Enhanced-Transient Expression of Hepatitis C Virus Core Protein in Nicotiana tabacum, a Protein With Potential Clinical Applications

Transient Expression of Flavivirus Structural Proteins in Nicotiana benthamiana

Flaviviruses are a threat to public health and can cause major disease outbreaks. Tick-borne encephalitis (TBE) is caused by a flavivirus, and it is one of the most important causes of viral encephalitis in Europe and is on the rise in Sweden. As there is no antiviral treatment available, vaccination remains the best protective measure against TBE. Currently available TBE vaccines are based on formalin-inactivated virus produced in cell culture. These vaccines must be delivered by intramuscular injection, have a burdensome immunization schedule, and may exhibit vaccine failure in certain populations. This project aimed to develop an edible TBE vaccine to trigger a stronger immune response through oral delivery of viral antigens to mucosal surfaces. We demonstrated successful expression and post-translational processing of flavivirus structural proteins which then self-assembled to form virus-like particles in Nicotiana benthamiana. We performed oral toxicity tests in mice using various plant species as potential bioreactors and evaluated the immunogenicity of the resulting edible vaccine candidate. Mice immunized with the edible vaccine candidate did not survive challenge with TBE virus. Interestingly, immunization of female mice with a commercial TBE vaccine can protect their offspring against TBE virus infection.

Combating Human Viral Diseases: Will Plant-Based Vaccines Be the Answer?

Molecular pharming or the technology of application of plants and plant cell culture to manufacture high-value recombinant proteins has progressed a long way over the last three decades. Whether generated in transgenic plants by stable expression or in plant virus-based transient expression systems, biopharmaceuticals have been produced to combat several human viral diseases that have impacted the world in pandemic proportions. Plants have been variously employed in expressing a host of viral antigens as well as monoclonal antibodies. Many of these biopharmaceuticals have shown great promise in animal models and several of them have performed successfully in clinical trials. The current review elaborates the strategies and successes achieved in generating plant-derived vaccines to target several virus-induced health concerns including highly communicable infectious viral diseases. Importantly, plant-made biopharmaceuticals against hepatitis B virus (HBV), hepatitis C virus (HCV), the cancer-causing virus human papillomavirus (HPV), human immunodeficiency virus (HIV), influenza virus, zika virus, and the emerging respiratory virus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have been discussed. The use of plant virus-derived nanoparticles (VNPs) and virus-like particles (VLPs) in generating plant-based vaccines are extensively addressed. The review closes with a critical look at the caveats of plant-based molecular pharming and future prospects towards further advancements in this technology. The use of biopharmed viral vaccines in human medicine and as part of emergency response vaccines and therapeutics in humans looks promising for the near future.

Expression of BMP2-Hydrophobin fusion protein in the tobacco plant and molecular dynamic evaluation of its simulated model

Plants are one of the ideal models for therapeutic protein production, however the recombinant protein purification problems in them must be overcome. Bone Morphogenetic Protein2 (BMP2) is employed for the restoration and construction of bone tissues. Hydrophobin is a fungal based protein with high hydrophobic characteristics. Due to this specificity, it is suitable for the purification of chimer protein from complex solutions when is fused to a protein utilizing an aqueous two-phase (A2P) technique. The plant optimized mature human BMP2 gene was designed and evaluated by in silico method. This process involves simulating molecular dynamics using the RMSD, RMSF and Gyration radius indexes. The synthesized Hyd-BMP2 gene was cloned into a pTRAkc-ERH plasmid and Transferred into Agrobacterium (Gv3101). The Nicotiana benthamiana plant leaves were co-agroinfiltrated with HA-Hyd-BMP2 and P19-pCambia1304 containing silencing suppressor. After purification of plant extract utilizing the A2P method, the sample was subjected to SDS-PAGE and Western-blot. By in silico study, the simulated fusion protein profitably shows reasonable protein compactness and the effect of amino acid substitution on protein-protein interaction is not remarkable. Western-blotting using anti HA tag has shown that the A2P technique partially purified the two 22 kDa and 44 kDa forms of Hydrophobin-BMP2. These results confirmed the presence of monomer and dimer forms of Hydrophobin-BMP2 proteins. Moreover, the expression level of the protein using P19 silencing suppressor increased six times and to 0.018% as shown by ELISA. This study presents a fast and easy technique for the purification of transient expressed pharmaceutical proteins from plants.

Heterologous expression of biologically active Mambalgin-1 peptide as a new potential anticancer, using a PVX-based viral vector in Nicotiana benthamiana

Mambalgin-1 is a peptide that acts as a potent analgesic through inhibiting acid-sensing ion channels (ASIC) in nerve cells. Research has shown that ASIC channels are involved in the proliferation and growth of cancer cells; therefore, Mambalgin-1 can be a potential anti-cancer by inhibiting these channels. In the present study, the Nicotiana benthamiana codon optimized Mambalgin-1 gene was synthesized and cloned in PVX (potato virus X) viral vector. The two cultures of Agrobacterium containing Mambalgin-1 and P19 silencing suppressor genes were co-agroinfiltrated into N. benthamiana leaves. Five days post infiltration, the production of recombinant Mambalgin-1 was determined by western blotting. For biological activity, MTT (3(4, 5-dimethylthiazole-2-yl)-2, 5-diphenyltetrazolium bromide) was analyzed for the cytotoxicity recombinant Mambalgin-1 from the transformed plants on nervous (SH-SY5Y) and breast (MCF7) cancer cells. The results showed that the plants expressing open reading frame of Mambalgin-1 showed recombinant 7.4 kDa proteins in the entire plant extract. In the MTT test, it was found that Mambalgin-1 had cytotoxic effects on SH-SY5Y cancer cells, yet no effects on MCF7 cancer cells were observed. According to the results, the expression of the biologically active recombinant Mambalgin-1 in the transformed plant leaves was confirmed and Mambalgin-1 can also have anti-cancer (inhibition of ASIC channels) potential along with its already known analgesic effect.

In silico and in vivo analyses of the mutated human tissue plasminogen activator (mtPA) and the antithetical effects of P19 silencing suppressor on its expression in two Nicotiana species

Human tissue-type plasminogen activator is one of the most important therapeutic proteins involved in the breakdown of blood clots following the stroke. A mutation was found at position 1541 bp (G514E) and the mutated form was cloned into the binary vector pTRAc-ERH. In silico analysis showed that this mutation might have no significant effect on the active site of the tissue plasminogen activator enzyme. Accordingly, zymography assay confirmed the serine protease activity of the mutated form and its derivatives. The expression of the mutated form was verified with/without co-agroinjection of the P19 gene silencing suppressor in both Nicotiana tabacum and N. benthamiana. The ELISA results showed that the concentration of the mutated form in the absence of P19 was 0.65% and 0.74% of total soluble protein versus 0.141% and 1.36% in the presence of P19 in N. benthamiana and N. tabacum, respectively. In N. tabacum, co-agroinjection of P19 had the synergistic effect and increased the mutated tissue plasminogen activator production two-fold higher. However, in N. benthamiana, the presence of P19 had the adverse effect of five-fold reduction in the concentration. Moreover, results showed that the activity of the mutated form and its derivatives was more than that of the purified commercial tissue plasminogen activator.

Transient Expression of Biologically Active Anti-rabies Virus Monoclonal Antibody in Tobacco Leaves

Background

Rabies virus is a neurotropic virus that causes fatal, but, a preventable disease in mammals. Administration of rabies immunoglobulin (RIG) is essential for the post-exposure of the prophylaxis to prevent the disease. However, replacement of polyclonal RIGs with alternative monoclonal antibodies (MAbs) that are capable of neutralizing rabies virus has been recommended.

Objectives

Here, we have investigated the transient expression of the full-size human MAb against rabies virus glycoprotein; the MAb SO57 in the tobacco plants using vacuum agro-infiltration. Previously, stably transformed plants expressing the MAb have been reported.

Materials and Methods

In this study three vectors carrying the codon-optimized genes for the heavy or light chain and p19 silencing-suppressor were constructed. These vectors were co-infiltrated into Nicotiana tabacum leaves and the transgenes were expressed.

Results

Dot blot, Western blotting, ELISA, and in vitro neutralization assays of the plant extracts showed that the human MAb could assemble in tobacco leaves and was able to neutralize rabies virus.

Conclusions

This study is the first report of transient expression of human MAb SO57 gene in tobacco plant within a few days after vacuum agro-infiltration.

Heterologous Expression of Hepatitis C Virus Core Protein in Oil Seeds of Brassica napus L

Background:

Hepatitis c virus (HCV), prevalent among 3% of the world population, is a major worldwide public health concern and an effective vaccination could help to overcome this problem. Plant seeds as low-cost vaccine expression platforms are highly desirable to produce antigens.

Objectives:

The present study was aimed at investigating the possible expression of recombinant HCV core protein, as a leading HCV vaccine candidate, in canola (Brassica napus) plant seeds in order to be used as an effective immunogen for vaccine researches.

Materials and Methods:

A codon-optimized gene harboring the Kozak sequence, 6 × His-tag, HCVcp (1 - 122 residues) and KDEL (Lys-Asp-Glu-Leu) peptide in tandem was designed and expressed under the control of the seed specific promoter, fatty acid elongase 1 (FAE1), to accumulate the recombinant protein in canola (B. napus L.) seeds. Transgenic lines were screened and the presence of the transgene was confirmed in the T0 plants by polymerase chain reaction (PCR). The quantity and quality of the HCV core protein (HCVcp) in transgenic seeds were evaluated by enzyme-linked immunosorbent assay (ELISA) and western blot, respectively.

Results:

Western blot analysis using anti-His antibody confirmed the presence of a 15 kDa protein in the seeds of T1 transgenic lines. The amount of antigenic protein accumulated in the seeds of these transgenic lines was up to 0.05% of the total soluble protein (TSP).

Conclusions:

The canola oilseeds could provide a useful expression system to produce HCV core protein as a vaccine candidate.

Monoclonal antibodies: Principles and applications of immmunodiagnosis and immunotherapy for hepatitis C virus

Hepatitis C virus (HCV) is a major health problem worldwide. Early detection of the infection will help better management of the infected cases. The monoclonal antibodies (mAb) of mice are predominantly used for the immunodiagnosis of several viral, bacterial, and parasitic antigens. Serological detection of HCV antigens and antibodies provide simple and rapid methods of detection but lack sensitivity specially in the window phase between the infection and antibody development. Human mAb are used in the immunotherapy of several blood malignancies, such as lymphoma and leukemia, as well as for autoimmune diseases. In this review article, we will discuss methods of mouse and human monoclonal antibody production. We will demonstrate the role of mouse mAb in the detection of HCV antigens as rapid and sensitive immunodiagnostic assays for the detection of HCV, which is a major health problem throughout the world, particularly in Egypt. We will discuss the value of HCV-neutralizing antibodies and their roles in the immunotherapy of HCV infections and in HCV vaccine development. We will also discuss the different mechanisms by which the virus escape the effect of neutralizing mAb. Finally, we will discuss available and new trends to produce antibodies, such as egg yolk-based antibodies (IgY), production in transgenic plants, and the synthetic antibody mimics approach.

Monoclonal antibodies: Principles and applications of immmunodiagnosis and immunotherapy for hepatitis C virus

Hepatitis C virus (HCV) is a major health problem worldwide. Early detection of the infection will help better management of the infected cases. The monoclonal antibodies (mAb) of mice are predominantly used for the immunodiagnosis of several viral, bacterial, and parasitic antigens. Serological detection of HCV antigens and antibodies provide simple and rapid methods of detection but lack sensitivity specially in the window phase between the infection and antibody development. Human mAb are used in the immunotherapy of several blood malignancies, such as lymphoma and leukemia, as well as for autoimmune diseases. In this review article, we will discuss methods of mouse and human monoclonal antibody production. We will demonstrate the role of mouse mAb in the detection of HCV antigens as rapid and sensitive immunodiagnostic assays for the detection of HCV, which is a major health problem throughout the world, particularly in Egypt. We will discuss the value of HCV-neutralizing antibodies and their roles in the immunotherapy of HCV infections and in HCV vaccine development. We will also discuss the different mechanisms by which the virus escape the effect of neutralizing mAb. Finally, we will discuss available and new trends to produce antibodies, such as egg yolk-based antibodies (IgY), production in transgenic plants, and the synthetic antibody mimics approach.