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In vitro and in vivo studies with an avian reovirus derived from a temperature-sensitive mutant clone
Abstract:
A temperature-sensitive (ts) mutant of avian reovirus isolate Maine 1-203 was obtained at 41 C. The 19th passage of this mutant (ts 19) was utilized for in vitro studies comparing its replication in macrophage cultures with that of its parent strain and an apathogenic S1133 virus. In vivo studies were initiated to determine the ts mutant's pathogenicity for day-old chicks, safety and protective levels for 6-day-old chicks, and interference with Marek's disease, Newcastle, and infectious bronchitis vaccinations. Although the results of in vitro trials indicated no difference among the three reoviruses in the in vitro pathogenicity for macrophage cultures, in vivo studies found the mutant to differ from its parent strain in pathogenicity for day-old chicks. When the ts mutant was administered at 6 days of age, it was a safe and effective vaccine against viral arthritis, with no resulting suppression of other vaccine responses.
Insights
A temperature-sensitive avian reovirus mutant showed no difference in lab replication but differed in pathogenicity in chicks. This mutant proved safe and effective as a vaccine against viral arthritis.
Area of Science:
- Veterinary Virology
- Avian Pathology
- Immunology
Background:
- Avian reoviruses cause significant economic losses in poultry.
- Temperature-sensitive (ts) mutants are valuable tools for studying viral replication and vaccine development.
- Understanding the pathogenicity and vaccine potential of ts mutants is crucial for poultry health.
Purpose of the Study:
- To characterize a temperature-sensitive (ts) mutant of avian reovirus (ARV).
- To compare the in vitro replication and in vivo pathogenicity of the ts mutant with its parent strain and an apathogenic strain.
- To evaluate the safety and efficacy of the ts mutant as a vaccine in young chicks.
Main Methods:
- Isolation and characterization of a ts mutant of ARV isolate Maine 1-203.
- In vitro replication studies in macrophage cultures.
- In vivo studies in day-old and 6-day-old chicks to assess pathogenicity, safety, and protective immunity.
- Evaluation of interference with other common poultry vaccinations.
Main Results:
- In vitro studies showed no difference in macrophage replication between the ts mutant, parent strain, and apathogenic strain.
- In vivo studies revealed differences in pathogenicity between the ts mutant and its parent strain in day-old chicks.
- The ts mutant was found to be safe and effective in protecting 6-day-old chicks against viral arthritis without suppressing other vaccine responses.
Conclusions:
- The ts mutant of ARV differs from its parent strain in pathogenicity in vivo.
- The ts mutant serves as a safe and effective vaccine candidate against viral arthritis in poultry.
- Further research can explore the broader application of this ts mutant in poultry vaccination strategies.