Vectors and Vector-borne Diseases Research Programme, Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, Pretoria, South Africa; Agricultural Research Council-Biotechnology Platform, Private Bag X5, Onderstepoort, 0110, Pretoria, South Africa.
Vectors and Vector-borne Diseases Research Programme, Department of Veterinary Tropical Diseases, University of Pretoria, Private Bag X04, Onderstepoort, 0110, Pretoria, South Africa; Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA.
Ticks Tick Borne Dis. 2020 Jul;11(4):101444. doi: 10.1016/j.ttbdis.2020.101444. Epub 2020 Apr 18.
Bovine anaplasmosis is a globally economically important tick-borne disease caused by the obligate intraerythrocytic rickettsia, Anaplasma marginale. A live Anaplasma centrale blood-based vaccine is available, but it does not protect against all A. marginale field strains and may also transmit other blood-borne pathogens. Five potential outer membrane protein (OMP) vaccine candidates have been well-characterised in A. marginale strains from the USA, however, their levels of conservation in other countries must be ascertained in order to inform their use in a vaccine with regional or global efficacy. This study assessed the amino acid variation in vaccine candidate OMPs in South African strains of A. marginale, and also compared the immunogenic properties between South African and US strains. OMP genes Am779, Am854, omp7, omp8 and omp9 were amplified and sequenced from a set of genetically diverse South African samples with different msp1α-genotypes. OMPs Am854 and Am779 were highly conserved, with 99-100 % amino acid identity, while Omp7, Omp8 and Omp9 had 79-100 % identity with US strains. As has been shown previously, Omp7-9 possess conserved N- and C- termini, a central variable region, and a highly conserved CD4 T-cell epitope, FLLVDDA(I/V)V, in the N-terminal region. Western blot analysis of recombinant OMPs indicates strong antigenic conservation between South African and US strains of A. marginale, suggesting that they are good candidates for use in a novel global vaccine cocktail, although further work on the best formulation and delivery methods will be necessary.
牛无浆体病是一种具有全球经济重要性的蜱传疾病，由专性红细胞内立克次体，边缘无浆体引起。目前已有一种基于活无浆体中央血的疫苗，但它不能预防所有的无浆体田间株，也可能传播其他血源性病原体。在美国的无浆体菌株中，已经很好地描述了 5 种潜在的外膜蛋白（OMP）疫苗候选物，然而，为了确定它们在其他国家的保守程度，以便在具有区域或全球疗效的疫苗中使用，必须确定它们在其他国家的保守程度。本研究评估了南非无浆体菌株中候选 OMP 的氨基酸变异，并比较了南非和美国菌株的免疫原性。从一组具有不同 msp1α 基因型的遗传多样性南非样本中扩增和测序了 OMP 基因 Am779、Am854、omp7、omp8 和 omp9。OMPs Am854 和 Am779 高度保守，氨基酸同一性为 99-100%，而 Omp7、Omp8 和 Omp9 与美国菌株的同一性为 79-100%。如前所述，Omp7-9 具有保守的 N-和 C-末端、中央可变区和高度保守的 CD4 T 细胞表位 FLLVDDA（I/V）V，位于 N 末端区域。重组 OMP 的 Western blot 分析表明，南非和美国无浆体菌株之间具有很强的抗原保守性，这表明它们是新型全球疫苗鸡尾酒的良好候选物，尽管需要进一步研究最佳配方和输送方法。
