ABSTRACT
From October 2016 to July 2017, 47 countries have been affected by highly pathogenic avian influenza (HPAI) viruses of the H5N8 clade 2.3.4.4 subtype, including European and African, and it has been the most severe HPAI outbreak ever in Europe. The development of effective influenza vaccines is required to combine preventive and control measures in order to avoid similar avian influenza epidemics taking place. Here we describe a novel prototype recombinant virus-like particle (VLP) vaccine based on a clade 2.3.4.4 H5 HA derived from a French duck HPAI H5N8 isolate of the 2016-2017 epidemics. Prototype vaccines with different antigen content were formulated and the immunogenicity was examined in specific-pathogen-free chickens and in ducks. Serum samples were collected at 3 and 4 weeks postvaccination, and development of the immune response was evaluated by hemagglutination inhibition test and ELISA. The VLP vaccines induced a dose-dependent and high level of antibody response in both chickens and ducks. The results of HPAI H5N8 challenge experiments in ducks are reported separately.
Construcción rápida y pruebas de inmunogenicidad de un nuevo prototipo de vacuna H5 con base en partículas similares a virus contra el clado 2.3.4.4 del virus de la influenza aviar altamente patógeno H5N8. Desde octubre del 2016 hasta julio del 2017, 47 países se han visto afectados por los virus de la influenza aviar altamente patógena del subtipo H5N8 clado 2.3.4.4, incluidos los europeos y africanos y ha sido el brote de influenza aviar de alta patogenicidad más grave en Europa. Se requiere del desarrollo de vacunas efectivas contra la influenza para combinar medidas preventivas y de control para evitar que ocurran epidemias similares de influenza aviar. En este estudio se describe un nuevo prototipo de vacuna recombinante con partículas similares a virus (VLP) basada en una hemaglutinina H5 clado 2.3.4.4 derivada de un aislamiento del virus de influenza aviar de alta patogenicidad H5N8 de patos en Francia presente en las epidemias entre los años 2016 al 2017. Se formularon prototipos de vacunas con diferente contenido de antígeno y se examinó la inmunogenicidad en pollos libres de patógenos específicos y en patos. Las muestras de suero se recolectaron a las tres y cuatro semanas después de la vacunación y el desarrollo de la respuesta inmune se evaluó mediante la prueba de inhibición de la hemaglutinación y ELISA. Las vacunas con partículas similares a virus indujeron un alto nivel de respuesta de anticuerpos dependiente de la dosis tanto en pollos como en patos. Los resultados de los experimentos de desafío con un virus de influenza aviar de alta patogenicidad H5N8 en patos se informan por separado.
Subject(s)
Chickens , Ducks , Influenza A Virus, H5N8 Subtype/drug effects , Influenza in Birds/prevention & control , Poultry Diseases/prevention & control , Vaccines, Virus-Like Particle/pharmacology , Viral Vaccines/pharmacology , Animals , Immunogenicity, Vaccine , Influenza in Birds/transmission , Poultry Diseases/transmission , Specific Pathogen-Free OrganismsABSTRACT
A preliminary experiment was carried out to determine whether a decontamination procedure using gamma irradiation, similar to that adopted in the European guideline for bovine serum contaminated by pestivirus, could be applied to chicken serum. Chicken sera spiked with known amounts of enveloped and non-enveloped chicken viruses were gamma irradiated. The remaining live viruses were then measured by titration and the virus reduction capacity of the irradiation process was established for both enveloped and non-enveloped virus models. In parallel with the irradiation procedure, a classical in vivo extraneous agent test was also evaluated in order to see if it has the capacity to detect low enough levels of live viruses to be used for testing irradiated serum. The results suggest that the principles of the bovine serum decontamination procedure may be applied to chicken serum. Further studies are required to determine if this process would provide an acceptable solution for the viral 'decontamination' of chicken serum.
Subject(s)
Chickens/virology , Decontamination/methods , Gamma Rays , Poultry Diseases/virology , RNA Virus Infections/virology , Animals , Cattle , Newcastle disease virus/isolation & purification , Newcastle disease virus/radiation effects , Orthoreovirus, Avian/isolation & purification , Orthoreovirus, Avian/radiation effects , Poultry Diseases/blood , RNA Virus Infections/blood , Reproducibility of Results , Specific Pathogen-Free OrganismsABSTRACT
Outbreaks of haemorrhagic nephritis and enteritis of geese (HNEG) have been reported in goose flocks in Hungary, Germany and France since 1969. HNEG is characterized by high morbidity and mortality rates in geese 3 to 10 weeks of age. The causative agent of HNEG is the goose haemorrhagic polyomavirus (GHPV), which has a circular double-stranded DNA genome encoding the structural proteins VP1, VP2 and VP3. In vitro culture of GHPV has been problematic, so the baculovirus system was used to construct a recombinant virus expressing the VP1 gene of GHPV under control of the polyhedrin promoter in Sf9 insect cells. The expression and the identity of recombinant goose polyomavirus VP1 in the crude Sf9 cell extracts were confirmed by mass spectrometry. Experimental oil-emulsion vaccines containing two different doses of antigen were prepared using this crude extract. Goslings were vaccinated either once at 1 day old or twice by boosting 18 days after the primary vaccination, and were challenged with a virulent polyomavirus isolate at 5 weeks of age. A single injection of either vaccine dose induced 95% protection against challenge. Using the booster vaccination regimen, 100% protection was achieved with either vaccine dose.
