Comparison of virulence and resistance genes in <i>Mannheimia haemolytica</i> and <i>Pasteurella multocida</i> from dairy cattle with and without bovine respiratory disease

This case-control study provides key microbial ecological advances by elucidating the role of bacteria in the bovine respiratory disease complex in dairy cattle. Previous research has identified specific virulence factors in both bacterial genomes that resulted in disease. Our results challenge this perception and are of high impact, revealing that the pan-genome of both bacteria did not differentiate among the clinical cases or age groups, and a specific pathogenic pathotype was not evident in the isolates from this study, and it did not emerge when including additional public whole-genome sequences to increase the analytical power of the analysis (the first study to use this approach to evaluate bovine respiratory disease in cattle). In addition to these novel discoveries, this study describes the first population-scale genomic comparison of both <i>Mannheimia haemolytica</i> and <i>Pasteurella multocida</i> genomes collected from affected and healthy dairy cattle from different age groups and from multiple farms.