DNA vaccines are considered as a promising technology platform. At least ten different vaccine candidates on the basis of plasmid DNA are under development alone for the protection from COVID-19. At present, there are no DNA vaccines for humans in Germany and world-wide with a marketing authorisation. A new guideline by the WHO summarises the scientific findings on the quality, efficacy, and safety of DNA vaccines. This guideline has recently been published in the scientific journal NPJ Vaccines. The guideline will be submitted to the WHO Expert Committee on Biological Standardization for adoption as early as this year.
DNA vaccines are innovative biomedicines which, instead of a protein component (antigen) of the pathogen concerned, contain a gene with the genetic information for the blueprint of this antigen. The carrier for this genetic information is usually a ring-shaped DNA molecule (plasmid) produced in innocuous bacteria under controlled conditions. The genetic information will then be expressed into the antigen in only few body cells of the vaccinee. On its surface, the cell presents the antigen to the immune system, thus inducing the immune response against the pathogen. The production of these vaccines in large quantities can be achieved relatively fast. For this reason, this vaccine technology is very promising especially in combating new emerging infectious diseases.
In 2005, the ECBS (Expert Committee on Biological Standardization) of the World Health Organization (WHO) adopted a guideline on DNA Vaccines for the first time. This guideline described the then scientific state of knowledge on this innovative vaccine concept. The guideline in particular also addresses the potential risks and quality requirements. Ever since, the development of the DNA vaccine technology has clearly advanced, but DNA vaccines for humans have still not been authorised for international markets. Marketing authorisations have been obtained only for veterinary use (horse, salmon). A major obstacle previously was the efficient absorption of the plasmid DNA in human cells and the subsequent transfer into the cell nucleus in which the gene must be read so that the appropriate antigen can subsequently be formed. New methods such as electroporation – a short impulse of an electrical field will temporarily increase the permeability of cell membranes – are designed to improve absorption, and thus the immunogenicity and efficacy or DNA vaccines.
What are the current quality requirements for the development of DNA vaccines, what theoretical risks must be considered and what new developments are available for efficient administration? To answer these questions and summarize the current state of knowledge, the WHO Product development for vaccines advisory committee (PDVAC) requested the WHO to update the guideline of 2005. For this purpose, an international WHO consultation with vaccines developers, vaccines manufacturers, and regulators of various national medicines authorities took place under the supervision of Dr Heid Meyer, head of Unit "International Co-ordination, Regulatory Service" of the Paul-Ehrlich-Institut. Based on this discussion and comments received during public consultation, the guideline was revised by an expert group and will be submitted to the ECBS for adoption. Members of staff of the Paul-Ehrlich-Institut actively contributed to the draft.
Sheets R, Kang HN, Meyer H, Knezevic I and WHO informal consultation on development of guidelines for assuring the quality, safety, and efficacy of DNA vaccine (2020): WHO informal consultation on the guidelines for evaluation of the quality, safety, and efficacy of DNA vaccines.
NPJ Vaccines Jun 18 [Epub ahead of print].
Text
Beasley DWC (2020): New international guidance on quality, safety and efficacy of DNA vaccines.
NPJ Vaccines Jun 18 [Epub ahead of print].
Text
Updated: 09.07.2020
