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Transgenic plants have been employed successfully as a low-cost system for the production of therapeutically valuable proteins, including antibodies, antigens and hormones. Here, we report the expression of a cytokine with immunomodulatory function, mouse interleukin-12 (IL-12), in transgenic tomato plants. Single-chain mouse IL-12 driven by the CaMV 35S promoter, accumulates to high levels in leaves and fruits (up to 7.3 and 3.4 μg per gram of fresh weight, respectively). Mouse IL-12 expressed in tomato displays biological activity in vitro, as determined by interferon-γ (IFN-γ) secretion by T cells. Possible uses of this plant-based cytokine involving mucosal delivery are discussed [ABSTRACT FROM AUTHOR]

We previously demonstrated that tumor necrosis factor (TNF)-?-matured CD16? and CD16+ human monocyte-derived dendritic cells (16?mDC and 16+mDC) differentially stimulate naive CD4+ lymphocytes by inducing Th1- and Th2-like responses, respectively. Here, we further characterized the role of different DC maturation factors on Th polarization. Immature 16+mDC and 16?mDC (iDC) obtained by culture of purified monocytes with GM-CSF and IL-4 were maturated with (i) Toll-like receptor (TLR) ligands [lipopolysaccharide (LPS)], (ii) lymphocyte-derived (soluble CD40 ligand, IFN-?) and (iii) endogenous inflammatory stimuli [TNF-?, prostaglandin (PG)E2]. After activation with these stimuli, DC secrete IL-12 only in presence of LPS, and 16+mDC produced lower amounts of IL-12 and IL-10 than 16?mDC. Allogeneic CD4+CD45RO? lymphocytes co-cultured with 16+mDC secreted higher levels of IL-4 and IL-10 than those co-cultured with 16?mDC, regardless of the maturation stimuli. Results were similar when DC were activated with TLR-2 or TLR-3 ligands. The higher induction of IL-4 by 16+mDC was primarily dependent on IL-12, IL-4 and IL-10. IFN-? production by CD4+ T cells was similar with all the conditions except with LPS-16+mDC, which induced reduced amounts of this cytokine. Those differences were totally eliminated by neutralization of IL-12, IL-4 or IL-10. Finally, 16?mDC could reverse the Th2 phenotype of already committed lymphocytes toward a Th1 pattern in short-term cultures, whereas 16+mDC had less ability to skew this phenotype. These results indicate that 16+mDC elicit superior Th2 responses independently of the maturation factors that they received, and suggest that they could represent an important population of regulatory DC. [ABSTRACT FROM AUTHOR]

The coronavirus disease 2019 (COVID-19) pandemic has reached an unprecedented level. There is a strong demand for diagnostic and serological supplies worldwide, making it necessary for countries to establish their own technologies to produce high-quality biomolecules. The two main viral antigens used for the diagnostics for severe acute respiratory syndrome coronavirus (SARS-CoV-2) are the structural proteins spike (S) protein and nucleocapsid (N) protein. The spike protein of SARS-CoV-2 is cleaved into S1 and S2, in which the S1 subunit has the receptor-binding domain (RBD), which induces the production of neutralizing antibodies, whereas nucleocapsid is an ideal target for viral antigen-based detection. In this study, we designed plasmids, pcDNA3.1/S1 and pcDNA3.1/N, and optimized their expression of the recombinant S1 and N proteins from SARS-CoV-2 in a mammalian system. The RBD was used as a control. The antigens were successfully purified from Expi293 cells, with high yields of the S1, N, and RBD proteins. The immunogenic abilities of these proteins were demonstrated in a mouse model. Further, enzyme-linked immunosorbent assays with human serum samples showed that the SARS-CoV-2 antigens are a suitable alternative for serological assays to identify patients infected with COVID-19.