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Journal of virology2003; 77(13); 7244-7253; doi: 10.1128/jvi.77.13.7244-7253.2003

A live attenuated equine infectious anemia virus proviral vaccine with a modified S2 gene provides protection from detectable infection by intravenous virulent virus challenge of experimentally inoculated horses.

Abstract: Previous evaluations of inactivated whole-virus and envelope subunit vaccines to equine infectious anemia virus (EIAV) have revealed a broad spectrum of efficacy ranging from highly type-specific protection to severe enhancement of viral replication and disease in experimentally immunized equids. Among experimental animal lentivirus vaccines, immunizations with live attenuated viral strains have proven most effective, but the vaccine efficacy has been shown to be highly dependent on the nature and severity of the vaccine virus attenuation. We describe here for the first time the characterization of an experimental attenuated proviral vaccine, EIAV(UK)deltaS2, based on inactivation of the S2 accessory gene to down regulate in vivo replication without affecting in vitro growth properties. The results of these studies demonstrated that immunization with EIAV(UK)deltaS2 elicited mature virus-specific immune responses by 6 months and that this vaccine immunity provided protection from disease and detectable infection by intravenous challenge with a reference virulent biological clone, EIAV(PV). This level of protection was observed in each of the six experimental horses challenged with the reference virulent EIAV(PV) by using a low-dose multiple-exposure protocol (three administrations of 10 median horse infectious doses [HID(50)], intravenous) designed to mimic field exposures and in all three experimentally immunized ponies challenged intravenously with a single inoculation of 3,000 HID(50). In contrast, naïve equids subjected to the low- or high-dose challenge develop a detectable infection of challenge virus and acute disease within several weeks. Thus, these data demonstrate that the EIAV S2 gene provides an optimal site for modification to achieve the necessary balance between attenuation to suppress virulence and replication potential to sufficiently drive host immune responses to produce vaccine immunity to viral exposure.
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Publication Date: 2003-06-14 PubMed ID: 12805423PubMed Central: PMC164776DOI: 10.1128/jvi.77.13.7244-7253.2003Google Scholar: Lookup
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  • U.S. Gov't
  • P.H.S.

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.

The research presents a study in which an experimental vaccine for equine infectious anemia virus (EIAV) is developed, resulting in protection against the disease. The vaccine, named EIAV(UK)deltaS2, modifies the S2 accessory gene to limit in vivo replication without affecting in vitro growth properties, and its efficacy was tested in horses and ponies.

Background

  • Equine infectious anemia virus (EIAV) affects horses and other members of the equid family.
  • Previous vaccine studies against EIAV were mentioned and their limitations explained: whole-virus and envelope subunit vaccines have shown inconsistent results, ranging from highly type-specific protection to severe enhancement of viral replication and disease.
  • Vaccines using live attenuated viral strains have proven effective in some animal trials, but their efficacy depends on the nature and severity of the vaccine virus attenuation.

Creation of the EIAV(UK)deltaS2 Vaccine

  • The researchers created EIAV(UK)deltaS2, an attenuated proviral vaccine that inactivates the S2 accessory gene.
  • The purpose of modifying the S2 gene was to control the in vivo replication of the virus without affecting its in vitro growth properties.

Testing the EIAV(UK)deltaS2 Vaccine

  • The vaccine was tested on horses, and the results indicated that it sparked mature virus-specific immune responses by 6 months.
  • The immunized horses were then exposed to a virulent biological clone of EIAV, called EIAV(PV), via intravenous challenge. Regardless of the dosing protocol applied, all experimental animals showed protection from the disease and detectable infection.

Comparing the Results with Control Group

  • The researchers compared the results to naïve (unvaccinated) horses exposed to the same EIAV(PV) challenge. The unvaccinated horses developed a detectable infection and disease symptoms within several weeks.

Conclusions

  • The research showed the potential of the EIAV S2 gene as a site for modification to balance between attenuation to suppress virulence and replication potential to stimulate host immune responses. This creation resulted in a vaccine that can immunize against viral exposure.

It is clear that the research proposes a potential solution to effectively vaccinate horses and related species against EIAV.

Cite This Article

APA
Li F, Craigo JK, Howe L, Steckbeck JD, Cook S, Issel C, Montelaro RC. (2003). A live attenuated equine infectious anemia virus proviral vaccine with a modified S2 gene provides protection from detectable infection by intravenous virulent virus challenge of experimentally inoculated horses. J Virol, 77(13), 7244-7253. https://doi.org/10.1128/jvi.77.13.7244-7253.2003

Publication

Journal of virology
ISSN: 0022-538X
NlmUniqueID: 0113724
Country: United States
Language: English
Volume: 77
Issue: 13
Pages: 7244-7253

Researcher Affiliations

Li, Feng
  • Department of Molecular Genetics and Biochemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Craigo, Jodi K
    Howe, Laryssa
      Steckbeck, Jonathan D
        Cook, Sheila
          Issel, Charles
            Montelaro, Ronald C

              MeSH Terms

              • Animals
              • Antibody Formation
              • Equine Infectious Anemia / immunology
              • Equine Infectious Anemia / prevention & control
              • Horses
              • Immunity, Cellular
              • Infectious Anemia Virus, Equine / pathogenicity
              • Viral Proteins / genetics
              • Viral Vaccines / administration & dosage
              • Viral Vaccines / immunology
              • Virulence

              Grant Funding

              • R01 AI025850 / NIAID NIH HHS
              • R01 AI25850 / NIAID NIH HHS

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