Here we report a recombinant baculoviral vector-based DNA vaccine system against Middle East respiratory syndrome coronavirus (MERS-CoV) and the severe acute respiratory syndrome coronavirus-2 (SARS-CoV2). A non-replicating recombinant baculovirus expressing the human endogenous retrovirus envelope gene (AcHERV) was constructed as a DNA vaccine vector for gene delivery into human cells. For MERS-CoV vaccine construction, DNA encoding MERS-CoV S-full, S1 subunit, or receptor-binding domain (RBD) was inserted into the genome of AcHERV. For COVID19 vaccine construction, DNA encoding SARS-CoV2 S-full or S1 or a MERS-CoV NTD domain-fused SARS-CoV2 RBD was inserted into the genome of AcHERV. AcHERV-DNA vaccines induce high humoral and cell-mediated immunity in animal models. In challenge tests, twice immunized AcHERV-MERS-S1 and AcHERV-COVID19-S showed complete protection against MERS-CoV and SARS-CoV2, respectively. Unlike AcHERV-MERS vaccines, AcHERV-COVID19-S provided the greatest protection against SARS-CoV2 challenge. These results support the feasibility of AcHERV-MERS or AcHERV-COVID19 vaccines in preventing pandemic spreads of viral infections.

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Porcine placenta extract (PPE) is known to possess anti-inflammatory properties owing to its high concentration of bioactive substances. However, the need to eliminate blood-borne infectious agents while maintaining biological efficacy raises concerns about the optimal method for sterilizing PPE. Therefore, the objective of this study was to compare the effects of the standard pressurized heat (autoclaving) method of sterilization with γ-irradiation on the anti-inflammatory effects of PPE. The anti-inflammatory actions of these two preparations of PPE were evaluated by measuring their inhibitory effects on the production of NO, the expression of iNOS protein, and the expression of iNOS, COX2, TNF-α, IL-1β, and IL-6 mRNA in lipopolysaccharide-stimulated RAW 264.7 cells. Compared with autoclaved PPE, γ-irradiated PPE showed significantly greater inhibition of NO production and iNOS protein expression, and produced a greater reduction in the expression of iNOS, COX2, TNF-α, IL-1β, and IL-6 mRNA. These results provide evidence that the sterilization process is crucial in determining the biological activity of PPE, especially its anti-inflammatory activity. Collectively, our data suggest that γ-irradiated PPE acts at the transcriptional level to effectively and potently suppresses the production of NO and the expression of pro-inflammatory cytokines.

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Recurrent spillovers of α- and β-coronaviruses (CoV) such as severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome-CoV, SARS-CoV-2, and possibly human CoV have caused serious morbidity and mortality worldwide. In this study, six receptor-binding domains (RBDs) derived from α- and β-CoV that are considered to have originated from animals and cross-infected humans were linked to a heterotrimeric scaffold, proliferating cell nuclear antigen (PCNA) subunits, PCNA1, PCNA2, and PCNA3. They assemble to create a stable mosaic multivalent nanoparticle, 6RBD-np, displaying a ring-shaped disk with six protruding antigens, like jewels in a crown. Prime-boost immunizations with 6RBD-np in mice induced significantly high Ab titers against RBD antigens derived from α- and β-CoV and increased interferon (IFN-γ) production, with full protection against the SARS-CoV-2 wild type and Delta challenges. The mosaic 6RBD-np has the potential to induce intergenus cross-reactivity and to be developed as a pan-CoV vaccine against future CoV spillovers.

IntroductionThe first identification of swine-originated influenza A/CA/04/2009 (pH1N1) as the cause of an outbreak of human influenza accelerated efforts to develop vaccines to prevent and control influenza viruses. The current norm in many countries is to prepare influenza vaccines using cell-based or egg-based killed vaccines, but it is difficult to elicit a sufficient immune response using this approach. To improve immune responses, researchers have examined the use of cytokines as vaccine adjuvants, and extensively investigated their functions as chemoattractants of immune cells and boosters of vaccine-mediated protection. Here, we evaluated the effect of Granulocyte-macrophage Colony-Stimulating Factor (GmCSF) as an influenza vaccine adjuvant in BALB/c mice.Method and ResultsFemale BALB/c mice were immunized with killed vaccine together with a murine GmCSF gene delivered by human endogenous retrovirus (HERV) envelope coated baculovirus (1×107 FFU AcHERV-GmCSF, i.m.) and were compared with mice immunized with the killed vaccine alone. On day 14, immunized mice were challenged with 10 median lethal dose of mouse adapted pH1N1 virus. The vaccination together with GmCSF treatment exerted a strong adjuvant effect on humoral and cellular immune responses. In addition, the vaccinated mice together with GmCSF were fully protected against infection by the lethal influenza pH1N1 virus.ConclusionThus, these results indicate that AcHERV-GmCSF is an effective molecular adjuvant that augments immune responses against influenza virus.

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