Cloning of a unique sequence specific to isolates of type B:2 Pasteurella multocida
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K M Townsend1, H J Dawkins, B J Zeng
1Department of Pathology, University of Western Australia.
Abstract:
Two Carter type B Pasteurella multocida isolates, Izatnagar 52 and 25, isolated from cases of haemorrhagic septicaemia (HS), were used in a modified subtractive hybridisation technique with the specific aim of cloning unique DNA sequences related to the pathogenesis of HS. Biochemical and protein analyses have shown these isolates to be similar, but reports indicate that they have differences in pathogenicity. The subtracted inserts were screened against genomic DNA from a wide range of P multocida isolates, with two distinct fragments demonstrating specific hybridisation with Carter type B isolates that cause HS. No identity was observed with either Carter type E isolates or non-HS type B strains. The clones were sequenced and a search of the GenBank database revealed significant identity of the clone A3b (296 nt) to P haemolytica lipoprotein, whereas there was no significant identity with 6b (956 nt). Both these fragments had a high level of identity (72.8 to 76.9 per cent) to the H influenzae Rd genome.
Insights
Researchers identified unique DNA fragments in Pasteurella multocida Carter type B isolates linked to haemorrhagic septicaemia (HS) pathogenesis. These fragments show specificity for HS-causing strains, aiding in understanding the disease.
Area of Science:
- Bacteriology
- Molecular Biology
- Veterinary Microbiology
Background:
- Pasteurella multocida Carter type B causes haemorrhagic septicaemia (HS) in animals.
- Isolates Izatnagar 52 and 25, though biochemically similar, exhibit varying pathogenicity.
- Understanding the genetic basis of HS pathogenesis is crucial for disease control.
Purpose of the Study:
- To clone unique DNA sequences associated with the pathogenesis of HS in Pasteurella multocida.
- To identify specific genetic markers differentiating pathogenic from non-pathogenic strains.
Main Methods:
- Modified subtractive hybridization technique was employed.
- Screening of subtracted DNA inserts against a diverse panel of Pasteurella multocida genomic DNA.
- DNA sequencing of identified clones and subsequent BLAST analysis against GenBank.
Main Results:
- Two distinct DNA fragments specifically hybridized with Pasteurella multocida Carter type B isolates causing HS.
- No cross-hybridization was observed with Carter type E or non-HS type B strains.
- Clone A3b showed significant identity to *P. haemolytica* lipoprotein; clone 6b showed no significant identity. Both fragments shared high identity with *H. influenzae* Rd genome.
Conclusions:
- Identified unique DNA fragments can serve as potential diagnostic markers for HS-causing Pasteurella multocida Carter type B.
- The findings contribute to the molecular understanding of HS pathogenesis.
- Further investigation into the function of these identified sequences is warranted.