Expression and characterization of a recombinant broadly-reactive monoclonal antibody against group 1 and 2 influenza viruses.

Production of broadly-reactive antibodies is critical for universal immunodiagnosis of rapidly-evolving influenza viruses. Most monoclonal antibodies (mAbs) are generated in mice using the hybridoma technology which involves labor- and time-consuming screening and low yield issues. In this study, a recombinant antibody based on a broadly-reactive mAb against the hemagglutinin (HA) stalk of H7N9 avian influenza virus was expressed in CHO cells and its biological characteristics, cross-reactivity and epitope recognition were identified. The variable genes of the parental antibody were amplified and cloned into the antibody-expressing plasmids containing the constant genes of murine IgG1. The recombinant antibody was expressed in high yield and purity in CHO cells and showed similar features to the parental antibody, including negative hemagglutination inhibition activity against H7N9 virus and high binding activity with the H7N9 HA protein. Notably, the recombinant antibody exhibited a broad reactivity with different influenza subtypes belonging to group 1 and group 2, which was associated with its recognition of a highly-conserved epitope in the stalk, as observed for the parental antibody. Our results suggest that cell-based antibody expression system can be utilized as an important alternative to the hybridoma technology for antibody production for influenza virus diagnostics.