Viral vector vaccine uses live virus to deliver DNA of the target pathogen into a cell for production of antigenic proteins to stimulate an immune response. This vaccine type combines the positive qualities of DNA vaccines with those of live vaccines.
A plasmid must be manufactured and purified. In cells (ex. HEK293), the DNA is combined with the viral vector (transfection) and replicated. The viral vector then needs to be purified. Product quality of DNA plasmid and transfected viral vector need to be monitored throughout the manufacturing process. There are several viral vectors used specifically for vaccines.
Analytical workflows for non-viral vector DNA vaccines
Non-viral vector DNA vaccines incorporate plasmids, that contain the sequence(s) for one or more protein antigens and replicate autonomously from the cell chromosome. When the DNA plasmid is introduced into human cells, the human cells express the protein encoded on the plasmid, stimulating an immune response against the encoded antigen. Because they have so far failed to provide a strong immune response, DNA vaccines are being explored as prime boosters that are given before a different vaccination.
For vaccines to be acceptable to regulatory agencies, in-depth analytical characterization and criteria defined for purity/impurity monitoring (CQAs) is needed to ensure safety and efficacy. This means impurities need to be understood through characterization, acceptable levels defined, and then monitored for safety and efficacy.
LC-based method for DNA vaccine product characterization through process development and QC:
Impurity: Open circular and linear forms of plasmid, RNA
The monitoring of supercoiled plasmid DNA and its impurities such as open circular and linear forms is important for the assessment of final product quality, safety, and efficacy.
Chromatographic methods in development include HIC, RP, and AEX.