Investigating Key Virulence Factors in Mannheimia haemolytica for Enhanced Disease Control Strategies

Background and objectives: Whereas our understanding of bovine pasteurellosis has greatly improved, it continues to be an important respiratory disease in feedlot cattle. Mannheimia (M.) haemolytica, is a primary cause of severe pneumonia in bovine respiratory disease (BRD). Although some research has been done in Iran and other countries to evaluate the prevalence of M. haemolytica, the general virulence factors of this bacteria are not clear yet. M. haemolytica ’s virulence factors aid lung colonization, trigger inflammation, and help evade host immunity. Environmental factors influence the pathogenicity and spread of M. haemolytica, which carries complete leukotoxin (LKT) genes. In this study Virulence factors were validated through key mucosal pathogenic components: fimbriae, capsule, endotoxins, and leukotoxin. 
Materials and : M. haemolytica samples from goats and sheep swabs were cultured on Blood Agar and then transferred to BHI medium for growth. Then, the samples were analyzed for virulence factors using the polymerase chain reaction (PCR) to identify and verify the virulence factors of M. haemolytica.
Results: in This study 10 virulence genes in M. haemolytica, identifying key pathogenic markers in most samples were examined. Genes associated with toxin production, adhesion, and immune evasion were prevalent, while others showed variable distribution. The results demonstrate the significance of the virulence factors in the pathogenic and colonization potential of M. haemolytica in sheep and goats.
Conclusion: investigating these virulence factors  helps refine strategies in vaccine development and disease control, aiming to reduce the pathogen’s impact on livestock respiratory health.