Advantages & Disadvantages of DNA Vaccines

DNA vaccines offer a novel method of immunising people against not only viral and bacterial diseases, but a host of parasitic and fungal infections as well. This technique relies on the introduction of genetic material from particular disease causing pathogen into human cells through a specially engineered delivery system. This leads to the secretion of proteins normally expressed on the surface of pathogens from human cells, and these proteins trigger a defensive response that can immunise an individual against the actual pathogen without any need for exposure to the disease causing agent.

While still in development, this vaccination technology offers some distinct advantages that would make it an invaluable asset in vaccination and immunisation programmes. In this article we look at some of the benefits of DNA vaccines when compared to existing vaccination techniques, and some of the obstacles we face in getting these vaccines into popular use.

What are the benefits of DNA vaccines?

Because of a number of distinct advantages DNA vaccines can offer over existing vaccination techniques, the technology has drawn a lot of interest. It would not be under developed if it didn’t offer a distinct solution to problems we face with immunisations today.

Firstly DNA vaccines do not contain an actual infectious agent, whether dead or alive. One of the classic methods of vaccination is the introduction of a live but weakened version of a pathogen into a person. This has proven effective thus far, but does offer some distinct safety concerns. The risk of reversion for example, where the vaccination strain mutates and becomes virulent, is one such issue, as is the fact that these vaccines can’t safely be used in people who are pregnant, elderly, or suffering from any one of a number of chronic diseases. These concerns are not relevant to DNA vaccines, which could potentially be given to virtually anyone regardless of health status safely, and without any risk of reversion.

DNA vaccines can effectively stimulate different dimensions of the immune response, thereby providing a person long lasting immunity after a small number of doses. One of the problems with some vaccination technologies is the fact that multiple booster doses are needed for a vaccine to effectively immunise an individual, and this can pose practical problems, particularly in countries where healthcare and transport infrastructure isn’t as well established as here in the UK.

DNA vaccines also offer advantages in terms of their production. Once tested for efficiency and safety, a DNA vaccine can be generated in large volumes at a much lower cost than some traditional vaccine types. The DNA vaccine in question would also be easier to transport as there are no particular storage requirements (live vaccines for example need to be kept refrigerated). 

Finally DNA vaccines can potentially be applied to a broader range of disease causing pathogens like fungi and parasitic organisms. At present most vaccination technologies are limited to viruses and bacteria.

What are the disadvantages of DNA vaccines?

At present there still some obstacles limiting the potential uses of DNA vaccines, these include the fact that this type of vaccination would be limited to pathogens with a distinctive protein immunogen (molecule that triggers an immune response). Some pathogens possess non-protein immunogens , bacteria with sugar coats for example. 

DNA vaccines also present a slight risk of potentially disrupting normal cellular processes. This has yet to be shown as a major concern, however there is a chance that the introduction of foreign DNA into the body could affect a cell’s normal protein expression pathways.

Two concerns regarding the effectiveness of the vaccine itself revolve around the body’s reaction to the vaccine. The first is the chance of an immune response against the DNA itself, or the DNA delivery vector, which would defeat the point of the vaccine as a whole. If such a reaction were to occur, no protein immunogens would be expressed, and there would be no immune response to those immunogens, and hence no immunity against the pathogen in question.

Secondly there is a chance that the body develops a resistance or tolerance towards the protein the vaccine introduces. This would again defeat the purpose of the vaccine, which is to stimulate a lasting immune response against the injection.

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