Virulence of South African isolates of Haemophilus paragallinarum. Part 3: experimentally produced NAD-independent isolate.
A NAD-dependent isolate 46 (C-3) of Haemophilus paragallinarum, which was previously demonstrated to be of high virulence, was transformed to NAD independence using a plasmid isolated from a naturally occurring NAD-independent isolate of H. paragallinarum. The transformation was performed by two different methods and the identity of all of the isolates, before and after transformation was confirmed using a H. paragallinarum-specific PCR test. The transformed NAD-independent serovar C-3 isolate and the wild-type serovar C-3 isolate were used to experimentally infect vaccinated layer chickens. It was shown that the transformation to NAD independence significantly altered the virulence of the serovar C-3 isolate that was used in the transformation experiment. The mechanisms responsible for a decrease in virulence are not clear, but may be related to the pathology of the transformed isolate in the sinus of the chickens.
D000818:Animals; D002645:Chickens; D006190:Haemophilus / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D006192:Haemophilus Infections / Q000382:microbiology / Q000662:veterinary*; D009243:NAD / Q000378:metabolism; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000382:microbiology*; D013019:South Africa; D014169:Transformation, Bacterial; D014774:Virulence
D009243:NAD