Protection and DifiFerentiation of Infected from Vaccinated Animals by an Inactivated Recombinant Newcastle Disease Virus/Avian Influenza H5 Vaccine

Specific-pathogen-free chickens immunized at 14 days of age with either an inactivated recombinant Newcastle disease virus—LaSota/avian influenza H5 (K-rNDV-LS/AI-H5) vaccine or a killed Newcastle disease/avian influenza whole-virus vaccine (K-ND/AI) were protected from disease when challenged with either A/chicken/Queretaro/14588-19/95 (H5N2), a high pathogenicity avian influenza virus (HPAIV) strain isolated in Mexico in 1995, or with a Mexican velogenic viscerotropic Newcastle disease virus (WNDV) strain 21 days postvaccination. All nonvaccinated chickens challenged with HPAIV or WNDV succumbed to disease, while those vaccinated with K-rNDV-LS/AI-H5 or K-ND/AI were protected from severe clinical signs and death. Both vaccines induced hemagglutination-inhibition (HI) antibody responses against NDV and AIV. Antibodies against AIV nucleoprotein were not detected by enzyme-linked immunosorbent assay (ELISA) in birds vaccinated with the inactivated rNDVLS/AI-H5 vaccine. These chickens became positive for AIV antibodies by ELISA only after challenge with HPAIV. The data clearly indicate that the inactivated rNDV-LS/AI-H5 vaccine confers protection comparable to that of the conventional killed whole-virus vaccine against both NDV and AIV, while still allowing differentiation of infected from vaccinated animals by HI and ELISA tests. Pollos libres de patógenos específicos vacunados a los 14 días de edad con una vacuna recombinante inactivada con los virus LaSota de Newcastle y de la influenza aviar H5 (K-rNDV-LS/AI-H5) o con una vacuna a virus muerto contra la enfermedad de Newcastle y la influenza aviar (K-ND/AI) mostraron protección contra la enfermedad cuando fueron desafiados a los 21 días después de la vacunación, ya sea con el virus de influenza aviar de alta patogenicidad A/pollo/Querétaro/14588-19/95 (H5N2), que es una cepa aislada en México en el año 1995, o con una cepa velogénica viscerotrópica del virus de la enfermedad de Newcastle. Todos los pollos no vacunados y desafiados con los virus de influenza aviar altamente patógeno o de Newcastle velogénico viscero trópico sucumbieron a las enfermedades, mientras que aquellos que fueron vacunados con las vacunas K-rNDV-LS/AI-H5 o K-ND/AI estuvieron protegidos contra el desarrollo de signos clínicos graves y mortalidad. Ambas vacunas estimularon respuestas de anticuerpos detectados por la prueba de inhibición de la hemaglutinación (HI) contra los virus de Newcastle y de influenza aviar. Los anticuerpos co