Characteristic profiling of CHO-cell expressed MERS-CoV RBD-Fc

The ongoing circulation of the Middle East Respiratory Syndrome coronavirus (MERS-CoV) in camels across Asia, the Middle East, and Africa, along with its occasional transmission to humans, demonstrates a need for a MERS vaccine. Previously, we have reported a receptor binding domain (RBD) of MERS-CoV fused with human Fc as a promising vaccine antigen (MERS-CoV RBD-Fc). We generated a stable recombinant CHO cell line expressing such a protein and developed a basic production process suitable for future technological transfer to pilot-scale manufacture. In this study, we employed various in-house analytical assays to examine the characteristics of purified RBD-Fc protein and evaluate its integrity and identity. We also performed buffer screening to assess the optimal formulation for protein stabilization. We discovered that the protein maintained its structure and functionality at a wide pH range from 3.5 to 9.5, but a neutral to basic environment was necessary to provide a more stabilizing condition that could reduce surface hydrophobicity and increase colloidal stability. Collectively, these data provide valuable insight into the product characteristics of our recombinant RBD-Fc protein, contributing to the advancement of MERS vaccine development.