Module 3: Viral vectors

Lecture 18: DNA Vaccines

The earliest form of protection against the diseases has been in the form of vaccines. Discovery of vaccines by Edward Jenner in the year 1796 witnessed a revolution in human medicine. A vaccine is a biological formulation that confers immunity to a specific disease. The role of the vaccine is to stimulate the immune system, recognize the attacking agent, eradicate it and keep it in memory so that if there is any repeated exposure of the same disease then the destruction of such agent would be easier. There are several types of vaccines like killed, attenuated, live, subunit, conjugated and Nucleic acid vaccines.

Nucleic acid vaccine means the vaccination done using RNA or DNA vaccines. Here we are going to deal with DNA vaccines in full detail and RNA part will be summarized briefly. In a layman's words DNA vaccine can be defined as the process of injecting manipulated DNA material in an organism to generate an immune response. In general DNA vaccines may be defined as those vaccines that provide immunity by transfecting host cells with DNA that encodes an antigen. Following transfection the specific immune response generated is along similar lines as responses that occur against conventional vaccines and this immune response arises by the protein produced by the host cell. The DNA vaccine seems to be a promising candidate as vaccines because they are very cost effective but still these are not listed for human use. There are some DNA vaccines for veterinary use though.

The reasons for announcing DNA vaccine as potential candidate are many but also when compared to other forms of vaccine it proves to be less cumbersome and offers many advantages too enlisted below-

  1. 1)  It is easy to form and construct the DNA vaccines as compared to attenuated viruses and subunit protein vaccines.

    2. 2)  It is cheap and cost effective.

    3)  It is quite stable at room temperature as compared to attenuated viral vaccines, whose repository and international transfer becomes difficult by the urgency to keep the vaccines cold.

    4)  The protection offered by DNA vaccines favors bias towards cellular immunity, which is trusted to be vital for successful vaccination against intracellular pathogens.

The classic methods for synthesizing vaccines are given in Table 1 which highlights their similarities or differences with DNA vaccines.