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Electron microscopy of Cowdria ruminantium infected reticulo-endothelial cells of the mammalian host
Abstract:
An electron microscopic study of structures suspected to represent a possible developmental cycle of Cowdria ruminantium in reticulo-endothelial cells of mice and ruminants is reported. After infection dense bodies increase in size and undergo division to form fragmented dense bodies. These in turn apparently sub-divide and become organized to give rise to mature "organisms". In none of these structures do limiting membranes separate the parasitic inclusions from the host cell cytoplasm. Present observations suggest that growth of the organism in reticulo-endothelial cells differs from that of chlamydial and rickettsial agents and somewhat resembles the replication of some viruses. Developmental stages observed after infection of ruminants with the Ball 3 strain of the heartwater agent are indistinguishable from those seen with the mouse adapted strain. These observations support the hypothesis that C. ruminantium released from reticulo-endothelial cells subsequently penetrates endothelial cells where further multiplication by binary fission occurs.
Insights
Cowdria ruminantium
Area of Science:
- Veterinary Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Cowdria ruminantium is an obligate intracellular bacterium responsible for heartwater disease in ruminants.
- The developmental cycle of C. ruminantium within host cells remains incompletely understood.
- Previous studies have suggested potential similarities with chlamydial and rickettsial agents.
Purpose of the Study:
- To investigate the ultrastructural morphology and developmental stages of Cowdria ruminantium in reticulo-endothelial cells.
- To compare the developmental cycle in mice and ruminants.
- To elucidate the intracellular replication mechanisms of C. ruminantium.
Main Methods:
- Electron microscopy was employed to examine infected reticulo-endothelial cells from mice and ruminants.
- Infected cells were analyzed at various time points post-infection.
- Morphological changes and structural organization of the bacterium were documented.
Main Results:
- Observed dense bodies increased in size and divided, forming fragmented bodies that further subdivided into mature organisms.
- No limiting membranes were found separating parasitic inclusions from host cytoplasm.
- Developmental stages in ruminants (Ball 3 strain) were indistinguishable from those in mice.
Conclusions:
- The intracellular growth of C. ruminantium in reticulo-endothelial cells differs from chlamydiae and rickettsiae, showing some resemblance to viral replication.
- These findings support the hypothesis that C. ruminantium is released from reticulo-endothelial cells to infect endothelial cells, where it multiplies via binary fission.
