title: Low molecular weight proteins of Cowdria ruminantium (Welgevonden isolate) induce bovine CD4+-enriched T-cells to proliferate and produce interferon-gamma.
abstract: An important objective in vaccination strategies is to activate lymphocytes with particular effector functions. Cellular immunity and the type I cytokine IFN-gamma have been implicated in protective immunity to heartwater. Furthermore, low molecular weight proteins of Cowdria ruminantium have been shown to induce peripheral blood mononuclear cells to proliferate. To determine which lymphocyte subset responds when stimulated with fractionated C. ruminantium proteins, specific short-term lymphocyte cultures were established from cattle immunized with the Welgevonden isolate. Four cattle were immunized, two by infection and treatment and two with inactivated organisms. Cell surface phenotypic analysis of the cultures indicated that CD4+ lymphocytes were enriched over time. This coincided with increased antigen-specific proliferation and IFN-gamma production. Proteins of molecular weights 13-18kDa induced the CD4+-enriched T-cell cultures, derived from each of the animals, to proliferate and produce IFN-gamma. Although the two groups of cattle were immunized differently, their lymphocytes responded similarly. These results extend previous findings by identifying the responder cells as being predominantly IFN-gamma producing CD4+ lymphocytes. This cytokine has been implicated in immunity to the parasite. The low molecular weight proteins that induced CD4+ lymphocytes to proliferate and produce IFN-gamma are therefore likely to be important in protection against heartwater and may have a role in vaccine development.
authors.affiliation: Immunology Division, Onderstepoort Veterinary Institute, Private Bag X5, 0110, Onderstepoort, South Africa. mirinda@moon.ovi.ac.za
authors.forename: M
authors.initials: M
authors.lastname: Van Kleef
authors.forename: H
authors.initials: H
authors.lastname: Macmillan
authors.forename: N J
authors.initials: NJ
authors.lastname: Gunter
authors.forename: E
authors.initials: E
authors.lastname: Zweygarth
authors.forename: B A
authors.initials: BA
authors.lastname: Allsopp
authors.forename: V
authors.initials: V
authors.lastname: Shkap
authors.forename: D H
authors.initials: DH
authors.lastname: Du Plessis
authors.forename: W C
authors.initials: WC
authors.lastname: Brown
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000517:prevention & control*; D016995:Ehrlichia ruminantium / Q000276:immunology*; D006357:Heartwater Disease / Q000276:immunology / Q000517:prevention & control*; D007114:Immunization / Q000662:veterinary*; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000276:immunology; D008213:Lymphocyte Activation; D008970:Molecular Weight
chemical_list: D001428:Bacterial Vaccines; D007371:Interferon-gamma