Occurrence of different strains of Dichelobacter nodosus in new clinical lesions in sheep exposed to footrot associated with multi-strain infections.

Autor: Jelinek PD; Agriculture Western Australia, Bunbury, Western Australia., Depiazzi LJ, Galvin DA, Spicer IT, Palmer MA, Pitman DR
Jazyk: angličtina
Zdroj: Australian veterinary journal [Aust Vet J] 2000 Apr; Vol. 78 (4), pp. 273-6.
DOI: 10.1111/j.1751-0813.2000.tb11756.x
Abstrakt: Objective: To investigate the occurrence of S1, U1 and T strains of Dichelobacter nodosus in new clinical lesions in sheep exposed to footrot associated with multi-strain infections.
Design: Seventy-seven donor sheep were grazed with 84 recipients for 33 weeks. The donor sheep were Merinos with a history of clinically virulent footrot associated with protease type S1, U1 and T strains of D nodosus that hybridised with gene sequences pJIR314B, pJIR318 and/or pB645-335. The recipient sheep were Merinos with no history of footrot.
Procedure: Each fortnight, all feet were examined, their lesion scores were recorded and samples of lesion material were taken for laboratory tests.
Results: Eighty-nine percent (299 of 336) of feet of recipient sheep developed new clinical lesions. S1, U1 and T strains of D nodosus were recovered from 58%, 22% and 18%, respectively, of these lesions at a ratio that remained constant during two apparent peaks in footrot transmission. Gene sequences homologous to pJIR314B and pB645-335 were detected in 56% (93 of 166) and 29% (48 of 166), respectively, of S1 strains of D nodosus at a ratio that was not constant during the experiment.
Conclusions: S1 was the dominant protease type of D nodosus in new clinical lesions. The occurrence of S1 strains did not increase relative to U1 and T strains of D nodosus during the experiment. S1, U1 and T strains of D nodosus remained in equilibrium despite changes in environment, genetic types in the population of S1 strains, and host resistance to footrot.
Databáze: MEDLINE
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