An attenuated mutant of avian pathogenic Escherichia coli serovar O78: a possible live vaccine strain for prevention of avian colibacillosis

Abstract

Here construction of an attenuated mutant of an avian pathogenic Escherichia coli serovar O78 using an allelic exchange procedure is described. The mutant AESN1331, which carries a deletion in the crp gene, lost tryptophan deaminase activity and therefore lacked the ability to produce indole. The mutant strain additionally lacked the ability to adsorb Congo red, no longer fermented sugars other than glucose and L‐arabinose, did not harbor four known virulence‐associated genes (iss, tsh, cvaA, papC), and was susceptible to many antimicrobials, with the exception of nalidixic acid. The lethal dose (LD50 value) of the mutant strain on intravenous challenge in chickens was approximately 10‐fold higher than that of the parent strain. Additionally, the mutant strain was rapidly eliminated from chickens, being detected in the respiratory tract only on the first day post‐inoculation by fine spray. Administration of the mutant strain via various routes such as spray and eye drop for chickens, as well as in ovo inoculation for embryonated egg, evoked an effective immune response that protected against a virulent wild‐type E. coli O78 strain. Specifically, after immunization with the mutant strain, chickens challenged intravenously with an E. coli O78 strain exhibited decreases in mortality, clinical scores, organ lesion scores, and recovery of the challenge strain from organs compared to non‐immunized chickens. These findings suggest that AESN1331 is a suitable candidate for a live vaccine strain to protect chickens from colibacillosis caused by avian E. coli O78.

An Assessment of the Level of Protection Against Colibacillosis Conferred by Several Autogenous and/or Commercial Vaccination Programs in Conventional Pullets upon Experimental Challenge

“…The immunization of pullets/hens against colibacillosis with live, inactivated or sub-unit vaccines has been reported, with variable outcomes [ 6 ]. Live vaccines have been repeatedly proven to contribute positively to bird protection [ 26 , 27 , 28 , 29 , 30 ], although exceptions have also been reported [ 31 ]. A commercial live vaccine is presently available in most regions; it was registered in the EU in 2013 [ 32 ] and it is an attenuated O78 E. coli strain and provides effective protection upon challenge with O78 wild strains [ 33 ].…”

Chaperonin GroEL: A novel phylogenetically conserved protein with strong immunoreactivity of Avian Pathogenic Escherichia coli isolates from duck identified by immunoproteomics

“…To date, a number of experimental vaccines have been developed to prevent colibacillosis [9,10]. The traditional wholecell inactivated vaccines can provide satisfactory protection to the homologous serotypes [11,12] but do not evoked cross-protection against non-homologous strains, which is also the disadvantage of gene deleted vaccines [13,14].…”

Preparation and Evaluation of Avian Pathogenic E.coli Lypopolysaccharide and ribosomal vaccines against avian colibacillosis in broiler chicken in AL-Sulaimania provnce

“…Currently, the control of APEC has become not only an urgent issue but also a great challenge. Vaccination is an effective method for controlling infectious diseases (Yang., 2003).To date, a number of experimental vaccines have been developed to prevent colibacillosis (Nagano et al 2012;Lynne et al .,2012) Infections caused by Escherichia coli have an economically significant impact on the poultry industry and a nonserotype-specific vaccine appears to be the most logical method of controlling them .The potential of controlling Escherichia coli infections in commercial poultry through vaccination has been explored widely over the past several decades. In these attempts, live or killed bacteria and their various cellular components have been used to immunize chickens (Deb and Harry, 1976;Arp, 1980 andKariyawasam et al, 2002(.…”