Moreno de Alborán I, Martínéz-alonso C, Barbas C F, Burton D R, Ditzel H J
Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA.
Immunotechnology. 1995 May;1(1):21-8. doi: 10.1016/1380-2933(95)00002-x.
IgA constitutes the first line of immune defense, interacting with a variety of environmental antigens. Following infection with respiratory syncytial virus (RSV) individuals frequently exhibit elevated serum IgA titers specific for the virus. Previously combinatorial IgG libraries have successfully been used to clone such human antibody responses.
Here we evaluate the possibility of constructing combinatorial IgA libraries on the surface of filamentous phage to retrieve human viral-specific IgA Fab fragments.
Bone marrow from an HIV-1 seropositive donor was used as RNA source to construct combinatorial IgA kappa and lambda libraries of approximately 10(7) clones.
By affinity selection using an immobilized recombinant RSV FG protein, two unique IgA Fab fragments producing clones (AD5 and AD23) reactive with the selecting antigen were isolated. One of the Fab fragments was found to be specific for RSV F glycoprotein and bind with high apparent affinity (2 x 10(8) M-1). The other binds with lower affinity and exhibits cross-reactivity with other antigens.
The strategy described, involving construction of combinatorial IgA libraries on the surface of filamentous phage, should be generally applicable to the investigation of both mucosal and systemic human IgA immune responses, and may become an important tool for evaluation of mucosal vaccine regimes.
免疫球蛋白A（IgA）构成免疫防御的第一道防线，与多种环境抗原相互作用。感染呼吸道合胞病毒（RSV）后，个体血清中针对该病毒的IgA滴度常常升高。此前，组合IgG文库已成功用于克隆此类人类抗体反应。
在此，我们评估在丝状噬菌体表面构建组合IgA文库以获取人类病毒特异性IgA Fab片段的可能性。
使用一名HIV-1血清阳性供体的骨髓作为RNA来源，构建了约10^7个克隆的组合IgA κ和λ文库。
通过使用固定化重组RSV FG蛋白进行亲和选择，分离出两个与选择抗原反应的独特IgA Fab片段产生克隆（AD5和AD23）。发现其中一个Fab片段对RSV F糖蛋白具有特异性，并以高表观亲和力（2×10^8 M^-1）结合。另一个结合亲和力较低，并与其他抗原表现出交叉反应性。
所描述的策略，即涉及在丝状噬菌体表面构建组合IgA文库，应普遍适用于研究黏膜和全身性人类IgA免疫反应，并可能成为评估黏膜疫苗方案的重要工具。
