# Rational Design of live-attenuated vaccines for flaviviruses

> **NIH NIH P20** · KANSAS STATE UNIVERSITY · 2020 · $220,203

## Abstract

Project summary:
The objective of the proposed study is to develop broadly effective attenuation strategies for the rational design
of live-attenuated vaccines (LAVs) against flaviviruses. Pathogenic flaviviruses cause severe human diseases
such as hemorrhagic fever and encephalitis. The use of two legacy vaccines, yellow fever virus (YFV) 17D and
Japanese encephalitis virus SA14-14-2, has demonstrated how immunization can be an efficient strategy for
disease control. However, the empirical approach used for the development of these LAVs has proven ineffective
in producing candidate LAVs for other flaviviruses, thereby demanding new strategies for rational vaccine design.
Previously, the rational design of flavivirus LAVs was based on the introduction of mutations that lead to
attenuated phenotypes observed in the two legacy vaccines and other attenuated mutants. This failed to produce
broadly effective attenuation concepts, because the mutagenesis targets lacked conserved sequences or
interacted with diverse host molecules. A major challenge in designing LAVs is the field's limited knowledge of
flavivirus virulence mechanisms. Target genes that contain consensus sequences, functionally important for the
virulence of different flaviviruses, are yet to be identified. In this study, the PI will develop two attenuation
strategies by interfering with the interdomain movements of flavivirus envelope (E) proteins. Interdomain
movements of E proteins are universally conserved mechanisms in all flaviviruses and critical for viral membrane
fusion and virion assembly; they are controlled by highly conserved sequences in two sets of interdomain
peptides, the envelope protein domain I (EDI) – envelope protein domain II (EDII) hinge and the EDI – envelope
protein domain III (EDIII) linker. The central hypothesis is that conserved residues in the interdomain
peptides are functionally important for flavivirus virulence, regardless of their tissue tropism and disease
pathogenesis. To remove virulence determinants in the two interdomain peptides, mutagenesis analyses will be
conducted in the following two specific aims: In Aim 1, highly conserved hydrophobic residues will be mutated to
interfere with the hydrophobic interactions that contribute to EDI-EDII hinge structure and functions; in Aim 2,
the structures and functions of EDI-EDIII linker will be disrupted by removing functionally important side-chains
of conserved residues and inserting additional glycine/prolin residues to increase peptide flexibility. Broadly
effective attenuation strategies will be developed by engineering selected mutations into the full-length
complementary DNA infectious clones of two model flaviviruses, West Nile virus and YFV, and then
demonstrating the loss of virulence in respective mouse models. The completion of the proposed study will lead
to an advancement in knowledge regarding the functional importance of the EDI-EDII hinge and EDI-EDIII linker
interdomain regions for flavi...

## Key facts

- **NIH application ID:** 9852901
- **Project number:** 1P20GM130448-01A1
- **Recipient organization:** KANSAS STATE UNIVERSITY
- **Principal Investigator:** Yan-Jang Huang
- **Activity code:** P20 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $220,203
- **Award type:** 1
- **Project period:** — → —

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9852901

## Citation

> US National Institutes of Health, RePORTER application 9852901, Rational Design of live-attenuated vaccines for flaviviruses (1P20GM130448-01A1). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9852901. Licensed CC0.

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