Department of Veterinary Microbiology & Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, United States.
Animal Health Department, Universidad Nacional de Colombia, Bogotá, Colombia.
Front Immunol. 2024 Apr 24;15:1380660. doi: 10.3389/fimmu.2024.1380660. eCollection 2024.
, a tick-borne apicomplexan parasite causing bovine babesiosis, remains a significant threat worldwide, and improved and practical vaccines are needed. Previous studies defined the members of the rhoptry associated protein-1 (RAP-1), and the neutralization-sensitive rhoptry associated protein-1 related antigen (RRA) superfamily in , as strong candidates for the development of subunit vaccines. Both RAP-1 and RRA share conservation of a group of 4 cysteines and amino acids motifs at the amino terminal end (NT) of these proteins.
Sequence comparisons among the RRA sequences of several strains and other spp parasites indicate a high level of conservation of a 15-amino acid (15-mer) motif located at the NT of the protein. BlastP searches indicate that the 15-mer motif is also present in adenylate cyclase, dynein, and other ATP binding proteins. AlphaFold2 structure predictions suggest partial exposure of the 15-mer on the surface of RRA of three distinct species. Antibodies in protected cattle recognize a synthetic peptide representing the 15-mer motif sequence in iELISA, and rabbit antibodies against the 15-mer react with the surface of free merozoites in immunofluorescence.
The presence of the 15-mer-like regions in dynein and ATP-binding proteins provides a rationale for investigating possible functional roles for RRA. The demonstrated presence of a surface exposed B-cell epitope in the 15-mer motif of the RRA, which is recognized by sera from protected bovines, supports its inclusion in future subunit epitope-based vaccines against .
巴贝斯虫病是一种由蜱传播的顶复门寄生虫，仍然是全球范围内的重大威胁，需要改进和实用的疫苗。以前的研究确定了 Rhoptry 相关蛋白-1（RAP-1）和中和敏感的 Rhoptry 相关蛋白-1相关抗原（RRA）超家族的成员是开发亚单位疫苗的强有力候选物。RAP-1 和 RRA 在这些蛋白质的氨基末端（NT）都具有保守的一组 4 个半胱氨酸和氨基酸基序。
对几种 株和其他 种寄生虫的 RRA 序列进行序列比较表明，位于蛋白质 NT 的 15 个氨基酸（15 个氨基酸）基序高度保守。BlastP 搜索表明，15 个氨基酸基序也存在于腺苷酸环化酶、动力蛋白和其他 ATP 结合蛋白中。AlphaFold2 结构预测表明，三个不同 种的 RRA 上的 15 个氨基酸基序部分暴露在表面。受保护牛的抗体在 iELISA 中识别代表 15 个氨基酸基序序列的合成肽，而针对 15 个氨基酸基序的兔抗体在免疫荧光中与游离裂殖体的表面反应。
动力蛋白和 ATP 结合蛋白中存在 15 个氨基酸类似区为研究 RRA 的可能功能作用提供了依据。在 种 RRA 的 15 个氨基酸基序中存在暴露的 B 细胞表位，并且受保护牛的血清识别该表位，这支持将其包含在未来针对 的亚单位表位基疫苗中。
