Induction of proliferative responses of T cells from Babesia bovis-immune cattle with a recombinant 77-kilodalton merozoite protein (Bb-1).
A major portion of a Babesia bovis-specific gene encoding a 77-kDa merozoite protein (Bb-1) produced during natural infection in cattle and in microaerophilous culture was subcloned into the pGEX1N expression vector. Recombinant Bb-1 protein fused to glutathione S-transferase (Bb-1-GST) was used to examine cellular immune responses in B. bovis-immune cattle. Sera from rabbits immunized with Bb-1-GST reacted with fusion protein and with the native antigen present in crude B. bovis but not with B. bigemina merozoites. Bb-1-GST but not GST induced strong proliferation of T lymphocytes from these immune cattle, and Bb-1-reactive T-cell lines which consisted of a mixed population of either CD4+ and CD8+ cells or CD4+, CD8+, and "null" (gamma delta T) cells were established by in vitro stimulation of peripheral blood mononuclear cells with the recombinant fusion protein. Three CD4+ CD8- and three CD4- CD8+ Bb-1-specific T-cell clones were identified after limiting-dilution cloning of the cell lines. The studies described here demonstrate that the 77-kDa protein of B. bovis contains T-cell epitopes capable of eliciting proliferation of two types of T cells in immune cattle, an important consideration for the design of a recombinant subunit vaccine.
Tetzlaff
C L
CL
Department of Veterinary Pathobiology, Texas A & M University, College Station 77843.
Rice-Ficht
A C
AC
Woods
V M
VM
Brown
W C
WC
D000818:Animals; D016793:Babesia bovis / Q000276:immunology*; D002417:Cattle; D005260:Female; D005982:Glutathione Transferase / Q000276:immunology; D007114:Immunization; D008213:Lymphocyte Activation; D015800:Protozoan Proteins / Q000276:immunology*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000276:immunology
D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D014614:Vaccines, Synthetic; D005982:Glutathione Transferase