Author/Authors :
Rajabi, Z Poultry diseases division - Clinical Sciences Department - Faculty of veterinary medicine - university of Tabriz , Aslnajjari, A Resident in poultry diseases at faculty of veterinary medicine - University of Shiraz
Abstract :
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 oil-emulsion Newcastle disease virus (OE-NDV) vaccines was evaluated
in in-vitro and in-vivo.
Materials and Methods: For in-vitro 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.
Keywords :
Hemagglutination activity , Total protein , vaccine potency , Hemagglutination inhibition
