Research Paper Example about Vaccines

📌Category: Biology, Health, Science, Vaccination
📌Words: 1256
📌Pages: 5
📌Published: 05 June 2022

As our understanding of biological processes continues to expand, so do the ways we apply those same functions. Vaccines stimulate parts or whole organisms to promote an immune response against the possible infection. Up to this point, pharmaceutical companies have been utilizing chemical means to obtain immune responses. Now, biotechnology companies/institutions, such as Medicago and Arizona State University, have been working on the production of proteins utilizing plants in order to create new treatments, drugs, and vaccines.

Currently, the process of creating and producing vaccines is very expensive, varying from around $200 to $500 per vaccine. (Serdobova) The length of time in which a new drug is developed, licensed, and presented to the market, from research to discovery, usually takes around 10 years. (IBID) There are many different ways of creating vaccines, each with its benefits and costs. Currently, there are a few common strategies of providing immunity to a patient, these being inactivated, live-attenuated, and recombinant vaccines. 

An inactivated vaccine uses a killed version of the original virus to promote an immune response. This is performed by propagating, purifying, and inactivating the virus. The process of inactivation can be performed either utilizing, a combination or separately, chemical, or physical means. (Sanders) Immunity in these types of vaccines are not as strong as live vaccines, propagating the possibility of multiple doses to have long-lasting immunity. (OIDP) There have been recorded cases of inactivated vaccines leading to an enhanced disease, & death when vaccinated patients were exposed to another pathogen. (Sanders)

Live-attenuated vaccines are variations of the original virus that grow at a slower rate and promote an immune response. (Treanor) Attenuation of a virus can be performed in many ways, two being by genetic manipulation (GHPHP), or by culturing under suboptimal conditions for long periods of time. (Mak) Attenuated vaccines tend to retain immunity for a longer period of time than inactivated vaccines, and as a result, do not require multiple doses to prolong the effects. (Bass) An issue with these types of vaccines is the need for refrigeration, limiting the distribution area. If the vaccine is exposed to hotter temperatures than needed, they become inactive, making them not as effective. People with weakened immune systems are at greater risk when taking attenuated vaccines, due to the possibility of mutation and infection. Attenuated “viral vectors” are currently being looked at as a method of gene therapy. (IBID)

Out of all the methods that could be used to promote immune responses in the body, the most efficient by far are recombinant vaccines. Recombinant/subunit protein vaccines utilize the proteins of a virus, in order to promote an immune response. A common branch of recombinant vaccines are virus-like particles. Virus-like particles are a sub-branch of recombinant protein vaccines that are based on proteins derived from viruses’, forming the outer layer of a virus. (Braeden. 2018) One of the many advantages of this method of vaccination is that the particles do not contain any genetic material, making them incapable of replicating. This means that there are no mutations that could alter the behavior of the particles, removing the possibility of different responses that could arise from a live-attenuated vaccine, making them safer. The particle also identically copies the outer layer of the parent virus, both in its complex shape and size, allowing for the immune system to identify the antigens on both the fake and real virus, promoting a strong immune response, comparable to if you were infected with the real virus. 

 In upstream processing, it is difficult to choose a good base to produce a vaccine. Some important factors that determine what type of culture is used are the way a protein folds, the time needed to make the final product, and the difficulty of protein purification. Depending on the protein’s structure, certain means of protein production are better than others. Traditional methods of producing proteins mainly come from two types of cells, bacterium, and mammalian.

Bacterial expression systems are generally well understood utilizing our knowledge of E.coli as a basis. E.coli are utilized frequently because of their ability to grow in cultures extremely quickly. (Thompson, J.) E.coli is also utilized because of how straightforward it is to keep them healthy. Their cell wall helps them withstand extreme temperature changes. Transformation in bacterium is made simple through processes like heat shock or calcium chloride solutions. E.coli excels for certain types of proteins, specifically those that need few post-translational modifications. “Unfortunately, trans-membrane proteins, glycoproteins, and other membrane-bound proteins are not so easily expressed because there is no endoplasmic reticulum to facilitate proper translation of the structure.” (IBID)

Mammalian expression systems have many advantages, and disadvantages. Animal cells tend to be more consistent when replicating clonal cells, which allows for replicating the experiment to be easier. The environment in which animal cells live can be controlled accurately. (Arango MT) Protein expression is effective due to having the correct mammalian post-translational modifications being applied to the proteins. (Thompson, J.) Mammalian cells tend to be more difficult to work with, due to being weaker against potential contaminants. (Arango MT) This forces stricter practices & procedures to prevent contamination, which increases the base skill level required. (IBID) Animal cells also do not grow as fast, nor do they produce as much as bacteria, which hinders the process of production. (IBID) 

Many other alternatives to both microbial and mammalian expression systems exist, one of the most interesting is in plants. Compared to mammalian cultures, plants take a shorter amount of time to culture/grow for a larger amount of product. (Lössl) Utilizing plants also gives the ability to consume the vaccine securely. (Moon) Oral delivery strategies may also allow for better induced mucosal immune responses, unlike injected vaccines. (Moon; Neutra) Plants can be produced close to the location where they are needed, making transportation easier. (Lössl) In a similar way to bacterial cultures, plants also have the ability to upscale production to a massive scale and increase the raw yield per plant if needed. (IBID) Unlike animal and bacterial cells, plants do not need to be cultured inside of an expensive bioreactor. Plants grow normally and produce the proteins inside of them over their lifespan, allowing them to be cost-competitive against mammalian and bacterial cultures. Another important characteristic is that plants are capable of producing complex, multicomponent isotypes. (Ma JK) Secretory immunoglobulin A (sIgA), a very complex antibody with four unique chains found in animals, was able to be assembled, and function correctly in plants. (IBID)

There are a few things that prevent the usage of plants from being widely utilized. One very limiting component is the variety of plants that can be utilized, due to concerns such as plant-specific sugars being immunogenic, creating complications in pharmacokinetics. (Moon) Another limitation is concerning the consistency of dosage in a plant. (Moon) Each plant varies between the amount of the product that is made. (IBID) There is also a risk of cross-pollination of these plants with wild ones. (IBID) Aside from technical problems, there is also the disadvantage of the public’s perspective on genetically modified plants.

Many recent discoveries allow for some concerns to be mitigated or eliminated. One such discovery is through certain N. benthamiana mutants. Various variations of N. benthamiana have been shown to mitigate the number of immunogenic sugars produced. (Strasser R) Some of these plants have developed human-like glycosylation, N-glycan. (IBID) Other studies show that plants are able to produce sialic acid (Castilho, A) and N-glycans with terminal galactose (Strasser, R) both of which are important mechanisms of action.

There are two techniques in which the creation of virus-like particles are made in plants. One method is to identify the proteins of the virus that are able to self-assemble inside of cells either through transgenesis or transiently. (Peyret) “If the envelope proteins are expressed, the production of VLPs relies on the ability of these proteins to interact productively with plant membranes.” (IBID) The second method is by utilizing phage display technology. Phage display technology allows for the identification of ligands, proteins, and other macromolecules. (Biolabs, N. E) Typically, particles from plant viruses’, isometric and helical morphologies, are most prominent. (Peyret) There are other self-assembling macromolecules that have been used for phage display technology in plants. One of which is a core antigen (HBcAg) derived from hepatitis B. (Mardanova).

+
x
Remember! This is just a sample.

You can order a custom paper by our expert writers

Order now
By clicking “Receive Essay”, you agree to our Terms of service and Privacy statement. We will occasionally send you account related emails.