Herpesvirus vaccines

BHV-1 DNA vaccination: effect of the adjuvant RN-205 on the modulation of the immune response in mice

It is well documented that adjuvants improve the immune response generated by traditional viral vaccines, but less is known about the effects of adjuvants on the immune response elicited by DNA vaccines. In this study, we have investigated the use of RN-205 (immunomodulator containing a membrane rich in lipopolysaccharide from gram-negative bacteria) as an adjuvant and analyzed the humoral and cellular specific immune responses elicited by DNA vaccines based on the bovine herpesvirus-1 (BHV-1) glycoprotein D (gD). The comparison of the antibody response induced in mice by a mixture of the three different versions of DNA gD (membrane-anchored, secreted and cytosolic) formulated with or without RN-205 showed that the immunomodulator did not affect the total specific humoral response. The cellular immune response induced in mice immunized with vaccines plus RN-205 was higher than that obtained in mice vaccinated without RN-205, not only in the indexes of proliferation tests but in the number of IL-4 and gammaIFN secreting cells. When total spleen cells were marked with specific monoclonal antibodies against surface markers, a significant increase in the macrophage population of all the groups receiving RN-205 was observed. CD8 and CD4 positive cells were also increased but to a lesser extent. Our results indicate that the incorporation of RN-205 into DNA vaccines induces an increase of the cellular specific immune response in mice.

Manufacturing and quality control of plasmid-based gene expression systems

DNA plasmid-based gene expression systems are being widely investigated for the potential treatment of genetic and acquired disease and for DNA-based vaccination. A number of human clinical trials are in progress using plasmid-based drugs. The regulatory framework that has been applied to biologicals such as recombinant DNA-derived proteins has proven to be generally applicable for regulating plasmid-based drugs as well. This was recently emphasized by the inclusion of therapeutic DNA plasmid products in the U.S. Food and Drug Administration's list of well-characterized biotechnology products. Present techniques for manufacturing and characterizing plasmids have been adapted from large-scale protein purification and from traditional molecular biology. Production of multi-gram quantities of plasmid, at purities of 95% or more, is currently possible, but further development of both manufacturing and analytical techniques is required. This review describes the approaches and methods currently used to manufacture and characterize DNA plasmids for pharmaceutical use, as well as recent changes in the regulatory environment that will impact future development and marketing of plasmids as human drugs.