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DNA vaccination has been developed in the last two decades in human and animal species as a promising alternative to conventional vaccination. It consists in the injection, in the muscle, for example, of plasmid DNA encoding the vaccinating polypeptide. Electroporation which forces the entrance of the plasmid DNA in cells at the injection point has been described as a powerful and promising strategy to enhance DNA vaccine efficacy. Due to the fact that the vaccine is composed of DNA, close attention on the fate of the plasmid DNA upon vaccination has to be taken into account, especially at the injection point. To perform such studies, the muscle injection point has to be precisely recovered and collected several weeks after injection. This is even more difficult for large and growing animals. A technique has been developed to localize precisely and collect efficiently the muscle injection points in growing piglets 6 weeks after DNA vaccination accompanied or not by electroporation. Electroporation did not significantly increase the level of remaining plasmids compared to nonelectroporated piglets, and, in all the cases, the levels were below the limit recommended by the FDA to research integration events of plasmid DNA into the host DNA. [ABSTRACT FROM AUTHOR]

Abstract: The porcine circovirus type 2 (PCV-2) is associated with several diseases including reproductive failure. This syndrome has been experimentally reproduced twice with two PCV-2 isolates representative of each major PCV-2 genogroup, i.e. PCV-2a and PCV-2b (Cariolet et al., 2002; Rose et al., 2007). In these two previous studies, the sows were infected by intra-uterine inoculation at insemination with 104.3 and 103.18 TCID50 of PCV-2a and PCV-2b, respectively, corresponding to 1.2×1011 and 3×1010 genome copies, respectively. The aim of this present study was to quantify viral shedding in semen from specific-pathogen-free (SPF) boars infected with isolates from the two major PCV-2 genogroups a and b. We studied the transmission of the PCV-2 virus through contaminated semen to SPF sows and their offspring. The four inoculated boars developed sub-clinical PCV-2 infections and PCV-2 genomes were occasionally detected in semen after nasal infection of boars, with up to 1.2×106 copies/mL in the sperm-rich fraction. When PCV-2-contaminated semen was inoculated in SPF sows at artificial insemination, the sows and their offspring did not show any signs of PCV-2 infection or PCV-2 antibodies or genomes. In the present study, sows were inoculated with a maximal dose of 1.7×107 viral genome copies, which is lower than the genomic loads (i.e. 1.2×1011 and 3×1010 genome copies) that have been shown to induce reproductive troubles in intra-uterine inoculated sows. Our results together with the previous experiment findings suggest that PCV-2-induced reproductive disorders depend on the infectious dose inoculated to sows by the intra-uterine route. [Copyright &y& Elsevier]

Abstract: The present study demonstrates the protective potential of a novel prime-boost vaccination strategy of pigs against lethal Pseudorabies virus (PRV; Herpes suid 1) infection. Animals were primed with Sindbis virus-derived plasmids that express viral glycoproteins gC and gD (gC- and gD-pSIN) and subsequently booster immunized with Orf virus (ORFV; Parapoxvirus) recombinants expressing gC and gD (D1701-VrVgC and -VrVgD). The prime-boost vaccination induced strong humoral and cellular-like PRV-specific immune responses. All prime-boost vaccinated pigs survived the lethal challenge infection without PRV-specific clinical symptoms and presented excellent body weight loss attenuation. Most notably, nasal shedding of challenge virus was reduced by more than about 3log10, clearly reducing the risk of infection of non-immunized pigs. [Copyright &y& Elsevier]

Abstract: The aim of this study was to determine the potential risk factors for PMWS at the individual pig level and assess the effect of the Pietrain paternal genetic background of the animals in a cohort study. The survey was set up in four PMWS-affected farms with 2 repetitions (batches) per farm. A representative sample of 60 pigs per batch, stratified according to the paternal genetic background (Pietrain: yes vs. no), was randomly selected after farrowing. The representative cohort was divided into 8 batches and the pigs were individually monitored from birth to slaughter. Survival analysis was used to determine the factors related to the time to PMWS. The litter-cluster effect was taken into account using the marginal Cox model (robust estimation of the covariance matrix) and the gamma shared frailty model which were compared. No protective effect of the Pietrain breed on the time to PMWS and the proportion of affected pigs in the offspring was found in this study. Piglets showing low circovirus type 2 (PCV2) titres at 7 weeks-old with no subsequent seroconversion and piglets from PCV2 negative sows were most likely to be affected by PMWS (HR=7.0 and 2.8, respectively). Active infection of the pregnant dams with parvovirus was related to an increased risk of PMWS in the offspring (HR=2.3). Neck injuries due to poorly performed injections in the dams were associated with an increased risk of PMWS with the marginal model (HR=2.1). Oxytocin injection (dams) during farrowing was protective against PMWS in the offspring (HR=0.6). [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]