evaluation of quality of two commercial oil-emulsion newcastle disease vaccines in-vivo and in-vitro

Background and aims: newcastle disease (nd) is a highly contagious disease in poultry with economic losses in the world. vaccination is one of the most important ways for prevention and control of ndv, but there are reports of nd outbreaks in vaccinated chickens. poor quality of the vaccines is one of the reasons of vaccine failure. in this study the quality of two commercial oilemulsion newcastle disease virus (oe-ndv) vaccines was evaluated in invitro and invivo.materials and methods: for invitro study, the amount of total protein and quantity of retrieved hemagglutination activity (ha) of the vaccines were recovered and measured, then, the amount of recovered total protein and retrieved ha were compared with the serologic responses induced in chickens by each vaccine(in-vivo study).results: the results showed that the extracted total protein , recovered ha titer, and mean hi titers to vaccine a are higher than vaccine b.the results also indicated that there is a good correlation between retrieved ha activity, extracted total protein and antibody response to vaccine a, but about vaccine b, there is no good correlation between total protein and retrieved ha activity and antibody response.conclusions: quality of vaccine b is lower than vaccine a, likely because of many reasons particularly improper storage of the vaccine, inappropriate harvesting of egg allantoic fluid and inactivation of ndv.