Abstract: An attenuated infectious laryngotracheitis virus (ILT) that has the antigenic and virulence characteristics of ECACC at Accession No. V89042602, produces an average pock diameter on chorio-allantoic membrane of commercial eggs between 1.0 and 3. mm, exhibits substantially reduced virulence in comparison to ILT SA2 strain, and results in substantially less weight loss in poultry as compared to poultry infected with SA2. A method of producing this ILT virus by serially passaging ILT viral strain SA2 in primary cell cultures followed by serial passaging in embryonated eggs. A method for preventing infection by ILT virus in birds by administering a vaccine with an effective amount sufficient to elicit an immune response.

Abstract: Embryonal vaccination of fowl against Newcastle disease is accomplished with ethyl methane sulfonate modified NDV-B1 virus.

Abstract: A gene sequence including a first promoter for the expression of a major early fowlpox virus (FPV) protein. In a preferred aspect, the gene sequence further includes a second promoter for the expression of a late fowlpox virus protein in opposite orientation to said first promoter. The promoter is useful in developing FPV based vectors for the delivery of vaccine antigens preferably to poultry, and as a tool to study the temporal regulation of poxvirus genes. The invention also offers methods useful in the construction of recombinant fowlpox viruses or related avian poxviruses, which methods are characterized by the introduction of foreign DNA into the fowlpox virus or into virus DNA sequences, which sequences are able to use native FPV promoter regions.

Abstract: A process for producing live, non-pathogenic, vaccines for the pathogens RNA turmor virus utilizes gene-altering technology to produce an altered genome which codes for the antigenic determinants of a pathogen, but has no genes coding for pathogenicity. The vaccine is the phenotypic expression of the altered genome. Specifically, an avian RNA tumor virus env gene is cloned into the non-pathogenic RNA virus RAV-O and the resulting recombinant product is replicated in host cells to provide a recombinant vaccine for the pathogen avian RNA tumor virus.