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Title: The Safety and Efficacy of a Live In-Ovo Vaccine against Newcastle Disease
Author: Dilaveris , Dimitrios
ISNI:       0000 0001 3424 4044
Awarding Body: Royal Veterinary College (University of London)
Current Institution: Royal Veterinary College (University of London)
Date of Award: 2008
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Newcastle disease is a commercially important viral disease ofpoultry and the vaccination ofchicks with live, low virulence strains, as early as the first day of life, is common. This work examined the effects ofvaccination in ovo, which is into the amniotic cavity of I8-day-old chicken embryos. A post-hatch vaccine, NDW, which received marketing licence for in ovo administration, was used at a dose that infected 50% ofembryos. This dose was the maximum recommended by the vaccine manufacturer (Fort Dodge). It killed, compared to non-vaccinated controls, 32% ofinbred line ZERO embryos within 11 days and 8% ofVaccine Lohmann (VALO) embryos. Virus was found deep in the developing lungs and in most viscera. Surviving VALOs madelO-times more IgM than surviving ZERO embryos but all survivors resisted re-infection post-hatch. This difference in IgM was also observed in sentinels that became sub-clinically infected after hatch. Thus the unsafe vaccination ofa minority could confer immunity to the majority. Cytokine-gene plasmids were co-administered with the vaccine, in attempts to make it safer, withou~ success. IFN-y reduced both virus replication and antibody responses, IL-4 had a minor effect on virus replication but did not alter immunity and IL-I8 had no effect. Furthermore, in ovo injection ofIFN-y reduced the local replication of live Newcastle disease virus after hatch. Finally DNA vaccines were examined as safer alternatives to live in ovo vaccines with no success. The thesis concludes with a discussion on several aspects ofin ovo vaccination against Newcastle Disease with live vaccines and possible future work with in ovo NDW.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available