Evaluation of Newcastle disease Clone12IR vaccine immune responses in SPF and commercial chickens

Objectives: Newcastle disease (ND) one of the most serious illnesses of chickens causes most economically damaging widespread diseases of poultry. In ND endemic areas, the live lentogenic vaccines include Hitchner B1 and LaSota have a key role in vaccination programs. The purpose of this study was to evaluate the immune responses induced by ND Clone12IR vaccine (Razi Institute) in both SPF and commercial chickens.Materials and Methods: Groups of SPF chickens were divided into two treatment groups based on administration route. Chickens in group A were received Clone12IR vaccine by eye-drop and group B by drinking water. One group of birds was kept as non-vaccinated control. At 3 weeks post-vaccination sera were collected and assayed for antibody levels against NDV by HI. Twenty chickens per groups were challenged by intra muscular with 10^5 EID50 of a vNDV Herts-33 strain at 3 weeks post vaccination. The chickens were observed up to 21 days for any clinical symptom or mortality. Groups of Ross-308 chickens were tested as the same manner.Results and conclusion: The geometric mean HI antibody titers were raised in both treated groups ( 4 log2) compared with the control chicks. In challenge test, no sign of ND was seen in chickens of group A until the end of experiment. All SPF vaccinated chicks and 90% of the Ross-308 chickens were protected from challenge. Seventeen chickens (85%) of control groups died and the remained were shown the marked signs of ND. The result indicates the ability of the Clone12IR vaccine to confer a high protection against NDV. ,