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The Thai Journal of Veterinary Medicine

Abstract

This study determined the efficacy of recombinant HVT- NDV ( rHVT- NDV) vaccine simultaneously vaccinated with live vaccine at 1 day old and a booster vaccination with live vaccine at 10 days old against Asiatic, Genotype VII NDV in broiler chickens. The chickens were divided into 5 groups. The chickens in groups 1, 2 and 3 were vaccinated with rHVT- NDV vaccine and different live vaccines at 1 day old, and then finally received a booster vaccination at 10 days old. The chickens in groups 4 and 5 served as the positive and negative control groups, respectively. The chickens in groups 1, 2, 3 and 4 were challenged with NDV at 14, 21, 28 and 35 days old, 20 chickens of each group at a time. Clinical signs and mortality were observed for 14 days after each time of challenge. Blood samples were collected at 1 and 10 days old, on the virus inoculation day and 14 days post- inoculation, to determine NDV antibodies. Swab samples were collected from the chickens challenged with the virus at 35 days old to detect NDV RNA by real- time PCR. The results reveal that the protection rate of the vaccinated chickens, which were challenged at 14 days old was 70- 95%, while the protection rate of all vaccinated groups increased to 90- 100% when they were challenged at 21, 28 or 35 days old. The vaccinated groups had a lower rate of virus shedding when compared to the challenged control group. It is concluded that all of the vaccination programs of rHVT-NDV vaccine in this study could be used to reduce economic loss due to infection by Genotype VII NDV.

Publisher

Faculty of Veterinary Science, Chulalongkorn University

First Page

603

Last Page

611

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