The emergence of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected global public health and economy. Despite the substantial efforts, only few vaccines are currently approved and some are in the different stages of clinical trials. As the disease rapidly spreads, an affordable and effective vaccine is urgently needed. In this study, we investigated the immunogenicity of plant-produced receptor-binding domain (RBD) of SARS-CoV-2 in order to use as a subunit vaccine. In this regard, RBD of SARS-CoV-2 was fused with Fc fragment of human IgG1 and transiently expressed in Nicotiana benthamiana by agroinfiltration. The plant-produced RBD-Fc fusion protein was purified from the crude extract by using protein A affinity column chromatography. Two intramuscular administration of plant-produced RBD-Fc protein formulated with alum as an adjuvant have elicited high neutralization titers in immunized mice and cynomolgus monkeys. Further it has induced a mixed Th1/Th2 immune responses and vaccine-specific T-lymphocyte responses which was confirmed by interferon-gamma (IFN-γ) enzyme-linked immunospot assay. Altogether, our results demonstrated that the plant-produced SARS-CoV-2 RBD has the potential to be used as an effective vaccine candidate against SARS-CoV-2. To our knowledge, this is the first report demonstrating the immunogenicity of plant-produced SARS-CoV-2 RBD protein in mice and non-human primates.

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Dendrimers have well-organized high branches with a layered architecture providing a series of versatile chemical modification for various purposes. Consequently, this dendrimer nanotechnology explores a new promising class of nanoscale carriers for therapeutic drugs and imaging reagents using passive and active targeting approaches. By controlling dendritic structures, the biological fate of dendrimer/dendrimer-based drugs can be significantly altered based on their intrinsic physicochemical properties, including the hydrophilicity of the unit molecules, particle size, surface charge, and modification. Accordingly, pharmacokinetic aspects play an important role in the design and development of dendrimer systems for successful in vivo application and clinical translation. This review focuses on the recent progress regarding dendritic architectures, structure-related toxicity, and critical factors affecting the pharmacokinetics and biodistribution of dendrimer/dendrimer-based drugs. A better understanding of the basic aspects of dendritic systems and their pharmacokinetics will help to develop a rationale for the design of dendrimers for the controlled delivery of drugs and imaging reagents for therapeutic or diagnostic purposes.

The genetic fusion of apoA-I with biologically active peptides potentially enables a simple assembly of biocompatible and versatile drug carriers.

Inhalation of bacterial endotoxin induces pulmonary inflammation by activation of nuclear factor B (NFB), production of cytokines and chemokines, and neutrophil activation. Although glucocorticoids are the drugs of choice, administration of free drugs results in adverse effects as a result of a lack of selectivity for the inflammatory effector cells. Because alveolar macrophages play a key role in the inflammatory response in the lung, selective targeting of glucocorticoids to alveolar macrophages offers efficacious pharmacological intervention with minimal side effects. We have demonstrated previously the selective targeting of mannosylated liposomes to alveolar macrophages via mannose receptor-mediated endocytosis after intratracheal administration. In this study, the anti-inflammatory effects of dexamethasone palmitate incorporated in mannosylated liposomes (DPML) at 0.5 mg/kg via intratracheal administration were investigated in lipopolysaccharide-induced lung inflammation in rats. DPML significantly inhibited tumor necrosis factor ␣, interleukin-1␤, and cytokine-induced neutrophil chemoattractant-1 levels, suppressed neutrophil infiltration and myeloperoxidase activity, and inhibited NFB and p38 mitogen-activated protein kinase activation in the lung. These results prove the value of inhaled mannosylated liposomes as powerful targeting systems for the delivery of anti-inflammatory drugs to alveolar macrophages to improve their efficacy against lung inflammation. Inhalation of lipopolysaccharide (LPS), which is a component of Gram-negative bacteria presenting as an environment pollutant, contributes to inflammation in the lung. The downstream signaling pathways after LPS stimulation include the activation of alveolar macrophages, which are key effector cells to release proinflammatory cytokines including tumor necrosis factor ␣ (TNF␣), interleukin-1␤ (IL-1␤) (Ulich et al., 1991), chemokines such as cytokine-induced neutrophil chemoattractant-1 (CINC-1) (Ulich et al., 1995), and activation of nuclear factor B (NFB) and p38 mitogen-activated protein kinase (p38MAPK). Thereafter, neutrophils are recruited into the lung and release protease enzymes, which trigger lung injury. Corresponding to these studies, depletion of alveolar macrophages by liposomal clodronate treatment completely suppressed the downstream signaling after LPS stimulation (Koay et al., 2002). These results indicate that alveolar macrophages play a key role in the inflammation to release proinflammatory cytokines and chemokines after LPS stimulation.Glucocorticoids (GCs) are the drugs of choice for treatment of lung inflammation via systemic or local administration. Although inhalation of free GC is a promising therapy with less systemic toxicity, the therapeutic efficacy has been ques-

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Trastuzumab, a humanized monoclonal antibody against human epidermal growth factor receptor 2 (HER2), offers a promising strategy of anticancer drug targeting to HER2-expressing cancer cells. Conjugation of trastuzumab to dendrimers, repeatedly branched polymers with a highly functionalized surface, can enhance the drug loading capacity. However, typical dendrimers such as cationic polyamidoamine dendrimers have exhibited a nonspecific cytotoxicity. In the present study, we developed a novel biocompatible amino acid dendrimer with potentially less toxicity by surface modification of the sixth generation lysine dendrimer with glutamate (KG6E). The synthesized KG6E showed a well-controlled particle size around 5-6 nm with low polydispersibility and negative surface potentials for negligible cytotoxicity. Next, the targeting efficiency of the fluorescent-labeled KG6E-trastuzumab conjugate was evaluated in HER2-positive (SKBR3) and -negative (MCF7) human breast cancer cell lines compared to free trastuzumab and KG6E dendrimers. The KG6E-trastuzumab conjugate was specifically bound to SKBR3 cells in a dose-dependent manner with low binding affinity to MCF7 cells. Furthermore, the conjugate was significantly internalized in SKBR3 cells and then trafficked to lysosomes. These results indicate the potential of KG6E-trastuzumab conjugates as HER2-targeting carriers for therapeutic and diagnostic approaches to cancer therapy.

More than 65 million people have been confirmed infection with SARS-CoV-2 and more than 1 million have died from COVID-19 and this pandemic remains critical worldwide. Effective vaccines are one of the most important strategies to limit the pandemic. Here, we report a construction strategy of DNA vaccine candidates expressing full length wild type SARS-CoV-2 spike (S) protein, S1 or S2 region and their immunogenicity in mice. All DNA vaccine constructs of pCMVkan-S, -S1 and -S2 induced high levels of specific binding IgG that showed a balance of IgG1/IgG2a response. However, only the sera from mice vaccinated with pCMKkan-S or -S1 DNA vaccines could inhibit viral RBD and ACE2 interaction. The highest neutralizing antibody (NAb) titer was found in pCMVkan-S group, followed by -S1, while -S2 showed the lowest PRNT50 titers. The geometric mean titers (GMTs) were 2,551, 1,005 and 291 for pCMVkan-S, -S1 and -S2, respectively. pCMVkan-S construct vaccine also induced the highest magnitude and breadth of T cells response. Analysis of IFN-γ positive cells after stimulation with SARS-CoV-2 spike peptide pools were 2,991, 1,376 and 1,885 SFC/106 splenocytes for pCMVkan-S, -S1 and -S2, respectively. Our findings highlighted that full-length S antigen is more potent than the truncated spike (S1 or S2) in inducing of neutralizing antibody and robust T cell responses.