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A proposed model to explain persistent infection of host cells with Coxiella burnetii
Abstract:
L929 mouse fibroblast cells and J774 macrophage-like cells are both susceptible to persistent infection with the Q fever agent Coxiella burnetti. Previously this laboratory has shown that persistently infected cell populations multiply with unaltered generation times or cell cycle progression. It has also been reported by others and us that highly infected cells typically exhibit one large parasite-containing vacuole. We now report that lightly and heavily infected cells are capable of division and in the process segregate the parasite-containing vacuole into one of the emerging daughter cells; the companion daughter cell emerges parasite-free. This asymmetric division of infected cells, revealed via photomicrography of stained cells, accounts for the appearance of uninfected cells within persistently infected host cell populations that were previously 100% infected. Some of the persistently infected L929 populations were maintained in culture for over two years without the addition of normal cells.
Insights
Persistently infected host cells divide asymmetrically, passing Coxiella burnetii to one daughter cell and leaving the other uninfected. This explains how uninfected cells appear in Q fever cell cultures.
Area of Science:
- Cell Biology
- Microbiology
- Infectious Diseases
Background:
- L929 mouse fibroblast and J774 macrophage-like cells are susceptible to Coxiella burnetii infection.
- Persistently infected cells normally multiply without altered cell cycle progression.
- Highly infected cells typically contain a single large parasite vacuole.
Purpose of the Study:
- To investigate the mechanism of cell division in Coxiella burnetii-infected host cells.
- To explain the presence of uninfected cells in persistently infected populations.
Main Methods:
- Photomicrography of stained L929 and J774 cells.
- Long-term cell culture of infected L929 populations.
Main Results:
- Infected cells undergo asymmetric division, segregating the parasite vacuole into one daughter cell.
- This results in one daughter cell being parasite-free.
- Uninfected cells emerge within previously 100% infected cell populations.
- Persistently infected L929 cells were maintained in culture for over two years.
Conclusions:
- Asymmetric cell division is a key mechanism for maintaining persistent Coxiella burnetii infections.
- This process generates uninfected cells, contributing to the dynamics of infected host cell populations.
- The findings provide insights into host-pathogen interactions and cell population maintenance in Q fever.