Antibody engineering: targeting Bacillus anthracis

描述（由申请人提供）： 炭疽杆菌构成了巨大的生物恐怖主义威胁。虽然抗生素可以有效治疗炭疽感染，但早期诊断是必不可少的。此外，已经开发出抗生素抗性菌株。现有疫苗的有效性和安全性也令人担忧，新生儿接种疫苗的安全性问题加剧。使用抗体的被动免疫疗法将提供一种有吸引力的替代保护途径，其将有效对抗抗生素耐药菌株。然而，合适的（人源化）抗体目前不可用。由于现有抗体的血清半衰期有限，在预防中使用被动抗体也需要频繁给药。我们将努力克服这些缺点。首先，我们计划使用当前的抗体工程方法来产生针对B的孢子和毒素组分的抗体。炭疽病其次，我们将使用我们实验室开发的技术来增加γ球蛋白（IgG）的血清半衰期。我们已经表明，可以通过工程化与Fc受体FcRn相互作用的抗体位点来增加血清持久性。该Fc受体还调节IgG穿过母胎屏障的转移。因此，血清半衰期增加的抗体可能会通过增加与FcRn的结合而更有效地转移到胎儿体内。我们的具体目标是：1）产生有效的抗保护性抗原和抗孢子外壳蛋白抗体; 2）增加抗体的血清半衰期; 3）分析保护性抗体穿过人和鼠母胎屏障的转移; 4）使最有希望的抗体人源化以用于进一步研究。拟议的分析应能为预防和治疗炭疽提供有效的试剂。它们还应该为理解抗体在限制感染中的作用提供新的见解，这对其他病原体具有更广泛的相关性。

DESCRIPTION (provided by applicant): Bacillus anthracis poses an enormous bioterrorism threat. Although antibiotics can be effective in treating anthrax infection, early diagnosis is essential. In addition, antibiotic resistant strains have been developed. There is also concern about the efficacy and safety of existing vaccines, and safety issues are exacerbated for the vaccination of neonates. Passive immunotherapy with antibodies would provide an attractive, alternative route for protection that would be effective against antibiotic resistant strains. However, suitable (humanized) antibodies are currently not available. The use of passive antibodies in prophylaxis also necessitates frequent doses due to the limited serum half-life of existing antibodies. We will attempt to overcome these shortcomings. First, we plan to use current methods of antibody engineering to generate antibodies that target both spore and toxin components of B. anthracis. Second, we will use technology that has been developed in our laboratory to increase the serum half-life of gamma globulins (IgGs). We have shown that it is possible to increase the serum persistence by engineering the site of an antibody that interacts with the Fc receptor, FcRn. This Fc receptor also regulates the transfer of IgG across the materno-fetal barrier. It is therefore likely that antibodies with increased serum half-lives will be transferred more efficiently to the fetus via increased binding to FcRn. Our specific aims are:1) to generate effective anti-protective antigen and anti-spore coat protein antibodies; 2) to increase the serum half-lives of the antibodies; 3) to analyze the transfer of protective antibodies across human and murine maternal-fetal barriers; 4) to humanize the most promising antibodies for use in further studies. The proposed analyses should provide effective reagents for the prophylaxis and treatment of anthrax. They should also give new insight into understanding the role of antibodies in limiting infection, and this has broader relevance to other pathogens.