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Home / Equine Research Bank / Viruses / V4020 Venezuelan Equine Encephalitis Vaccine: Mitigating Neu...
Viruses2025; 17(8); 1136; doi: 10.3390/v17081136

V4020 Venezuelan Equine Encephalitis Vaccine: Mitigating Neuroinvasion and Reversion Through Rational Design.

Abstract: There is a need for safe and effective vaccines against the Venezuelan equine encephalitis virus that infects both humans and equines. However, development of a live-attenuated vaccine using the TC-83 strain has been hampered by substantial reactogenicity and the potential for neuroinvasion. In this study, we demonstrate that V4020, a new TC-83-based investigational VEEV vaccine with redundant safety features preventing neuroinvasion and reversion, exhibited no neuroinvasion potential in a murine model. Following subcutaneous or intramuscular administration, a subset of mice that received the TC-83 vaccine succumbed to central nervous system infection, with replicating virus detected in the CNS, demonstrating a low, yet detectable neuroinvasion potential of the TC-83 vaccine in vivo. Sequencing analysis of the TC-83 virus recovered from the brains identified a pseudoreversion of E2 R120I, as E2 R120 is known to confer attenuation for TC-83. In contrast, V4020 showed no evidence of virus in the CNS, highlighting one of the V4020 features, a new synonymous codon to minimize reversion to the wild-type residue. Overall, our study establishes V4020 as a rationally designed, safe vaccine candidate for VEEV with significantly reduced neuroinvasion risk.
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Publication Date: 2025-08-19 PubMed ID: 40872849PubMed Central: PMC12390694DOI: 10.3390/v17081136Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This research evaluates V4020, a newly designed live-attenuated vaccine for Venezuelan equine encephalitis virus (VEEV), focusing on its safety and ability to prevent viral neuroinvasion and genetic reversion compared to the traditional TC-83 vaccine strain.

Background

  • Venezuelan equine encephalitis virus (VEEV) is a pathogen that affects both humans and horses, causing serious neurological illness.
  • There is a need for vaccines that are both effective and safe, especially avoiding harmful side effects like reactogenicity (adverse reactions) and neuroinvasion (virus entering the central nervous system, CNS).
  • The existing live-attenuated vaccine, based on the TC-83 strain, has limitations: some vaccinated individuals suffer CNS infections due to residual neuroinvasion potential and possible viral reversion to a more virulent form.

Objectives of the Study

  • To evaluate the safety of V4020, a novel vaccine based on the TC-83 strain but with engineered safety features.
  • To determine if V4020 eliminates or reduces the risk of neuroinvasion in vivo using a mouse model.
  • To assess whether V4020 prevents reversion mutations that restore the virus’s virulence.

Methodology

  • V4020, a TC-83-derived investigational vaccine, was designed with redundant safety modifications, such as a new synonymous codon that reduces the chance of mutation back to the wild-type virulent form.
  • Mice were vaccinated either subcutaneously or intramuscularly with either V4020 or the original TC-83 vaccine.
  • Researchers observed the mice for signs of CNS infection and measured viral presence in the brain tissue.
  • Virus recovered from CNS infections was sequenced to identify genetic changes like pseudoreversion mutations.

Key Findings

  • Some mice vaccinated with TC-83 developed central nervous system infections, confirming that TC-83 retains a low but meaningful potential for neuroinvasion.
  • Virus replicated within the CNS of these mice, and sequencing revealed a pseudoreversion mutation at position E2 R120I, which is significant because E2 R120 normally attenuates TC-83’s virulence.
  • In contrast, mice vaccinated with V4020 showed no detectable virus in the CNS, indicating no neuroinvasion occurred.
  • The synonymous codon change in V4020 likely contributed to minimizing the risk of reversion to the virulent wild-type sequence.

Conclusions and Implications

  • V4020, through rational design, successfully addresses two critical safety concerns of live-attenuated vaccines for VEEV: neuroinvasion and reversion to virulence.
  • By eliminating neuroinvasion in the mouse model and preventing pseudoreversion mutations, V4020 represents a promising vaccine candidate with improved safety over TC-83.
  • The findings support further development and potential clinical testing of V4020 as an effective and safe vaccine against Venezuelan equine encephalitis virus.

Cite This Article

APA
Centers A, Barnaby K, Goedeker S, Pignataro A, Tretyakova I, Lukashevich I, Pushko P, Chung D. (2025). V4020 Venezuelan Equine Encephalitis Vaccine: Mitigating Neuroinvasion and Reversion Through Rational Design. Viruses, 17(8), 1136. https://doi.org/10.3390/v17081136

Publication

Viruses
ISSN: 1999-4915
NlmUniqueID: 101509722
Country: Switzerland
Language: English
Volume: 17
Issue: 8
PII: 1136

Researcher Affiliations

Centers, Adrian
  • School of Medicine, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202, USA.
Barnaby, Koji
  • School of Medicine, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202, USA.
Goedeker, Sidney
  • School of Medicine, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202, USA.
Pignataro, Ava
  • School of Medicine, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202, USA.
Tretyakova, Irina
  • Medigen, Inc., 8420-S Gas House Pike, Frederick, MD 21701, USA.
Lukashevich, Igor
  • School of Medicine, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202, USA.
Pushko, Peter
  • Medigen, Inc., 8420-S Gas House Pike, Frederick, MD 21701, USA.
Chung, Donghoon
  • School of Medicine, University of Louisville, 505 S. Hancock Street, Louisville, KY 40202, USA.

MeSH Terms

  • Encephalitis Virus, Venezuelan Equine / immunology
  • Encephalitis Virus, Venezuelan Equine / genetics
  • Animals
  • Encephalomyelitis, Venezuelan Equine / prevention & control
  • Encephalomyelitis, Venezuelan Equine / virology
  • Encephalomyelitis, Venezuelan Equine / immunology
  • Mice
  • Viral Vaccines / immunology
  • Viral Vaccines / administration & dosage
  • Viral Vaccines / genetics
  • Vaccines, Attenuated / immunology
  • Vaccines, Attenuated / administration & dosage
  • Disease Models, Animal
  • Female
  • Humans
  • Horses
  • Brain / virology
  • Antibodies, Viral / immunology

Grant Funding

  • U01 AI155406 / NIAID NIH HHS
  • AI155406 / NIH HHS

Conflict of Interest Statement

I.T. and P.P. are employees and stakeholders at Medigen, Inc., and declare no conflicts of interest. All authors declare no conflicts of interest.

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