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Use of cell cultures to study spiroplasma infections
Abstract:
Invertebrate and mammalian cell cultures have been utilized to study various properties of spiroplasmas. Recent studies have focused on the interaction of Spiroplasma mirum with AG-4676, a cell line derived from the rat eye lens. S. mirum produced cytotoxicity in this cell line, consisting of vacuolization and an increase in the number of binucleated cells. The number of S. mirum organisms attached to the cell increased with increased age of infection. S. mirum does not grow in Dulbecco's modified Earle's medium + 10% fetal bovine serum, the growth medium for AG-4676. It does, however, grow in conditioned medium obtained as supernatant of 1- to 5-day-old AG-4676. This conditioned medium from AG-4676 also supported growth of S. mirum (GT-48), corn stunt spiroplasmas (Rio Grande) and the following unspeciated strains: M-55 (I-6), N-525 (I-7), CN-5 (IX) and AES-1 (X). It did not support S. citri, honeybee BC-3, EA-1 (VIII), MQ-6 (XII) or CC-1 (XIII). The growth promotion titer for S. mirum was 1:8, but this varied with the lot of fetal bovine serum. Biochemical characterization of this growth-promoting factor is in progress.
Insights
Spiroplasma mirum causes cell damage in rat eye lens cells (AG-4676). This bacterium grows in AG-4676 conditioned medium, indicating a specific growth factor is present.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Cell cultures are vital for studying spiroplasma properties.
- Spiroplasma mirum interactions with mammalian cells are under investigation.
Purpose of the Study:
- To investigate the cytotoxicity of Spiroplasma mirum on the AG-4676 rat eye lens cell line.
- To determine the growth requirements of S. mirum in vitro.
Main Methods:
- Exposure of AG-4676 cells to S. mirum.
- Observation of cellular changes (vacuolization, binucleation).
- Testing S. mirum growth in various media, including conditioned AG-4676 supernatant.
Main Results:
- S. mirum induced cytotoxicity, including vacuolization and binucleation in AG-4676 cells.
- S. mirum attachment increased with infection duration.
- S. mirum grew in AG-4676 conditioned medium but not standard growth medium.
- Conditioned medium supported growth of various spiroplasma strains, but not all.
Conclusions:
- AG-4676 conditioned medium contains a factor promoting S. mirum growth.
- This factor may be specific, as not all spiroplasma strains grew.
- Further research is needed to biochemically characterize this growth factor.