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researchsquare; 2022.


The ongoing coronavirus disease pandemic has fostered major advances in vaccination technologies; however, there are urgent needs of mucosal immune responses and single-dose, non-invasive administration. Here, we develop a SARS-CoV-2 vaccine for single-dose, dry-powder aerosol inhalation that induces potent systemic and mucosal immune responses. Our vaccine encapsulates proteinaceous cholera toxin B subunit-assembled nanoparticles displaying the SARS-CoV-2 RBD antigen (R-CNP) within microcapsules of optimal aerodynamic size, and such unique nano-micro coupled structure supports efficient alveoli delivery, sustained R-CNP release, and antigen presenting cell uptake, which are favorable for invocation of immune responses. Moreover, our vaccine successfully induces robust serological IgG and secretory IgA production, collectively conferring effective protection from SARS-CoV-2 challenge (including pseudovirus and the authentic virus) in mice, hamsters, and non-human primates. Finally, we also demonstrate a “mosaic iteration” of our vaccine that co-displays ancestral and Omicron’s antigens, thus extending the breadth of antibody response against co-circulating strains and transmission of Omicron variant. These findings support our inhalable vaccine as a promising candidate to prevent SARS-CoV-2 infection, disease, and transmission.

researchsquare; 2021.


The recent emergence of new variants in the COVID-19 pandemic has led to new requirements for vaccines, with a focus on the capacity of vaccines to elicit high levels of neutralizing antibodies with specific recognition of S antigen variants based on the characterized vaccines licensed for use. A new strategy involving a heterologous vaccine composed of one or two doses of inactivated vaccine and a boost with the S1 protein with mutations (K-S) administered via the intradermal route was designed in this work and was found to improve immune efficacy by increasing neutralizing antibody titers and promoting specific T cell responses against 5 variants of the RBD peptide. A viral challenge test with the B.1.617.2 (Delta) variant confirmed that the both schedules of “1+1” and “2+1” administration ensured a clinical protective effect against this strain. All of these results not only suggested the feasibility of our strategy for protecting against new variants but also provided a technical pathway to enhance the anamnestic immune response in the immunized population.

medrxiv; 2020.
Preprint in English | medRxiv | ID: ppzbmed-10.1101.2020.09.27.20189548


BACKGROUND In-depth investigations of the safety and immunogenicity of inactivated SARS-CoV-2 vaccines are needed. METHOD In a phase I randomized, double-blinded, and placebo-controlled trial involving 192 healthy adults 18-59 years of age, two injections of three different doses (50 EU, 100 EU and 150 EU) of an inactivated SARS-CoV-2 vaccine or the placebo were administered intramuscularly with a 2- or 4-week interval between the injections. The safety and immunogenicity of the vaccine were evaluated within 28 days. FINDING In this study, 191 subjects assigned to three doses groups or the placebo group completed the 28-day trial. There were 44 adverse reactions within the 28 days, most commonly mild pain and redness at the injection site or slight fatigue, and no abnormal variations were observed in 48 cytokines in the serum samples of immunized subjects. The serum samples diluted from 1:32 to 1:4096 and incubated with the virus did not show antibody-dependent enhancement effects (ADEs) with regard to human natural killer cells, macrophages or dendritic cells. At day 14, the seroconversion rates had reached 92%, 100% and 96% with geometric mean titers (GMTs) of 18.0, 54.5 and 37.1, and at day 28, the seroconversion rates had reached 80%, 96% and 92% with GMTs of 10.6, 15.4 and 19.6in 0, 14 and 0, 28 procedures, respectively. Seroconversion was associated with the synchronous upregulation of ELISA antibodies against the S protein, N protein and virion and a cytotoxic T lymphocyte (CTL) response. Transcriptome analysis shaped the genetic diversity of immune response induced by the vaccine. INTERPRETATION In a population aged 18-59 years, this inactivated SARS-CoV-2 vaccine was safe and immunogenic.

biorxiv; 2020.
Preprint in English | bioRxiv | ID: ppzbmed-10.1101.2020.08.04.235747


With the relatively serious global epidemic outbreak of SARS-CoV-2 infection, public concerns focus on not only clinical therapeutic measures and public quarantine for this disease but also the development of vaccines. The technical design of our SARS-CoV-2 inactivated vaccine provides a viral antigen that enables the exposure of more than one structural protein based upon the antibody composition of COVID-19 patients convalescent serum. This design led to valid immunity with increasing neutralizing antibody titers and a CTL response detected post-immunization of this vaccine by two injections in rhesus macaques. Further, this elicited immunoprotection in macaques enables not only to restrain completely viral replication in tissues of immunized animals, compared to the adjuvant control and those immunized by an RBD peptide vaccine, but also to significantly alleviate inflammatory lesion in lung tissues in histo-pathologic detection, compared to the adjuvant control with developed interstitial pneumonia. The data obtained from these macaques immunized with the inactivated vaccine or RBD peptide vaccine suggest that immunity with a clinically protective effect against SARS-CoV-2 infection should include not only specific neutralizing antibodies but also specific CTL responses against at least the S and N antigens.

biorxiv; 2020.
Preprint in English | bioRxiv | ID: ppzbmed-10.1101.2020.07.15.205211


The COVID-19 pandemic has taken a significant toll on people worldwide, and there are currently no specific antivirus drugs or vaccines. We report herein a therapeutic based on catalase, an antioxidant enzyme that can effectively breakdown hydrogen peroxide and minimize the downstream reactive oxygen species, which are excessively produced resulting from the infection and inflammatory process. Catalase assists to regulate production of cytokines, protect oxidative injury, and repress replication of SARS-CoV-2, as demonstrated in human leukocytes and alveolar epithelial cells, and rhesus macaques, without noticeable toxicity. Such a therapeutic can be readily manufactured at low cost as a potential treatment for COVID-19.