Efficacy of Experimental Inactivated Vaccine for Infectious Bronchitis Disease

Abstract

Summary Experimental oil-emulsion vaccine was formulated with a ratio of one part of 0.05% β-propiolactone inactivated antigen and four parts oil adjuvant ISA-70. Four hundred white Hy-Line (w-36) chicks were reared in four groups. Groups 1 and 2 were vaccinated by live attenuated H120 at day 10 and reared separately from groups 3 and 4. At week 16 groups 1 and 2 were received experimental oil-emulsion and commercial oil-emulsion vaccines respectively. At this time, group 3 was received single dose of experimental oil-emulsion vaccine and group 4 was unvaccinated control. At week 29 all of groups were challenged by 0.25×10 7 EID50/bird of infected allantoic fluid when they were on peak of production. All groups were bled frequently and the sera were assayed by ELISA and AGID tests. Clinical signs and high percentage drop in egg production in groups 3 and 4 were noted. Moreover, no virus and/or viral antigen in the trachea of groups 1 and 2 were detected at days 5 and 10 postchallenge. The results of clinical observation egg production, virus isolation and detection in the trachea and levels of antibody suggested that layers vaccinated with a combination of live attenuated and the experimental inactivated vaccines had the highest protection.