Project description:In pandemic scenarios involving novel human pathogenic viruses, it is highly desirable that vaccines induce strong neutralizing antibodies as quickly as possible. However, current vaccine strategies require multiple immunization doses to produce high titers of neutralizing antibodies and are poorly protective after a single vaccination. We therefore wished to design a vaccine candidate that would induce increased protective immune responses following the first vaccine dose. We hypothesized that antibodies against the receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein could be increased by drawing upon immunity to a previous infection. We generated a fusion protein containing the influenza H1N1 PR8 virus nucleoprotein (NP) and the SARS-CoV-2 spike RBD. Mice with or without preexisting immunity to PR8 were then vaccinated with NP/RBD. We observed significantly increased SARS-CoV-2 neutralizing antibodies in mice with PR8 immunity compared to mice without preexisting PR8 immunity. Vaccination with NP/RBD protected mice from SARS-CoV-2-induced morbidity and mortality after a single dose. Additionally, we compared SARS-CoV-2 virus titers in the lungs and nasal turbinates 4 days post-challenge of mice vaccinated with NP/RBD. SARS-CoV-2 virus was detectable in the lungs and nasal turbinate of mice without preexisting PR8 immunity, while SARS-CoV-2 virus was completely undetectable in mice with preexisting PR8 immunity. We also found that CD4-positive T cells in mice with preexisting immunity to PR8 play an essential role in producing the increased antibody response against RBD. This vaccine strategy potentially can be modified to target other pathogens of concern and offers extra value in future pandemic scenarios.IMPORTANCEIncreased globalization and changes in human interactions with wild animals has increased the likelihood of the emergence of novel viruses with pandemic potential. Vaccines can be effective in preventing severe disease caused by pandemic viruses. However, it takes time to develop protective immunity via prime-boost vaccination. More effective vaccine designs should quickly induce protective immunity. We propose leveraging preexisting immunity to a different pathogen to boost protection against emerging viruses. We targeted SARS-CoV-2 as a representative pandemic virus and generated a fusion protein vaccine that combines the nucleoprotein from influenza A virus and the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Our vaccine design significantly increased the production of RBD-specific antibodies in mice that had previously been exposed to influenza virus, compared to those without previous exposure. This enhanced immunity reduced SARS-CoV-2 replication in mice. Our results offer a vaccine design that could be valuable in a future pandemic setting.
Project description:The emergence of the global Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic underscores the importance of the rapid development of a non-invasive vaccine that can be easily administered. A vaccine administered by nasal delivery is endowed with such characteristics against respiratory viruses. In this study, we generated a recombinant SARS-CoV-2 receptor-binding domain (RBD)-based subunit vaccine. Mice were immunized via intranasal inoculation, microneedle-intradermal injection, or intramuscular injection, after which the RBD-specific immune responses were compared. Results showed that when administrated intranasally, the vaccine elicited a robust systemic humoral immunity with high titers of IgG antibodies and neutralizing antibodies as well as a significant mucosal immunity. Besides, antigen-specific T cell responses were also analyzed. These results indicated that the non-invasive intranasal administration should be explored for the future SARS-CoV-2 vaccine design.
Project description:Mucosal immunity plays a significant role in host defense against viruses in the respiratory tract. Because the upper respiratory airway is a primary site of SARS-CoV-2 entry, immunization at the mucosa via the intranasal route could potentially lead to induction of local sterilizing immunity that protects against SARS-CoV-2 infection. In this study, we evaluated the immunogenicity of a receptor-binding domain (RBD) of SARS-CoV-2 spike glycoprotein loaded into N,N,N-trimethyl chitosan nanoparticles (RBD-TMC NPs). We showed that intranasal delivery of RBD-TMC NPs into mice induced robust local mucosal immunity, as evidenced by the presence of IgG and IgA responses in BALs and the lungs of immunized mice. Furthermore, mice intranasally administered with this platform of immunogens developed robust systemic antibody responses including serum IgG, IgG1, IgG2a, IgA and neutralizing antibodies. In addition, these immunized mice had significantly higher levels of activated splenic CD4+ and CD8+ cells compared with those that were administered with soluble RBD immunogen. Collectively, these findings shed light on an alternative route of vaccination that mimics the natural route of SARS-CoV-2 infection. This route of administration stimulated not only local mucosal responses but also the systemic compartment of the immune system.
Project description:The study of specific T-cell responses against SARS-CoV-2 is important for understanding long-term immunity and infection management. The aim of this study was to assess the dual IFN-γ and IL-2 detection, using a SARS-CoV-2 specific fluorescence ELISPOT, in patients undergoing acute disease, during convalescence, and after vaccination. We also evaluated humoral response and compared with T-cells with the aim of correlating both types of responses, and increase the number of specific response detection. Blood samples were drawn from acute COVID-19 patients and convalescent individuals classified according to disease severity; and from unvaccinated and vaccinated uninfected individuals. IgGs against Spike and nucleocapsid, IgMs against nucleocapsid, and neutralizing antibodies were also analyzed. Our results show that IFN-γ in combination with IL-2 increases response detection in acute and convalescent individuals (p = 0.023). In addition, IFN-γ detection can be a useful biomarker for monitoring severe acute patients, as our results indicate that those individuals with a poor outcome have lower levels of this cytokine. In some cases, the lack of cellular immunity is compensated by antibodies, confirming the role of both types of immune responses in infection, and confirming that their dual detection can increase the number of specific response detections. In summary, IFN-γ/IL-2 dual detection is promising for characterizing and assessing the immunization status, and helping in the patient management.
Project description:The critical role of the innate immune system has been confirmed in driving local and systemic inflammation and the cytokine release storm in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This dysregulated immune response is focused on interferon (IFN) and complement activation, which are crucial for the development of metabolic inflammation, local lung tissue damage, and systemic multi-organ failure. IFNs control viral infections by inducing expression of IFN-stimulated genes (ISGs) that restrict distinct steps of viral replication. Therefore, in this review article, we propose the mechanism of SARS-CoV-2-associated acute respiratory disease syndrome, and assess treatment options by considering IFNs and by targeting IFN-antagonist SARS-CoV-2 virulent gene products. Furthermore, we elaborate on the mechanism of the amplified complement-mediated inflammatory cytokine storm, and propose an antiviral and immunotherapeutic strategy against coronavirus disease 2019 (COVID-19).
Project description:The outbreak of coronavirus disease 2019 (COVID-19) has posed great threats to global health and economy. Several effective vaccines are available now, but additional booster immunization is required to retain or increase the immune responses owing to waning immunity and the emergency of new variant strains. The deficiency of intramuscularly delivered vaccines to induce mucosal immunity urged the development of mucosal vaccines. Here, we developed an adjuvanted intranasal RBD vaccine and monitored its long-term immunogenicity against both wild-type and mutant strains of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), including Omicron variants, in mice. Three-dose intranasal immunization with this vaccine induced and maintained high levels of neutralizing IgG antibodies in the sera for at least 1 year. Strong mucosal immunity was also provoked, including mucosal secretory IgA and lung-resident memory T cells (TRM). We also demonstrated that the long-term persistence of lung TRM cells is a consequence of local T-cell proliferation, rather than T-cell migration from lymph nodes. Our data suggested that the adjuvanted intranasal RBD vaccine is a promising vaccine candidate to establish robust, long-lasting, and broad protective immunity against SARS-CoV-2 both systemically and locally.
Project description:The novel coronavirus-19 (SARS-CoV-2), has infected numerous individuals worldwide, resulting in millions of fatalities. The pandemic spread with high mortality rates in multiple waves, leaving others with moderate to severe symptoms. Co-morbidity variables, including hypertension, diabetes, and immunosuppression, have exacerbated the severity of COVID-19. In addition, numerous efforts have been made to comprehend the pathogenic and host variables that contribute to COVID-19 susceptibility and pathogenesis. One of these endeavours is understanding the host genetic factors predisposing an individual to COVID-19. Genome-Wide Association Studies (GWAS) have demonstrated the host predisposition factors in different populations. These factors are involved in the appropriate immune response, their imbalance influences susceptibility or resistance to viral infection. This review investigated the host genetic components implicated at the various stages of viral pathogenesis, including viral entry, pathophysiological alterations, and immunological responses. In addition, the recent and most updated genetic variations associated with multiple host factors affecting COVID-19 pathogenesis are described in the study.
Project description:Optimization of protective immune responses against SARS-CoV-2 remains an urgent worldwide priority. In this regard, type III interferon (Interferon-lambda, IFNl) restricts SARS-CoV-2 infection in vitro and treatment with IFNl limits infection, inflammation, and pathogenesis in murine models. Further, IFNl has been developed for clinical use to prevent illness during COVID-19. However, whether endogenous IFNl signaling has an impact on SARS-CoV-2 antiviral immunity and long-term immune protection in vivo is unknown. In this study, we identified a requirement for IFNl signaling in promoting viral clearance and protective immune programming in SARS-CoV-2 infection of mice. Both IFN and IFN-stimulated gene (ISG) expression in the lungs was independent of IFNl signaling. Instead, IFNl promoted generation of protective CD8 T cell responses against SARS-CoV-2 by facilitating accumulation of CD103+ DC in lung-draining lymph nodes. Conversely, CD8 T cell immunity to SARS-CoV-2 is independent of type I IFN signaling, revealing a unique dependence on IFNl. Overall, these studies demonstrate that IFNl is critical for protective innate and adaptive immunity upon infection with SARS-CoV-2, and suggest that IFNl serves as an immune adjuvant to support CD8 T cell immunity.
Project description:SARS-CoV-2 mRNA vaccination induces robust humoral and cellular immunity in the circulation; however, it is currently unknown whether it elicits effective immune responses in the respiratory tract, particularly against variants of concern (VOCs), including Omicron. We compared the SARS-CoV-2 S-specific total and neutralizing antibody responses, and B and T cell immunity, in the bronchoalveolar lavage fluid (BAL) and blood of COVID-19-vaccinated individuals and hospitalized patients. Vaccinated individuals had significantly lower levels of neutralizing antibody against D614G, Delta (B.1.617.2), and Omicron BA.1.1 in the BAL compared with COVID-19 convalescents despite robust S-specific antibody responses in the blood. Furthermore, mRNA vaccination induced circulating S-specific B and T cell immunity, but in contrast to COVID-19 convalescents, these responses were absent in the BAL of vaccinated individuals. Using a mouse immunization model, we demonstrated that systemic mRNA vaccination alone induced weak respiratory mucosal neutralizing antibody responses, especially against SARS-CoV-2 Omicron BA.1.1 in mice; however, a combination of systemic mRNA vaccination plus mucosal adenovirus-S immunization induced strong neutralizing antibody responses not only against the ancestral virus but also the Omicron BA.1.1 variant. Together, our study supports the contention that the current COVID-19 vaccines are highly effective against severe disease development, likely through recruiting circulating B and T cell responses during reinfection, but offer limited protection against breakthrough infection, especially by the Omicron sublineage. Hence, mucosal booster vaccination is needed to establish robust sterilizing immunity in the respiratory tract against SARS-CoV-2, including infection by the Omicron sublineage and future VOCs.
Project description:The unprecedented Coronavirus pandemic of 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Like other coronaviruses, to establish its infection, SARS-CoV-2 is required to overcome the innate interferon (IFN) response, which is the first line of host defense. SARS-CoV-2 has also developed complex antagonism approaches involving almost all its encoding viral proteins. Here, we summarize our current understanding of these different viral factors and their roles in suppressing IFN responses. Some of them are conserved IFN evasion strategies used by SARS-CoV; others are novel countermeasures only employed by SARS-CoV-2. The filling of gaps in understanding these underlying mechanisms will provide rationale guidance for applying IFN treatment against SARS-CoV-2 infection.