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Introduction: Japanese encephalitis virus (JEV) and Zika virus (ZIKV) are prevalent in over 80 countries or territories worldwide, causing hundreds of thousands of cases annually. But currently there is a lack of specific antiviral agents and effective vaccines. Methods: In the present study, to identify human neutralizing monoclonal antibody (mAb) against JEV or/and ZIKV, we isolated ZIKV-E protein-binding B cells from the peripheral venous blood of a healthy volunteer who had received the JEV live-attenuated vaccine and performed 10× Genomics transcriptome sequencing and BCR sequencing analysis, we then obtained the V region amino acid sequences of a novel mAb LZY3412. We expressed mAb LZY3412 and evaluated its ability to bind to E proteins of dengue virus, JEV and ZIKV, neutralize JEV and ZIKV infections in vitro , protect mice against lethal JEV or ZIKV attack. The epitopes on E proteins of JEV/ZIKV recognized by mAb LZY3412 were analyzed using molecular docking and constructing E protein mutants. Results: Our results show that recombinant mAb LZY3412 has high-affinity with the E proteins of three viruses, with the kinetically derived binding affinity (KD) values of 440 and 482.5 nM against JEV-E protein and ZIKV-E protein, respectively; recombinant mAb LZY3412 can efficiently neutralize JEV and ZIKV infections in vitro , with the NT50 values of 19.9 ng/mL and 631 ng/mL, respectively; application of recombinant mAb LZY3412 can significantly improve the percentage survival and reduce the serum viral loads of neonatal mice infected with JEV or ZIKV. Finally, two amino acid residues (Ala399 and Gly400) located in EDIII of JEV-E protein were potentially recognized by LZY3412 whereas two amino acid residues (Met15 and Thr406) out of EDIII of ZIKV-E proteins were recognized by LZY3412. Discussion: Considering mAb LZY3412 has neutralizing effects on various flaviviruses, this mAb is expected to be developed as therapeutic or preventive drug for these flaviviruses, and can also be used to guide the development of vaccines against these flaviviruses. [ABSTRACT FROM AUTHOR]

Introduction: Japanese encephalitis virus (JEV) and Zika virus (ZIKV) pose a severe threat to human health. Our previous research results, as well as those of other research groups, indicated that antibodies (Abs) induced by JEV infection or JEV vaccine vaccination could enhance ZIKV infection in vitro and exacerbate the mortality of ZIKV-infected mice, vice versa, which is known as antibody-dependent enhancement (ADE). Although studies on other flaviviruses revealed that altering the amino acid residues located in the fusion loop (FL) of envelope (E) protein can reduce the level of flavivirus-cross-reactive Abs, thereby abating the ADE of heterologous flavivirus infection, it is unclear whether this strategy is equally applicable to JEV. Methods: In this study, we constructed recombinant adenoviruses and nucleotide-modified mRNA-lipid nanoparticle (LNP) encoding JEV wild-type E protein or E protein mutant (designated as Ad5-JEV-EWT and Ad5-JEV-Emut; JEV-EWT mRNA-LNP, and JEV-Emut mRNA-LNP). We evaluated the immunogenicity of these vaccine candidates in mice and the capacity of vaccine-immune mouse sera to neutralize JEV infection or mediate ADE of ZIKV infection in vitro and in vivo. Results: Ad5-JEV-Emut or JEV-Emut mRNA-LNP immunization induced ZIKV-cross-reactive Ab response which is dramatically lower than that induced by Ad5-JEV-EWT and JEV-EWT mRNA-LNP, respectively. The levels of JEV-neutralizing Abs induced by Ad5-JEV-Emut or JEV-Emut mRNA-LNP are comparable to that induced by Ad5-JEV-EWT and JEV-EWT mRNA-LNP, respectively. The ability of Abs induced by Ad5-JEV-Emut to enhance ZIKV infection in vitro is attenuated as compared with that induced by Ad5-JEV-EWT. Moreover, JEV-Emut mRNA-LNP immunization elicited potent T cell response similar to JEV-EWT mRNA-LNP in mice. Mice immunized with each mRNA-LNP exhibited lower level of serum viral load than the mock-immunized mice post JEV challenge. Mice receiving JEV-EWT mRNA-LNP-immune mouse sera exhibited ADE post ZIKV challenge whereas passively transferred JEV-Emut mRNA-LNP-immune mouse sera did not lead to obvious ADE of ZIKV infection in recipient mice. Most importantly, maternally acquired Abs did not enhance the mortality of 1-day-old neonates born to JEV-Emut mRNA-LNP-immunized mice post ZIKV challenge. Discussion: These results suggest that optimizing the FL sequence of JEV could significantly reduce the level of JEV/ZIKV-cross-reactive Abs and abrogate the ADE of ZIKV infection, providing a promising strategy to develop effective and safety JEV vaccine. [ABSTRACT FROM AUTHOR]

Introduction: Japanese encephalitis virus (JEV) and Zika virus (ZIKV) are prevalent in over 80 countries or territories worldwide, causing hundreds of thousands of cases annually. But currently there is a lack of specific antiviral agents and effective vaccines., Methods: In the present study, to identify human neutralizing monoclonal antibody (mAb) against JEV or/and ZIKV, we isolated ZIKV-E protein-binding B cells from the peripheral venous blood of a healthy volunteer who had received the JEV live-attenuated vaccine and performed 10× Genomics transcriptome sequencing and BCR sequencing analysis, we then obtained the V region amino acid sequences of a novel mAb LZY3412. We expressed mAb LZY3412 and evaluated its ability to bind to E proteins of dengue virus, JEV and ZIKV, neutralize JEV and ZIKV infections in vitro , protect mice against lethal JEV or ZIKV attack. The epitopes on E proteins of JEV/ZIKV recognized by mAb LZY3412 were analyzed using molecular docking and constructing E protein mutants., Results: Our results show that recombinant mAb LZY3412 has high-affinity with the E proteins of three viruses, with the kinetically derived binding affinity (KD) values of 440 and 482.5 nM against JEV-E protein and ZIKV-E protein, respectively; recombinant mAb LZY3412 can efficiently neutralize JEV and ZIKV infections in vitro , with the NT 50 values of 19.9 ng/mL and 631 ng/mL, respectively; application of recombinant mAb LZY3412 can significantly improve the percentage survival and reduce the serum viral loads of neonatal mice infected with JEV or ZIKV. Finally, two amino acid residues (Ala399 and Gly400) located in EDIII of JEV-E protein were potentially recognized by LZY3412 whereas two amino acid residues (Met15 and Thr406) out of EDIII of ZIKV-E proteins were recognized by LZY3412., Discussion: Considering mAb LZY3412 has neutralizing effects on various flaviviruses, this mAb is expected to be developed as therapeutic or preventive drug for these flaviviruses, and can also be used to guide the development of vaccines against these flaviviruses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chen, Zhang, Liu, Zhu, Chen, Ni and Wen.)