Stability Engineering of Recombinant Secretory IgA.

Area of Science:

• Immunology
• Biotechnology
• Protein Engineering

Background:

• Secretory IgA (SIgA) is a key immunotherapy candidate for mucosal surfaces.
• Challenges in SIgA expression, purification, and stability hinder its therapeutic application.
• IgA1 and IgA2 isotypes, along with IgA2 allotypes (IgA2m(1), IgA2m(2)), possess distinct structural and functional properties.

Purpose of the Study:

• To engineer stable secretory IgA2 (SIgA2) variants for enhanced mucosal immunotherapy.
• To address production and stability issues associated with the IgA2m(1) allotype.
• To compare engineered SIgA2 with SIgA1 for SARS-CoV-2 topical delivery.

Main Methods:

• Introduction of specific mutations to facilitate disulfide bond formation in IgA2.
• Expression and purification of engineered SIgA2 variants in *Nicotiana benthamiana*.
• Comparative analysis of expression levels, assembly efficacy, thermal stability, and aerosolization potential.

Main Results:

• Engineered SIgA2 (P221R) demonstrated significantly improved expression and assembly in *Nicotiana benthamiana*.
• Enhanced SIgA2 variants exhibited increased thermal stability under physiological and acidic conditions.
• Engineered SIgA2 proved suitable for aerosolization via a mesh nebulizer.

Conclusions:

• Stability-enhancing mutations effectively overcome hurdles in SIgA expression and stability.
• Engineered SIgA2 represents a promising platform for developing stable and effective mucosal immunotherapies.
• These findings pave the way for improved topical delivery of SIgA antibodies, including against SARS-CoV-2.