Targeted Collection of Plasmid DNA in Large and Growing Animal Muscles 6 Weeks after DNA Vaccination with and without Electroporation

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

The identification of a new genotype of avian paramyxoviruses type I in West-Africa provides new outcomes for phylogeny reconstruction

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Identification of a new reovirus causing tendinitis in broilers in France

Clinical cases of tendinitis have appear sporadically and then more regularly in broilers flocks among different regions in France since 2010. These tendinitis have been identified as a consequence of Reovirus infection despite the vaccination of breeders stock with vaccines containing different strains of Reovirus previously described in the field ; additionnally an horizontal transmission, especially at the time of hatch, has been observed. Virological studies conducted in two laboratories lead to the identification of a new type of Reovirus non described in Europe until now. In addition to genetic differences between this new virus and the vaccine strains used on the field, cross seroneutralisation tests have shown antigenic differences which could explain the inefficacy of the vaccines used in the field. In order to prevent the multiplication of theses viruses it seems usefull to update the composition of vaccines for a better protection of breeders and their progenyDes cas cliniques de tendinite sont apparus sporadiquement, puis plus régulièrement, dans des élevages de poulets de chair dans différentes régions de France depuis 2010. Ces tendinites ont été identifiées comme dues à une réovirose en dépit de la vaccination des poules parentales avec des vaccins contenant différentes valences de réovirus précédemment décrits comme présents sur le terrain ; en outre une transmission horizontale notamment lors de l’éclosion a été observée. Les études virologiques conduites dans deux laboratoires aboutissent à l’identification d’un nouveau réovirus jusqu’à présent non décrit en Europe. Outre des différences au plan génétique entre ce nouveau virus et les souches vaccinales utilisées sur le terrain, des tests de séroneutralisation croisée ont montré des différences antigéniques, ce qui peut expliquer l’inefficacité des vaccins observée sur le terrain. Pour prévenir la multiplication de ces virus il apparait donc utile de réactualiser la composition des vaccins de manière à protéger les poules reproductrices et leur descendanc

New avian paramyxoviruses type I strains identified in Africa provide new outcomes for phylogeny reconstruction and genotype classification

Newcastle disease (ND) is one of the most lethal diseases of poultry worldwide. It is caused by an avian paramyxovirus 1 that has high genomic diversity. In the framework of an international surveillance program launched in 2007, several thousand samples from domestic and wild birds in Africa were collected and analyzed. ND viruses (NDV) were detected and isolated in apparently healthy fowls and wild birds. However, two thirds of the isolates collected in this study were classified as virulent strains of NDV based on the molecular analysis of the fusion protein and experimental in vivo challenges with two representative isolates. Phylogenetic analysis based on the F and HN genes showed that isolates recovered from poultry in Mali and Ethiopia form new groups, herein proposed as genotypes XIV and sub-genotype VIf with reference to the new nomenclature described by Diel's group. In Madagascar, the circulation of NDV strains of genotype XI, originally reported elsewhere, is also confirmed. Full genome sequencing of five African isolates was generated and an extensive phylogeny reconstruction was carried out based on the nucleotide sequences. The evolutionary distances between groups and the specific amino acid signatures of each cluster allowed us to refine the genotype nomenclature. (Résumé d'auteur

An enzyme-linked immunosorbent assay for detection of avian influenza virus subtypes H5 and H7 antibodies

BACKGROUND: Avian influenza virus (AIV) subtypes H5 and H7 attracts particular attention because of the risk of their potential pathogenicity in poultry. The haemagglutination inhibition (HI) test is widely used as subtype specific test for serological diagnostics despite the laborious nature of this method. However, enzyme-linked immunosorbent assays (ELISAs) are being explored as an alternative test method. H5 and H7 specific monoclonal antibodies were experimentally raised and used in the development of inhibition ELISAs for detection of serological response specifically directed against AIV subtypes H5 and H7. The ELISAs were evaluated with polyclonal chicken anti-AIV antibodies against AIV subtypes: H1N2, H5N2, H5N7, H7N1, H7N7, H9N9, H10N4 and H16N3. RESULTS: Both the H5 and H7 ELISA proved to have a high sensitivity and specificity and the ELISAs detected H5 and H7 antibodies earlier during experimental infection than the HI test did. The reproducibility of the ELISA’s performed at different times was high with Pearson correlation coefficients of 0.96-0.98. CONCLUSIONS: The ELISAs are a potential alternative to the HI test for screening of large amounts of avian sera, although only experimental sera were tested in this study

Newcastle Disease Virus in Madagascar: Identification of an Original Genotype Possibly Deriving from a Died Out Ancestor of Genotype IV

In Madagascar, Newcastle disease (ND) has become enzootic after the first documented epizootics in 1946, with recurrent annual outbreaks causing mortality up to 40%. Four ND viruses recently isolated in Madagascar were genotypically and pathotypically characterised. By phylogenetic inference based on the F and HN genes, and also full-genome sequence analyses, the NDV Malagasy isolates form a cluster distant enough to constitute a new genotype hereby proposed as genotype XI. This new genotype is presumably deriving from an ancestor close to genotype IV introduced in the island probably more than 50 years ago. Our data show also that all the previously described neutralising epitopes are conserved between Malagasy and vaccine strains. However, the potential implication in vaccination failures of specific amino acid substitutions predominantly found on surface-exposed epitopes of F and HN proteins is discussed