Evaluation of a novel intramuscular prime/intranasal boost vaccination strategy against influenza in the pig model.

Live-attenuated influenza vaccines (LAIV) offer advantages over the commonly used inactivated split influenza vaccines. However, finding the optimal balance between sufficient attenuation and immunogenicity has remained a challenge. We recently developed an alternative LAIV based on the 2009 pandemic H1N1 virus with a truncated NS1 protein and lacking PA-X protein expression (NS1(1-126)-ΔPAX). This virus showed a blunted replication and elicited a strong innate immune response. In the present study, we evaluated the efficacy of this vaccine candidate in the porcine animal model as a pertinent in vivo system. Immunization of pigs via the nasal route with the novel NS1(1-126)-ΔPAX LAIV did not cause disease and elicited a strong mucosal immune response that completely blocked replication of the homologous challenge virus in the respiratory tract. However, we observed prolonged shedding of our vaccine candidate from the upper respiratory tract. To improve LAIV safety, we developed a novel prime/boost vaccination strategy combining primary intramuscular immunization with a haemagglutinin-encoding propagation-defective vesicular stomatitis virus (VSV) replicon, followed by a secondary immunization with the NS1(1-126)-ΔPAX LAIV via the nasal route. This two-step immunization procedure significantly reduced LAIV shedding, increased the production of specific serum IgG, neutralizing antibodies, and Th1 memory cells, and resulted in sterilizing immunity against homologous virus challenge. In conclusion, our novel intramuscular prime/intranasal boost regimen interferes with virus shedding and transmission, a feature that will help combat influenza epidemics and pandemics.

An Fe3O4-Au heterodimer nanoparticle-based lateral flow assay for rapid and simultaneous detection of multiple influenza virus nucleic acids.

Sensitive, convenient and rapid detection and subtyping of influenza viruses are crucial for timely treatment and management of infected people. Compared with antigen detection, nucleic acid detection has higher specificity and can shorten the detection window. Hence, in this work, we improved the lateral flow assay (LFA, one of the most promising user-friendly and on-site methods) to achieve detection and subtyping of H1N1, H3N2 and H9N2 influenza virus nucleic acids. Firstly, the antigen-antibody recognition mode was transformed into a nucleic acid hybridization reaction. Secondly, Fe3O4-Au heterodimer nanoparticles were prepared to replace frequently used Au nanoparticles to obtain better coloration. Thirdly, four lines were arranged on the LFA strip, which were three test (T) lines and one control (C) line. Three T lines were respectively sprayed by the DNA sequences complementary to one end of H1N1, H3N2 and H9N2 influenza virus nucleic acids, while Fe3O4-Au nanoparticles were respectively coupled with the DNA sequences complementary to the other end of H1N1, H3N2 and H9N2 nucleic acids to construct three kinds of probes. The C line was sprayed by the complementary sequences to the DNAs on all three kinds of probes. In the detection, by hybridization reaction, the probes were combined with their target nucleic acids which were captured by the corresponding T lines to form color bands. Finally, according to the position of the color bands and their grey intensity, simultaneous qualitative and semi-quantitative detection of the three influenza virus nucleic acids was realized. The detection results showed that this multi-channel LFA had good specificity, and there was no significant cross reactivity among the three subtypes of influenza viruses. The simultaneous detection achieved comparable detection limits with individual detections. Therefore, this multi-channel LFA had good application potential for sensitive and rapid detection and subtyping of influenza viruses.

Lipid nanoparticle-encapsulated DNA vaccine confers protection against swine and human-origin H1N1 influenza viruses.

In 2009, a novel swine-origin H1N1 virus emerged, causing a pandemic. The virus, known as H1N1pdm09, quickly displaced the circulating H1 lineage and became the dominant seasonal influenza A virus subtype infecting humans. Human-to-swine spillovers of the H1N1pdm09 have occurred frequently, and each occurrence has led to sustained transmission of the human-origin H1N1pdm09 within swine populations. In the present study, we developed a lipid nanoparticle-based DNA vaccine (LNP-DNA) containing the hemagglutinin gene of a swine-origin H1N1pdm09. In pigs, this LNP-DNA vaccine induced a robust antibody response after a single intramuscular immunization and protected the pigs against challenge infection with the homologous swine-origin H1N1pdm09 virus. In a mouse model, the LNP-DNA vaccine induced antibody and T-cell responses and protected mice against lethal challenge with a mouse-adapted human-origin H1N1pdm09 virus. These findings demonstrate the potential of the LNP-DNA vaccine to protect against both swine- and human-origin H1N1pdm09 viruses. IMPORTANCE: Swine influenza A virus (IAV) is widespread and causes significant economic losses to the swine industry. Moreover, bidirectional transmission of IAV between swine and humans commonly occurs. Once introduced into the swine population, human-origin IAV often reassorts with endemic swine IAV, resulting in reassortant viruses. Thus, it is imperative to develop a vaccine that is not only effective against IAV strains endemic in swine but also capable of preventing the spillover of human-origin IAV. In this study, we developed a lipid nanoparticle-encapsulated DNA plasmid vaccine (LNP-DNA) that demonstrates efficacy against both swine- and human-origin H1N1 viruses. The LNP-DNA vaccines are non-infectious and non-viable, meeting the criteria to serve as a vaccine platform for rapidly updating vaccines. Collectively, this LNP-DNA vaccine approach holds great potential for alleviating the impact of IAV on the swine industry and preventing the emergence of reassortant IAV strains.

Antibody response to sequential vaccination with cell culture, recombinant, or egg-based influenza vaccines among U.S. adults.

The immune response to inactivated influenza vaccines (IIV) is influenced by multiple factors, including hemagglutinin content and egg-based manufacturing. Only two US-licensed vaccines are manufactured without egg passage: cell culture-based inactivated vaccine (ccIIV) and recombinant vaccine (RIV). We conducted a randomized open-label trial in central Wisconsin during the 2018-19 and 2019-20 seasons to compare immunogenicity of sequential vaccination. Participants 18-64 years old were randomized 1:1:1 to receive RIV, ccIIV or IIV in strata defined by number of influenza vaccine doses in the prior 3 years. They were revaccinated with the same product in year two. Paired serum samples were tested by hemagglutination inhibition against egg-adapted and cell-grown vaccine viruses. Serologic endpoints included geometric mean titer (GMT), mean fold rise, and percent seroconversion. There were 373 participants randomized and vaccinated in 2018-19; 332 were revaccinated in 2019-20. In 2018-19, RIV and ccIIV were not more immunogenic than IIV against A/H1N1. The post-vaccination GMT against the cell-grown 3C.2a A/H3N2 vaccine virus was higher for RIV vs IIV (p = .001) and RIV vs ccIIV (p = .001). The antibody response to influenza B viruses was similar across study arms. In 2019-20, GMT against the cell-grown 3C.3a A/H3N2 vaccine virus was higher for RIV vs IIV (p = .03) and for RIV vs ccIIV (p = .001). RIV revaccination generated significantly greater backboosting to the antigenically distinct 3C.2a A/H3N2 virus (2018-19 vaccine strain) compared to ccIIV or IIV. This study adds to the evidence that RIV elicits a superior immunologic response against A/H3N2 viruses compared to other licensed influenza vaccine products.

Single-cell analysis reveals lasting immunological consequences of influenza infection and respiratory immunization in the pig lung.

The pig is a natural host for influenza viruses and integrally involved in virus evolution through interspecies transmissions between humans and swine. Swine have many physiological, anatomical, and immunological similarities to humans, and are an excellent model for human influenza. Here, we employed single cell RNA-sequencing (scRNA-seq) and flow cytometry to characterize the major leukocyte subsets in bronchoalveolar lavage (BAL), twenty-one days after H1N1pdm09 infection or respiratory immunization with an adenoviral vector vaccine expressing hemagglutinin and nucleoprotein with or without IL-1ß. Mapping scRNA-seq clusters from BAL onto those previously described in peripheral blood facilitated annotation and highlighted differences between tissue resident and circulating immune cells. ScRNA-seq data and functional assays revealed lasting impacts of immune challenge on BAL populations. First, mucosal administration of IL-1ß reduced the number of functionally active Treg cells. Second, influenza infection upregulated IFI6 in BAL cells and decreased their susceptibility to virus replication in vitro. Our data provide a reference map of porcine BAL cells and reveal lasting immunological consequences of influenza infection and respiratory immunization in a highly relevant large animal model for respiratory virus infection.

Protection against the H1N1 influenza virus using self-assembled nanoparticles formed by lumazine synthase and bearing the M2e peptide.

There is an urgent need for influenza vaccines that offer broad cross-protection. The highly conserved ectodomain of the influenza matrix protein 2 (M2e) is a promising candidate; however, its low immunogenicity can be addressed. In this study, we developed influenza vaccines using the Lumazine synthase (LS) platform. The primary objective of this study was to determine the protective potential of M2e proteins expressed on Lumazine synthase (LS) nanoparticles. M2e-LS proteins, produced through the E. coli system, spontaneously assemble into nanoparticles. The study investigated the efficacy of the M2e-LS nanoparticle vaccine in mice. Mice immunized with M2e-LS nanoparticles exhibited significantly higher levels of intracellular cytokines than those receiving soluble M2e proteins. The M2e-LS protein exhibited robust immunogenicity and provided 100% protection against cross-clade influenza.

Inter- and intra-individual differences regarding SARS-CoV-2 and influenza vaccination in pediatric kidney transplant recipients: An observational study.

In kidney transplant recipients (KTRs), viral infection can lead to antibody and/or T-cell mediated rejection, resulting in kidney transplant dysfunction. Therefore, it is critical to prevent infections. However, KTRs exhibit suboptimal responses to SARS-CoV-2 and/or influenza vaccines, partly due to immunosuppressant therapy. Inter- and intra-individual differences in the biological responses to vaccines may also affect patients' antibody production ability. This study included KTRs who received an messenger RNA SARS-CoV-2 vaccine (3 doses), and an inactivated quadrivalent influenza vaccine (1 or 2 doses). We measured the patients' total antibody titers against SARS-CoV-2 spike antigen, and hemagglutination inhibition (HI) titers against influenza A/H1N1, A/H3N2, B/Yamagata, and B/Victoria. Five patients were eligible for this study. Of these 5 KTRs, two produced anti-SARS-CoV-2 spike antibody titers to a seroprotective level, and also produced HI titers against A/H1N1 to a seroprotective level. Another 2 KTRs did not produce seroprotective anti-SARS-CoV-2 antibody titers, but produced seroprotective HI titers against A/H1N1. The remaining KTR produced a seroprotective anti-SARS-CoV-2 antibody titer, but did not produce a seroprotective HI titer against A/H1N1. The 2 KTRs who did not produce seroprotective anti-SARS-CoV-2 antibody titers following vaccination, later developed COVID-19, and this infection increased their titers over the seroprotective level. This study demonstrated that inter- and intra-individual differences in biological responses to vaccines should be considered in pediatric KTRs, in addition to immunosuppressant effects. Personalized regimens, such as augmented or booster doses of vaccines, could potentially improve the vaccination efficacy against SARS-CoV-2 and influenza.

Influenza Vaccine Effectiveness Against Influenza A-Associated Emergency Department, Urgent Care, and Hospitalization Encounters Among US Adults, 2022-2023.

BACKGROUND: The 2022-2023 United States influenza season had unusually early influenza activity with high hospitalization rates. Vaccine-matched A(H3N2) viruses predominated, with lower levels of A(H1N1)pdm09 activity also observed. METHODS: Using the test-negative design, we evaluated influenza vaccine effectiveness (VE) during the 2022-2023 season against influenza A-associated emergency department/urgent care (ED/UC) visits and hospitalizations from October 2022 to March 2023 among adults (aged ≥18 years) with acute respiratory illness (ARI). VE was estimated by comparing odds of seasonal influenza vaccination among case-patients (influenza A test positive by molecular assay) and controls (influenza test negative), applying inverse-propensity-to-be-vaccinated weights. RESULTS: The analysis included 85 389 ED/UC ARI encounters (17.0% influenza A positive; 37.8% vaccinated overall) and 19 751 hospitalizations (9.5% influenza A positive; 52.8% vaccinated overall). VE against influenza A-associated ED/UC encounters was 44% (95% confidence interval [CI], 40%-47%) overall and 45% and 41% among adults aged 18-64 and ≥65 years, respectively. VE against influenza A-associated hospitalizations was 35% (95% CI, 27%-43%) overall and 23% and 41% among adults aged 18-64 and ≥65 years, respectively. CONCLUSIONS: VE was moderate during the 2022-2023 influenza season, a season characterized with increased burden of influenza and co-circulation with other respiratory viruses. Vaccination is likely to substantially reduce morbidity, mortality, and strain on healthcare resources.

Anti-hemagglutinin monomeric nanobody provides prophylactic immunity against H1 subtype influenza A viruses.

Influenza viruses constitute a major threat to human health globally. The viral surface glycoprotein hemagglutinin (HA) is the immunodominant antigen, contains the site for binding to the cellular receptor (RBS), and it is the major target of neutralizing antibody responses post-infection. We developed llama-derived single chain antibody fragments (VHHs) specific for type A influenza virus. Four VHHs were identified and further characterized. VHH D81 bound residues in the proximity of the C-terminal region of HA1 of H1 and H5 subtypes, and showed weak neutralizing activity, whereas VHH B33 bound residues in the proximity of the N-terminal region of the HA's stem domain (HA2) of H1, H5, and H9 subtypes, and showed no neutralizing activity. Of most relevance, VHHs E13 and G41 recognized highly conserved conformational epitopes on the H1 HA's globular domain (HA1) and showed high virus neutralizing activity (ranging between 0.94 to 0.01µM), when tested against several human H1N1 isolates. Additionally, E13 displayed abrogated virus replication of a panel of H1N1 strains spanning over 80 years of antigenic drift and isolated from human, avian, and swine origin. Interestingly, E13 conferred protection in vivo at a dose as low as 0.05 mg/kg. Mice treated with E13 intranasally resulted in undetectable virus challenge loads in the lungs at day 4 post-challenge. The transfer of sterilizing pan-H1 immunity, by a dose in the range of micrograms given intranasally, is of major significance for a monomeric VHH and supports the further development of E13 as an immunotherapeutic agent for the mitigation of influenza infections.

Cytomegalovirus vaccine vector-induced effector memory CD4 + T cells protect cynomolgus macaques from lethal aerosolized heterologous avian influenza challenge.

An influenza vaccine approach that overcomes the problem of viral sequence diversity and provides long-lived heterosubtypic protection is urgently needed to protect against pandemic influenza viruses. Here, to determine if lung-resident effector memory T cells induced by cytomegalovirus (CMV)-vectored vaccines expressing conserved internal influenza antigens could protect against lethal influenza challenge, we immunize Mauritian cynomolgus macaques (MCM) with cynomolgus CMV (CyCMV) vaccines expressing H1N1 1918 influenza M1, NP, and PB1 antigens (CyCMV/Flu), and challenge with heterologous, aerosolized avian H5N1 influenza. All six unvaccinated MCM died by seven days post infection with acute respiratory distress, while 54.5% (6/11) CyCMV/Flu-vaccinated MCM survived. Survival correlates with the magnitude of lung-resident influenza-specific CD4 + T cells prior to challenge. These data demonstrate that CD4 + T cells targeting conserved internal influenza proteins can protect against highly pathogenic heterologous influenza challenge and support further exploration of effector memory T cell-based vaccines for universal influenza vaccine development.

Human Infant Fecal Microbiota Differentially Influences the Mucosal Immune Pathways Upon Influenza Infection in a Humanized Gnotobiotic Pig Model.

In this study, we evaluated the impact of human gut microbiota on the immune pathways in the respiratory tract using a gnotobiotic (Gn) piglet model. We humanized piglets with rural and urban infant fecal microbiota (RIFM and UIFM, respectively) and then infected them with a H1N1 swine influenza virus. We analyzed the microbial diversity and structure of the intestinal and respiratory tracts of the piglets before and after the influenza virus infection and measured the viral load and immune responses. We found that the viral load in the upper respiratory tract of UIFM transplanted piglets was higher than their rural cohorts (RIFM), while virus-specific antibody responses were comparable. The relative cytokine gene expression in the tracheobronchial (respiratory tract) and mesenteric (gastrointestinal) lymph nodes, lungs, blood, and spleen of RIFM and UIFM piglets revealed a trend in reciprocal regulation of proinflammatory, innate, and adaptive immune-associated cytokines as well as the frequency of T-helper/memory cells, cytotoxic T cells, and myeloid immune cell subsets. We also observed different phylum-level shifts of the fecal microbiota in response to influenza virus infection between the two piglet groups, suggesting the potential impact of the gut microbiota on the immune responses to influenza virus infection and lung microbiota. In conclusion, Gn piglets humanized with diverse infant fecal microbiota had differential immune regulation, with UIFM favoring the activation of proinflammatory immune mediators following an influenza virus infection compared to their rural RIFM cohorts. Furthermore, Gn piglets can be a useful model in investigating the impact of diverse human microbiota of the gastrointestinal tract, probably also the respiratory tract, on respiratory health and testing specific probiotic- or prebiotic-based therapeutics.

Occurrence of Circulating Antibodies against the Hemagglutinins of Influenza Viruses in the 2022/2023 Epidemic Season in Poland.

The aim of this study was to determine the level of anti-hemagglutinin antibodies in blood sera collected from patients during the 2022/2023 epidemic season in Poland. A total of 700 sera samples from patients across the country were tested. The samples were divided into seven groups according to the age of the patients, with 100 samples from each age group. The hemagglutination inhibition test (OZHA) was used to determine the level of anti-hemagglutinin antibodies. The test results have confirmed the presence of anti-hemagglutinin antibodies for antigens A/Victoria/2570/2019 (H1N1)pdm09, A/Darwin/9/2021 (H3N2), B/Austria/1359417/2021 (B/Yamagata lineage) and B/ Phuket/3073/2013 (B/Victoria lineage) present in the influenza vaccine recommended by the World Health Organization (WHO) for the 2022/2023 epidemic season. The highest geometric mean antibody titres (GMT) and protection rate values (%) were recorded for hemagglutinin A/H3N2. In Poland, in the 2022/2023 epidemic season, the percentage of the population vaccinated against influenza was 5.7%. Therefore, the test results can be interpreted as the response of the immune system in patients who have been previously infected with an influenza virus.

Hemagglutination Inhibition Antibody Titers as Mediators of Influenza Vaccine Efficacy Against Symptomatic Influenza A(H1N1), A(H3N2), and B/Victoria Virus Infections.

BACKGROUND: The hemagglutination inhibition antibody (HAI) titer contributes only a part of vaccine-induced protection against influenza virus infections. Using causal mediation analysis, we quantified the proportion of vaccine efficacy mediated by postvaccination HAI titers. METHODS: We conducted causal mediation analyses using data from a randomized, active-comparator controlled, phase III, trial of an inactivated, split-virion seasonal quadrivalent influenza vaccine in children conducted from October 2010 to December 2011 in 8 countries. Vaccine efficacy was estimated using a weighted Cox proportional hazards model. Estimates were decomposed into the direct and indirect effects mediated by postvaccination HAI titers. RESULTS: The proportions of vaccine efficacy mediated by postvaccination HAI titers were estimated to be 22% (95% confidence interval, 18%--47%) for influenza A(H1N1), 20% (16%-39%) for influenza A(H3N2), and 37% (26%-85%) for influenza B/Victoria. CONCLUSIONS: HAI titers partially mediate influenza vaccine efficacy against influenza A(H1N1), A(H3N2), and B/Victoria. Our estimates were lower than in previous studies, possibly reflecting expected heterogeneity in antigenic similarity between vaccine and circulating viruses across seasons.

A label-free H1N1 influenza virus immunosensor based on an N-LIG/Au laser induced graphene microelectrode.

A label-free immunosensor based on an N-doped laser direct graphene (N-LIG)/Au electrode was proposed for H1N1 influenza virus detection. By utilizing the instantaneous high temperature of laser irradiation, N atoms are generated by the decomposition of melamine dripped onto the surface of an LIG electrode to obtain N-LIG with higher conductivity. The doping of N atoms provides a large number of active sites for LIG microelectrodes. Combined with the electrodeposition of Au NPs, and covalently crosslinking antibodies, a simple, highly sensitive and stable immunosensing interface is constructed. The proposed H1N1 influenza virus immunosensor has a detection range of 0.01 fg mL-1 to 10 ng mL-1 with a detection limit as low as 0.004 fg mL-1. The constructed sensor has ultra-high sensitivity and good selectivity and can be used for complex biological sample analysis, with potential application prospects in preventing the large-scale spread of influenza. Taking advantage of N-LIG electrode's properties will provide opportunities for developing portable electrochemical biosensors for health and environmental applications.

Effectiveness of influenza vaccine among the population in Chongqing, China, 2018-2022: A test negative design-based evaluation.

Influenza vaccination is the most cost-effective strategy for influenza prevention. Influenza vaccines have been found to be effective against symptomatic and medically attended outpatient influenza illnesses. However, there is currently a lack of data regarding the effectiveness of inactivated influenza vaccines in Chongqing, China. We conducted a prospective observational test-negative design study. Outpatient and emergency cases presenting with influenza-like illnesses (ILI) and available influenza reverse transcription polymerase chain reaction (RT-PCR) were selected and classified as cases (positive influenza RT-PCR) or controls (negative influenza RT-PCR). A total of 7,307 cases of influenza and 7,905 control subjects were included in this study. The overall adjusted influenza vaccine effectiveness (IVE) was 44.4% (95% confidence interval (CI): 32.5-54.2%). In the age groups of less than 6 years old, 6-18 years old, and 19-59 years old, the adjusted IVE were 32.2% (95% CI: 10.0-48.9%), 48.2% (95% CI: 30.6-61.4%), and 72.0% (95% CI: 43.6-86.1%). The adjusted IVE for H1N1, H3N2 and B (Victoria) were 71.1% (95% CI: 55.4-81.3%), 36.1% (95% CI: 14.6-52.2%) and 33.7% (95% CI: 14.6-48.5%). Influenza vaccination was effective in Chongqing from 2018 to 2022. Evaluating IVE in this area is feasible and should be conducted annually in the future.

Color-encoded multicompartmental hydrogel microspheres for multiplexed bioassays.

We develop color-encoded multicompartmental hydrogel (MH) microspheres tailored for multiplexed bioassays using a drop-based microfluidic approach. Our method involves the creation of triple emulsion drops that feature thin sacrificial oil layers separating two prepolymer phases. This configuration leads to the formation of poly(ethylene glycol) (PEG) multi-compartmental core-shell microspheres through photopolymerization, followed by the removal of the thin oil layers. The core compartments stably incorporate pigments, ensuring their retention within the hydrogel network without leakage, which facilitates reliable color encoding across varying spatial positions. Additionally, we introduce small molecule fluorescent labeling into the chemically functionalized shell compartments, achieving consistent distribution of functional components without the core's contamination. Importantly, our integrated one-pot conjugation of these color-encoded microspheres with affinity peptides enables the highly sensitive and selective detection of influenza virus antigens using a fluorescence bioassay, resulting in an especially low detection limit of 0.18 nM and 0.66 nM for influenza virus H1N1 and H5N1 antigens, respectively. This approach not only highlights the potential of our microspheres in clinical diagnostics but also paves the way for their application in a wide range of multiplexed assays.

Modeling the CD8＋ T cell immune response to influenza infection in adult and aged mice.

The CD8＋ T cell response is the main determinant of viral clearance during influenza infection. However, influenza viral dynamics and the respective immune responses are affected by the host's age. To investigate age-related differences in the CD8＋ T cell immune response dynamics, we propose 16 ordinary differential equation models of existing experimental data. These data consist of viral titer and CD8＋ T cell counts collected periodically over a period of 19 days from adult and aged mice infected with influenza A/Puerto Rico/8/34 (H1N1). We use the corrected Akaike Information Criterion to identify the models which best represent the considered data. Our model selection process indicates differences in mechanisms which reduce the CD8＋ T cell response: linear downregulation is favored for adult mice, while baseline exponential decay is favored for aged mice. Parameter fitting of the top ranked models suggests that the aged population has reduced CD8＋ T cell proliferation compared to the adult population. More experimental work is needed to determine the specific immunological features through which age might cause these differences. A better understanding of the immunological mechanisms by which aging leads to discrepant CD8＋ T cell dynamics may inform future treatment strategies.

Potential pandemic risk of circulating swine H1N2 influenza viruses.

Influenza A viruses in swine have considerable genetic diversity and continue to pose a pandemic threat to humans due to a potential lack of population level immunity. Here we describe a pipeline to characterize and triage influenza viruses for their pandemic risk and examine the pandemic potential of two widespread swine origin viruses. Our analysis reveals that a panel of human sera collected from healthy adults in 2020 has no cross-reactive neutralizing antibodies against a α-H1 clade strain (α-swH1N2) but do against a γ-H1 clade strain. The α-swH1N2 virus replicates efficiently in human airway cultures and exhibits phenotypic signatures similar to the human H1N1 pandemic strain from 2009 (H1N1pdm09). Furthermore, α-swH1N2 is capable of efficient airborne transmission to both naïve ferrets and ferrets with prior seasonal influenza immunity. Ferrets with H1N1pdm09 pre-existing immunity show reduced α-swH1N2 viral shedding and less severe disease signs. Despite this, H1N1pdm09-immune ferrets that became infected via the air can still onward transmit α-swH1N2 with an efficiency of 50%. These results indicate that this α-swH1N2 strain has a higher pandemic potential, but a moderate level of impact since there is reduced replication fitness and pathology in animals with prior immunity.

Mastoparan-7 adjuvanted COBRA H1 and H3 hemagglutinin influenza vaccines.

Adjuvants enhance, prolong, and modulate immune responses by vaccine antigens to maximize protective immunity and enable more effective immunization in the young and elderly. Most adjuvants are formulated with injectable vaccines. However, an intranasal route of vaccination may induce mucosal and systemic immune responses for enhancing protective immunity in individuals and be easier to administer compared to injectable vaccines. In this study, a next generation of broadly-reactive influenza hemagglutinin (HA) vaccines were developed using the Computationally Optimized Broadly Reactive Antigen (COBRA) methodology. These HA vaccines were formulated with Mastoparan 7 (M7-NH2) mast cell degranulating peptide adjuvant and administered intranasally to determine vaccine-induced seroconversion of antibodies against a panel of influenza viruses and protection following infection with H1N1 and H3N2 viruses in mice. Mice vaccinated intranasally with M7-NH2-adjuvanted COBRA HA vaccines had high HAIs against a panel of H1N1 and H3N2 influenza viruses and were protected against both morbidity and mortality, with reduced viral lung titers, following challenge with an H1N1 influenza virus. Additionally, M7-NH2 adjuvanted COBRA HA vaccines induced Th2 skewed immune responses with robust IgG and isotype antibodies in the serum and mucosal lung lavages. Overall, this intranasally delivered M7-NH2 -adjuvanted COBRA HA vaccine provides effective protection against drifted H1N1 and H3N2 viruses.

Constructing a Ready-to-Use mRNA Vaccine Delivery System for the Prevention of Influenza A virus, Utilizing FDA-Approved Raw Materials.

Messenger ribonucleic acid (mRNA) vaccines, serving as a rapid and easily scalable emergency preventive measure, have played a pivotal role in preventing infectious diseases. The effectiveness of mRNA vaccines heavily relies on the delivery carrier, but the current market options are predominantly lipid nanoparticles. Their intricate preparation process and high transportation costs pose challenges for widespread use in remote areas. In this study, we harnessed FDA-approved polymer PLGA and lipid components widely employed in clinical experiments to craft a ready-to-use mRNA vaccine delivery system known as lipid-polymer hybrid nanoparticles (LPP). Following formulation optimization, the PDCD nanoparticles emerged as the most effective, showcasing exceptional mRNA delivery capabilities both in vitro and in vivo. Loading PDCD nanoparticles with mRNA encoding the H1N1 influenza virus HA antigen-fused M2e peptide enabled the successful induction of M2e-specific antibodies and T cell immune responses in immunized mice. After three rounds of vaccine immunization, the mice demonstrated weight recovery to normal levels and maintained a survival rate exceeding 80% following an encounter with the H1N1 influenza virus. The innovative mRNA delivery system that we designed demonstrates outstanding effectiveness in preventing infectious diseases, with the potential to play an even more significant role in future clinical applications.