Messenger RNA (mRNA) vaccines emerge as promising vaccines to prevent infectious diseases. Compared with traditional vaccines, mRNA vaccines present numerous advantages, such as high potency, safe administration, rapid production potentials, and cost-effective manufacturing. In 2020, two COVID-19 vaccines (BNT162b2 and mRNA-1273) were approved by the Food and Drug Administration (FDA). The two vaccines showed high efficiency in combating COVID-19, which indicates the great advantages of mRNA technology in developing vaccines against emergent infectious diseases. Here, we summarize the type, immune mechanisms, modification methods of mRNA vaccines, and their applications in preventing infectious diseases. Current challenges and future perspectives in developing mRNA vaccines are also discussed.
United States ; Humans ; mRNA Vaccines ; BNT162 Vaccine ; COVID-19 Vaccines/genetics* ; Communicable Diseases ; RNA, Messenger/genetics*

During the global efforts to prevent and control the COVID-19 pandemic, extensive research and development of SARS-CoV-2 vaccines using various technical approaches have taken place. Among these, vaccines based on adenovirus vector have gained substantial knowledge and experience in effectively combating potential emerging infectious diseases, while also providing novel ideas and methodologies for vaccine research and development (R&D). This comprehensive review focuses on the adenovirus vector technology platform in vaccine R&D, emphasizing the importance of mucosal immunity induced by adenoviral vector-based vaccine for COVID-19 prevention. Furthermore, it analyzes the key technical challenges and obstacles encountered in the development of vaccines based on the adenovirus vector technology platform, with the aim of providing valuable insights and references for researchers and professionals in related fields.
Humans ; COVID-19 Vaccines ; Pandemics/prevention & control* ; COVID-19/prevention & control* ; SARS-CoV-2/genetics* ; Viral Vaccines/genetics* ; Adenoviridae/genetics* ; Technology

Since the outbreak of corona virus disease 2019 (COVID-19), viral strains have mutated and evolved. Vaccine research is the most direct and effective way to control COVID-19. According to different production mechanisms, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines included inactivated virus vaccine, live attenuated vaccine, mRNA vaccine, DNA vaccine, viral vector vaccine, virus-like particle vaccine and protein subunit vaccine. Among them, viral protein subunit vaccine has a wide application prospect due to its high safety and effectiveness. Viral nucleocapsid protein has high immunogenicity and low variability which could be a new direction for vaccine production. We summarized the current development of vaccine research by reviewing the current progress, vaccine safety and vaccine immune efficiency. It is hoped that the proposed possible development strategies could provide a reference for epidemic prevention work in future.
Humans ; SARS-CoV-2/genetics* ; COVID-19/prevention & control* ; Protein Subunits ; Vaccines, DNA ; Nucleocapsid Proteins

A fusion protein containing a tetanus toxin peptide, a tuftsin peptide and a SARS-CoV-2S protein receptor-binding domain (RBD) was prepared to investigate the effect of intramolecular adjuvant on humoral and cellular immunity of RBD protein. The tetanus toxin peptide, tuftsin peptide and S protein RBD region were connected by a flexible polypeptide, and a recombinant vector was constructed after codon optimization. The recombinant S-TT-tuftsin protein was prepared by prokaryotic expression and purification. BALB/c mice were immunized after mixed with aluminum adjuvant, and the humoral and cellular immune effects were evaluated. The recombinant S-TT-tuftsin protein was expressed as an inclusion body, and was purified by ion exchange chromatography and renaturated by gradient dialysis. The renaturated protein was identified by Dot blotting and reacted with serum of descendants immunized with SARS-CoV-2 subunit vaccine. The results showed that the antibody level reached a plateau after 35 days of immunization, and the serum antibody ELISA titer of mice immunized with recombinant protein containing intramolecular adjuvant was up to 1:66 240, which was significantly higher than that of mice immunized with S-RBD protein (P < 0.05). At the same time, the recombinant protein containing intramolecular adjuvant stimulated mice to produce a stronger lymphocyte proliferation ability. The stimulation index was 4.71±0.15, which was significantly different from that of the S-RBD protein (1.83±0.09) (P < 0.000 1). Intramolecular adjuvant tetanus toxin peptide and tuftsin peptide significantly enhanced the humoral and cellular immune effect of the SARS-CoV-2 S protein RBD domain, which provideda theoretical basis for the development of subunit vaccines for SARS-CoV-2 and other viruses.
Adjuvants, Immunologic ; Aluminum ; Animals ; Antibodies, Neutralizing ; Antibodies, Viral ; COVID-19/prevention & control* ; COVID-19 Vaccines/genetics* ; Humans ; Mice ; Mice, Inbred BALB C ; Recombinant Proteins/genetics* ; SARS-CoV-2/genetics* ; Spike Glycoprotein, Coronavirus/genetics* ; Tetanus Toxin ; Tuftsin ; Vaccines, Subunit ; Viral Vaccines

Objective To construct a recombinant poxvirus vector vaccine, rVTTδTK-RBD, and to evaluate its safety and immunogenicity. Methods The receptor-binding domain (RBD) gene was synthesized with reference to the gene sequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was inserted into the polyclonal site of the self-constructed recombinant plasmid pSTKE, to construct the recombinant poxvirus shuttle vector pSTKE-RBD. This was then transfected into BHK-21 cells pre-infected with the vaccinia virus Tiantan strain (VTT). The recombinant poxvirus rVTTδTK-RBD was successfully obtained after several rounds of fluorescence phage screening. The effect of rVTTδTK-RBD on the body mass of BALB/c mice was detected after immunizing mice by intra-nasal vaccination. The levels of specific and neutralizing antibodies produced by rVTTδTK-RBD on BALB/c mice were analyzed after immunizing mice intramuscularly. The effect of rVTTδTK-RBD on T cell subsets in BALB/c mice was detected by flow cytometry. Results Through homologous recombination, enhanced green fluorescent protein (EGFP) screening marker, and multiple rounds of fluorescent phosphorescence phage screening, a recombinant poxvirus rVTTδTK-RBD, expressing RBD with deletions in the thymidine kinase (TK) gene, was successfully obtained, which was validated by PCR. The in vivo experiments on BALB/c mice showed that rVTTδTK-RBD was highly immunogenic against SARS-CoV-2 and significantly reduced toxicity to the body compared to the parental strain VTT. Conclusion The recombinant poxvirus vaccine rVTTδTK-RBD against SARS-CoV-2 is successfully constructed and obtained, with its safety and immunogenicity confirmed through various experiments.
Animals ; Mice ; SARS-CoV-2/genetics* ; COVID-19 ; Vaccines, Synthetic/genetics* ; Genes, Reporter ; Bacteriophages ; Mice, Inbred BALB C