the most effective immune responses to significantly reduce disease burden. Protection was primarily mediated by antibodies, with minor but distinct contributions from T cells in reducing virus spread and inflammation. Immunization with SMEN carrying ancestral spike resulted in 100, 75, or 0% protection against ancestral, Delta, or Beta variant-induced mortality, respectively. However, SMEN with an Omicron spike provided only limited protection against ancestral (50%), Delta (0%), and Beta (25%) challenges. By contrast, SMEN with Beta spikes offered 100% protection against the variants used in this study. Thus, the Beta variant not only overcame the immunity produced by other variants, but the Beta spike also elicited diverse and effective humoral immune responses. Our findings suggest that leveraging the Beta variant spike protein can enhance SARS-CoV-2 immunity, potentially leading to a more comprehensive vaccine against emerging variants.

Mucosal and systemic immune correlates of viral control after SARS-CoV-2 infection challenge in seronegative adults.

Human infection challenge permits in-depth, early, and pre-symptomatic characterization of the immune response, enabling the identification of factors that are important for viral clearance. Here, we performed intranasal inoculation of 34 young adult, seronegative volunteers with a pre-Alpha severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain. Of these participants, 18 (53%) became infected and showed an interferon-dominated mediator response with divergent kinetics between nasal and systemic sites. Peripheral CD4+ and CD8+ T cell activation and proliferation were early and robust but showed distinct kinetic and phenotypic profiles; antigen-specific T cells were largely CD38+Ki67+ and displayed central and effector memory phenotypes. Both mucosal and systemic antibodies became detectable around day 10, but nasal antibodies plateaued after day 14 while circulating antibodies continued to rise. Intensively granular measurements in nasal mucosa and blood allowed modeling of immune responses to primary SARS-CoV-2 infection that revealed CD8+ T cell responses and early mucosal IgA responses strongly associated with viral control, indicating that these mechanisms should be targeted for transmission-reducing intervention.

Intranasal vaccination with engineered BCG expressing CCL2 induces a stronger immune barrier against Mycobacterium tuberculosis than BCG

Intradermal Mycobacterium bovis Bacillus Calmette-Guérin (BCG) vaccination is currently the only licensed strategy for preventing tuberculosis (TB). It provides limited protection against pulmonary TB. To enhance the efficacy of BCG, we developed a recombinant BCG expressing exogenous monocyte chemoattractant CC chemokine ligand 2 (CCL2), termed rBCG-CCL2. Co-culturing macrophages with rBCG-CCL2 enhances their abilities in migration, phagocytosis, and effector molecules expression. In the mouse model, intranasal vaccination with rBCG-CCL2 induced greater immune cells infiltration and a more extensive innate immune responses in lung compared to vaccination with parental BCG, as determined by multiparameter flow cytometry, transcriptomic analysis, and pathological assessments. Moreover, rBCG-CCL2 induced a high frequency of activated macrophages and antigen-specific Th1 and Th17 T cells in lungs. The enhanced immune microenvironment responded more effectively to intravenous challenge with Mycobacterium tuberculosis (Mtb) H37Ra, leading to significant reductions in H37Ra burden and pathological damage to the lungs and spleen. Intranasal rBCG-CCL2 vaccinated mice rapidly initiated pro-inflammatory Th1 cytokine release and reduced pathological damage to the lungs and spleen during the early stage of H37Ra challenge. The finding that co-expression of CCL2 synergistically enhances the immune barrier induced by BCG provides a model for defining immune correlates and mechanisms of vaccine-elicited protection against TB.

Safety and Immunogenicity of the Intranasal Vaccine Candidate Mambisa and the Intramuscular Vaccine Abdala Used as Booster Doses for COVID-19 Convalescents: A Randomized Phase 1-2 Clinical Trial.

A phase 1-2, prospective, multicenter, randomized, open-label clinical trial (Code RPCEC00000382), with parallel groups, involving 1161 participants, was designed to assess the safety and immunogenicity of two Cuban COVID-19 vaccines (Mambisa and Abdala) in boosting COVID-19 immunity of convalescent adults after receiving one dose of either vaccine. The main safety outcome was severe vaccination adverse events occurring in <5% of vaccinees. Main immunogenicity success endpoints were a ≥4-fold anti-RBD IgG seroconversion or a ≥20% increase in ACE2-RBD inhibitory antibodies in >55% of vaccinees in Phase 1 and >70% in Phase 2. Neutralizing antibody titers against SARS-CoV-2 variants were evaluated. Both vaccines were safe-no deaths or severe adverse events occurred. Mild intensity adverse events were the most frequent (>73%); headaches predominated for both vaccines. Phase 1 responders were 83.3% (p = 0.0018) for Abdala. Mambisa showed similar results. Phase 2 responders were 88.6% for Abdala (p < 0.0001) and 74.2% for Mambisa (p = 0.0412). In both phases, anti-RBD IgG titers, inhibition percentages and neutralizing antibody titers increased significantly after the booster dose. Both vaccines were safe and their immunogenicity surpassed the study endpoints.

Nanoplatform Based Intranasal Vaccines: Current Progress and Clinical Challenges.

Multiple vaccine platforms have been employed to develop the nasal SARS-CoV-2 vaccines in preclinical studies, and the dominating pipelines are viral vectored as protein-based vaccines. Among them, several viral vectored-based vaccines have entered clinical development. Nevertheless, some unsatisfactory results were reported in these clinical studies. In the face of such urgent situations, it is imperative to rapidly develop the next-generation intranasal COVID-19 vaccine utilizing other technologies. Nanobased intranasal vaccines have emerged as an approach against respiratory infectious diseases. Harnessing the power of nanotechnology, these vaccines offer a noninvasive yet potent defense against pathogens, including the threat of COVID-19. The improvements made in vaccine mucosal delivery technologies based on nanoparticles, such as lipid nanoparticles, polymeric nanoparticles, inorganic nanoparticles etc., not only provide stability and controlled release but also enhance mucosal adhesion, effectively overcoming the limitations of conventional vaccines. Hence, in this review, we overview the evaluation of intranasal vaccine and highlight the current barriers. Next, the modern delivery systems based on nanoplatforms are summarized. The challenges in clinical application of nanoplatform based intranasal vaccine are finally discussed.

Rousettus aegyptiacus Fruit Bats Do Not Support Productive Replication of Cedar Virus upon Experimental Challenge.

Cedar henipavirus (CedV), which was isolated from the urine of pteropodid bats in Australia, belongs to the genus Henipavirus in the family of Paramyxoviridae. It is closely related to the Hendra virus (HeV) and Nipah virus (NiV), which have been classified at the highest biosafety level (BSL4) due to their high pathogenicity for humans. Meanwhile, CedV is apathogenic for humans and animals. As such, it is often used as a model virus for the highly pathogenic henipaviruses HeV and NiV. In this study, we challenged eight Rousettus aegyptiacus fruit bats of different age groups with CedV in order to assess their age-dependent susceptibility to a CedV infection. Upon intranasal inoculation, none of the animals developed clinical signs, and only trace amounts of viral RNA were detectable at 2 days post-inoculation in the upper respiratory tract and the kidney as well as in oral and anal swab samples. Continuous monitoring of the body temperature and locomotion activity of four animals, however, indicated minor alterations in the challenged animals, which would have remained unnoticed otherwise.

Anti-aminoacyl-tRNA synthetase-interacting multifunctional protein-1 antibody improves airway inflammation in mice with house dust mite induced asthma

BackgroundSeveral biologics have been developed and used to treat severe asthma. However, commercialized biologics have limitations in treating T2-low asthma because their main target is the T2 inflammation marker. Therefore, there is an unmet need for treating T2-low severe asthma. Aminoacyl-tRNA synthetase-interacting multifunctional protein 1 (AIMP1) is an auxiliary protein in the mammalian multi-aminoacyl-tRNA synthetase complex. AIMP1 also acts as a cytokine and induces the secretion of proinflammatory cytokines. Since anti-AIMP1 has been shown to reduce interleukin (IL)-6, tumor necrosis factor-α, and IL-17A levels in a mouse model, it could be effective in the treatment of T2-low severe asthma. MethodsWild-type BALB/c mice were sensitized and challenged with intranasal inoculation of a crude HDM extract. Atliximab, a chimeric AIMP1 antibody, was administered once (20 μg, 40 μg, 100 μg) on Day 14. We evaluated airway hyperresponsiveness (AHR), performed cellular analyses of the bronchoalveolar lavage fluid (BALF), measured inflammatory cytokine levels, and examined peribronchial histological features. ResultsAtliximab reduced AIMP1 levels in asthmatic mice in a dose-dependent manner. AHR and Inflammatory cells such as neutrophils and eosinophils in the BALF decreased in asthmatic mice treated with atliximab. The levels of IL-6, IL-13, and transforming growth factor-β (TGF-β) in the lung tissue decreased in asthmatic mice treated with a high dose of atliximab (100 μg). Atliximab also reduced goblet cell hyperplasia and peribronchial fibrosis. ConclusionsAtliximab improved asthmatic airway inflammation including neutrophilic inflammation in HDM-induced asthma mice. These data suggest that anti-AIMP1 plays an important role in the treatment of severe T2-low asthma.

The Rift Valley fever (RVF) vaccine candidate 40Fp8 shows an extreme attenuation in IFNARKO mice following intranasal inoculation.

Rift Valley fever (RVF) is an important zoonotic viral disease affecting several species of domestic and wild ruminants, causing major economic losses and dozens of human deaths in various geographical areas of Africa, where it is endemic. Although it is not present in Europe, there is a risk of its introduction and spread linked to globalisation and climate change. At present, the only measure that could help to prevent the disease is vaccination of flocks in areas at risk of RVF. Available live attenuated vaccines are an effective means of controlling the disease, but their use is often questioned due to residual virulence, particularly in susceptible hosts such as pregnant sheep. On the other hand, no vaccine is currently licensed for use in humans. The development of safe and effective vaccines is therefore a major area of research. In previous studies, we selected under selective mutagenic pressure a highly attenuated RVFV 56/74 virus variant called 40Fp8. This virus showed an extremely attenuated phenotype in both wild-type and immunodeficient A129 (IFNARKO) mice, yet was still able to induce protective immunity after a single inoculation, thus supporting its use as a safe, live attenuated vaccine. To further investigate its safety, in this work we have analysed the attenuation level of 40Fp8 in immunosuppressed mice (A129) when administered by the intranasal route, and compared it with other attenuated RVF viruses that are the basis of vaccines in use or in development. Our results show that 40Fp8 has a much higher attenuated level than these other viruses and confirm its potential as a candidate for safe RVF vaccine development.

Intranasal Administration of Recombinant Newcastle Disease Virus Expressing SARS-CoV-2 Spike Protein Protects hACE2 TG Mice against Lethal SARS-CoV-2 Infection.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), emerged as a global outbreak in 2019, profoundly affecting both human health and the global economy. Various vaccine modalities were developed and commercialized to overcome this challenge, including inactivated vaccines, mRNA vaccines, adenovirus vector-based vaccines, and subunit vaccines. While intramuscular vaccines induce high IgG levels, they often fail to stimulate significant mucosal immunity in the respiratory system. We employed the Newcastle disease virus (NDV) vector expressing the spike protein of the SARS-CoV-2 Beta variant (rK148/beta-S), and evaluated the efficacy of intranasal vaccination with rK148/beta-S in K18-hACE2 transgenic mice. Intranasal vaccination with a low dose (106.0 EID50) resulted in an 86% survival rate after challenge with the SARS-CoV-2 Beta variant. Administration at a high dose (107.0 EID50) led to a reduction in lung viral load and 100% survival against the SARS-CoV-2 Beta and Delta variants. A high level of the SARS-CoV-2 spike-specific IgA was also induced in vaccinated mice lungs following the SARS-CoV-2 challenge. Our findings suggest that rK148/beta-S holds promise as an intranasal vaccine candidate that effectively induces mucosal immunity against SARS-CoV-2.

Engineered probiotic Escherichia coli elicits immediate and long-term protection against influenza A virus in mice

Influenza virus infection remains a major global health problem and requires a universal vaccine with broad protection against different subtypes as well as a rapid-response vaccine to provide immediate protection in the event of an epidemic outbreak. Here, we show that intranasal administration of probiotic Escherichia coli Nissle 1917 activates innate immunity in the respiratory tract and provides immediate protection against influenza virus infection within 1 day. Based on this vehicle, a recombinant strain is engineered to express and secret five tandem repeats of the extracellular domain of matrix protein 2 from different influenza virus subtypes. Intranasal vaccination with this strain induces durable humoral and mucosal responses in the respiratory tract, and provides broad protection against the lethal challenge of divergent influenza viruses in female BALB/c mice. Our findings highlight a promising delivery platform for developing mucosal vaccines that provide immediate and sustained protection against respiratory pathogens.

Associations between Ultrasonographically Diagnosed Lung Lesions, Clinical Parameters and Treatment Frequency in Veal Calves in an Austrian Fattening Farm.

This study evaluated the significance and predictive value of ultrasonographic and physical examination on arrival at an Austrian fattening farm. Treatment frequency and average daily weight gain (ADG) were related to physical and ultrasonographic examination results. Additionally, the effect of an intranasal vaccination in half of the examined calves was studied. The clinical and ultrasonographic health status 600 calves was recorded at the beginning and end of fattening. Half of the calves received an intranasal vaccination (Bovalto® Respi Intranasal). Overall, 44.5% showed an abnormal respiratory scoring (RS) and 56.0% showed signs of respiratory diseases in transthoracic ultrasonography (TUS) at arrival on the farm. For both RS and TUS, a categorization between ILL and HEALTHY was conducted. Results showed lower ADG in ILL calves (RS median: 0.93 kg/d; TUS median: 0.96 kg/d) compared to HEALTHY calves (RS median: 1.01 kg/d; TUS median: 1.01 kg/d). The median ADG was lower in not treated and ILL calves (RS median 0.90 kg/d; TUS: 0.93 kg/d) compared to treated and ILL calves (RS median 1.01 kg/d; TUS: 1.02 kg/d). Vaccination did not affect growth performance or occurrence of ILL, though treatment frequency was lower in VAC calves (17.0% in NVAC; 11.3% in VAC). The implementation of examination protocols for respiratory diseases may have a positive impact on production parameters (e.g., treatment frequency and ADG).

Influenza virus strains expressing SARS-CoV-2 receptor binding domain protein confer immunity in K18-hACE2 mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease (COVID-19), rapidly spread across the globe in 2019. With the emergence of the Omicron variant, COVID-19 shifted into an endemic phase. Given the anticipated rise in cases during the fall and winter seasons, the strategy of implementing seasonal booster vaccines for COVID-19 is becoming increasingly valuable to protect public health. This practice already exists for seasonal influenza vaccines to combat annual influenza seasons. Our goal was to investigate an easily modifiable vaccine platform for seasonal use against SARS-CoV-2. In this study, we evaluated the genetically modified influenza virus ΔNA(RBD) as an intranasal vaccine candidate for COVID-19. This modified virus was engineered to replace the coding sequence for the neuraminidase (NA) protein with a membrane-anchored form of the receptor binding domain (RBD) protein of SARS-CoV-2. We designed experiments to assess the protection of ΔNA(RBD) in K18-hACE2 mice using lethal (Delta) and non-lethal (Omicron) challenge models. Controls of COVID-19 mRNA vaccine and our lab’s previously described intranasal virus like particle vaccine were used as comparisons. Immunization with ΔNA(RBD) expressing ancestral RBD elicited high anti-RBD IgG levels in the serum of mice, high anti-RBD IgA in lung tissue, and improved survival after Delta variant challenge. Modifying ΔNA(RBD) to express Omicron variant RBD shifted variant-specific antibody responses and limited viral burden in the lungs of mice after Omicron variant challenge. Overall, this data suggests that ΔNA(RBD) could be an effective intranasal vaccine platform that generates mucosal and systemic immunity towards SARS-CoV-2.

An intranasal attenuated Coxsackievirus B3 vaccine induces strong systemic and mucosal immunity against CVB3 lethal challenge.

Coxsackievirus B3 (CVB3) triggers viral myocarditis, with no effective vaccine yet. This fecal-oral transmitted pathogen has prompted interest in mucosal immunization strategies to impede CVB3 spread. We developed a new attenuated vaccine strain, named CVB3(mu). The potential of CVB3(mu) to stimulate mucosal immune protection remains to be elucidated. This study evaluates the attenuation characteristics of CVB3(mu) via a rapid evolution cellular model and RNA sequencing. Its temperature sensitivity and safety were evaluated through in vitro and in vivo experiments. The mucosal immunity protection of CVB3(mu) was assessed via intranasal immunization in Balb/c mice. The results indicate that CVB3(mu) exhibits temperature sensitivity and forms smaller plaques. It sustains fewer genetic mutations and still possesses certain attenuated traits up to the 25th passage, in comparison to CVB3(WT). Intranasal immunization elicited a significant serum neutralizing antibodies, and a substantial sIgA response in nasal washes. In vivo trials revealed CVB3(mu) protection in adult mice and passive protection in suckling mice against lethal CVB3(WT) challenges. In conclusion, CVB3(mu), a live attenuated intranasal vaccine, provides protection involving humoral and mucosal immunity, making it a promising candidate to control CVB3 spread and infection.

A BSL-2 compliant mouse model of SARS-CoV-2 infection for efficient and convenient antiviral evaluation.

Animal models of authentic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection require operation in biosafety level 3 (BSL-3) containment. In the present study, we established a mouse model employing a single-cycle infectious virus replicon particle (VRP) system of SARS-CoV-2 that can be safely handled in BSL-2 laboratories. The VRP [ΔS-VRP(G)-Luc] contains a SARS-CoV-2 genome in which the spike gene was replaced by a firefly luciferase (Fluc) reporter gene (Rep-Luci), and incorporates the vesicular stomatitis virus glycoprotein on the surface. Intranasal inoculation of ΔS-VRP(G)-Luc can successfully transduce the Rep-Luci genome into mouse lungs, initiating self-replication of Rep-Luci and, accordingly, inducing acute lung injury mimicking the authentic SARS-CoV-2 pathology. In addition, the reporter Fluc expression can be monitored using a bioluminescence imaging approach, allowing a rapid and convenient determination of viral replication in ΔS-VRP(G)-Luc-infected mouse lungs. Upon treatment with an approved anti-SARS-CoV-2 drug, VV116, the viral replication in infected mouse lungs was significantly reduced, suggesting that the animal model is feasible for antiviral evaluation. In summary, we have developed a BSL-2-compliant mouse model of SARS-CoV-2 infection, providing an advanced approach to study aspects of the viral pathogenesis, viral-host interactions, as well as the efficacy of antiviral therapeutics in the future.IMPORTANCESevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly contagious and pathogenic in humans; thus, research on authentic SARS-CoV-2 has been restricted to biosafety level 3 (BSL-3) laboratories. However, due to the scarcity of BSL-3 facilities and trained personnel, the participation of a broad scientific community in SARS-CoV-2 research had been greatly limited, hindering the advancement of our understanding on the basic virology as well as the urgently necessitated drug development. Previously, our colleagues Jin et al. had generated a SARS-CoV-2 replicon by replacing the essential spike gene in the viral genome with a Fluc reporter (Rep-Luci), which can be safely operated under BSL-2 conditions. By incorporating the Rep-Luci into viral replicon particles carrying vesicular stomatitis virus glycoprotein on their surface, and via intranasal inoculation, we successfully transduced the Rep-Luci into mouse lungs, developing a mouse model mimicking SARS-CoV-2 infection. Our model can serve as a useful platform for SARS-CoV-2 pathological studies and antiviral evaluation under BSL2 containment.

Multi-antigen intranasal vaccine protects against challenge with sarbecoviruses and prevents transmission in hamsters

Immunization programs against SARS-CoV-2 with commercial intramuscular vaccines prevent disease but are less efficient in preventing infections. Mucosal vaccines can provide improved protection against transmission, ideally for different variants of concern (VOCs) and related sarbecoviruses. Here, we report a multi-antigen, intranasal vaccine, NanoSTING-SN (NanoSTING-Spike-Nucleocapsid), eliminates virus replication in both the lungs and the nostrils upon challenge with the pathogenic SARS-CoV-2 Delta VOC. We further demonstrate that NanoSTING-SN prevents transmission of the SARS-CoV-2 Omicron VOC (BA.5) to vaccine-naïve hamsters. To evaluate protection against other sarbecoviruses, we immunized mice with NanoSTING-SN. We showed that immunization affords protection against SARS-CoV, leading to protection from weight loss and 100% survival in mice. In non-human primates, animals immunized with NanoSTING-SN show durable serum IgG responses (6 months) and nasal wash IgA responses cross-reactive to SARS-CoV-2 (XBB1.5), SARS-CoV and MERS-CoV antigens. These observations have two implications: (1) mucosal multi-antigen vaccines present a pathway to reducing transmission of respiratory viruses, and (2) eliciting immunity against multiple antigens can be advantageous in engineering pan-sarbecovirus vaccines.

Intranasal adenovirus-vectored Omicron vaccine induced nasal immunoglobulin A has superior neutralizing potency than serum antibodies

The upper respiratory tract is the initial site of SARS-CoV-2 infection. Nasal spike-specific secretory immunoglobulin A (sIgA) correlates with protection against Omicron breakthrough infection. We report that intranasal vaccination using human adenovirus serotype 5 (Ad5) vectored Omicron spike in people who previously vaccinated with ancestral vaccine could induce robust neutralizing sIgA in the nasal passage. Nasal sIgA was predominantly present in dimeric and multimeric forms and accounted for nearly 40% of total proteins in nasal mucosal lining fluids (NMLFs). A low-level IgG could also be detected in NMLFs but not IgM, IgD, and IgE. After a complete nasal wash, sIgA in the nasal passage could be replenished rapidly within a few hours. A comparison of purified paired serum IgA, serum IgG, and nasal sIgA from the same individuals showed that sIgA was up to 3-logs more potent than serum antibodies in binding to spikes and in neutralizing Omicron subvariants. Serum IgG and IgA failed to neutralize XBB and BA.2.86, while nasal sIgA retained potent neutralization against these newly emerged variants. Further analysis showed that sIgA was more effective than IgG or IgA in blocking spike-mediated cell-to-cell transmission and protecting hACE2 mice from XBB challenge. Using a sIgA monoclonal antibody as a reference, we estimated that the total nasal sIgA contains about 2.6–3.9% spike-specific sIgA in NMLFs collected approximately one month after intranasal vaccination. Our study provided insights for developing intranasal vaccines that can induce sIgA to build an effective and mutation-resistant first-line immune barrier against constantly emerging variants.

Intranasally Inoculated SARS-CoV-2 Spike Protein Combined with Mucoadhesive Polymer Induces Broad and Long-Lasting Immunity.

Current mRNA vaccines against SARS-CoV-2 effectively induce systemic and cell-mediated immunity and prevent severe disease. However, they do not induce mucosal immunity that targets the primary route of respiratory infection, and their protective effects wane after a few months. Intranasal vaccines have some advantages, including their non-invasiveness and the additional ability to activate mucosal immunity. In this study, we aimed to explore the effectiveness of an intranasally inoculated spike protein of SARS-CoV-2 mixed with a carboxy-vinyl polymer (S-CVP), a viscous agent. Intranasally inoculated S-CVP strongly induced antigen-specific IgG, including neutralizing antibodies, in the mucosal epithelium and serum and cellular immunity compared to the spike protein mixed with aluminum potassium sulfate. Furthermore, IgA production was detected only with S-CVP vaccination. S-CVP-inoculation in mice significantly suppressed the viral load and inflammation in the lung and protected mice against SARS-CoV-2 challenges, including an early circulating strain and the Omicron BA.1 variant in a manner dependent on CD8+ cells and monocytes/neutrophils. Surprisingly, high antibody responses and protective effects against multiple variants of SARS-CoV-2, including Omicron BA.5, persisted for at least 15 months after the S-CVP immunization. Hence, we propose intranasal inoculation with S-CVP as a promising vaccine strategy against SARS-CoV-2.

Immunogenicity and Protective Efficacy of a Single Intranasal Dose Vectored Vaccine Based on Sendai Virus (Moscow Strain) against SARS-CoV-2 Variant of Concern.

The mouse paramyxovirus Sendai, which is capable of limited replication in human bronchial epithelial cells without causing disease, is well suited for the development of vector-based intranasal vaccines against respiratory infections, including SARS-CoV-2. Using the Moscow strain of the Sendai virus, we developed a vaccine construct, Sen-Sdelta(M), which expresses the full-length spike (S) protein of the SARS-CoV-2 delta variant. A single intranasal delivery of Sen-Sdelta(M) to Syrian hamsters and BALB/c mice induced high titers of virus-neutralizing antibodies specific to the SARS-CoV-2 delta variant. A significant T-cell response, as determined by IFN-γ ELISpot and ICS methods, was also demonstrated in the mouse model. Mice and hamsters vaccinated with Sen-Sdelta(M) were well protected against SARS-CoV-2 challenge. The viral load in the lungs and nasal turbinates, measured by RT-qPCR and TCID50 assay, decreased dramatically in vaccinated groups. The most prominent effect was revealed in a highly sensitive hamster model, where no tissue samples contained detectable levels of infectious SARS-CoV-2. These results indicate that Sen-Sdelta(M) is a promising candidate as a single-dose intranasal vaccine against SARS-CoV-2, including variants of concern.

Lung-resident CD3-NK1.1+CD69+CD103+ Cells Play an Important Role in Bacillus Calmette-Guérin Vaccine-Induced Protective Immunity against Mycobacterium tuberculosis Infection.

Tissue-resident immune cells play important roles in local tissue homeostasis and infection control. There is no information on the functional role of lung-resident CD3-NK1.1+CD69+CD103+ cells in intranasal Bacillus Calmette-Guérin (BCG)-vaccinated and/or Mycobacterium tuberculosis (Mtb)-infected mice. Therefore, we phenotypically and functionally characterized these cells in mice vaccinated intranasally with BCG. We found that intranasal BCG vaccination increased CD3-NK1.1+ cells with a tissue-resident phenotype (CD69+CD103+) in the lungs during the first 7 d after BCG vaccination. Three months post-BCG vaccination, Mtb infection induced the expansion of CD3-NK1.1+CD69+CD103+ (lung-resident) cells in the lung. Adoptive transfer of lung-resident CD3-NK1.1+CD69+CD103+ cells from the lungs of BCG-vaccinated mice to Mtb-infected naive mice resulted in a lower bacterial burden and reduced inflammation in the lungs. Our findings demonstrated that intranasal BCG vaccination induces the expansion of CD3-NK1.1+CD69+CD103+ (lung-resident) cells to provide protection against Mtb infection.

Preparation and immunological activity evaluation of an intranasal protein subunit vaccine against ancestral and mutant SARS-CoV-2 with curdlan sulfate/O-linked quaternized chitosan nanoparticles as carrier and adjuvant

Chitosan and its derivatives are ideal nasal vaccine adjuvant to deliver antigens to immune cells. Previously, we successfully used a chitosan derivative, O-(2-Hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (O-HTCC), and a β-glucan derivative, curdlan sulfate (CS), to prepare a nanoparticle adjuvant CS/O-HTCC which could deliver ovalbumin to antigen presenting cells (APCs) through nasal inhalation. In this article, we used SARS-CoV-2 spike receptor binding domain (S-RBD) as the antigen and CS/O-HTCC nanoparticles as the adjuvant to develop a nasal mucosal protein subunit vaccine, CS/S-RBD/O-HTCC. The humoral immunity, cell-mediated immunity and mucosal immunity induced by vaccines were evaluated. The results showed that CS/S-RBD/O-HTCC could induce desirable immunization with single or bivalent antigen through nasal inoculation, giving one booster vaccination with mutated S-RBD (beta) could bring about a broad cross reaction with ancestral and different mutated S-RBD, and vaccination of the BALB/c mice with CS/S-RBD/O-HTCC containing S-RBD mix antigens (ancestral and omicron) could induce the production of binding and neutralizing antibodies against both of the two antigens. Our results indicate that CS/O-HTCC is a promising nasal mucosal adjuvant to prepare protein subunit vaccine for both primary and booster immunization, and the adjuvant is suitable for loading more than one antigen for preparing multivalent vaccines.