Dataset Information

Plant-Produced S1 Subunit Protein of SARS-CoV-2 Elicits Immunogenic Responses in Mice.

ABSTRACT: SARS-CoV-2 is responsible for the ongoing COVID-19 pandemic. The virus spreads rapidly with a high transmission rate among humans, and hence virus management has been challenging owing to finding specific therapies or vaccinations. Hence, an effective, low-cost vaccine is urgently required. In this study, the immunogenicity of the plant-produced S1 subunit protein of SARS-CoV-2 was examined in order to assess it as a potential candidate for SARS-CoV-2. The SARS-CoV-2 S1-Fc fusion protein was transiently produced in Nicotiana benthamiana. Within four days of infiltration, the SARS-CoV-2 S1-Fc protein was expressed in high quantities, and using protein A affinity column chromatography, plant-produced S1-Fc protein was purified from the crude extracts. The characterization of plant-produced S1-Fc protein was analyzed by SDS-PAGE and Western blotting. Immunogenicity of the purified S1-Fc protein formulated with alum induced both RBD specific antibodies and T cell immune responses in mice. These preliminary results indicated that the plant-produced S1 protein is immunogenic in mice.

SUBMITTER: Panapitakkul C

PROVIDER: S-EPMC9695278 | biostudies-literature | 2022 Nov

REPOSITORIES: biostudies-literature

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Plant-Produced S1 Subunit Protein of SARS-CoV-2 Elicits Immunogenic Responses in Mice.

Panapitakkul Chalisa C Khorattanakulchai Narach N Rattanapisit Kaewta K Srisangsung Theerakarn T Shanmugaraj Balamurugan B Buranapraditkun Supranee S Ketloy Chutitorn C Prompetchara Eakachai E Phoolcharoen Waranyoo W

Vaccines 20221118 11

SARS-CoV-2 is responsible for the ongoing COVID-19 pandemic. The virus spreads rapidly with a high transmission rate among humans, and hence virus management has been challenging owing to finding specific therapies or vaccinations. Hence, an effective, low-cost vaccine is urgently required. In this study, the immunogenicity of the plant-produced S1 subunit protein of SARS-CoV-2 was examined in order to assess it as a potential candidate for SARS-CoV-2. The SARS-CoV-2 S1-Fc fusion protein was tra ...[more]

PMID: 36423056

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Project description:The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has raised concerns about reduced vaccine effectiveness and the increased risk of infection, and while repeated homologous booster shots are recommended for elderly and immunocompromised individuals, they cannot completely protect against breakthrough infections. In our previous study, we assessed the immunogenicity of an adenovirus-based vaccine expressing SARS-CoV-2 S1 (Ad5.S1) in mice, which induced robust humoral and cellular immune responses (E. Kim, F. J. Weisel, S. C. Balmert, M. S. Khan, et al., Eur J Immunol 51:1774-1784, 2021, https://doi.org/10.1002/eji.202149167). In this follow-up study, we found that the mice had high titers of anti-S1 antibodies 1 year after vaccination, and one booster dose of the nonadjuvanted rS1Beta (recombinant S1 protein of SARS-CoV-2 Beta [B.1.351]) subunit vaccine was effective at stimulating strong long-lived S1-specific immune responses and inducing significantly high neutralizing antibodies against Wuhan, Beta, and Delta strains, with 3.6- to 19.5-fold increases. Importantly, the booster dose also elicited cross-reactive antibodies, resulting in angiotensin-converting enzyme 2 (ACE2) binding inhibition against spikes of SARS-CoV-2, including Omicron variants, persisting for >28 weeks after booster vaccination. Interestingly, the levels of neutralizing antibodies were correlated not only with the level of S1 binding IgG but also with ACE2 inhibition. Our findings suggest that the rS1Beta subunit vaccine candidate as a booster has the potential to offer cross-neutralization against broad variants and has important implications for the vaccine control of newly emerging breakthrough SARS-CoV-2 variants in elderly individuals primed with adenovirus-based vaccines like AZD1222 and Ad26.COV2.S. IMPORTANCE Vaccines have significantly reduced the incidences of severe coronavirus disease 2019 (COVID-19) cases and deaths. However, the emergence of SARS-CoV-2 variants has raised concerns about their increased transmissibility and ability to evade neutralizing antibodies, especially among elderly individuals who are at higher risks of mortality and reductions of vaccine effectiveness. To address this, a heterologous booster vaccination strategy has been considered as a solution to protect the elderly population against breakthrough infections caused by emerging variants. This study evaluated the booster effect of an S1 subunit vaccine in aged mice that had been previously primed with adenoviral vaccines, providing valuable preclinical evidence for elderly people vaccinated with the currently approved COVID-19 vaccines. This study confirms the potential for using the S1 subunit vaccine as a booster to enhance cross-neutralizing antibodies against emerging variants of concern.

Project description:The coronavirus disease 2019 (COVID-19) pandemic has highlighted the need for safe and effective vaccines to be rapidly developed and distributed worldwide, especially considering the emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. Protein subunit vaccines have emerged as a promising approach due to their proven safety record and ability to elicit robust immune responses. In this study, we evaluated the immunogenicity and efficacy of an adjuvanted tetravalent S1 subunit protein COVID-19 vaccine candidate composed of the Wuhan, B.1.1.7 variant, B.1.351 variant, and P.1 variant spike proteins in a nonhuman primate model with controlled SIVsab infection. The vaccine candidate induced both humoral and cellular immune responses, with T and B cell responses mainly peaking post boost immunization. The vaccine also elicited neutralizing and cross-reactive antibodies, angiotensin-converting enzyme 2 (ACE2)-blocking antibodies, and T cell responses, including spike-specific CD4+ T cells. Importantly, the vaccine candidate was able to generate Omicron variant spike-binding and ACE2-blocking antibodies without specifically vaccinating with Omicron, suggesting potential broad protection against emerging variants. The tetravalent composition of the vaccine candidate has significant implications for COVID-19 vaccine development and implementation, providing broad antibody responses against numerous SARS-CoV-2 variants. IMPORTANCE The study provides important insights into the immunogenicity and efficacy of a tetravalent protein subunit vaccine candidate against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The vaccine induced both humoral and cellular immune responses in nonhuman primates with controlled SIVagm infection and was able to generate Omicron variant-specific antibodies without specifically vaccinating with Omicron. These findings suggest that the tetravalent composition of the vaccine candidate could provide broad protection against multiple SARS-CoV-2 variants while minimizing the risk of immune escape and the emergence of new variants. Additionally, the use of rhesus macaques with controlled SIVsab infection may better represent vaccine immunogenicity in humans with chronic viral diseases, highlighting the importance of preclinical animal models in vaccine development. Overall, the study provides valuable information for the development and implementation of coronavirus disease 2019 vaccines, particularly for achieving global vaccine equity and addressing emerging variants.

Project description:Molecular farming of vaccines has been heralded as a cheap, safe and scalable production platform. In reality, however, differences in the plant biosynthetic machinery, compared to mammalian cells, can complicate the production of viral glycoproteins. Remodelling the secretory pathway presents an opportunity to support key post-translational modifications, and to tailor aspects of glycosylation and glycosylation-directed folding. In this study, we applied an integrated host and glyco-engineering approach, NXS/T Generation™, to produce a SARS-CoV-2 prefusion spike trimer in Nicotiana benthamiana as a model antigen from an emerging virus. The size exclusion-purified protein exhibited a characteristic prefusion structure when viewed by transmission electron microscopy, and this was indistinguishable from the equivalent mammalian cell-produced antigen. The plant-produced protein was decorated with under-processed oligomannose N-glycans and exhibited a site occupancy that was comparable to the equivalent protein produced in mammalian cell culture. Complex-type glycans were almost entirely absent from the plant-derived material, which contrasted against the predominantly mature, complex glycans that were observed on the mammalian cell culture-derived protein. The plant-derived antigen elicited neutralizing antibodies against both the matched Wuhan and heterologous Delta SARS-CoV-2 variants in immunized hamsters, although titres were lower than those induced by the comparator mammalian antigen. Animals vaccinated with the plant-derived antigen exhibited reduced viral loads following challenge, as well as significant protection from SARS-CoV-2 disease as evidenced by reduced lung pathology, lower viral loads and protection from weight loss. Nonetheless, animals immunized with the mammalian cell-culture-derived protein were better protected in this challenge model suggesting that more faithfully reproducing the native glycoprotein structure and associated glycosylation of the antigen may be desirable.

Project description:BackgroundThe intricacies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing acute lung injury (ALI) and modulating inflammatory factor dynamics in vivo remain poorly elucidated. The present study endeavors to explore the impact of the recombinant SARS-CoV-2 spike protein S1 subunit (S1SP) on ALI and inflammatory factor profiles in mice, aiming to uncover potential therapeutic targets and intervention strategies for the prevention and management of Coronavirus Disease 2019 (COVID-19).MethodsTo mimic COVID-19 infection, K18-hACE2 transgenic mice were intratracheally instilled with S1SP, while C57BL/6 mice were administered LPS to form a positive control group. This setup facilitated the examination of lung injury severity, inflammatory factor levels, and alterations in signaling pathways in mice mimicking COVID-19 infection. Histopathological assessment through HE staining, along with analysis of lung wet/dry ratio and ultrasound imaging, revealed severe lung injury.ResultsAfter molding, K18-hACE2 mice exhibited a pronounced reduction in body weight and showed more significant lung injury (P < 0.05). Notably, there was a significant elevation in vascular permeability, total protein, and total white blood cells in bronchoalveolar lavage fluid (BALF) (P < 0.05), indicative of tissue damage. Additionally, the tight junction of lung tissue was compromised (P < 0.05), accompanied by intense oxidative stress marked by decreased SOD activity and elevated MDA content (P < 0.05). Cytokine levels, including IL-6, IL-1β, TNF-α, and MIG, were significantly upregulated in both BALF and serum of S1SP + K18 mice (P < 0.05). Furthermore, S1SP prominently augmented the expression of p-p65/P65 and attenuated IκBα expression in the NF-κB signaling pathway of humanized mice (P < 0.05), corroborating a heightened inflammatory response at the tissue level (P < 0.05).ConclusionThe administration of S1SP to K18-hACE2 mice resulted in severe lung injury, enhanced vascular permeability, and compromised epithelial barrier function in vivo. This was accompanied by disruption of lung tight junctions, the manifestation of severe oxidative stress and a cytokine storm, as well as the activation of the NF-κB signaling pathway, highlighting key pathological processes underlying COVID-19-induced lung injury.

Dataset Information

Plant-Produced S1 Subunit Protein of SARS-CoV-2 Elicits Immunogenic Responses in Mice.

Publications

Plant-Produced S1 Subunit Protein of SARS-CoV-2 Elicits Immunogenic Responses in Mice.

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