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Merozoite surface antigen 2 proteins of Babesia bovis vaccine breakthrough isolates contain a unique hypervariable region composed of degenerate repeats

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Berens, S. J., Brayton, K. A., Molloy, J. B., Bock, R. E., Lew, A. E. and McElwain, T. F. (2005) Merozoite surface antigen 2 proteins of Babesia bovis vaccine breakthrough isolates contain a unique hypervariable region composed of degenerate repeats. Infection and immunity, 73 (11). pp. 7180-7189. ISSN 0019-95671098-5522


Article Link: https://doi.org/10.1128/IAI.73.11.7180-7189.2005

Article URL: https://pubmed.ncbi.nlm.nih.gov/16239512
Article URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1273907/


The merozoite surface antigen 2 (MSA-2) proteins of Babesia bovis are members of the variable merozoite surface antigen (VMSA) family that have been implicated in erythrocyte invasion and are important targets for antibody-mediated blocking of invasion. Extensive sequence variation in another VMSA member, MSA-1, has been shown in all vaccine breakthrough isolates. To test the hypothesis that the msa-2 genes of vaccine breakthrough isolates would also encode a diverse set of proteins, the complete msa-2 locus was characterized from 12 Australian B. bovis strains and isolates, including two vaccine strains and eight vaccine breakthrough isolates, and compared to the loci in previously and newly characterized American strains. In contrast to American strains, the msa-2 loci of all Australian strains and isolates examined contain, in addition to msa-2c, only a solitary gene (designated msa-2a/b) closely related to American strain msa-2a and msa-2b. Nevertheless, the proteins encoded by these genes are quite diverse both between and within geographic regions and harbor evidence of genetic exchange among other VMSA family members, including msa-1. Moreover, all but one of the Australian breakthrough isolate MSA-2a/b proteins is markedly different from the vaccine strain from which immune escape occurred, consistent with their role in strain-specific protective immunity. The densest distribution of polymorphisms occurs in a hypervariable region (HVR) within the carboxy third of the molecule that is highly proline rich. Variation in length and content of the HVR is primarily attributable to differences in the order and number of degenerate nucleotide repeats encoding three motifs of unknown function.

Item Type:Article
Additional Information:Open access PDF attached
Keywords:Amino Acid Sequence Animals Antigens, Protozoan/*chemistry/genetics/*immunology Babesia bovis/*chemistry/genetics/*immunology Genetic Variation Membrane Proteins/chemistry/genetics/immunology Molecular Sequence Data Protozoan Proteins/chemistry/genetics/immunology Protozoan Vaccines/*immunology Repetitive Sequences, Amino Acid/genetics/*immunology Sequence Homology, Amino Acid
Subjects:Science > Microbiology
Animal culture > Cattle
Veterinary medicine > Veterinary microbiology
Veterinary medicine > Veterinary bacteriology
Live Archive:29 Sep 2020 04:46
Last Modified:03 Sep 2021 16:46

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