Herpes simplex virus type 1 (HSV-1), an α subgroup member of the human herpesvirus family, infects cells via the binding of its various envelope glycoproteins to cellular membrane receptors, one of which is herpes virus entry mediator (HVEM), expressed on dendritic cells. Here, HVEM gene-deficient mice were used to investigate the immunologic effect elicited by the HSV-1 infection of dendritic cells. Dendritic cells expressing the surface marker CD11c showed an abnormal biological phenotype, including the altered transcription of various immune signaling molecules and inflammatory factors associated with innate immunity after viral replication. Furthermore, the viral infection of dendritic cells interfered with dendritic cell function in the lymph nodes, where these cells normally play roles in activating the T-cell response. Additionally, the mild clinicopathological manifestations observed during the acute phase of HSV-1 infection were associated with viral replication in dendritic cells.

Objective: We constructed two DNA vaccines containing the receptor-binding domain (RBD) genes of multiple SARS-CoV-2 variants and used them in combination with inactivated vaccines in a variety of different protocols to explore potential novel immunization strategies against SARS-CoV-2 variants. Methods: Two DNA vaccine candidates with different signal peptides (namely, secreted and membrane signal peptides) and RBD protein genes of different SARS-CoV-2 strains (Wuhan-Hu-1, B.1.351, B.1.617.2, C.37) were used. Four different combinations of DNA and inactivated vaccines were tested, namely, Group A: three doses of DNA vaccine; B: three doses of DNA vaccine and one dose of inactivated vaccine; C: two doses of inactivated vaccine and one dose of DNA vaccine; and D: coadministration of DNA and inactivated vaccines in two doses. Subgroups were grouped according to the signal peptide used (subgroup 1 contained secreted signal peptides, and subgroup 2 contained membrane signal peptides). The in vitro expression of the DNA vaccines, the humoral and cellular immunity responses of the immunized mice, the immune cell population changes in local lymph nodes, and proinflammatory cytokine levels in serum samples were evaluated. Results: The antibody responses and cellular immunity in Group A were weak for all SARS-CoV-2 strains; for Group B, there was a great enhancement of neutralizing antibody (Nab) titers against the B.1.617.2 variant strain. Group C showed a significant increase in antibody responses (NAb titers against the Wuhan-Hu-1 strain were 768 and 1154 for Group C1 and Group C2, respectively, versus 576) and cellular immune responses, especially for variant B.1.617.2 (3240 (p < 0.001) and 2430 (p < 0.05) for Group C1 and Group C2, versus 450); Group D showed an improvement in immunogenicity. Group C induced higher levels of multiple cytokines. Conclusion: The DNA vaccine candidates we constructed, administered as boosters, could enhance the humoral and cellular immune responses of inactivated vaccines against COVID-19, especially for B.1.617.2.

Background : Herpes simplex virus (HSV) is a neurotropic virus that can be categorized into two serotypes: HSV-1 and HSV-2. HSV-1 causes symptoms such as herpes labialis, herpetic keratitis, genital ulcers, and encephalitis, and primarily establishes latent infection in the trigeminal ganglion. The complexity of membrane fusion mechanisms and potential infection in nerves allow HSV to easily evade recognition and clearance by host immune cells. Therefore, developing a vaccine that can prevent both primary and reactivated HSV-1 infection is critical. Currently, no preventive or therapeutic HSV-1 vaccines have been approved for marketing. Methods: In this study, we utilized the gC, gD, and gE proteins of HSV-1, which are associated with viral fusion and immune escape, to design a trivalent antigen vaccine that is capable of inducing a cellular immune response. Two formulations of the vaccine are available: a subunit vaccine incorporating oligodeoxynucleotides with CpG motifs (CpG ODNs) and QS-21 as adjuvants, as well as an mRNA vaccine. Mice were immunized via intramuscular injection to evaluate and compare the immunological responses and protective efficacy of the two vaccines. Results: After the challenge, the viral load in the tissues of both vaccine groups was significantly lower than that in the positive control group, indicating that both vaccines were able to control viral proliferation in the tissues. Conclusions: The findings indicated that both mRNA and subunit vaccines were capable of eliciting comparable humoral and cellular immune responses.

The constant mutation of SARS-CoV-2 has led to the continuous appearance of viral variants and their pandemics and has improved the development of vaccines with a broad spectrum of antigens to curb the spread of the virus. The work described here suggested a novel vaccine with a virus-like structure (VLS) composed of combined mRNA and protein that is capable of stimulating the immune system in a manner similar to that of viral infection. This VLS vaccine is characterized by its ability to specifically target dendritic cells and/or macrophages through S1 protein recognition of the DC-SIGN receptor in cells, which leads to direct mRNA delivery to these innate immune cells for activation of robust immunity with a broad spectrum of neutralizing antibodies and immune protective capacity against variants. Research on its composition characteristics and structural features has suggested its druggability. Compared with the current mRNA vaccine, the VLS vaccine was identified as having no cytotoxicity at its effective application dosage, while the results of safety observations in animals revealed fewer adverse reactions during immunization.

Background: Rabies virus (RABV) causes approximately 59,000 human deaths annually. Current pre- and post-exposure vaccination relies on inactivated vaccines (INVs) with limited yield and immunogenicity. We engineered a dual-cationic LNP-based nucleocapsid-like nanostructure (NLS) that co-encapsulates RABV G-mRNA and recombinant RABV-N to engage MHC-I/II pathways and enhance protection. Methods: A pVAX-RABV-G plasmid containing 5′/3′UTRs, Kozak, and poly(A) was transcribed in vitro. RABV-N with an N-terminal 6× His tag was expressed in E. coli BL21(DE3) and purified by Ni-Sepharose affinity chromatography. Dual-cationic LNPs (DHA, DOTAP Cl, mPEG-DTA2K, DOPC) were formulated by microfluidics at a 4:1 (G-mRNA:RABV-N) mass ratio. Vaccine quality was assessed by encapsulation efficiency, DLS, PDI, zeta potential, and TEM. Mice received empty LNPs, INV, G-mRNA, or NLS under varied schedules and doses. ELISA measured RABV-G/N-IgG; RFFIT determined neutralizing antibody (nAb) titers; ELISPOT quantified CTL response; qPCR assessed T-cell activation genes. On day 35 after the first immunization of vaccines, mice were challenged intramuscularly with 25 LD₅₀ of CVS-24. Results: G-mRNA purity was >95% and drove strong RABV-G expression in 293T cells. Purified RABV-N was approximately 52 kDa, >90% pure, and reactive to anti-His and anti-N antibodies. NLS achieved >95% encapsulation, a diameter of 136.9 nm, PDI 0.09, and a +18.7 mV zeta potential. A single dose yielded approximately 10 IU mL⁻¹ nAb by day 7; two doses peaked at approximately 1000 IU mL⁻¹. Mice showed 100% survival and no viral rebound in brain, spinal cord, and sciatic nerve. NLS induced stronger MHC-I/II-linked cellular immunity and higher RABV G/N-specific IFN-γ spot frequencies than G-mRNA or INV. Conclusions: The dual-antigen NLS vaccine co-delivering G-mRNA and RABV-N via dual-cationic LNPs robustly activates MHC-I/II, rapidly generates high-titer nAb (≥10 IU mL⁻¹ within 1 week), and sustains potent CD8⁺ CTL and CD4⁺ Th responses. A two-dose regimen (days 0 and 21) conferred complete protection, supporting the NLS platform as a next-generation rabies vaccine candidate.