title: B cell signatures of BCWD-resistant and susceptible lines of rainbow trout: a shift towards more EBF-expressing progenitors and fewer mature B cells in resistant animals.
abstract: Bacterial cold water disease (BCWD) is a chronic disease of rainbow trout, and is caused by the Gram-negative bacterium Flavobacterium psychrophilum (Fp), a common aquaculture pathogen. The National Center for Cool and Cold Water Aquaculture has bred two genetic lines of rainbow trout: a line of Fp-resistant trout (ARS-Fp-R or R-line trout) and a line of susceptible trout (ARS-Fp-S, or S-line). Little is known about how phenotypic selection alters immune response parameters or how such changes relate to genetic disease resistance. Herein, we quantify interindividual variation in the distribution and abundance of B cell populations (B cell signatures) and examine differences between genetic lines of naive animals. There are limited trout-specific cell surface markers currently available to resolve B cell subpopulations and thus we developed an alternative approach based on detection of differentially expressed transcription factors and intracellular cytokines. B cell signatures were compared between R-line and S-line trout by flow cytometry using antibodies against transcription factors early B cell factor-1 (EBF1) and paired domain box protein Pax5, the pro-inflammatory cytokine IL-1β, and the immunoglobulin heavy chain mu. R-line trout had higher percentages of EBF(+) B myeloid/ progenitor and pre-B cells in PBL, anterior and posterior kidney tissues compared to S-line trout. The opposite pattern was detected in more mature B cell populations: R-line trout had lower percentages of both IgM(+) mature B cells and IgM-secreting cells in anterior kidney and PBL compared to S-line trout. In vitro LPS-activation studies of PBL and spleen cell cultures revealed no significant induction differences between R-line and S-line trout. Together, our findings suggest that selective resistance to BCWD may be associated with shifts in naive animal developmental lineage commitment that result in decreased B lymphopoiesis and increased myelopoiesis in BCWD resistant trout relative to susceptible trout.
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA. Electronic address: pxzwol@wm.edu.
authors.forename: Patty
authors.initials: P
authors.lastname: Zwollo
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Jocelyn C
authors.initials: JC
authors.lastname: Ray
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Sestito
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kiernan
authors.affiliation: National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, USDA, Kearneysville, WV 25430, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Wiens
authors.affiliation: Department of Environmental and Aquatic Animal Health, Virginia Institute of Marine Science, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Kaattari
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Brittany
authors.initials: B
authors.lastname: StJacques
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Lidia
authors.initials: L
authors.lastname: Epp
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D045826:Flavobacteriaceae Infections / Q000276:immunology*; D005417:Flavobacterium / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D007148:Immunoglobulin mu-Chains / Q000235:genetics / Q000276:immunology; D016130:Immunophenotyping; D053583:Interleukin-1beta / Q000235:genetics / Q000276:immunology; D007668:Kidney / Q000166:cytology / Q000276:immunology; D038041:Lymphopoiesis / Q000276:immunology; D038042:Myelopoiesis / Q000276:immunology; D017686:Oncorhynchus mykiss / Q000276:immunology*; D051757:PAX5 Transcription Factor / Q000235:genetics / Q000276:immunology*; D054448:Precursor Cells, B-Lymphoid / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D016207:Cytokines; D007075:Immunoglobulin M; D007148:Immunoglobulin mu-Chains; D053583:Interleukin-1beta; D051757:PAX5 Transcription Factor; D014157:Transcription Factors
keywords: B lymphoid development; Disease resistance; Flavobacterium psychrophilum; Humoral immunity; Rainbow trout; Selective breeding