# Replacement of pr gene with Japanese encephalitis virus pr using reverse genetics reduces antibody-dependent enhancement of dengue virus 2 infection

## TL;DR

Replacing a gene in dengue virus with one from Japanese encephalitis virus reduces antibody-dependent enhancement of dengue infection, potentially improving vaccine development.

## Contribution

A novel chimeric dengue virus was created to reduce antibody-dependent enhancement by replacing its pr gene with one from Japanese encephalitis virus.

## Key findings

- Chimeric JEVpr/DENV2 showed reduced virulence and good immunogenicity.
- Anti-JEVpr/DENV2 sera had broad cross-reactivity and efficient neutralizing activity against all four DENV serotypes.
- Anti-JEVpr/DENV2 sera significantly reduced dengue infection enhancement in K562 cells compared to anti-DENV2 sera.

## Abstract

Severe dengue is more likely found during secondary heterologous dengue virus (DENV) infection or primary infection of infants born to dengue-immune mothers and led to the hypothesis of antibody-dependent enhancement (ADE). It has been reported that pre-membrane (prM)-reactive antibodies do not efficiently neutralize DENV infection but instead potently promote ADE infection. Meanwhile, these enhancing anti-prM antibodies mainly react with the precursor (pr) peptide. To evaluate the effect of pr gene substitution on neutralization and ADE of DENV infection, a novel chimeric dengue virus (JEVpr/DENV2) was rationally constructed by replacing the DENV pr gene with Japanese encephalitis virus (JEV) pr gene, based on the full-length infectious complementary DNA (cDNA) clone of DENV2 ZS01/01. We found that chimeric JEVpr/DENV2 showed reduced virulence and good immunogenicity. In addition, anti-JEVpr/DENV2 sera showed broad cross-reactivity and efficient neutralizing activity with all four DENV serotypes and immature DENV2 (ImDENV2). Most importantly, compared with anti-DENV2 sera, anti-JEVpr/DENV2 sera showed significantly reduced enhancing activity of DENV infection in K562 cells. These results suggest that the ADE activities could be reduced by replacing the DENV pr gene with JEV pr gene. These findings may help us better understand the pathogenesis of DENV infection and provide a reference for the development of a vaccine against DENV.