Dynamics and restriction of murine leukemia virus cores in mitotic and interphase cells
Efrat Elis1, Marcelo Ehrlich2, Eran Bacharach3
1Department of Cell Research and Immunology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. efi.elis@gmail.com.
Background:
Murine leukemia viruses (MLVs) naturally infect unsynchronized T and B lymphocytes, thus, the incoming virus encounters both interphase and mitotic cells. While it is well accepted that MLV requires cell division to complete its replication cycle, it is not known if ab initio infection of mitotic cells can result in productive infection. This question is highly relevant since the milieu of mitotic cells is markedly different from this of interphase cells; e.g. lacking radial microtubule network and intact nuclear envelope. To follow MLV infection in mitotic and interphase cells in real-time, we employed our recently developed infectious MLV particles with labeled cores, cellular models expressing fluorescence markers of different intracellular compartments and protocols for reversible mitotic arrest of MLV-susceptible cells.
Results:
Multi-wavelength live cell imaging was employed to simultaneously visualize GFP-labeled MLV cores, DiD-labeled viral or cellular membranes, and fluorescently-labeled microtubules or chromosomes. Cells were imaged either at interphase or upon mitotic arrest with microtubule poisons. Analysis of virus localization and trajectories revealed entry by endocytosis at interphase and mitosis, and correlation between viral mobility parameters and presence or absence of polymerized interphase microtubules. The success of infection of viruses that entered cells in mitosis was evidenced by their ability to reverse transcribe, their targeting to condensed chromosomes in the absence of radial microtubule network, and gene expression upon exit from mitosis. Comparison of infection by N, B or NB -tropic viruses in interphase and mitotic human cells revealed reduced restriction of the N-tropic virus, for infection initiated in mitosis.
Conclusions:
The milieu of the mitotic cells supports all necessary requirements for early stages of MLV infection. Such milieu is suboptimal for restriction of N-tropic viruses, most likely by TRIM5α.
Insights
Murine leukemia viruses can infect cells during mitosis, completing their replication cycle. Mitotic cell environments support early viral stages and reduce restriction of N-tropic viruses.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Murine leukemia viruses (MLVs) infect both interphase and mitotic lymphocytes.
- The ability of MLVs to productively infect cells during mitosis remains unclear.
- Mitotic cells present a unique intracellular environment compared to interphase cells.
Purpose of the Study:
- To investigate the capacity of MLVs to infect cells during mitosis.
- To analyze the early stages of MLV infection in real-time within mitotic and interphase cells.
Main Methods:
- Utilized fluorescently labeled MLV particles and cellular markers.
- Employed multi-wavelength live-cell imaging and reversible mitotic arrest.
- Analyzed viral localization, mobility, and replication markers.
Main Results:
- MLVs enter cells via endocytosis during both interphase and mitosis.
- Viral mobility correlates with microtubule presence.
- Infection initiated in mitosis leads to reverse transcription, chromosome targeting, and gene expression.
- N-tropic MLV infection is less restricted in mitotic human cells.
Conclusions:
- The mitotic cellular environment supports early-stage MLV infection.
- Mitotic arrest may reduce TRIM5α-mediated restriction of N-tropic MLVs.
