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Updated: Aug 14, 2026
Handling of the Cotton Rat in Studies for the Pre-clinical Evaluation of Oncolytic Viruses
Published on: November 24, 2014
A live RSV vaccine with engineered thermostability is immunogenic in cotton rats despite high attenuation
Christopher C Stobart1,2, Christina A Rostad1,2, Zunlong Ke3
1Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Insights
Developing a new live-attenuated vaccine (LAV) for respiratory syncytial virus (RSV) in infants is crucial. This engineered RSV LAV candidate, OE4, shows enhanced immunogenicity and efficacy while maintaining safety.
Area of Science:
- Virology
- Vaccinology
- Immunology
Background:
- Respiratory syncytial virus (RSV) is a major cause of infant hospitalization, with no approved pediatric vaccine.
- Live-attenuated vaccines (LAVs) for RSV have been tested in infants, but balancing attenuation and immunogenicity remains difficult.
Purpose of the Study:
- To engineer a novel respiratory syncytial virus (RSV) live-attenuated vaccine (LAV) candidate with enhanced immunogenicity.
- To identify specific fusion (F) protein residues crucial for pre-fusion antigen stability and infectivity.
Main Methods:
- Genetic mapping of RSV strain line 19 fusion (F) protein to identify key residues.
- Engineering of the OE4 LAV candidate through codon-deoptimization of non-structural genes (NS1, NS2) and attachment gene (G), deletion of the small hydrophobic (SH) gene, and ablation of secreted G.
- Evaluation of OE4 immunogenicity and efficacy in cotton rat models.
Main Results:
- The engineered OE4 LAV candidate expresses a stabilized line 19F protein, maintaining pre-fusion antigen levels.
- OE4 demonstrated enhanced thermal stability, immunogenicity, and efficacy in preclinical models.
- Despite significant attenuation in the airways, OE4 maintained protective immune responses.
Conclusions:
- The engineered OE4 RSV LAV demonstrates a promising balance of attenuation and immunogenicity.
- This strategy of targeting F protein residues and genetic modifications offers a viable path toward an effective pediatric RSV vaccine.
- Further development of OE4 could address the unmet need for a safe and immunogenic RSV vaccine for infants.
Abstract:
Respiratory syncytial virus (RSV) is a leading cause of infant hospitalization and there remains no pediatric vaccine. RSV live-attenuated vaccines (LAVs) have a history of safe testing in infants; however, achieving an effective balance of attenuation and immunogenicity has proven challenging. Here we seek to engineer an RSV LAV with enhanced immunogenicity. Genetic mapping identifies strain line 19 fusion (F) protein residues that correlate with pre-fusion antigen maintenance by ELISA and thermal stability of infectivity in live RSV. We generate a LAV candidate named OE4 which expresses line 19F and is attenuated by codon-deoptimization of non-structural (NS1 and NS2) genes, deletion of the small hydrophobic (SH) gene, codon-deoptimization of the attachment (G) gene and ablation of the secreted form of G. OE4 (RSV-A2-dNS1-dNS2-ΔSH-dGm-Gsnull-line19F) exhibits elevated pre-fusion antigen levels, thermal stability, immunogenicity, and efficacy despite heavy attenuation in the upper and lower airways of cotton rats.
