title: A cyclophosphamide-sensitive cell compartment is essential for homologous protection conferred by licensed vaccines for the control of avian pathogenic Escherichia coli in chickens.
abstract: Avian pathogenic Escherichia coli (APEC) exert substantial economic costs on poultry producers worldwide. Vaccination is an attractive method of control, but the immunological basis of protection is poorly understood. Here, we examine the effect of intramuscular injection of cyclophosphamide or saline on homologous protection induced by licensed inactivated or live-attenuated APEC O78 vaccines in chickens. In saline-treated birds, both vaccines induced significant APEC-specific IgY and protection against homologous challenge, as evidenced by enumeration of tissue-associated bacteria and analysis of pathology. In cyclophosphamide-treated birds, B cells were severely depleted whereas percentages of circulating CD4- and CD8-positive T cells were normal as detected by flow cytometry. Further, such birds did not produce APEC-specific IgY and were as susceptible to challenge as age-matched unvaccinated controls. The data indicate that homologous protection conferred by licensed APEC vaccines strictly requires a cyclophosphamide-sensitive cell population that includes B cells.
authors.affiliation: Avian Infectious Diseases Programme, The Pirbright Institute, Compton RG20 7NN, Berkshire, United Kingdom.
authors.forename: Jean-Rémy
authors.initials: JR
authors.lastname: Sadeyen
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, United Kingdom.
authors.forename: Pete
authors.initials: P
authors.lastname: Kaiser
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, United Kingdom.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Stevens
authors.affiliation: Avian Infectious Diseases Programme, The Pirbright Institute, Compton RG20 7NN, Berkshire, United Kingdom. Electronic address: francis.dziva@sta.uwi.edu.
authors.forename: Francis
authors.initials: F
authors.lastname: Dziva
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology; D058491:Bacterial Load; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002645:Chickens; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000633:toxicity*; D004926:Escherichia coli / Q000276:immunology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000473:pathology / Q000517:prevention & control / Q000662:veterinary*; D022361:Escherichia coli Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D007136:Immunoglobulins / Q000097:blood; D007273:Injections, Intramuscular; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D022361:Escherichia coli Vaccines; C016512:IgY; D007136:Immunoglobulins; D014613:Vaccines, Attenuated; D015164:Vaccines, Inactivated; D003520:Cyclophosphamide
keywords: APEC; Antibody; Bursectomy; Chicken; Cyclophosphamide; Vaccination