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Replication of Marek's disease virus in cell cultures derived from genetically resistant chickens
Abstract:
Various parameters of replication of Marek's disease virus (MDV) were studied in cells derived from genetically resistant (line 6) and susceptible (line 7) chickens. Cell-free and cell-associated preparations of three strains of pathogenic MDV (JM, GA, and Id-1) replicated equally well in cells of resistant and susceptible chickens. There were no demonstrable differences between the two genetic sources of cells for the chronological appearance and type of cytopathic effects and for the type of virus-induced antigens detectable by immunofluorescent and agar-gel precipitin tests. MDV propagated for about 4 weeks in cells of resistant line 6 chickens remained nonvirulent for line 6 and fully virulent for line 7 chickens. The lack of expression of genetic resistance to Marek's disease at cellular level contrasts the infection mechanisms of MDV from those of viruses associated with lymphoid leukosis in chickens.
Insights
Marek's disease virus (MDV) replicates similarly in resistant and susceptible chicken cells, indicating genetic resistance isn't expressed at the cellular level. This contrasts with other poultry viruses affecting lymphoid leukosis.
Area of Science:
- Virology
- Immunology
- Genetics
Background:
- Marek's disease (MD) is a significant lymphoproliferative disease in chickens.
- Genetic resistance in chickens offers a key strategy for MD control.
- Understanding cellular mechanisms of MDV resistance is crucial.
Purpose of the Study:
- To investigate the cellular-level replication of Marek's disease virus (MDV) in genetically resistant versus susceptible chicken cells.
- To determine if genetic resistance to MDV is expressed at the cellular level.
- To compare MDV infection parameters in different chicken genetic lines.
Main Methods:
- Replication studies of pathogenic MDV strains (JM, GA, Id-1) in cell cultures from resistant (line 6) and susceptible (line 7) chickens.
- Assessment of cell-free and cell-associated virus preparations.
- Evaluation of cytopathic effects and virus-induced antigens using immunofluorescence and agar-gel precipitation tests.
- Virulence assays of MDV propagated in resistant cells.
Main Results:
- MDV replicated equally well in both resistant (line 6) and susceptible (line 7) chicken cells.
- No significant differences were observed in cytopathic effects or viral antigen expression between the cell lines.
- MDV propagated in resistant cells maintained its virulence for susceptible chickens but remained nonvirulent for resistant chickens.
Conclusions:
- Genetic resistance to Marek's disease is not expressed at the cellular level in chicken cells.
- MDV infection mechanisms differ from those of viruses causing lymphoid leukosis in chickens.
- Cellular factors do not appear to mediate genetic resistance to MDV infection.