NPJ Vaccines最新文献

This study explored the development and evaluation of mRNA vaccine candidates targeting Schistosoma mansoni tetraspanin-2 (Sm-TSP-2). We designed constructs encoding either full-length Sm-TSP-2, or its large extracellular loop (EC2) domain in secretory, membrane-anchored, or cytosolic forms. In a murine model, the secreted and membrane-anchored versions of Sm-TSP-2-EC2 induced the highest antigen-specific antibody titers. These two construct designs, along with full-length Sm-TSP-2 mRNA, also significantly reduced adult worm and egg burden compared to controls. The membrane-anchored Sm-TSP-2-EC2 mRNA was the most effective, lowering worm and egg burdens by 66.7% and 66.9%, respectively. Protective responses induced by the mRNA vaccines were comparable to those elicited by the Sm-TSP-2-EC2 protein formulated with Alum. Histopathological analysis revealed smaller hepatic granulomas surrounding worm eggs, supporting the immunopathological benefit of vaccination. Using a systematic mRNA-based approach, we optimized the presentation of the Sm-TSP-2-EC2 and demonstrated that extracellular exposure of EC2 is essential for eliciting a protective response.

Canine distemper virus (CDV) is a highly contagious morbillivirus that causes severe disease in carnivores, with raccoon dogs (Nyctereutes procyonoides) serving as major reservoirs for transmission. To address the limitations of current vaccines-such as virulence reversion, multiple doses, and poor efficacy in raccoon dogs-we developed a novel mRNA-lipid nanoparticle (LNP) vaccine encoding a secreted, tetrameric CDV hemagglutinin (H) protein fused to a signal peptide and Tetrabrachion domain to enhance stability and immunogenicity. The vaccine showed high purity, uniform particle size (~108 nm), and efficient in vivo expression of glycosylated H protein. In BALB/c mice, it induced strong H-specific IgG and increased splenic CD4⁺ T cells, suggesting a Th-skewed immune response. In raccoon dogs, high neutralizing antibody titers were maintained post-immunization, and all vaccinated animals survived lethal CDV challenge, whereas controls showed 100% mortality. Compared with a live-attenuated CDV vaccine, the mRNA-LNP vaccine markedly reduced clinical signs, preserved intestinal integrity, and nearly eliminated viral RNA in mucosal and systemic tissues. This study provides the first evidence that an mRNA-LNP vaccine encoding CDV hemagglutinin can confer complete protection against CDV challenge in raccoon dogs, highlighting its potential for veterinary and wildlife disease prevention.

DNA vaccines have garnered considerable attention due to their recent success in humans for SARS-CoV-2 and immunotherapy for cancer. However, conventional methods for creating and manufacturing DNA vaccines at-scale are slow and rate-limiting for timely response. Herein, we introduce a rapid and completely synthetic workflow that harnesses enzymes to create bulk DNA from a sequence text file. This synthetic workflow termed Enzymatic DNA Synthesis & Rolling-Circle Amplification (EDS-RCA) leverages multiple enzymes to print DNA oligos and assemble them into genes prior to cloning into circular constructs for rolling-circle amplification (RCA). We show that the resulting EDS-RCA DNA elicits comparable vaccine immunogenicity as standard plasmid format, despite the DNA being a large concatemeric repeat. The EDS-RCA method generated the hemagglutinin gene of H1N1 at a mean per-base error rate as low as ~1 mutation every 10,000 bases and, upon DNA vaccination, elicited strong antibody and cellular immune responses. Skin delivery of EDS-DNA using gene gun facilitated striking vaccine dose-sparing capabilities in comparison to intramuscular electroporation methods. In total, DNA vaccines produced by EDS-RCA are immunogenic and amenable to numerous delivery-modalities with preclinical mouse models and could offer an alternative for rapid scale-up of DNA vaccines for future human use.

Despite substantial evidence for benefits of vaccination in mitigating the COVID-19 pandemic, the use of mRNA vaccines faces skepticism built on coincidental health events occurring after vaccination without proven causality. One of the claims regarding excessive amounts of residual DNA from the vaccine manufacturing process has arisen from misinterpretation of improperly conducted analyses. Here, we assessed the quantity, quality and identity of residual DNA in mRNA vaccines based on thoroughly performed and properly interpreted orthogonal methods, including qPCR, fluorometry, capillary electrophoresis and short-read DNA sequencing. Our results show that the quantity of residual DNA in all 15 analysed batches of Comirnaty and Spikevax vaccines is below approved limits and that it consists of small fragments originating from the template used to transcribe mRNA during vaccine production. We demonstrate that reliable mRNA vaccine analysis for DNA impurities requires rigorous application of well-controlled methods that minimise mutual interference of vaccine components.

Mucosal immunity may be required to prevent the ongoing transmission of SARS-CoV-2 emerging variants of concern. To define the most efficient way to induce protective mucosal immunity, we compared three different forms of mucosal antigen exposure in mRNA pre-immunized rhesus macaques. Two vaccine groups received an oropharyngeal spray immunization with either an adenoviral vector or a live-attenuated SARS-CoV-2 vaccine (LAV). A third group was infected with SARS-CoV-2 Delta variant as a comparator group representing the exposure history of most humans. Profound levels of SARS-CoV-2-specific IgA antibodies and mucosal T cell responses in the bronchoalveolar lavage next to systemic IgG antibodies were induced after the adenoviral vector boost and the delta infection, but not after LAV immunization. Consequently, these two groups were better protected against a challenge infection with an immune-escape variant of the Omicron lineage EG.5.1.1 showing almost no upper and lower respiratory tract infection. The adenoviral vector vaccine would be a promising candidate for booster vaccinations to interrupt ongoing viral transmission and could generate similar levels of protection as a natural encounter with heterologous SARS-CoV-2.

The COVID-19 pandemic spurred mRNA vaccine innovation, but new SARS-CoV-2 variants highlight the need for vaccines with improved potency and durability. This report presents a novel mRNA vaccine platform encoding virus-like particle antigens (mRNA-VLPs) that mimic native virus structures, aiming to boost antibody responses via enhanced B cell activation. In animal studies, mRNA-VLP vaccines generated stronger neutralizing antibody responses across multiple variants compared to conventional mRNA vaccines expressing native spike proteins. In non-human primates, these elevated antibodies lasted at least six months. An mRNA-VLP vaccine encoding the Omicron spike outperformed traditional mRNA vaccines in mice as both a monovalent and bivalent (with ancestral spike) formulation. In hamsters, even low doses of mRNA-VLP vaccine provided complete protection, similar to high doses of native spike mRNA vaccines. These results suggest the mRNA-VLP platform could significantly strengthen vaccine efficacy and breadth against evolving SARS-CoV-2 variants.

Shigella is a major cause of morbidity and mortality in children in low- and middle-income countries. The O-antigen (OAg) component of the lipopolysaccharide is considered a protective antigen, however, their diversity challenges vaccine development, since more than 50 OAg serotypes have been identified. No licensed vaccine against shigellosis is available. A 4-component GMMA-based vaccine, altSonflex1-2-3, delivering S. sonnei and S. flexneri 1b, 2a and 3a OAg has been developed. Coverage is expected against non-vaccine serotypes, due to cross-reactivity, mediated by structural similarities among S. flexneri OAg. The vaccine is currently being tested in phase I and II clinical trials. In this work, sera from mice, rats, and rabbits injected with altSonflex1-2-3 were analyzed for their ability to bind to and kill S. flexneri serotypes not included in the vaccine. Results obtained were compared to corresponding results from vaccinated European adults. While no cross-reactive antibodies were measured in mouse sera, the antibodies elicited by altSonflex1-2-3 in rats, rabbits and humans were able to bind and kill the tested S. flexneri X, Y, 6, 4a and 5b strains. A study in African children and infants will confirm how data from animal models may predict the immune response in different age groups.

Klebsiella pneumoniae is a leading cause of nosocomial infections, bacteremia, and worldwide mortality. Further, a drastic rise in antibiotic-resistant isolates poses an urgent threat to humanity. Unfortunately, despite its clinical importance, a licensed K. pneumoniae vaccine is not yet available. Here, we report on the production and characterization of the broadest K. pneumoniae capsule bioconjugate vaccine to date. We tested this vaccine for its immunogenicity, functionality, efficacy, and antibody durability against a variety of K. pneumoniae isolates in a murine bacteremia model. We also established an immunocompromised murine model of bacteremia to better recapitulate human infection and tested our vaccine's efficacy in this background. The tetravalent capsule vaccine is highly immunogenic in mice, generating a robust immune response against all capsule types included (K1, K2, KL102, and KL107). Further, the generated antibodies persist for at least 6 months. The vaccine-induced antibodies are highly functional against a variety of clinical isolates of K. pneumoniae, including both classical and hypervirulent strains. Finally, the vaccine led to increased survival after bacteremia challenge compared to placebo-immunized mice. Our findings confirm that a capsule-based bioconjugate vaccine has clinical potential in preventing K. pneumoniae infections. These experiments signify much-needed progress towards a multivalent vaccine to combat this increasingly troublesome pathogen.

The emergence of SARS-CoV-2 and its subsequent variants in addition to the previous SARS-CoV-1 outbreak indicates the importance of developing broadly protective sarbecovirus vaccines. To date, broadly protective vaccines have primarily focused on clade 1 sarbecoviruses including SARS-CoV-2 variants and SARS-like animal viruses. The discovery of clade 2 and clade 3 sarbecoviruses capable of infecting human cells highlights a need to preemptively develop vaccines that can protect against these viruses. Here, we develop stabilized multivalent subunit vaccines from clade 2 and clade 3 sarbecovirus S2 proteins and evaluate their immunogenicity. Clade 2 and clade 3 S2-subunit vaccines elicit cross-reactive antibodies in mice capable of binding to clade 1, 2, and 3 sarbecovirus antigens. Female mice immunized with these S2-based vaccines also provide protection against sarbecovirus challenges from clades 1a and 1b, including a mouse-adapted SARS-CoV-2 strain, XBB, and WIV1.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus of the Orthonairovirus genus, Nairoviridae family, that causes severe febrile hemorrhagic disease in humans with a case fatality rate ranging from approximately 3-30%. This zoonotic pathogen is distributed across a broad geographic area spanning Asia, Europe, and Africa. Despite its significant public health threat and outbreak potential, no licensed vaccines are available. In this study, we developed and systematically assessed the immunogenicity and protective efficacy of mRNA vaccines encoding either CCHFV nucleoprotein (NP) or glycoprotein precursor (GPC) in mouse models. Vaccination with the NP-encoding mRNA alone provided complete protection against lethal cross-genotype CCHFV challenge. Moreover, combined vaccination with both the NP and GPC mRNAs elicited robust immune responses and conferred protection against CCHFV infection. Notably, a single-dose immunization with 2 μg mRNA-NP was sufficient to confer protection against lethal challenge. Furthermore, the passive transfer of NP-immune serum provided partial protection, supporting the role of NP-specific antibodies in mediating protection. Overall, these mRNA vaccines demonstrate protective efficacy against CCHFV, with combined antigenic protection and dose-sparing potential, highlighting their potential for outbreak preparedness and further clinical development.