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Genetic research

DNA Vaccines Show Limited Protection Against Viral Transmission in Field Conditions

Strategic Insights

— 1 min read

Researchers from the Virginia Institute of Marine Science, in collaboration with colleagues, conducted a study to evaluate the efficacy of three vaccine regimens against infectious hematopoietic necrosis virus (IHNV) in rainbow trout. They assessed the protection against viral transmission using various delivery methods, including intramuscular injection, intraperitoneal injection, and bath immersion. The study found that all three vaccine regimens provided significant protection against fish mortality, but only the DNA vaccine regimen demonstrated substantial protection against viral shedding. The researchers also observed that the viral genotype fish were exposed to influenced vaccine efficacy, and the DNA vaccine reduced direct transmission in fish cohabitation experiments from 100% to 50%.

Key Takeaways:

  • The three vaccine regimens (DNA, inactivated, and attenuated) showed significant protection against fish mortality in rainbow trout.
  • The DNA vaccine regimen was qualitatively the most protective, while the attenuated vaccine regimen was the least effective.
  • The vaccine regimens provided limited protection against viral shedding, with a 10% reduction in cumulative shedding over the course of the infection.
  • The researchers observed a correlation between the viral genotype and vaccine efficacy, suggesting that genetic similarity between the vaccine strain and the fish exposed to the virus influenced vaccine performance.
  • The study's results suggest that existing IHNV vaccines may not provide long-term efficacy in field conditions due to limited protection against viral transmission.
  • The findings support the need for further research to enhance the transmission protection of IHNV vaccines.

Statistics:

  • 100% direct transmission reduction in fish cohabitation experiments using the DNA vaccine regimen.
  • 10% reduction in cumulative shedding over the course of the infection using all three vaccine regimens.
  • 50% protection against fish mortality achieved by the DNA vaccine regimen.
  • 48% and 25% protection against fish mortality achieved by the attenuated and inactivated vaccine regimens, respectively.
  • The study measured viral shedding in rainbow trout for 14 days post-exposure.

Sources:

  • Vaccines. Efficacy of Three Vaccine Regimens Against Infectious Hematopoietic Necrosis Virus Transmission Potential in Rainbow Trout. Vaccines, 2025,13(8):864. (Vaccines - http://www.mdpi.com/journal/vaccines).
  • NewsRx. Researchers' Work from Virginia Institute of Marine Science Focuses on DNA Vaccines (Efficacy of Three Vaccine Regimens Against Infectious Hematopoietic Necrosis Virus Transmission Potential in Rainbow Trout). Biotech Week. September 10, 2025; p 483.

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