3R-NC

3R-NC is a recombinant protein subunit vaccine candidate designed for intranasal administration to provide broad-spectrum protection against SARS-CoV-2 variants and other sarbecoviruses. Developed by the Wuhan Institute of Virology and Sun Yat-sen University, the name "3R-NC" refers to its chimeric structure, which incorporates three distinct Receptor Binding Domains (RBDs) from different coronavirus strains (such as BA.2.86, EG.5, and the bat-derived WIV1) into a scaffold derived from the N-terminal and C-terminal domains of flagellin (NC). The vaccine is typically administered alongside the recombinant flagellin protein adjuvant KFD1 (a TLR5 agonist) to enhance mucosal immunogenicity. Unlike traditional intramuscular vaccines, 3R-NC aims to induce high levels of both systemic IgG and local secretory IgA (sIgA) in the respiratory tract, creating a first-line immune barrier to prevent viral infection and transmission. It is currently being evaluated in Phase 1 clinical trials as a booster for individuals previously immunized with inactivated COVID-19 vaccines.

Other names

triple-RBD scaffold proteintriple receptor-binding domain scaffold proteinSARS-CoV-2 subunit mucosal vaccineSARS-CoV2 subunit mucosal vaccineSARS-CoV 2 subunit mucosal vaccine