ABSTRACT
The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has had and still has a considerable impact on global public health. One of the characteristics of SARS-CoV-2 is a surface homotrimeric spike protein, the primary responsible for the host immune response upon infection. Here we show the preclinical studies of a broad protective SARS-CoV-2 subunit vaccine developed from our Trimer Domain platform using the Delta spike protein, from antigen design to purification, vaccine evaluation and manufacturability. The prefusion trimerized Delta spike protein, PF-D-Trimer, was highly expressed in Chinese hamster ovary (CHO) cells, purified by a rapid one-step anti-Trimer Domain monoclonal antibody immunoaffinity process and prepared as a vaccine formulation with an adjuvant. The immunogenicity studies demonstrated that this vaccine candidate induces robust immune responses in mouse, rat and Syrian hamster models. It also protects K18-hACE2 transgenic mice in a homologous virus challenge. The neutralizing antibodies induced by this vaccine display a cross-reactive capacity against the ancestral WA1 and Delta variants as well as different Omicron, including BA.5.2. The Trimer Domain platform was proven to be a key technology in the rapid production of the PF-D-Trimer vaccine and may be crucial to accelerate the development of updated versions of SARS-CoV-2 vaccines.
Subject(s)
COVID-19ABSTRACT
The livelihood recovery strategy is utilized for peasants during the COVID-19 pandemic. This strategy serves a salient role to help them recover from the relevant hazardous impacts. Disaster risk has been a major concern among hazards for the increasing likelihood of exposure and vulnerability, especially in the process of poverty alleviation in China. However, few studies have discussed the factors and mechanisms that influence peasants to adopt livelihood recovery strategies in the context of the COVID-19 pandemic in China. Based on a case study of Ningqiang County, China, this study explores the mechanisms that catalyze the proactive recovery of peasants from the COVID-19 pandemic from a livelihood perspective. Methodologically, the study proposes a framework that integrates the modified pressure-state-response (PSR) framework and the sustainable livelihoods approach (SLA), and it employs structure equation modeling (SEM) approach to examine how specific factors affect peasants to proactively adopt livelihood strategies to recover from the COVID-19 pandemic. The results indicate that the COVID-19 pressure significantly increases the risk perception of peasants and decreases their livelihood capital. Further, the decreased livelihood capital, the improvement of risk perception and supportive policy will promote peasants to adopt livelihood recovery strategies. Moreover, the results specify that risk perception and supportive policy mediate the relation between livelihood capital and recovery strategy. The findings will be beneficial for policymakers and researchers to understand the mechanisms that peasants adopt livelihood strategies to recover from disasters, and can serve as references for formulating disaster risk reduction and resilience policies.
ABSTRACT
A novel uncapped mRNA platform was developed. Five lipid nanoparticle (LNP)-encapsulated mRNA constructs were made to evaluate several aspects of our platform, including transfection efficiency and durability in vitro and in vivo and the activation of humoral and cellular immunity in several animal models. The constructs were eGFP-mRNA-LNP (for enhanced green fluorescence mRNA), Fluc-mRNA-LNP (for firefly luciferase mRNA), S{delta}T-mRNA-LNP (for Delta strain SARS-CoV-2 spike protein trimer mRNA), gDED-mRNA-LNP (for truncated glycoprotein D mRNA coding ectodomain from herpes simplex virus type 2 (HSV2)) and gDFR-mRNA-LNP (for truncated HSV2 glycoprotein D mRNA coding amino acids 1~400). Quantifiable target protein expression was achieved in vitro and in vivo with eGFP- and Fluc-mRNA-LNP. S{delta}T-mRNA-LNP, gDED-mRNA-LNP and gDFR-mRNA-LNP induced both humoral and cellular immune responses comparable to those obtained by previously reported capped mRNA-LNP constructs. Notably, 25, 50 and 100 g of S{delta}T-mRNA-LNP all elicited neutralizing antibodies in hamsters against the Omicron and Delta strains. Additionally, gDED-mRNA-LNP and gDFR-mRNA-LNP induced potent neutralizing antibodies in rabbits and mice. The mRNA constructs with uridine triphosphate (UTP) outperformed those with N1-methylpseudouridine triphosphate (N1m{psi}TP) in the in vivo expression of luciferase and the induction of antibodies via S{delta}T-mRNA-LNP. Our uncapped, process-simplified, and economical mRNA platform may have broad utility in vaccines and protein replacement drugs.