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[Temperature-sensitive mutant of influenza virus: isolation and evaluation in mice]
Abstract:
A provisional temperature-sensitive mutant, ProTs8, of influenza A/WSN (H0N1) virus was isolated from primary chicken embryo fibroblast culture inoculated with influenza A/WSN (H0N1) and incubated with medium 199, containing 2% chicken embryo extract, and 400 micrograms/ml of 5-fluorouracil. Its EOP (efficiency of plaquing) value between 39.5 degrees C and 33 degrees C was about 0.007, and the control was about 0.82. Through lowering the shut-off-temperature to 38 degrees C, we had successfully isolated two temperature-sensitive mutants, Ts8-38 and Ts8-37, from their parent, ProTs8. 50% mouse virulent doses (MVD50) of these two mutants were around 10(-0.6), while the control group was 10(-4.0). Groups of mice immunized with 0.4 MVD50 or 0.04 MVD50 of Ts8-38 or Ts8-37 mutant by nasal instillation had shown significant resistance to the challenging infection of the wild type virus, influenza A/WSN (H0N1) (challenge dose, 1,000 MVD50 or 100 MVD50), if compared to the control group.
Insights
Researchers developed temperature-sensitive influenza A mutants (ProTs8, Ts8-38, Ts8-37) for vaccine potential. Nasal immunization with these mutants protected mice against wild-type influenza A/WSN (H0N1) virus challenge.
Area of Science:
- Virology
- Immunology
- Genetics
Context:
- Influenza A virus poses a significant public health threat.
- Development of safe and effective influenza vaccines is crucial.
- Temperature-sensitive mutants offer a potential avenue for vaccine development.
Purpose:
- To isolate and characterize temperature-sensitive mutants of influenza A/WSN (H0N1) virus.
- To evaluate the immunogenicity and protective efficacy of these mutants in a mouse model.
Summary:
- A provisional temperature-sensitive mutant (ProTs8) was derived from influenza A/WSN (H0N1) using 5-fluorouracil.
- Two further attenuated mutants (Ts8-38, Ts8-37) were generated from ProTs8 with reduced virulence (MVD50).
- Mice immunized intranasally with Ts8-38 or Ts8-37 showed significant resistance to challenge with wild-type influenza A/WSN (H0N1).
Impact:
- These temperature-sensitive mutants demonstrate potential as live attenuated vaccine candidates against influenza A.
- The study highlights a method for generating attenuated influenza virus strains with potential vaccine applications.
- Successful immunization suggests these mutants could form the basis for a new generation of influenza vaccines.