ABSTRACT
Strain 0083 and two field isolates of H. paragallinarum were previously converted into NAD-independent organisms by the use of crude DNA extractions from naturally occurring NAD-independent H. paragallinarum isolates. Two of these transformed isolates [0083(T) and A745(T)] were used as DNA donors in another transformation experiment in which another field isolate (M85) was used as the DNA recipient. Transformation was confirmed by lack of NAD requirement for growth, by carbohydrate fermentation patterns and by a comparison of the monoclonal antibody patterns of the isolates before and after transformation. Previously, antigenic differences were observed when DNA from an NAD-independent isolate was introduced into strain 0083. Antigenic differences were also seen in the transformed M85 organisms prepared in this work, and these differences were dependent on the antigenic patterns of the DNA donors. It was established by haemagglutination (HA) and haemagglutination inhibition (HI) that the hemagglutinins of 0083, A745/92 and M85 were not affected by transformation. The use of strains transformed to NAD independence for vaccine production appears to be a valid approach, as the transformation appears not to affect the hemagglutinins of the transformed organisms The major advantage would be the alleviation of the requirement for chicken serum or NAD in the bacterial growth medium used for infectious-coryza-vaccine production.
