# A rationally-designed, live-attenuated RSV vaccine for the elderly

> **NIH NIH R44** · CODAGENIX, INC. · 2022 · $809,351

## Abstract

PROJECT SUMMARY/ABSTRACT
Respiratory syncytial virus (RSV) is a common respiratory virus that usually causes mild, cold-like symptoms.
Most people recover within two weeks, but RSV is the most common cause of bronchiolitis and pneumonia in
children under one year of age, and leads to hospitalization of ~177,000 adults aged 65 and older of which
~14,000 die annually. Despite many attempts, a vaccine to protect these at-risk populations from RSV infection
remains elusive. To remediate this critical unmet need, Codagenix has applied its core technology, Synthetic
Attenuated Virus Engineering (SAVE) to the development of an RSV vaccine. SAVE is based on rational,
computer-aided gene design and chemical synthesis to produce live attenuated viruses through gene
“deoptimization.” SAVE generates live-attenuated viruses that are 100% antigenically identical to wild type
virus in all their proteins. MinL4.0, our lead RSV vaccine candidate contains 1,378 synonymous mutations in
the polymerase L open reading frame. It grows well at 32°C, is highly attenuated, displays wt-like
immunogenicity, and is genetically stable for at least 8 passages at 32°C in Vero cells. In this Phase IIb SBIR, we
will build on our successful Phase II SBIR and subsequent studies to further develop MinL4.0. Our initial
target patient population will be adults aged 50-75, a population that is at-risk for severe RSV disease. In this
Phase IIb work, we will reformulate MinL4.0 to make it commercially suitable for intranasal administration
and storage and then perform FDA-required stability and release testing of the re-formulated vaccine. We will
also perform preclinical safety and efficacy testing in cotton rats. No animal model of RSV recapitulates all of
the aspects of human RSV disease, but the cotton rat is probably the best small animal model. The cotton rat is
relatively permissive, can be infected throughout its life, exhibits immuno-senescence, including T-cell loss as
is found in older humans, and, like humans, is less resistant to RSV infection with age. Even though most
adults have some immunity to RSV and elderly adults are at risk for severe RSV infections, vaccine studies are
typically performed in young RSV naïve animals. Here, we will develop a new model of RSV pre-immunity in
aged cotton rats to more accurately model conditions found in older adults and serve as a more relevant and
stringent pre-clinical test of safety and efficacy that can be used by others. We will then test the safety and
efficacy of MinL4.0 in this new pre-immune aged cotton rat model of RSV disease. Our animal studies will be
conducted in partnership with Sigmovir, a contract research organization whose sole focus is the study of
infectious human diseases in the cotton rat model. Finally, based on these and other data, we will complete all
required documentation and submit an Investigational New Device (IND) application to the US Food and
Drug Administration (FDA) in order to conduct Phase I clini...

## Key facts

- **NIH application ID:** 10449335
- **Project number:** 5R44AI131756-05
- **Recipient organization:** CODAGENIX, INC.
- **Principal Investigator:** Steffen Mueller
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $809,351
- **Award type:** 5
- **Project period:** 2017-08-16 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10449335

## Citation

> US National Institutes of Health, RePORTER application 10449335, A rationally-designed, live-attenuated RSV vaccine for the elderly (5R44AI131756-05). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10449335. Licensed CC0.

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