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Actinomycin D cytotoxicity for mouse peritoneal macrophages and effect on lactate dehydrogenase-elevating virus
Abstract:
Treatment of lactate dehydrogenase-elevating virus(LDV)-infected mouse peritoneal macrophage cultures with actinomycin D (1 microgram/ml) resulted in a progressive reduction in the formation of LDV-specific RNA and mature virus as the time of incubation with actinomycin D increased beyond 2-3 h. This effect, however, seemed to reflect an unusual sensitivity of macrophages to toxic effects of actinomycin D. Macrophage cytotoxicity and lysis became apparent 3-4 h after addition of actinomycin D; the initiation of synthesis of Sindbis virus RNA, which is insensitive to inhibition by actinomycin D in other cell culture systems, was also reduced in actinomycin-D-treated macrophages. Macrophages propagated in L-cell-conditioned medium were found to be less sensitive to actinomycin D cytotoxicity and, correspondingly, the initiation and synthesis of LDV RNA were less affected.
Insights
Actinomycin D treatment reduced lactate dehydrogenase-elevating virus (LDV) RNA and virus formation in macrophages due to toxicity. Macrophages grown in L-cell-conditioned medium showed reduced sensitivity to actinomycin D, preserving LDV RNA synthesis.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Lactate dehydrogenase-elevating virus (LDV) infects mouse macrophages.
- Actinomycin D is a known inhibitor of RNA synthesis.
Purpose of the Study:
- To investigate the effect of actinomycin D on LDV replication in mouse macrophages.
- To assess the role of macrophage sensitivity to actinomycin D toxicity in viral RNA synthesis.
Main Methods:
- Primary mouse peritoneal macrophages were infected with LDV.
- Cultures were treated with actinomycin D (1 microgram/ml) for varying durations.
- LDV-specific RNA and mature virus formation were quantified.
- Sindbis virus RNA synthesis was monitored as a control.
- Macrophage sensitivity to actinomycin D was evaluated.
- Macrophages cultured in L-cell-conditioned medium were tested.
Main Results:
- Actinomycin D treatment progressively reduced LDV RNA and virus formation after 2-3 hours.
- Macrophage cytotoxicity and lysis occurred 3-4 hours post-treatment.
- Actinomycin D also inhibited Sindbis virus RNA synthesis in these macrophages.
- Macrophages cultured in L-cell-conditioned medium exhibited reduced sensitivity to actinomycin D.
- This reduced sensitivity correlated with less impact on LDV RNA initiation and synthesis.
Conclusions:
- Mouse macrophages are highly sensitive to the cytotoxic effects of actinomycin D.
- This toxicity interferes with viral RNA synthesis, including LDV.
- Culturing macrophages in L-cell-conditioned medium mitigates actinomycin D toxicity, preserving viral RNA synthesis.