Related Experiment Videos
Theiler's virus growth in murine macrophage cell lines depends on the state of differentiation
M L Jelachich1, P Bandyopadhyay, K Blum
1Division of Neurology, Evanston Hospital, Northwestern University, Evanston, Illinois 60201, USA.
Abstract:
Theiler's murine encephalomyelitic virus (TMEV) preferentially replicates in macrophages in the central nervous system of mice during the persistent phase of infection. Macrophages accumulate in demyelinating lesions and are evidently the primary cell to harbor virus. To investigate TMEV-macrophage interactions, we studied GDVII infection of three cell lines, M1, P388D1, and RAW264.7, representing various stages of macrophage differentiation/activation. GDVII virus was bound and internalized by RAW264.7 and P388D1 cells, but not by the precursor cell line M1. While infection of P388D1 cells produced a typical lytic cytopathology with marked loss of cellular activity to 10-20% of the uninfected control cells, RAW264.7 cells showed little cytopathology despite a decrease in cellular activity of 50-60%. Morphologic changes in infected RAW264.7 cells were similar to those occurring after cell activation. Although an infectious center assay showed that all P388D1 and RAW264.7 cells were infected, synthesis of viral RNA and proteins was markedly reduced and virus titers were restricted compared to permissive BHK-21 cells. Infected RAW264.7, but not infected P388D1, cells secreted tumor necrosis factor-alpha and nitric oxide. Therefore, depending on the differentiation and/or activation state, murine macrophages may be resistant to TMEV infection (M1), semipermissive and activated to secrete cytokines (RAW264.7), or semipermissive and not activated to secrete cytokines (P388D1).
Insights
Murine macrophages show varied responses to Theiler's murine encephalomyelitic virus (TMEV) infection. Macrophage differentiation and activation state influence TMEV replication and cytokine secretion, impacting central nervous system disease progression.
Area of Science:
- Neurovirology
- Immunology
- Cell Biology
Background:
- Theiler's murine encephalomyelitic virus (TMEV) establishes persistent infections in the mouse central nervous system, primarily within macrophages.
- Macrophages are key players in demyelinating lesions and serve as the main viral reservoir during chronic TMEV infection.
Purpose of the Study:
- To investigate the interactions between TMEV and murine macrophages at different differentiation and activation states.
- To understand how macrophage characteristics influence viral replication, cytopathology, and immune responses.
Main Methods:
- Infection of three murine macrophage cell lines (M1, P388D1, RAW264.7) with GDVII strain of TMEV.
- Assessment of viral binding, internalization, replication (RNA and protein synthesis), and infectious virus production.
- Evaluation of cellular viability, cytopathology, and secretion of inflammatory mediators like TNF-α and nitric oxide.
Main Results:
- GDVII virus was internalized by P388D1 and RAW264.7 cells, but not M1 cells.
- P388D1 cells exhibited lytic cytopathology, while RAW264.7 cells showed less cytopathology but reduced cellular activity and signs of activation.
- Viral RNA and protein synthesis were restricted in both P388D1 and RAW264.7 cells compared to permissive BHK-21 cells.
- Infected RAW264.7 cells secreted TNF-α and nitric oxide, unlike infected P388D1 cells.
Conclusions:
- Murine macrophage responses to TMEV are dependent on their differentiation and activation status.
- Macrophages can be resistant (M1), semipermissive with cytokine secretion (RAW264.7), or semipermissive without cytokine secretion (P388D1) to TMEV infection.
- These differential responses have implications for understanding TMEV pathogenesis in the central nervous system.