|MC GUIRE, T|
|Knowles Jr, Donald|
Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/1999
Publication Date: N/A
Interpretive Summary: These data show for the first time a bovine immune response to a DNA vaccine containing an A. marginale major surface protein. The significance of this work is that is demonstrates that in principle, a DNA vector can be used to deliver vaccine candidates of A. marginale. An interesting outcome of this research was the finding that the antibody response to the A. marginale protein, delivered via a DNA vector, was biased in that only immunoglobulin IgG1 was detected. This work may indicate that DNA vectors, used to deliver vaccine candidates may also be useful in directing the character of the bovine immune response.
Technical Abstract: Immunization with the native major surface protein 1 (MSP1) (a heterodimer containing disulfide and noncovalently bonded polypeptides designated MSP1a and MSP1b) of the erythrocytic stage of Anaplasma marginale conferred protection against homologous challenge. The plasmid pVCL/MSP1a, whichencodes the complete msp1a gene of A. marginale under the control of human cytomegalovirus immediate-early enhance/promoter and intron A, was constructed. The immune responses elicited by immunization with pVCL/MSP1a were evaluated in mice and cattle. Antibody reactive with native MSP1a was detected in pooled sera of immunized BALB/c mice 3 weeks following primary immunization. Two calves seronegative for A. marginale were immunized four times, at weeks 0, 3, 7 and 13 with pVCL/MSP1a. By 8 weeks, both calves responded to MSP1a with an antibody titer of 1:100, which peaked at 1:1,600 and 1:800 by 16 weeks after the initial immunization. Interestingly, immunoblotting with anti-immunoglobulin G1 (anti-IgG1) and anti-IgG2 specific monoclonal antibodies revealed a restricted IgG1 anti-MSP1a response in both animals. T-lymphocyte lines, established after the fourth immunization, proliferated specifically against A. marginale homogenate and purified MSP1 in a dose-depended manner. These data provide a basis for an immunization strategy to direct bovine immune responses by using DNA vaccine vectors containing single or multiple genes encoding major surface proteins of A. marginale.