title: Virulence of South African isolates of Haemophilus paragallinarum. Part 2: naturally occurring NAD-independent field isolates.
abstract: Naturally occurring NAD-independent variants of Haemophilus paragallinarum, which have been isolates from poultry showing clinical signs of infectious coryza, were used to determine their virulence using a newly developed challenge model for infectious coryza. It was established that the NAD-independent isolates belonging to a particular serogroup, were less virulent when compared to the virulence of the NAD-dependent isolates from the same serogroup. It was shown that the virulence of the NAD-independent isolates belonging to serogroup C and serogroup A were very similar to each other. This differs to the results obtained with NAD-dependent isolates reported on previously, in which the serogroup C isolates were found to be more virulent then the serogroup A isolates.
authors.affiliation: Department of Microbiology and Biochemistry, University of the Free State, Bloemfontein, South Africa. BraggRR@Sci.uovs.ac.za
authors.forename: R R
authors.initials: RR
authors.lastname: Bragg
mesh_terms: D000818:Animals; D002645:Chickens; D005260:Female; D006190:Haemophilus / Q000145:classification / Q000201:enzymology / Q000472:pathogenicity*; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D009243:NAD / Q000378:metabolism; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology*; D012703:Serotyping / Q000662:veterinary; D013019:South Africa / Q000453:epidemiology; D014774:Virulence
chemical_list: D009243:NAD