The value of the marker genes identified in this study was extended to consider the genetic diversity between C. pecorum infections in koalas and non-koala hosts. Previous research has suggested that, supported by ompA VD3/4 sequence data, C. pecorum is a polyphyletic organism in Australian koala populations. This hypothesis originated from the similarity of one or two koala ompA genotypes to European bovine isolates of C. pecorum [7, 11] and based on this data, a model was proposed whereby koalas obtained C. pecorum BMS-907351 ic50 infections as a result of a series of cross-species transmission events from sheep and/or cattle [7, 8, 11, 60]. While similar results were obtained using ompA data in this

study (Figure 3), the phylogenetic analysis has already suggested in inadequacy of the ompA gene alone in representing C. pecorum’s true evolutionary course within koala populations. Indeed, both this and previous studies GF120918 in vitro utilised a 465 bp fragment of the ompA locus (VD 3/4) which, while containing the majority of ompA’s nucleotide variation, would remain largely insufficient to describe the extensive genetic diversity that has accumulated in global isolates of C. pecorum. Consequently, we prepared an unrooted phylogenetic tree from the concatenation of incA, ompA, and ORF663 sequences, revealing a surprising alternative picture that clearly

distinguishes koala C. pecorum strains from non-koala hosts (Figure 4). This distinction Fenbendazole is further supported by the noticeable difference in branch lengths between koala C. pecorum sequences and non-koala hosts, suggesting that as a whole, koala strains are much more closely related to each other

than to other non-koala host strains. This result is significant as it may be an example of an alternate evolutionary model in which koalas obtained C. pecorum as a result of a limited number of cross-host transmission events in the past and have subsequently evolved along an evolutionary trajectory that is distinct from that seen in sheep and cattle isolates. This result also reinforces the benefit and efficacy of applying more phylogenetically-robust data (the concatenation of three congruent genes) to the epidemiological study of C. pecorum infections, both in koala and non-koala hosts. It must be noted however, that this remains a cautionary finding. Without ompA, incA, and ORF663 nucleotide sequences from Australian sheep and cattle isolates it remains impossible to truly establish a compelling cross-host transmission hypothesis for koala isolates. Nevertheless, this data cannot be completely discounted and functions as preliminary insight into the genetic diversity of koala isolates of C. pecorum. Conclusions The findings of this study have highlighted the opportunities and drawbacks of estimating phylogenetic relationships from multiple independent datasets [61].