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Immunogenicity of an experimental vaccine against Newcastle disease (ND) was tested on chickens and turkeys under laboratory and field condition, respectively.Vaccine, prepared in form of a water-in-oil-in-water (WOW), contained detergent solubilized ND virus. 21-day-old chickens, hatched from SPF eggs, were intramuscularlly (i.m.) vaccinated with 0.2 ml vaccine containing 1, 1/25, 1/50 and 1/100 viral doses. Also, 21-day-old light laying chickens received i.m. 0.2 ml vaccine containing 1, 1/5 1/25 and 1/50 viral doses. Control groups were not vaccinated. Three weeks postvaccination, chickens were i.m. challenge infected with 106 ELD50 Herts33 strain of NDV. The vaccinal dose recommended by Eu.Ph for safetly chicken protection was detrmined according to the Spaerman-Kärber methode and it amounted to 0.5 ml vaccine with 50 PD50/dose. Turkey breeders, vaccinated with 1.0 ml vaccine at the age of 16 weeks developed a high level of NDV antibodies persisting till the end of experiment, i.e. turkey age of 50 weeks. This suggest that no additional vaccination is requred during the whole laying period.

A Newcastle disease virus (NDV) vaccine, prepared as a water-in-oil-in-water emulsion (WOWE) with low contents of both viral material and mineral oil and high aqueous- to oil-phase and applied for the primary vaccination of chickens, can elicit both humoral immune response and protection against infection. Accordingly, ecological safe NDV subunit vaccine can be used for chicken priming and as a substitute for live vaccines usually accompainied by unesirable side-effects.

The efficacy of the vaccination of one-day-old broiler chickens possessing maternal NDV antibodies was studied. It was found that the live NDV vaccine as well as the live NDV vaccine given simultaneously with antigenic NDv subunits did not interfere with passive virus-neutralizing antibodies.