title: Strain-dependent cellular immune responses in cattle following Escherichia coli O157:H7 colonization.
abstract: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic diarrhea and potentially fatal renal failure in humans. Ruminants are considered to be the primary reservoir for human infection. Vaccines that reduce shedding in cattle are only partially protective, and their underlying protective mechanisms are unknown. Studies investigating the response of cattle to colonization generally focus on humoral immunity, leaving the role of cellular immunity unclear. To inform future vaccine development, we studied the cellular immune responses of cattle during EHEC O157:H7 colonization. Calves were challenged either with a phage type 21/28 (PT21/28) strain possessing the Shiga toxin 2a (Stx2a) and Stx2c genes or with a PT32 strain possessing the Stx2c gene only. T-helper cell-associated transcripts at the terminal rectum were analyzed by reverse transcription-quantitative PCR (RT-qPCR). Induction of gamma interferon (IFN-γ) and T-bet was observed with peak expression of both genes at 7 days in PT32-challenged calves, while upregulation was delayed, peaking at 21 days, in PT21/28-challenged calves. Cells isolated from gastrointestinal lymph nodes demonstrated antigen-specific proliferation and IFN-γ release in response to type III secreted proteins (T3SPs); however, responsiveness was suppressed in cells isolated from PT32-challenged calves. Lymph node cells showed increased expression of the proliferation marker Ki67 in CD4(+) T cells from PT21/28-challenged calves, NK cells from PT32-challenged calves, and CD8(+) and γδ T cells from both PT21/28- and PT32-challenged calves following ex vivo restimulation with T3SPs. This study demonstrates that cattle mount cellular immune responses during colonization with EHEC O157:H7, the temporality of which is strain dependent, with further evidence of strain-specific immunomodulation.
authors.affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, United Kingdom The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Alexander
authors.initials: A
authors.lastname: Corbishley
authors.affiliation: The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Nur Indah
authors.initials: NI
authors.lastname: Ahmad
authors.affiliation: SRUC, Edinburgh, United Kingdom.
authors.forename: Kirsty
authors.initials: K
authors.lastname: Hughes
authors.affiliation: SRUC, Edinburgh, United Kingdom.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hutchings
authors.affiliation: The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Sean P
authors.initials: SP
authors.lastname: McAteer
authors.affiliation: The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Connelley
authors.affiliation: The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Brown
authors.affiliation: The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom.
authors.forename: David L
authors.initials: DL
authors.lastname: Gally
authors.affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, United Kingdom tom.mcneilly@moredun.ac.uk.
authors.forename: Tom N
authors.initials: TN
authors.lastname: McNeilly
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002353:Carrier State / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000382:microbiology; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000276:immunology*; D020869:Gene Expression Profiling; D007111:Immunity, Cellular; D007694:Killer Cells, Natural / Q000276:immunology; D008198:Lymph Nodes / Q000473:pathology; D060888:Real-Time Polymerase Chain Reaction; D012007:Rectum / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction