Efficacy of B1 Newcastle disease vaccine against the prevalent virulent strain of Newcastle disease virus isolated from broiler farms of Khouzestan province

In order to evaluate protection of B1 ND vaccine against the prevalent virulent ND virus isolated from broiler farms in Khuzestan province, samples from trachea, lungs, liver, kidney, spleen, proventriculus, cecal tonsils and brain were collected from 50 Newcastle disease suspected flocks. One isolated ND virus was belonged to genotype II and 7 isolates were belonged to genotype VII. In order to evaluate protection of Newcasle B1 vaccine aginst virulent isolate belonged to genotype VII, 160 day-old broiler chicks were randomlly divided into 4 equal groups and kept in separated rooms. Groups 1 and 3 chicks were vaccinated two times with live B1 strain vaccine at 8 and 18 days of age via eye-drop route and groups 2 and 4 chocks were kept as unvaccinated control groups. Groups 2 and 3 chicks were challenged intraocularly with 105 EID50 doses of the virulent prevalent isolated ND virus. Blood samples from all groups were collected on days 1, 14, 25, 32, 37 and 42 and antibody titer was measured by hemagglutination inhibition (HI) test. It was concluded that, very virulent ND virus are present in poultry farms of Khuzestan province and two times vaccination with B1 vaccine probably produced sufficient protection against very virulent ND virus.