In: Biology
Answer: DNA vaccines are currently being developed for various bacterial and viral infections. DNA vaccines are not same as the DNA viruses.
When the virus attacks the cell, it undergoes a series of steps starting from attachment to the host cell by identification of receptors, penetration of the viral nucleic acid which takes over the host chromosome and ensues a lytic cycle where many copies of the viral particles are made, assembled and then come out of the cell by the lysis of the cell. Sometimes instead of lytic cycle, viral nucleic acid integrates into the host chromosome and replicates along with the host genome and after some time, may start with the lytic cycle.
In case of DNA vaccine, it is just one particular antigen (protein) producing gene which is incorporated into the host chromosome and not the entire viral genome. Hence it is incapable of causing an infection. DNA vaccine is made by incorporating the antigen of interest into a plasmid, this recombined plasmid is then transferred into a bacterial cells where more copies of the plasmids are generated, the plasmid is then isolated and used as a vaccine to introduce into humans through intradermal, intramuscular or intravenous injection.
After the delivery the host’s cells take up the plasmid synthesizes the protein encoded, this protein is then cleaved by host’s protease and presented along with MHC molecules by the antigen presenting cells so that it is recognised by the host’s immune cells and it elicits and immune response without causing an infection just like the other vaccines.