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Infection and Immunity, July 1999, p. 3481-3487, Vol. 67, No. 7
Program in Vector-Borne Diseases,
Received 5 January 1999/Returned for modification 24 February
1999/Accepted 27 April 1999
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 (G. H. Palmer, A. F. Barbet, W. C. Davis, and
T. C. McGuire, Science 231:1299-1302, 1986). The MSP1a
polypeptide possesses a conserved neutralization-sensitive epitope. In
the present study, the immune response to DNA-mediated immunization
using msp1a was studied. The plasmid pVCL/MSP1a, which
encodes the complete msp1a gene of A. marginale
under the control of human cytomegalovirus immediate-early enhancer/promoter and intron A, was constructed. The immune responses elicited by immunization with pVCL/MSP1a into cardiotoxin-induced regenerating muscle 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-dependent 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.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Biased Immunoglobulin G1 Isotype Responses Induced
in Cattle with DNA Expressing msp1a of Anaplasma
marginale
*
Corresponding author. Mailing address: Animal Disease
Research Unit, ARS/USDA, Department of Veterinary Microbiology and
Pathology, Washington State University, Pullman, WA 99164-7030. Phone: (509) 335-6022. Fax: (509) 335-8328. E-mail:
dknowles{at}vetmed.wsu.edu.
Infection and Immunity, July 1999, p. 3481-3487, Vol. 67, No. 7
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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