Virulence-associated Genome Sequences of Pasteurella canis and Unique Toxin Gene Prevalence of P. canis and Pasteurella multocida Isolated from Humans and Companion Animals.

BACKGROUND: Comparative analysis of virulence factors (VFs) between Pasteurella canis and Pasteurella multocida are lacking, although both cause zoonotic infections. We determined the virulence-associated genome sequence characteristics of P. canis and assessed the toxin gene prevalence unique to P. canis among clinical isolates of P. canis and P. multocida. METHODS: We selected 10 P. canis and 16 P. multocida whole-genome sequences (WGSs) from the National Center for Biotechnology database. The VFanalyzer tool was used to estimate P. canis-characteristic VFs. Amino acid sequences of VFs were compared with multiple-aligned sequences. The genome structure containing P. canis-characteristic and adjacent loci was compared to the corresponding P. multocida genome structure. After designing primer sequences and assessing their accuracy, we examined the gene prevalence of the P. canis-characteristic VFs using PCR among clinical isolates of P. multocida and P. canis. RESULTS: Using VFanalyzer, we found virulence-associated cytolethal distending toxin (cdt)A-cdtB-cdtC loci common to all P. canis WGSs that were not found in P. multocida WGSs. Similarities in the multiple alignments of CdtA-CdtB-CdtC amino acid sequences were found among the 10 P. canis WGSs. Shared or similar loci around cdtA-cdtB-cdtC were identified between the P. canis and P. multocida genome structures. The PCR-based cdtA-cdtB-cdtC prevalence differed for P. canis and P. multocida clinical isolates. CONCLUSIONS: P. canis-specific cdtA-cdtB-cdtC prevalence was identified among clinical isolates. These three loci may be unique toxin genes and promising targets for the rapid identification of P. canis in clinical settings.