Molecular, pathogenic, and phylogenetic characterization of strains of avian pathogenic Escherichia coli and of infectious bronchitis virus in co-infections of poultry flocks in Brazil

Abstract

The infectious diseases remain the leading causes of the most severe economic impacts on poultry production, especially infections caused by avian pathogenic Escherichia coli (APEC) which result in significant losses annually to the poultry industry due to mortality, growth retardation, and condemnation of carcasses in slaughterhouses. In Brazil, despite all the technological advances in the poultry industry, there are recent reports of increased condemnation of carcasses in the slaughterhouses due to the presence of colibacillosis, which may be associated or not with other infectious agents, particularly infectious bronchitis virus (IBV), including attenuated vaccine strains of this virus. The IBV infection increased collibacillosis susceptibility, affecting the respiratory tract, or systemic organs, and causing airsacculitis or collisepticemia, respectively. Thus, the current study was proposed, aiming to characterize the virulence profiles of strains of avian pathogenic Escherichia coli (APEC), characterizing them genotypically, phenotypically and phylogenetically, as well as to investigate the occurrence of co-infection between APEC and IBV in Brazilian poultry flocks, in order to better understand the epidemiology of avian colibacillosis and the co-infection with IBV in Brazil and to define a more effective control strategy for this infectious disease.