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Abstract: A plasmid rendered replicative in mammalian cells by inserting the Porcine circovirus 2 (PCV2) origin of replication and replicase gene (Ori-rep) has been previously constructed. The aim of the present study was to evaluate if the replication capacity of this plasmid could be advantageously used to improve the protective immunity induced by DNA vaccination. In this case we used the porcine Pseudorabies virus (PrV) DNA vaccination model. The replicative capacity of the DNA vaccine did not improve the protective immunity against PrV in pigs, but on the contrary the presence of the PCV2 Ori-rep sequence was harmful in the induction of this immunity compared to an equivalent but non-replicative DNA vaccine. In addition, the distribution and the persistence of the replicative and non-replicative plasmids inside the body were the same. This is the first study showing an in vivo deleterious effect of the replicative active PCV2 Ori-rep on the natural and specific protection against PrV infection. [Copyright &y& Elsevier]

Abstract: This study was performed to determine whether electroporation can be used to enhance the efficacy of a DNA vaccine against pseudorabies virus (PrV) in pigs. Immune responses to PrV were measured in pigs following a single intramuscular injection of plasmids encoding PrV glycoprotein B, with or without electroporation. Plasmid injection coupled with electroporation increased production of specific antibodies against PrV and peripheral blood mononuclear cells proliferated in response to stimulation with PrV glycoproteins. These results show that electroporation can improve the performance of a DNA vaccine against PrV in pigs. However, additional work is required to maximise the effectiveness of the vaccination protocol. [Copyright &y& Elsevier]

Abstract: Previous biodistribution studies of plasmids following intramuscular or intradermal injections of DNA vaccines have been performed in mice, rats or rabbits, but not in large mammals. The aim of the present study was to determine the biodistribution of plasmids in swine using the PRV-specific DNA vaccination model consisting of a single intramuscular (i.m.) injection of three plasmids individually encoding glycoproteins gB, gC and gD. The weak bioavailability of the plasmids (less than 10%) after i.m. injection was consistent with the tissue distribution study. Plasmids remained in the injected muscle for at least 4 weeks and were also detected in liver, spleen, kidney, lung, remote muscle, lymph nodes and ovaries for shorter periods. Differences in persistence, apparent elimination half-lives and clearance in blood were observed between the three plasmids. In conclusion, the three plasmids behaved differently and were transiently detected in most of the organs tested. The exact persistence in the injected muscle was not determined but exceeded 4 weeks. To date this is the first published DNA vaccine tissue distribution study in large animals. [Copyright &y& Elsevier]

Abstract: The pseudorabies virus code for an ICP0 protein which is half the size of the HSV1 ICP0 protein. In this work, we made the assumption that some function might have been lost in the ICP0 from PRV. One function attributed to the ICP0 from HSV1 was the stabilization of cyclins D. We then looked at the stability of these cyclins during the lytic infection with the PRV. Our results show that cyclins D are not stabilized during infection with the PRV. These results are in accord with recent data from the literature. [Copyright &y& Elsevier]

Abstract: This study compared protection of pigs against lethal Pseudorabies virus (PrV) infection induced by a single injection of various quantities of Sindbis virus-derived plasmids encoding PrV glycoproteins gB, gC and gD. Pigs were injected with 340, 68 or 13μg of each plasmid. Few immune differences were observed after DNA injection and more importantly the pigs of the three groups were equally protected against virulent PrV infection. Single-shot injection of 13μg of each PrV glycoprotein encoding Sindbis virus-derived plasmid is able to effectively protect pigs from PrV infection. [Copyright &y& Elsevier]