Blog Medical Innovation: Future Promise of DNA Vaccines
Medical Innovation: Future Promise of DNA Vaccines
Current vaccines consist of inactive pathogens that are inserted into the body in order to activate an immune response and produce memory white blood cells. While usually effective, conventional vaccines can potentially become inert in improper environments or trigger an actual infection in a weakened immune system. However, recent advances in DNA vaccines represent a new generation of vaccination that can bring worldwide relief with lessened probability of causing additional damage.
Vaccines are considered a baseline in most medical records today, inducing an immune response against an inert pathogen to prevent future infection. DNA vaccines provide an alternative method to produce immunity in organisms. First developed during 1990s, DNA vaccines continue to undergo clinical trial and testing today [1]. Used when modified pathogenic substances are unavailable or difficult to manufacture, DNA vaccines produce immunity within an organism without ever presenting the pathogen to the subject organism.
DNA vaccines consist of bacterial plasmids with particular pathogenic gene inserts [1]. These inserts, which code for the surface proteins that cover the infectious agent, become integrated within the cell's DNA. The surface proteins are transcripted and displayed by the altered cells prompting the body to produce an immune response. The plasmid also sequences a unique promoter sequence that will allow the targeted organism to successfully transcript the encoded proteins. White blood cells and lymphocytic B-cells and T-cells recognize the displayed proteins and produce the appropriate antibodies, creating a successful immune response [2,3].
The medical value of DNA vaccines is immense. They have the capability to produce a stronger and wider immunity within the organism and can be modified to cover multiple diseases [2]. Because of their construct with specific inserts, a plasmid can encode multiple surface proteins. DNA vaccines are also less susceptible to damage due to environmental conditions, such as extreme temperatures or humidity. They can safely be administered to people who live in areas where regular vaccines are difficult to maintain or may be compromised due to the lack of proper storage facilities in unique environmental conditions [4]. DNA vaccines, if integrated into the body appropriately, can produce a sustained immune response, making booster vaccinations unnecessary. By receiving a DNA vaccine, an individual can have lifelong immunity towards a disease by simply receiving a single shot. This would decrease the demand for boosters along with the price of the vaccines.
Besides the general medical benefits, DNA vaccines can provide a large economic benefit as well. Due the decreased restrictions in the production and storage of DNA vaccines compared to regular vaccines, the cost of producing and maintaining DNA vaccines is much lower [2]. The prevention of disease by using DNA vaccines reduces the amount of money spent on medication. This can be especially beneficial to people in developing countries. This lower price can also be attributed to the difference in the production cost of current vaccines and DNA vaccines. According to specific case studies, it can be seen that the cost of developing and manufacturing a successful and beneficial regular vaccine can range from $500 million to $1 billion [5]. Comparatively, the development and manufacturing of a DNA vaccine ranges between $200 and $300 million [4].
The versatility and potential of DNA vaccines can also be utilized to produce vaccines against some of the fatal and incurable diseases of today [6]. Studies over the past decade have indicated that DNA vaccines can be used to mimic diseases such as HIV/AIDS or malaria and produce suitable immunity [1,2]. These two diseases contribute to the greatest number of deaths in underdeveloped countries. By producing immunity against HIV/AIDS or malaria, the mortality rates of individuals will decrease dramatically and the population structure of many developing countries will shift to have more adults than children, effectively slowing down the population growth of those countries.
Despite the medical, economic, and humanitarian benefits of DNA vaccines, there are also several ethical concerns about this new method of inoculation. Because DNA vaccines alter the genome of the targeted cells, many consider DNA vaccines to be a form of genetically modifying organisms, a cause for great ethical debate [3]. Some individuals feel that scientists are attempting to alter organisms at the molecular level and are thereby playing "God." Others worry about the long term impacts of adding sequences to the human genome. By inserting a foreign DNA fragment into an organism's genome, there is a concern about the possible effect that the new encoding will have on the host. If DNA can be introduced to produce specific proteins to prevent infection, could the same procedure not also be used to deliberately modify an organism? A DNA fragment could potentially be inserted into an organism's genome at an early stage of development and could alter the organism as a whole. The long-term effects of DNA vaccines on the human genome are not yet fully understood. Theoretically speaking, the DNA vaccine should only be potent for a short amount of time due to the natural cell cycle. However, there is still not enough scientific evidence to indicate the conclusive long-term impacts of tinkering with an organism's DNA.
There is also some concern with the application of DNA vaccines on infants. Since the fetal immune system often cannot differentiate between the transformed cells and regular cells, this child essentially develops no immunity. This raises concerns that DNA vaccines may in fact be highly detrimental to the immune system of the infant. This inability of self-differentiation renders many potential, and basic, infant DNA vaccines ineffectual. Adults do not face this problem as the immune system can readily differentiate between the self and the non-self. While theoretically, and in the future, a single dosage of DNA vaccine could be applied to an infant for all common childhood diseases and produce a strong immunity, current methods of construction of DNA vaccines do not allow this to be successful. At the current stage, however, DNA vaccines cannot be administered to infants [2].
Though the methodology is not foolproof as of yet, DNA vaccines could potentially become the next greatest technology of the century and give rise to further biotechnological advances in the future.
1. "DNA Vaccines, HIV/." National Institute of Allergy and Infectious Disease. http://www.niaid.nih.gov///////.aspx (accessed October 19, 2010).
2. Brandsma, Janet L, Donna L Montgomery, Kristala Jones Prather, Steve Pascolo, and Petra Reidl. DNA Vaccine: Methods and Protocols. 2nd ed. Edited by W Mark Saltzman, Hong Shen, and Janet L Brandsma. Vol. 127. Totowa: Humana Press, 2006. http://www.springerprotocols.com///‌.1385/‌(accessed October 19, 2010).
3. Gale Encyclopedia of Science. 4th ed. 2008. S.v. "DNA Vaccine." http://puffin.harker.org:2073//.do?&contentSet=GSRC&type=retrieve&tabID=T001&prodId=DC&docId=EJ2644040728&source=gale&srcprod=DISC&userGroupName=harker&version=1.0 (accessed October 19, 2010).
4. Mahoney, Richard T., Yu-Mei Wen, and Henry, Wilde. "The Introduction of New DNA Vaccines into Developing Countries." National Center for Biotechnology Information. http://www.ncbi.nlm.nih.gov///‌(accessed January 11, 2011).
5. UPenn Center for Bioethics. "The Vaccine Industry – An Overview." VaccineEthics.org. http://www.vaccineethics.org/_briefs/.php (accessed January 11, 2011).
6. Rice, Jason, Christian H Ottensmeier, and Freda K Stevenson. "DNA vaccines: precision tools for activating effective immunity against cancer." Nature Reviews 8 (February 2008): 108-120. (accessed October 19, 2010).
7. "DNA Vaccines" Scientific American: Feature Article: Genetic Vaccines: July 1999 http://www.immune.org.nz/site_resources/Making_DNA_vaccine.gif (accessed January 20, 2011).
Trisha Basu is a senior at the Harker School in California
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