DNA vaccination is a technique for protecting against disease by injection with genetically engineered DNA so that cells can directly produce an antigen, producing a protective immunological response. DNA vaccines are third generation vaccines. In this vaccine DNA is injected into cells whose machinery uses the DNA to synthesize the proteins. Since these proteins are recognized as foreign, when they are processed by the host cells and displayed on their surface, the immune system is alerted, which then triggers immune responses.
In 2016, a DNA vaccine for the Zika virus began testing at the National Institutes of Health and is under trail. Till now no DNA vaccines have been approved for human use in the United States. A veterinary DNA vaccine to protect horses from West Nile virus has been approved.
Chimeric vaccine is a graft or ‘chimera’ of DNA that codes for proteins hooked onto a viral DNA vector called a backbone. The backbone ensures that the vaccine will be presented to the proper portion of our immune system and the DNA graft codes for the proteins we want our immune system to fight.
Advantages of these chimeric DNA vaccines
• Induction of T and B cell-specific antigen
• Inability to revert to virulent forms
• The efficacy does not depends on toxic treatments
• Modifications in the transgene construct and vaccine can be made in short time
• Optimization of plasmids and transcript is possible
• Easy storage and transport―No need for constant refrigeration
• Rapid production and formulation
• Reproducible in large-scale production
DNA vaccine is a simple concept with a complex mechanism of action. DNA vaccines have been proved to be efficient for prophylaxis against infectious diseases, cancer immunotherapy and gene therapy has already been approved for veterinary use.