NEWCASTLE DISEASE .I. USE OF EGG YOLK DERIVED ANTIBODY FOR PASSIVE IMMUNISATION OF CHICKENS

The yolk of eggs, laid by hens recovered from Newcastle Disease, when injected into three week old chicken conferred passive immunity which persisted up to 28 days. The simultaneous inoculation of this yolk and B.P.L. inactivated Newcastle Disease vaccine resulted in the development of a similar level of passive immunity which was superseded after 8 to 11 days by active immunitv, but a lower proportion of birds were resistant to challenge after 42 days than was seen in birds injected with vaccine alone. Immuno-globulin chemically extracted from the yolk of eggs laid by hens recovered from Newcastle Disease possessed specific haemagglutination inhibiting antibody and was as effective as the raw yolk in conferring passive protection, but for a shorter period of time. When this immuno-globulin was administered simultaneously with vaccine, passive and active immunity were conferred, the latter superseding the former. The degree of immunity produced was independent of whether the immuno-globulin and vaccine were administered separately or in combination. The process used to extract antibody from egg yolk is described and the possibility of using immuno-globulin of yolk origin for passive protection of other species against non avian diseases is discussed. © 1969.