Genomic evidence for a globally distributed, bimodal population in the ovine footrot pathogen Dichelobacter nodosus.
Bottom Line: However, single nucleotide polymorphism analysis of the 31,627 nucleotides that were found to differ in one or more of the 103 sequenced isolates divided them into two distinct clades.To determine the relationship between virulent and benign isolates and the relationship of isolates from different geographical regions, a genomic study that involved the sequencing and subsequent analysis of 103 D. nodosus isolates was undertaken.The results showed that D. nodosus isolates are highly conserved at the genomic level but that they can be divided into two distinct clades that correlate with their disease phenotypes and with a single amino acid substitution in one of the extracellular proteases.
Affiliation: Norwegian Veterinary Institute, Oslo, Norway.Show MeSH
Related in: MedlinePlus
Mentions: The vrl region was present in the historical virulent Australian isolates but was absent from the more recent isolates from Tasmania and South Australia (Fig. 5A). SNP analysis (Fig. 5B) revealed that the Australian clade I isolates, but not the clade II isolates, formed clusters, with most of the historical isolates forming one large cluster. The more recent isolates from Tasmania formed two distinct clusters, possibly indicating that these isolates, which remained in the population after a vaccination program, were derived from two different strains. The three South Australian isolates also grouped into a distinct cluster. Finally, two of the isolates from Western Australia grouped into a cluster quite separate from the other historical isolates, which was consistent with previous observation suggesting that isolates from this state were different from other Australian isolates (10). The clustering of distinct sets of related isolates may indicate some sampling bias; the sequencing of more isolates will be required to build a complete picture of the genetic diversity of the virulent D. nodosus isolates present in Australia, where virulent footrot has been endemic over an extended period of time.