[3P-28] 複数のフラビウイルスを中和するモノクローナル抗体の認識機構
West Nile Virus (WNV), which is one of the flavivirus family, causes West Nile fever and lethal encephalitis and is distributed throughout the world. We established a monoclonal antibody (WN_83) from Japanese Encephalitis Virus (JEV) - vaccinated volunteers. WN_83 neutralizes not only JEV but also WNV. To elucidate the mechanism how WN_83 recognizes both viruses, we determined a crystal structure of the antigen-antibody complex.
The Fab fragment of WN_83 and the domain III of the WNV envelope protein (WNVE DIII) complex was isolated by SEC. We obtained the 2.5 Å resolution structure from cluster crystals by using the automated crystallization robot, PXS2 in KEK and the automated data collection system, ZOO in SPring-8.
Both CDR3s interacted with Arg388 of WNVE DIII. Site-directed mutagenesis and ELISA showed that Arg388 is critical for the binding. Sequence alignment showed that Arg388 is conserved in the envelope protein of JEV (JEVE). In addition, several residues of the CDR-L1 and L3 interacted with WNVE DIII. The residues were not identical but similar in JEVE. These results suggest that the cross-reaction is probably caused by (1) the recognition of Arg388 conserved in JEVE and WNVE, and (2) the tolerance of the CDRs in the L chain.
The Fab fragment of WN_83 and the domain III of the WNV envelope protein (WNVE DIII) complex was isolated by SEC. We obtained the 2.5 Å resolution structure from cluster crystals by using the automated crystallization robot, PXS2 in KEK and the automated data collection system, ZOO in SPring-8.
Both CDR3s interacted with Arg388 of WNVE DIII. Site-directed mutagenesis and ELISA showed that Arg388 is critical for the binding. Sequence alignment showed that Arg388 is conserved in the envelope protein of JEV (JEVE). In addition, several residues of the CDR-L1 and L3 interacted with WNVE DIII. The residues were not identical but similar in JEVE. These results suggest that the cross-reaction is probably caused by (1) the recognition of Arg388 conserved in JEVE and WNVE, and (2) the tolerance of the CDRs in the L chain.