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Influence of Toxoplasma on manifestations of Moloney virus infections
Abstract:
Considerable evidence documents the importance of co-factors, including the immune response, in expression of oncogenicity of tumour viruses. To determine whether a common protozoal infection that can depress lymphocyte function alters manifestations of oncogenic virus infection, a mouse model of Toxoplasma infection with depressed T lymphocyte function was developed. In this model, Toxoplasma depressed blastogenic transformation to the T-cell mitogen Concanavalin A and primary antibody response to sheep red blood cells which requires T cell help. Uninfected and Toxoplasma-infected mice were then infected with Moloney leukaemia or Moloney sarcoma viruses and development of lymphoma and sarcoma were evaluated. Toxoplasma infection, which induced depression of T-cell function, decreased the incidence of Moloney sarcoma virus induced rhabdomyosarcomas but did not alter progression or regression of tumour in those mice that developed tumour. Conjoint infection with Toxoplasma and Moloney leukaemia virus did not increase incidence of lymphoma when compared with incidence of lymphoma in mice infected with Moloney leukaemia virus alone.
Insights
Toxoplasma infection can impair T-cell function. This study found that Toxoplasma infection decreased the incidence of certain virus-induced tumors (rhabdomyosarcomas) in mice but did not affect lymphoma development.
Area of Science:
- Immunology
- Virology
- Parasitology
Background:
- Co-factors, including immune responses, are crucial for oncogenic virus expression.
- Protozoal infections can potentially alter the course of oncogenic virus infections by affecting immune function.
Purpose of the Study:
- To investigate if Toxoplasma gondii infection, known to depress T-lymphocyte function, influences the development of virus-induced tumors.
- To establish a mouse model for studying the interplay between Toxoplasma infection and oncogenic viruses.
Main Methods:
- Developed a mouse model of Toxoplasma infection exhibiting depressed T-lymphocyte function.
- Assessed T-cell function by measuring blastogenic transformation to Concanavalin A and antibody response to sheep red blood cells.
- Infected both uninfected and Toxoplasma-infected mice with Moloney sarcoma virus or Moloney leukaemia virus.
- Evaluated the incidence, progression, and regression of induced rhabdomyosarcomas and lymphomas.
Main Results:
- Toxoplasma infection significantly decreased the incidence of Moloney sarcoma virus-induced rhabdomyosarcomas.
- Tumor progression and regression rates were not altered in mice that developed rhabdomyosarcomas.
- Conjoint infection with Toxoplasma and Moloney leukaemia virus did not increase the incidence of lymphoma compared to Moloney leukaemia virus infection alone.
Conclusions:
- Toxoplasma infection, by impairing T-cell function, can reduce the susceptibility to certain oncogenic virus-induced sarcomas.
- The study suggests a complex interaction between parasitic infections and viral oncogenesis, specifically impacting tumor initiation rather than progression.