The role of transgenic plants in coping with acute respiratory syndrome SARS-Cov2
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mohammad ramezani kaporchali,1,* Naser farrokhi,2
1. Faculty of Biological Sciences and Technology, Shahid Beheshti University
2. Faculty of Biological Sciences and Technology, Shahid Beheshti University
- Introduction: Currently, more than 45% of deaths in developing countries are due to infectious diseases. The most important way to prevent these diseases is to vaccinate people. But more than 30 million children worldwide have not yet been immunized against these preventable and treatable diseases. Because current methods of vaccine production are technologically complex and therefore expensive. In particular, the conditions and facilities of packing, storage in the cold and their transportation lead to an increase in prices. Therefore, the existence of these conditions causes a large part of the population of developing and poor countries to not have access to the vaccination process [1]. On the other hand, various antibiotics are used to treat diseases caused by viral and bacterial infections; Increasingly inappropriate use of antibiotics is increasing the resistance of bacteria to them, and this has been a concern for researchers for the past decade. For this reason, achieving new strategies to immunize the human body is based on methods of preventing infectious diseases [2]. In December 2019, a new strain of the coronavirus (SARS-CoV-2) appeared in Wuhan, leading to the development of an epidemic of acute respiratory syndrome (COV). Over a period of three months, the virus spread to more than 118,000 people in 114 countries and killed more than 4,000 people [4] [3]. With the involvement of 114 countries, the World Health Organization on March 11, 2020 declared this disease as a global epidemic [5]. Governments took control measures, aimed at delaying the spread of infection and thus reducing the strain on hospital beds, the front lines of treatment, staff, and medical resources. Reducing the rate of infection and thus reducing the total number of acute cases at any time can help prevent the collapse of national health systems. These techniques also give researchers more time to develop effective experimental methods to identify carriers of the disease, as well as find treatments to reduce the severity of symptoms and eliminate the infection more quickly. This time also allows researchers to introduce candidate vaccines to protect sections of the population that have not been exposed to the disease. Therefore, researchers working on plant applications can play an important role at this time. Existing knowledge and scientific infrastructure can be used as a tool to develop new diagnostic and therapeutic methods; Therefore, plants can be used as hosts to make such referrals over a period of several weeks, and this time seems to be economical and wise compared to the time required for cell-based systems, which may take several months to several years arrives.
- Methods: 1- Resistance to coat protein (CP): This phenomenon was first reported by Sherwood and Fulto in 1982 and by Bawan et al In 1985. The concept of pathogen resistance was first reported by Sanford and Johnson in 1985, and was demonstrated in transgenic tobacco plants by Paul-Abel et al In 1986. In this study, the expression of tobacco mosaic virus (TMV) envelope protein was delayed until the onset of symptoms due to tobacco disease. Similar experiments were performed rapidly and the occurrence of this phenomenon in various viruses such as alfalfa mosaic virus (AMV), PVX and cabbage mosaic virus (CMV) was confirmed. Coating protein (CP) resistance can be widespread or limited to the RNA of viruses [16] [17].
2- Resistance by virus replication sequence: Genes encoding protein replicase viruses can cause immunity to the disease. All plant viruses have replicase genes. Plant translocation with this method creates a high resistance that is only created against the target virus or very close strains. The mechanisms involved in resistance to replication sequences are not well understood, as they are likely to interfere with virus replication and gene expression [18].
3- 3- Resistance due to viral motor protein: Motor protein resistance is created by competing between the motor protein produced from the transgenic plant and the virus attack to find binding sites on the host plant plasmodsmata. Thus, resistance to virus motility protein overshadows a wider range of viruses than replicase resistance [19].
4- RNA-mediated resistance: Some methods of resistance to pathogens are genes that do not encode proteins. One of these methods is the expression of RNA heterogeneous sequences to prevent virus replication through RNA suppression [20]. RNA resistance in transgenic plants acts as a trap to prevent the production of proteins that multiply and move the virus through competition of the virus with the transgenic plant or its RNA version. This process works in different ways. In some studies, it has been reported that a transgene with inadequate DI inhibition in virus RNA reduced virus replication [21].
- Results: Compared to traditional methods of vaccine production, oral herbal vaccines have low production costs, easy storage conditions, cost-effective transportation, and also provide oral immunity and are easy to use. Therefore, the medical community has a strong tendency to produce recombinant human proteins in transgenic plants. The prevailing view is that transgenic plants can produce significant amounts of low-cost antigen. The use of oral vaccines, especially when used as part of a diet, eliminates the need to train staff to administer the vaccine, but before this new method can be further developed, More research should be done on different types of antigens. The basic idea of oral plant vaccines is that humans can consume transgenic fruits or vegetables that express the antigen of a virus or bacterium in their raw form. Therefore, the eaten plant acts as an active vaccine and provides an adequate immune response against certain diseases. Many scientists call this theory simple because the different fruits of a plant express different amounts of an antigen. Therefore, in order to achieve the appropriate concentration of the desired antigen, a minimum amount of production should be considered, including storage of fruits of different plants, homogenization and dry freezing before packaging. The use of oral antigens in transgenic plants also causes unusual sensitivities in laboratory animals, which is called oral resistance. Therefore, it is necessary to determine the amount of antigen that reaches the body through the consumption of plant material is less than the amount that induces oral resistance. Oral resistance depends on the concentration and type of antigen, so when producing a protein in a transgenic plant, the issue of oral resistance should also be considered. Also, the use of transgenic plants as bioreactors producing recombinant proteins has caused a great deal of consideration; Therefore, before transgenic organisms are released into the environment, environmental safety must be taken into account in order to separate medicinal fruits and vegetables from ordinary edible fruits and vegetables. On the other hand, the molecular farming community is very active in creating plant-based processes to produce diagnostic and therapeutic proteins to combat Covid-19 disease. The two currents of the EU Consortium on Molecular Agriculture state that their efforts will lead to the production of such targeted proteins. So we can help curb the current Covid-19 epidemic by providing accurate modeling for a quick and targeted response.
- Conclusion: VLPs (Virus-like particles) vaccines with SARS-CoV-2 antigens have several advantages; Because of their size, these particles are more effectively absorbed by antigen-containing cells and stimulate the adaptive immune system, and regular protein structures can stimulate strong cellular and humoral responses to detect danger signals [28]. Therefore, VLPs based on plant viruses provide an additional layer of immunity because even protein particles cannot reproduce in humans; Therefore, large quantities of them can be produced through molecular agriculture in plants [29]. Medicago recently announced that it intends to use its platforms to rapidly produce VLP-based vaccines against SARS-CoV-2, while the exact nature of VLPs remains a mystery [30]. Virus antigens and VLPs elicit an immune response to the pathogen when exposed to the cell, while injecting recombinant antibodies to SARS-CoV-2 slows the rate of infection and allows the body to secrete its own antibodies before it can succumb to the disease [31]. Therefore, plants can be used to produce antibodies, not only as diagnostic reagents for the virus, but also as a form of inactivated immunotherapy.
In addition to producing antibodies that directly kill the virus, plants can be used to produce large amounts of therapeutic antibodies. Because cytokine storms inhibit SARS-CoV-2 infection in many fatalities. The two antibodies that can be used for this purpose to treat Covid-19 are Kevzara / Sarilumab and tocilizumab / Actemra, both of which bind to the interleukin-6 (IL-6) receptor and are used to treat rheumatoid arthritis, that both of them are in the clinical trial phase of Covid -19 [33] [32].
- Keywords: Transgenic plants, SARS- Cov-2, Herbal vaccines
