MOLECULAR-BASIS FOR SURFACE-ANTIGEN SIZE POLYMORPHISMS AND CONSERVATION OF A NEUTRALIZATION-SENSITIVE EPITOPE IN ANAPLASMA-MARGINALE

被引:153
|
作者
ALLRED, DR [1 ]
MCGUIRE, TC [1 ]
PALMER, GH [1 ]
LEIB, SR [1 ]
HARKINS, TM [1 ]
MCELWAIN, TF [1 ]
BARBET, AF [1 ]
机构
[1] WASHINGTON STATE UNIV,DEPT VET MICROBIOL & PATHOL,PULLMAN,WA 99164
关键词
gene structure; rickettsia; tandem repeats; tick-borne diseases;
D O I
10.1073/pnas.87.8.3220
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Anaplasmosis is one of several tick-borne diseases severely constraining cattle production and usage in many parts of the world. Cattle can be protected from anaplasmosis by immunization with major surface protein 1, a surface protein of Anaplasma marginale carrying a neutralization-sensitive epitope. Marked size polymorphisms exist among different isolates of A. marginale in the AmF105 subunit of major surface protein 1, yet all isolates still contain the neutralization-sensitive epitope. To clarify the basis for these observations, the msp1α gene encoding AmF105 was cloned from four isolates and sequenced. The encoded polypeptides share a high degree of overall homology between isolates but contain a domain with various numbers of tandemly repeated sequences and three regions of clustered amino acid substitutions outside the repeat domain. The polypeptide size differences are completely explained by the variations in the numbers of tandem repeat units. We have mapped the neutralization-sensitive epitope to a sequence that is present within each repeat unit. These results identify a basis for size polymorphisms of the surface polypeptide antigen concomitant with B-cell epitope conservation in rickettsiae.
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页码:3220 / 3224
页数:5
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