Adenovirus vaccination of pregnant ewes and studies on the colostral immunity of their lambs

Pregnant ewes were vaccinated 1 month before parturition with mono or bivalent adenovirus vaccines. Vaccination resulted in increased levels of homologous and heterologous antibody in ewes, with corresponding increases in passive immunity of lambs. Challenge of lambs with homologous or heterologous virus at 21 days of age was associated with significant resistance to development of lesions in lambs challenged with homologous virus, and partial resistance in those challenged with heterologous virus. Bivalent vaccines gave comparable protection to challenge with both virus types.