Novel Solutions for Vaccines and Diagnostics To Combat Brucellosis
Novel Solutions for Vaccines and Diagnostics To Combat Brucellosis
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DOI：
10.1021/acscentsci.7b00019
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发表时间：
2017-03-22
影响因子：
18.2
通讯作者：
McGiven, John
中科院分区：
文献类型：
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作者：
Mandal, Satadru Sekhar;Duncombe, Lucy;McGiven, John
布鲁氏菌病是通过检测动物和人类血液中对两种碳水化合物抗原（称为 A 和 M）特异的抗体来诊断的，这两种抗原同时存在于单个细胞壁 O-多糖中。动物布鲁氏菌病疫苗含有这些抗原决定簇，因此无法区分受感染和接种疫苗的动物，因为两组动物都会产生 A 和 M 特异性抗体。我们假设纯 A 疫苗的化学合成将通过合成的 M 诊断抗原对受感染的动物进行独特的识别，该抗原不会与该疫苗产生的抗体发生反应。合成了两种形式的 A 抗原，即通过还原性和非还原性末端糖与破伤风类毒素缀合的六糖和七糖，并用作先导候选疫苗。针对这些免疫原的小鼠抗体谱表明，为了避免与诊断性 M 抗原发生反应，必须最大限度地诱导结合内部寡糖序列的抗 A 抗体，并最大限度地减少针对末端非还原性单糖的抗体的产生。这一目标是通过布鲁氏菌 O-多糖通过其高碘酸盐氧化末端非还原性单糖与破伤风类毒素结合来实现的，从而破坏末端表位并将抗体反应集中在内部 A 表位上。这建立了一种方法来解决数十年来如何在不影响受感染动物诊断的情况下制造有效的布鲁氏菌病疫苗的挑战。
Brucellosis is diagnosed by detection of antibodies in the blood of animals and humans that are specific for two carbohydrate antigens, termed A and M, which are present concurrently in a single cell wall O-polysaccharide. Animal brucellosis vaccines contain these antigenic determinants, and consequently infected and vaccinated animals cannot be differentiated as both groups produce A and M specific antibodies. We hypothesized that chemical synthesis of a pure A vaccine would offer unique identification of infected animals by a synthetic M diagnostic antigen that would not react with antibodies generated by this vaccine. Two forms of the A antigen, a hexasaccharide and a heptasaccharide conjugated to tetanus toxoid via reducing and nonreducing terminal sugars, were synthesized and used as lead vaccine candidates. Mouse antibody profiles to these immunogens showed that to avoid reaction with diagnostic M antigen it was essential to maximize the induction of anti-A antibodies that bind internal oligosaccharide sequences and minimize production of antibodies directed toward the terminal nonreducing monosaccharide. This objective was achieved by conjugation of Brucella O-polysaccharide to tetanus toxoid via its periodate oxidized terminal nonreducing monosaccharide, thereby destroying terminal epitopes and focusing the antibody response on internal A epitopes. This establishes the method to resolve the decades-long challenge of how to create effective brucellosis vaccines without compromising diagnosis of infected animals.