Taole, M.Albertyn, J.Van Heerden, E.Bragg, R.R. (Robert Richard)Boomker, Jacob Diederik Frederik2012-02-282012-02-2820122002Taole, M, Albertyn, J, Van Heerden, E & Bragg, RR 2002, 'Virulence of South African isolates of Haemophilus paragallinarum. Part 3: Experimentally produced NAD-independent isolate’. Onderstepoort Journal of Veterinary Research, vol. 69, no. 3, pp. 189-196.0030-2465http://hdl.handle.net/2263/18254The 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.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.© ARC-Onderstepoort and Faculty of Veterinary Science, University of Pretoria (original). © University of Pretoria. Dept of Library Services (digital).Veterinary medicineHaemophilus paragallinarumInfectious coryzaNAD dependentNAD independentTransformationVeterinary medicine -- South AfricaHaemophilus -- South AfricaHaemophilus parainfluenzaeArticle