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.

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.

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).

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.

Influenza is a highly contagious respiratory disease, resulting in an estimated 3 to 5 million cases of severe illness annually. While most influenza vaccines are administered parenterally via injection, one shortcoming is that they do not generate a strong immune response at the site of infection, which can become important in a pandemic. Intranasal vaccines can generate both local and systemic protective immune responses, can reduce costs, and enhance ease of administration. Previous studies showed that parenterally administered outer membrane vesicles (OMVs) that carry sequences of the M2e protein (OMV-M2e) protect against influenza A/PR8 challenge in mice and ferrets. In the current study, we measured the effectiveness of the intranasal route of the OMV-M2e vaccine against the influenza A/PR8 strain in mice. We observed high anti-M2e IgG and IgA titers post-challenge in mice vaccinated intranasally with OMV-M2e. In addition, we observed a Th1/Tc1 bias in the vaccinated mice, and an increased Th17/Tc17 response, both of which correlated with survival to A/PR8 challenge and significantly lower lung viral titers. We conclude that the intranasal-route administration of the OMV-M2e vaccine is a promising approach toward generating protection against influenza A as it leads to an increased proinflammatory immune response correlating with survival to viral challenge.

BACKGROUND: Vaccination is the primary method of preventing influenza infection and complications in young children. We evaluated the efficacy and safety of a single dose of MEDI3250 (intranasal, quadrivalent, live attenuated influenza vaccine) in healthy Japanese children during the 2016/17 influenza season.
METHODS: In this multicenter, randomized, double-blind, phase 3 study (jRCT2080223345), participants aged 2-18 years received MEDI3250 or placebo (2:1), stratified by age (2-6 years, 7-18 years). The primary and secondary endpoints were the incidence of confirmed symptomatic onset of influenza caused by a circulating wild-type strain or by a vaccine-matched strain, respectively. Safety outcomes included the incidence of adverse events (AEs) and vaccine-related AEs.
RESULTS: Overall, 910 participants received MEDI3250 (n = 608) or placebo (n = 302). For the primary endpoint (regardless of the influenza subtype), the incidence of influenza onset was 25.5 % (MEDI3250) and 35.9 % (placebo); relative risk reduction, 28.8 % (95 % confidence interval, 12.5 %-42.0 %). For the secondary endpoint (vaccine-matched strain), the incidence was 10.9 % (MEDI3250) and 17.2 % (placebo); relative risk reduction, 36.6 % (95 % confidence interval, 6.5 %-56.8 %). Solicited AEs occurred in 67.6 % (MEDI3250) and 63.6 % (placebo). Most events were mild; nasal discharge was most common (59.2 % [MEDI3250] and 52.6 % [placebo]). Unsolicited AEs occurred in 36.0 % (MEDI3250) and 33.1 % (placebo). The most common unsolicited vaccine-related AE was diarrhea (2.3 %, both groups).
CONCLUSIONS: MEDI3250 had a greater preventive effect against influenza onset in Japanese children than placebo; no new safety signals were observed relative to previous clinical and post-marketing studies of MEDI3250.

A chimeric protein, formed by two fragments of the conserved nucleocapsid (N) and S2 proteins from SARS-CoV-2, was obtained as a recombinant construct in Escherichia coli. The N fragment belongs to the C-terminal domain whereas the S2 fragment spans the fibre structure in the post-fusion conformation of the spike protein. The resultant protein, named S2NDH, was able to form spherical particles of 10 nm, which forms aggregates upon mixture with the CpG ODN-39M. Both preparations were recognized by positive COVID-19 human sera. The S2NDH + ODN-39M formulation administered by the intranasal route resulted highly immunogenic in Balb/c mice. It induced cross-reactive anti-N humoral immunity in both sera and bronchoalveolar fluids, under a Th1 pattern. The cell-mediated immunity (CMI) was also broad, with positive response even against the N protein of SARS-CoV-1. However, neither neutralizing antibodies (NAb) nor CMI against the S2 region were obtained. As alternative, the RBD protein was included in the formulation as inducer of NAb. Upon evaluation in mice by the intranasal route, a clear adjuvant effect was detected for the S2NDH + ODN-39M preparation over RBD. High levels of NAb were induced against SARS-CoV-2 and SARS-CoV-1. The bivalent formulation S2NDH + ODN-39M + RBD, administered by the intranasal route, constitutes an attractive proposal as booster vaccine of sarbecovirus scope.

Human parainfluenza virus type 3 (HPIV3) is a major pediatric respiratory pathogen lacking available vaccines or antiviral drugs. We generated live-attenuated HPIV3 vaccine candidates by codon-pair deoptimization (CPD). HPIV3 open reading frames (ORFs) encoding the nucleoprotein (N), phosphoprotein (P), matrix (M), fusion (F), hemagglutinin-neuraminidase (HN), and polymerase (L) were modified singly or in combination to generate 12 viruses designated Min-N, Min-P, Min-M, Min-FHN, Min-L, Min-NP, Min-NPM, Min-NPL, Min-PM, Min-PFHN, Min-MFHN, and Min-PMFHN. CPD of N or L severely reduced growth in vitro and was not further evaluated. CPD of P or M was associated with increased and decreased interferon (IFN) response in vitro, respectively, but had little effect on virus replication. In Vero cells, CPD of F and HN delayed virus replication, but final titers were comparable to wild-type (wt) HPIV3. In human lung epithelial A549 cells, CPD F and HN induced a stronger IFN response, viral titers were reduced 100-fold, and the expression of F and HN proteins was significantly reduced without affecting N or P or the relative packaging of proteins into virions. Following intranasal infection in hamsters, replication in the nasal turbinates and lungs tended to be the most reduced for viruses bearing CPD F and HN, with maximum reductions of approximately 10-fold. Despite decreased in vivo replication (and lower expression of CPD F and HN in vitro), all viruses induced titers of serum HPIV3-neutralizing antibodies similar to wt and provided complete protection against HPIV3 challenge. In summary, CPD of HPIV3 yielded promising vaccine candidates suitable for further development.

Mucosal vaccines have the potential to elicit protective immune responses at the point of entry of respiratory pathogens, thus preventing even the initial seed infection. Unlike licensed injectable vaccines, mucosal vaccines comprising protein subunits are only in development. One of the primary challenges associated with mucosal vaccines has been identifying and characterizing safe yet effective mucosal adjuvants that can effectively prime multi-factorial mucosal immunity. In this study, we tested NanoSTING, a liposomal formulation of the endogenous activator of the stimulator of interferon genes (STING) pathway, cyclic guanosine adenosine monophosphate (cGAMP), as a mucosal adjuvant. We formulated a vaccine based on the H1 antigen (fusion protein of Ag85b and ESAT-6) adjuvanted with NanoSTING. Intranasal immunization of NanoSTING-H1 elicited a strong T-cell response in the lung of vaccinated animals characterized by (a) CXCR3+ KLRG1- lung resident T cells that are known to be essential for controlling bacterial infection, (b) IFNγ-secreting CD4+ T cells which is necessary for intracellular bactericidal activity, and (c) IL17-secreting CD4+ T cells that can confer protective immunity against multiple clinically relevant strains of Mtb. Upon challenge with aerosolized Mycobacterium tuberculosis Erdman strain, intranasal NanoSTING-H1 provides protection comparable to subcutaneous administration of the live attenuated Mycobacterium bovis vaccine strain Bacille-Calmette-Guérin (BCG). Our results indicate that NanoSTING adjuvanted protein vaccines can elicit a multi-factorial immune response that protects from infection by M. tuberculosis.

Urgent research into innovative severe acute respiratory coronavirus-2 (SARS-CoV-2) vaccines that may successfully prevent various emerging emerged variants, particularly the Omicron variant and its subvariants, is necessary. Here, we designed a chimeric adenovirus-vectored vaccine named Ad5-Beta/Delta. This vaccine was created by incorporating the receptor-binding domain from the Delta variant, which has the L452R and T478K mutations, into the complete spike protein of the Beta variant. Both intramuscular (IM) and intranasal (IN) vaccination with Ad5-Beta/Deta vaccine induced robust broad-spectrum neutralization against Omicron BA.5-included variants. IN immunization with Ad5-Beta/Delta vaccine exhibited superior mucosal immunity, manifested by higher secretory IgA antibodies and more tissue-resident memory T cells (TRM) in respiratory tract. The combination of IM and IN delivery of the Ad5-Beta/Delta vaccine was capable of synergically eliciting stronger systemic and mucosal immune responses. Furthermore, the Ad5-Beta/Delta vaccination demonstrated more effective boosting implications after two dosages of mRNA or subunit recombinant protein vaccine, indicating its capacity for utilization as a booster shot in the heterologous vaccination. These outcomes quantified Ad5-Beta/Delta vaccine as a favorable vaccine can provide protective immunity versus SARS-CoV-2 pre-Omicron variants of concern and BA.5-included Omicron subvariants.