长春军需大学兽医研究所,Center for Vaccine Development,University of Maryland School of Medicine,Baltimore,Center for Vaccine Development,University of Maryland School of Medicine,Baltimore,Center for Vaccine Development,University of Maryland School of Medicine,Baltimore 长春,130062
,MD21201,USA
,MD21201,USA
,MD21201,USA
Construction and Immunization of a ler Deletion mutant of REPEC O103
Abstract:Aim The goal of this study was to genetically characterize ler gene of rabbit EPEC strains (REPEC O103 and RDEC-1) to determine the effects of deletion of ler on in vivo virulence Methods A ler internal deletion mutant of REPEC O103 was constructed using suicide delivery vector (pCVD442) technology Following immunization with ler deletion mutant of REPEC O103 and challenge with parental wild type REPEC O103,rabbits were observed daily for clinical signs of disease including weight change and diarrhea,and for fecal shedding of the inocula Results ler deletion mutant of REPEC O103 showed increased responses in cell density and growth rates in PAB medium while completmentation of the entire ler gene restored the ability to normal levels After wild type challenge,immunized rabbits exhibited normal weight gain,no diarrhea and,at sacrifice,had no mucosally adherent organisms In contrast,unimmunized rabbits had severe diarrhea and weight loss and histological analysis revealed extensive mucosal colonization Conclusion A ler deletion mutation results in marked attenuation of REPEC O103 virulence and maintains its immunogenicity This study provides the important information for human attenuated vaccine against EHEC and EPEC