Characterization of a cross-reactive monoclonal antibody against Norovirus genogroups I, II, III and V

Noroviruses cause the majority of epidemic outbreaks of acute viral gastroenteritis worldwide. In a previous study of monoclonal antibodies against Norovirus GII/4 strain, we identified a continuous epitope 55WIRNNF60 that was recognized by MAb N2C3. Subsequent studies found that this MAb could recognize several different strains of Noroviruses, not just GII/4. In the present study, we used homology modeling to confirm that the epitope of N2C3 was exposed on the surface of GII/4 capsid protein. To determine the conservation of this epitope in different strains of Noroviruses, an amino acid sequence alignment was constructed of 37 Norovirus strains representing all strains of GI and GII, 2 strains of Bovine Norovirus (GIII) and 3 strains of murine Norovirus (GV). ELISA was performed using recombinant fusion proteins of 15 mutations identified in Noroviruses and 12 were recognized by N2C3. These 12 peptides represented 29 Norovirus strains that were distributed throughout genogroups I, II, III and V. To our knowledge, this is the first study to identify a cross-reactive monoclonal antibody able to detect both human and animal-associated Noroviruses. Thus, MAb N2C3 is likely to be a useful tool for detecting a broad range of Norovirus strains.