Development of a synthetic virus for enterovirus A71 vaccine candidate

[[abstract]]Human enterovirus A71 (EV-A71) has become an emergent infectious disease worldwide most notably in Asia. EV-A71 infection occasionally causes neurological diseases with pulmonary edema, which is fatal for children. Based on phylogenetic analysis of VP1 protein coding sequences, most EVA71 isolates are classified into genotypes A, B and C, while some isolates belong to the recently discovered genotypes D, E, and F. Synthetic viruses have been applied to produce vaccine seed viruses for influenza virus and others. To produce a synthetic virus of EV-A71, we used 4643-TW-98 (genotype C2) as the template (r4643), de novo synthesized the capsid protein genome of genotype C4 and introduced into the cDNA clone of r4643 to produce reverse genetics virus (r4643-C4VP). We then compared the viral properties of this r4643-C4VP with parental r4643 and native 4643 virus. The r4643-C4VP showed relatively smaller plaque morphology than native 4643, but the virus-induced cytopathic effect was similar to both r4643 and native 4643. Synthetic reverse genetics viruses and native virus showed no significant difference in growth rate in both RD and Vero cell lines. In addition, mouse anti-r4643 and anti- r4643-C4VP sera showed similar neutralizing antibody titers against both r4643-C4VP and r4643 viruses, suggesting that both viruses had similar antigenicity. Furthermore, both antisera had similar neutralization activity to different genotypes of EV-A71, including genotypes B2, B4, B5, C2, and C4. Collectively, these results prove that the synthetic virus could be applied to EV-A71 vaccine seed candidate which will contribute to next generation vaccine development