Chimeric Hepatitis B core virus-like particles harboring SARS-CoV2 epitope elicit a humoral immune response in mice.

BACKGROUND: Virus-like particles are an interesting vector platform for vaccine development. Particularly, Hepatitis B virus core antigen has been used as a promising VLP platform. It is highly expressed in different recombinant expression systems, such as E. coli, and self-assembled in vitro. It effectively improves the immunogenicity of foreign antigenic epitopes on its surface. Various foreign antigens from bacteria, viruses, and protozoa can be genetically inserted into such nanoparticles. The effective immunogenicity due to VLP vaccines has been reported. However, no research has been performed on the SARS-CoV2 vaccine within this unique platform through genetic engineering. Considering the high yield of target proteins, low cost of production, and feasibility of scaling up, E. coli is an outstanding expression platform to develop such vaccines. Therefore, in this investigation, we planned to study and develop a unique HBc VLP-based vaccine against SARS-Cov2 utilizing the E. coli expression system due to its importance. RESULTS: Insertion of the selected epitope was done into the major immunodominant region (MIR) of truncated (149 residues) hepatitis B core capsid protein. The chimeric protein was constructed in PET28a+ and expressed through the bacterial E. coli BL21 expression system. However, the protein was expressed in inclusion body forms and extracted following urea denaturation from the insoluble phase. Following the extraction, the vaccine protein was purified using Ni2 + iminodiacetic acid (IDA) affinity chromatography. SDS-PAGE and western blotting were used to confirm the protein expression. Regarding the denaturation step, the unavoidable refolding process was carried out, so that the chimeric VLP reassembled in native conformation. Based on the transmission electron microscopy (TEM) analysis, the HBC VLP was successfully assembled. Confirming the assembled chimeric VLP, we explored the immunogenic effectivity of the vaccine through mice immunization with two-dose vaccination with and without adjuvant. The utilization of adjuvant was suggested to assess the effect of adjuvant on improving the immune elicitation of chimeric VLP-based vaccine. Immunization analysis based on anti-spike specific IgG antibody showed a significant increase in antibody production in harvested serum from immunized mice with HBc-VLP harboring antigenic epitope compared to HBc-VLP- and PBS-injected mice. CONCLUSIONS: The results approved the successful production and the effectiveness of the vaccine in terms of humoral IgG antibody production. Therefore, this platform can be considered a promising strategy for developing safe and reasonable vaccines; however, more complementary immunological evaluations are needed.

Plant-derived VLP: a worthy platform to produce vaccine against SARS-CoV-2.

After its emergence in late 2019 SARS-CoV-2 was declared a pandemic by the World Health Organization on 11 March 2020 and has claimed more than 2.8 million lives. There has been a massive global effort to develop vaccines against SARS-CoV-2 and the rapid and low cost production of large quantities of vaccine is urgently needed to ensure adequate supply to both developed and developing countries. Virus-like particles (VLPs) are composed of viral antigens that self-assemble into structures that mimic the structure of native viruses but lack the viral genome. Thus they are not only a safer alternative to attenuated or inactivated vaccines but are also able to induce potent cellular and humoral immune responses and can be manufactured recombinantly in expression systems that do not require viral replication. VLPs have successfully been produced in bacteria, yeast, insect and mammalian cell cultures, each production platform with its own advantages and limitations. Plants offer a number of advantages in one production platform, including proper eukaryotic protein modification and assembly, increased safety, low cost, high scalability as well as rapid production speed, a critical factor needed to control outbreaks of potential pandemics. Plant-based VLP-based viral vaccines currently in clinical trials include, amongst others, Hepatitis B virus, Influenza virus and SARS-CoV-2 vaccines. Here we discuss the importance of plants as a next generation expression system for the fast, scalable and low cost production of VLP-based vaccines.

Hepatitis B core-based virus-like particles: A platform for vaccine development in plants.

Virus-like particles (VLPs) are a class of structures formed by the self-assembly of viral capsid protein subunits and contain no infective viral genetic material. The Hepatitis B core (HBc) antigen is capable of assembling into VLPs that can elicit strong immune responses and has been licensed as a commercial vaccine against Hepatitis B. The HBc VLPs have also been employed as a platform for the presentation of foreign epitopes to the immune system and have been used to develop vaccines against, for example, influenza A and Foot-and-mouth disease. Plant expression systems are rapid, scalable and safe, and are capable of providing correct post-translational modifications and reducing upstream production costs. The production of HBc-based virus-like particles in plants would thus greatly increase the efficiency of vaccine production. This review investigates the application of plant-based HBc VLP as a platform for vaccine production.

Mysterious Virus: A Review on Behavior and Treatment Approaches of the Novel Coronavirus, 2019-nCoV.

At the end of the year 2019, the novel coronavirus (2019-nCoV) was spreading in Wuhan, China, and the outbreak process has a high speed. It was recognized as a pandemic by the World Health Organization (WHO) on 11 March 2020. Coronaviruses are enveloped and single-stranded RNA that have several families including Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). The pathogenesis mechanism and disease outcomes of SARS and MERS are now clear to some extent, but little information is available for 2019-nCoV. This newly identified corona virus infection represents flu-like symptoms, but usually the first symptoms are fever and dry cough. There has been no specific treatment against 2019-nCoV up to now, and physicians only apply supportive therapy. In the present article, we made an attempt to review the behavior of the virus around the world, epidemiology, a pathway for influx into the host cells, clinical presentation, as well as the treatments currently in use and future approaches; nitazoxanide may be our dream drug. We hope that this review has a positive impact on public knowledge for helping to deal with the 2019-nCoV and move one step forward toward its treatment in the near future.

Optimization of homogenization-sonication technique for the production of cellulose nanocrystals from cotton linter.

Recently, cellulose nanocrystals (CNCs) have attracted a significant interest in different fields including drug delivery, biomedical, and food applications. In this study, homogenization-ultrasonication as a non-hazardous, time-saving, and organic solvent free technique was applied for fabrication of CNCs from cotton linter, containing over 90% cellulose. First, acid hydrolysis was applied on raw cellulose using sulfuric acid at 55, 60 and 65% for 3, 5 and 7 min and at various homogenization speeds. Final CNCs were produced by ultrasonication (350 W) for 3 min. The physicochemical properties of CNCs, particle size, X-ray diffraction (XRD) pattern, Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), atomic force microscopy (AFM) and transmission electron microscopy (TEM) were studied. Production yield of CNCs was 59-72%, and their water holding capacity was two times higher than raw cellulose. The average length of CNCs was 133 nm with a width of 10 nm and the XRD pattern revealed a 82% crystallinity degree. The FTIR spectrum detected almost similar frequencies in the raw and crystalline cellulose, while intensity of CNC peaks was reduced. TEM results showed rod-like CNCs with a length of 229 nm. TGA results also showed that thermal stability of CNCs was reduced compared to raw cellulose.

Synthesis and characterization of cellulose nanocrystals derived from walnut shell agricultural residues.

Cellulose nanocrystals (CNCs) have novel and diversified applications in different fields including packaging and nanodelivery systems. This study was dedicated to fabricate CNCs from walnut shell as an abundant source of agricultural byproducts using alkali/acidic hydrolysis method. Moreover, homogenizer and ultrasound devices were applied to produce the CNCs with minimum hazardous solvents in the preparation steps. The physicochemical characteristics of CNCs, such as color, size, yield, and swelling capacity plus their characterization using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR) were studied. The mean equivalent spherical diameter of the fabricated CNCs was about 130 nm and the production efficiency was 91.5%. Besides, the swelling capacity of CNCs was 1.5-fold of cellulose with a swelling of 400%. The crystallinity degree of the cellulose obtained from walnut shell was 49%, which was improved following acidic and alkali hydrolysis (60%). TGA analysis revealed that the thermal stability of the CNCs was lower than cellulose; moreover, the FTIR results demonstrated that there is not a considerable difference between normal cellulose and CNCs. Overall, it was concluded that walnut shell-derived CNCs have the potential to be employed as promising nanocarriers in different sectors, especially in the food and drug delivery sectors.