Japanese Encephalitis DNA Vaccines with Epitope Modification Reduce the Induction of Cross-Reactive Antibodies against Dengue Virus and Antibody-Dependent Enhancement of Dengue Virus Infection

Abstract

Infection with viruses belonging to the genus Flavivirus, such as Japanese encephalitis virus (JEV) and dengue virus (DENV), is a worldwide health problem. Vaccines against JEV and DENV are currently available. However, the dengue vaccine possibly increases the risk of severe dengue due to antibody-dependent enhancement (ADE). Moreover, the Japanese encephalitis (JE) vaccine reportedly induces cross-reactive ADE-prone antibodies against DENV, potentially leading to symptomatic dengue. Therefore, it is necessary to eliminate the risk of ADE through vaccination. In this study, we attempted to develop a JE vaccine that does not induce ADE of DENV infection using an epitope modification strategy. We found that an ADE-prone monoclonal antibody cross-reactive to DENV and JEV recognizes the 106th amino acid residue of the E protein of JEV (E-106). The JE DNA vaccine with a mutation at E-106 (E-106 vaccine) induced comparable neutralizing antibody titers against JEV to those induced by the wild-type JE DNA vaccine. Meanwhile, the E-106 vaccine induced 64-fold less cross-reactive ADE-prone antibodies against DENV. The mutation did not compromise the protective efficacy of the vaccine in the lethal JEV challenge experiment. Altogether, the modification of a single amino acid residue identified in this study helped in the development of an ADE-free JE vaccine.

Epitope(s) involving amino acids of the fusion loop of Japanese encephalitis virus envelope protein is(are) important to elicit protective immunity

“…Here, we demonstrated DII FL 106/107 residues were involved in inducing neutralizing antibodies against JEV and these two residues together with the 101 residue were involved in eliciting neutralizing antibodies against JEV and WNV. However, a recent study showed that JEV GIII VLP-expressing plasmids encoding single or double DII FL G106V and L107F mutations performed comparably to the wild-type plasmid in eliciting neutralizing antibodies against JEV ( 39 ). This discrepancy could be due to the use of different amino acids at the DII FL 106 and 107 residues, the method to measure neutralizing antibody titers, or the type of immunogens (VLP vs DNA) used in the study ( 39 ).…”

“…However, a recent study showed that JEV GIII VLP-expressing plasmids encoding single or double DII FL G106V and L107F mutations performed comparably to the wild-type plasmid in eliciting neutralizing antibodies against JEV ( 39 ). This discrepancy could be due to the use of different amino acids at the DII FL 106 and 107 residues, the method to measure neutralizing antibody titers, or the type of immunogens (VLP vs DNA) used in the study ( 39 ). By contrast, DENV2 VLP-expressing plasmids encoding DII FL G106R/L107D mutations elicited comparable neutralizing antibodies to the wild-type plasmid by reducing DII FL immunogenicity and manipulating antibody profile ( 30 ).…”

“…It has been suggested that DII FL of JE serocomplex viruses is not necessary for inducing neutralizing antibodies, as the most potent neutralizing antibodies recognize DIII rather than DII FL ( 33 – 36 ). Some studies have indicated that encoding DII FL mutations could influence the antigenicity of JE serocomplex virus-derived VLPs or the immunogenicity of JEV VLP-expressing plasmids ( 37 – 39 ). However, there is a need to conduct comprehensive research on the impact of DII FL mutations on the antigenicity, immunogenicity, and protective potency of JE serocomplex virus-derived immunogens.…”

Immunization with different recombinant West Nile virus envelope proteins induces varying levels of serological cross-reactivity and protection from infection

“…In WNV serology, a modified FL has been demonstrated to abolish the binding of antibodies induced by heterologous flavivirus infections ( Chabierski et al., 2014 ). In addition, FL-mutated E proteins have been used as parts of virus-like particles (VLPs) in vaccine development against ZIKV, DENV and JEV, resulting in a strong reduction of cross-reactive antibodies ( Crill et al., 2012 ; Richner et al., 2017 ; Kotaki et al., 2022 ). In contrast to these previous vaccine studies, we have used recombinant E ectodomains rather than VLPs, and demonstrate that the WNV E protein with mutated FL significantly reduces the induction of antibodies to heterologous flaviviruses.…”