Generation of a Human–Mouse Chimeric Anti-Japanese Encephalitis Virus and Zika Virus Monoclonal Antibody Using CDR Grafting

Japanese encephalitis (JE) caused by Japanese encephalitis virus (JEV) is a dominant arthropod-borne disease in Asian countries. However, effective antiviral treatment for JEV has not yet been established. 2H4 is a previously identified mouse monoclonal antibody (mAb) which exhibited neutralizing activity against JEV infection. Herein, we designed a novel mAb F(ab')₂ 2A10-2H4-CDR by transplanting the complementarity-determining regions (CDRs) of 2H4 into the corresponding regions of a murine mAb 2A10 which has high homology with human mAb. We further expressed the recombinant human-mouse chimeric mAb 2A10-2H4-CDR-hFc by linking 2A10-2H4-CDR with CH2 and CH3 domains of one human mAb. The results of indirect immunofluorescence assay and ELISA show that 2A10-2H4-CDR-hFc can recognize the E proteins of JEV and Zika virus (ZIKV), similar to its original form 2H4. Moreover, 2A10-2H4-CDR-hFc displayed neutralizing activities against JEV and ZIKV equivalent to that of 2H4 in vitro (NT₅₀ value against JEV = 0.079 μg/mL versus 0.022 μg/mL, respectively; NT₅₀ value against ZIKV = 1.584 μg/mL versus 0.446 μg/mL, respectively). Both 2H4 and 2A10-2H4-CDR-hFc significantly increased the survival and reduced the serum viral burden of mice challenged by JEV or ZIKV. This study successfully validates an anti-JEV and ZIKV human-mouse chimeric mAb and establishes a basis for future application of this Ab in preventing or/and treating of both JEV and ZIKV infections.