Recombinant Secretory IgA (SIgA) complexes have the potential to improve antibody-based passive immunotherapeutic approaches to combat many mucosal pathogens. In this report, we describe the expression, purification and characterization of a human SIgA format of the broadly neutralizing anti-HIV monoclonal antibody (mAb) 2G12, using both transgenic tobacco plants and transient expression in Nicotiana benthamiana as expression hosts (P2G12 SIgA). The resulting heterodecameric complexes accumulated in intracellular compartments in leaf tissue, including the vacuole. SIgA complexes could not be detected in the apoplast. Maximum yields of antibody were 15.2 μg/g leaf fresh mass (LFM) in transgenic tobacco and 25 μg/g LFM after transient expression, and assembly of SIgA complexes was superior in transgenic tobacco. Protein L purified antibody specifically bound HIV gp140 and neutralised tier 2 and tier 3 HIV isolates. Glycoanalysis revealed predominantly high mannose structures present on most N-glycosylation sites, with limited evidence for complex glycosylation or processing to paucimannosidic forms. O-glycan structures were not identified. Functionally, P2G12 SIgA, but not IgG, effectively aggregated HIV virions. Binding of P2G12 SIgA was observed to CD209 / DC-SIGN, but not to CD89 / FcalphaR on a monocyte cell line. Furthermore, P2G12 SIgA demonstrated enhanced stability in mucosal secretions in comparison to P2G12 IgG mAb.

重组分泌型IgA（SIgA）复合物具有改进基于抗体的被动免疫治疗方法以对抗许多粘膜病原体的潜力。在本报告中，我们使用转基因烟草植物和本氏烟草的瞬时表达，描述了广泛中和的抗HIV单克隆抗体（mAb）2G12的人SIgA格式的表达，纯化和特​​征作为表达宿主（P2G12 SIgA）。所得的异十聚体复合物积聚在叶片组织（包括液泡）的细胞内区室中。在质外体中未检测到SIgA复合物。转基因烟草中抗体的最大产量为15.2μg/ g叶片新鲜质量（LFM），瞬时表达后为25μg/ g LFM，在转基因烟草中，SIgA复合物的组装效果更好。蛋白L纯化的抗体与HIV gp140特异性结合，并中和了2级和3级HIV分离株。糖分析表明，大多数N-糖基化位点上主要存在高甘露糖结构，而复杂糖基化或加工成甘露糖苷形式的证据有限。未鉴定出O-聚糖结构。在功能上，P2G12 SIgA而非IgG有效聚集了HIV病毒粒子。在单核细胞系上观察到P2G12 SIgA与CD209 / DC-SIGN结合，但未与CD89 / FcalphaR结合。此外，与P2G12 IgG mAb相比，P2G12 SIgA在粘膜分泌中显示出增强的稳定性。