Preparation of live attenuated and killed vaccines of Newcastle disease (strain AG 68) and immunity evaluation

Abstract

This study has been conducted to propagate Newcastle Disease virus, strain AG68 in (9-11) day old chicken's embryonated eggs . Five passages have been runned to obtain different titers three of them (EID50 ml 109.1, EID50 ml 109.5, EID50 ml 109.9) titers were used to produce three killed different vaccine doses used in this study. The EID50 ml 109.5 has been diluted to give different dosage attenuated vaccine .Two hundreds and ten birds were divided to seven groups each 30 chicks each. First three groups were vaccinated with different doses subcutaneously with the oil adjuvant vaccine while the other three groups were vaccinated via eye drop at one day old, the seventh group was left as control. All first six groups were vaccinated with AG68 strain by spray on 12th day .Indirect enzyme linked immunosobent assay (ELISA) technique was used to estimate the immune titer at (1st, 14th, 28 th) day and with challenge test at (28) day , in ELISA test in all groups there were significant differences (p < 0.05) between 14th and 28th day . ELISA test at day 14 in groups vaccinated with attenuated vaccine through eye drop at the first day showed high antibody level. At 28th day, groups vaccinated with oil inactivated vaccine have shown higher anti body titers than those vaccinated with attenuated vaccine , all six groups have shown higher antibody titer than control . All vaccinated groups have shown 100% protection against challenge test indicating the protective efficacy of AG68 strain and the two types of vaccine prepared (killed and attenuated) through eye drop , spray , and injection, while the protection percentage in group seven was 20% . As a conclusion, the best killed vaccine dose was EID50 ml 109.5 from economical point of view, this dose shows no significant difference with high dose EID50 ml 1010 through ELISA, also protection percentage through challenge test was the same , The EID50 ml 107 is The best of attenuated vaccine doses, although it showed lower significant difference to the high dose EID50 ml 108 through ELISA test, but it shows no clinical signs of Newcastle disease and has the same protection percentage in challenge test .