Efficacy of Experimental Inactivated Vaccine for Infectious Bronchitis Disease

Experimental oil-emulsion vaccinc \Vas l'onnulated \Vith a ratio of one part of 0.05% ~-propiolactonc inactivatcd antigcn and l'our parts oil adjuvant ISA-70. Four hundn.:d whitc Ily-Linc (\\'-36) chicks were rearcd in t'our groups. Groups 1 and 2 \Vere vaccinated b) live attenuated 1·1120 at day 10 and reared separately from groups 3 and 4. At weck 16 groups 1 and 2 were received experirnental oil-emulsion and commercial oil-emulsion vaccines respectively. At this time. group 3 \Vas n:ceivcd single dose of experimental oil-emulsion vaccine and group 4 \\"s unvaccinated conlrol. At \Vcck 29 ail or groups \\cre challenged by 0.25' I07r': ID,,/bird or intCcted allantoic Iluid whcn the)' were on peak of production. Ali groups were bled fi-cl]uently and the sera were assayed by ELISA and ACJI J) tests. Clinical signs and high percentage drop in egg production in groups 3 and 4 v.ere notcd. Moreover. no virus and/or viral antigen in the trachea or groups 1 and 2 \Vere dctcctcd at days 5 and 10 postchallengc. The results or clinical observation cgg producl ion. virus isolation and delcction in Ihe trachea and levels of antibody suggcsted Ihal layers vaecinated wilh a combinalion of live allcnuated and the cxpcrimcntal inactivalcd vaccines had Ihc highcsi proteclion.