Bragg, R.R. (Robert Richard)Boomker, Jacob Diederik Frederik2012-02-282012-02-2820122002Bragg, RR 2002, 'Virulence of South African isolates of Haemophilus paragallinarum. Part 2: Naturally occurring NAD-independent field isolates’. Onderstepoort Journal of Veterinary Research, vol. 69, no. 2, pp. 171-175.0030-2465http://hdl.handle.net/2263/18256The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.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.© ARC-Onderstepoort and Faculty of Veterinary Science, University of Pretoria (original). © University of Pretoria. Dept of Library Services (digital).Veterinary medicineHaemophilus paragallinarumNAD-independenceVirulenceVeterinary medicine -- South AfricaHaemophilus parainfluenzaeHaemophilus -- South AfricaArticle