Research on Techology of EDS Vaccine Porduction.

Egg drop syndrome (EDS) which caused by an avian adenovirus is a widespread disease among laying chickens and has caused severe economic losses in the poultry industry of the world. An oil-adjuvant inactivated vaccine is widely used and gives good protection against clinical disease. The EDS vaccination has become mandatory and common in Iran and the vaccine has been imported from foreign countries. There has been no research on the production and evaluation of the EDS vaccine in Iran. The purpose of this study was to access the technology of the production and evaluation of this vaccine comparable to imported one. Two strains of the EDS virus were propagated in allantoic sac of embryonated duck eggs free of diseases such as Newcastle disease, avian influenza, Mycoplasmosis and chlamydiosis. One of the strains also propagated in allantoic sac of SPF chicken eggs. Inactivation of the virus was carried out by formalin and oil-adjuvant was montanide that mixed with virus suspension by the homogenizer device. Two types of vaccine based on their doses were prepared. At first, a vaccine with 3500 HAU dose per 0.5 ml was produced and evaluated and then upon the results of the first experiments the second vaccine with 2500 HAU dose was produced. The sterility, safety and stability tests were carried out. The potency of the vaccines was evaluated and compared with the imported vaccine by vaccination of SPF chickens and adult commercial layers by using HI and challenge tests. The vaccines were sterile, safe and stable according to the control tests. Comparison of the EDS virus antibody titers in sera of SPF chickens 3 to 19 weeks after vaccination by produced and imported vaccines showed no significant difference between them. The results of challenge test showed that all the produced vaccines like the foreign one can protect layers effectively against the challenged virus. Unvaccinated layers showed an obvious decrease in normal eggs production since one week after challenge until the end of the test and there was failure to achieve predicted egg production. The production of the aberrant eggs including thin shelled, soft shelled, or shell less eggs increased obviously. In the all vaccinated and the control birds decreased normal egg production was not seen and they could achieve the predicted egg production. Upon the results the produced vaccines showed acceptable potency similar to the imported one. Production of vaccine using the SPF eggs was the other interesting findings of this research. The results of this study can be used to produce the EDS vaccine in Iran.