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Live fish vaccines: history and perspectives
1Institut National de la Recherche Agronomique (INRA), Unité de Virologie et Immunologie Moléculaires, Jouy-en-Josas, France.
Developments in Biological Standardization
|January 1, 1997
Summary
Researchers identified key mutations in fish viral glycoprotein to create safe and effective live vaccines. These novel strains show promise for preventing enzootic fish viral diseases.
Area of Science:
- Veterinary Virology
- Fish Immunology
- Molecular Biology
Background:
- Conventional and genetically-engineered vaccine approaches for enzootic fish viral diseases have yielded unsatisfactory results.
- Understanding the molecular basis of viral virulence and antigenicity is crucial for developing effective live vaccines.
Observation:
- Sequence analysis of neutralization-escape mutants revealed specific amino acid positions on the glycoprotein involved in viral pathogenesis.
- Attenuated viral phenotypes were consistently linked to simultaneous mutations in two distinct glycoprotein regions (125-140 and 430-433).
- Reversion to virulence correlated with the loss of these specific mutations, confirming their role in pathogenicity.
Findings:
- Further attenuation of a temperature-resistant variant (tr25) identified mutants with additional mutations at position 139.
- These highly attenuated mutants demonstrated complete non-virulence in fish (1000-1400 degree-days) via bath administration.
- The selected mutants retained immunogenicity and possessed desirable markers, including thermo-resistance and antigenicity.
Implications:
- The identified non-virulent, immunogenic mutants are ideal candidates for developing novel live vaccines against fish viral diseases.
- Further confirmation through field trials is necessary to validate their protective activity and containment.
- This research provides a molecular framework for designing safer and more effective fish vaccines.