Mycoplasmas produce double-stranded ribonuclease

Area of Science:

• Cell Biology
• Microbiology
• Molecular Biology

Background:

• Mycoplasmas (Mollicutes) are known contaminants in animal cell cultures.
• These contaminants can cause biochemical reactions attributed to host cells.
• Previous research suggested a double-stranded ribonuclease (dsRNase) inducible in mammalian cells.

Purpose of the Study:

• To investigate the source of an observed dsRNA-inducible dsRNase in mammalian cells.
• To identify the specific agent responsible for dsRNase activity.
• To characterize the dsRNase and its production by the identified agent.

Main Methods:

• Investigating dsRNase activity in mammalian cell cultures.
• Analyzing vesicular stomatitis virus stocks for contaminants.
• Isolating and identifying microbial contaminants.
• Characterizing the enzymatic activity and production of the contaminant.

Main Results:

• A specific stock of vesicular stomatitis virus contained a contaminant responsible for high dsRNase levels.
• The contaminant was identified as Mycoplasma hyorhinis.
• Mycoplasmas were found to ubiquitously distribute dsRNase.
• Characteristics of the enzyme and its production by mycoplasmas were presented.

Conclusions:

• Mycoplasma hyorhinis, not mammalian cells, was the source of the investigated dsRNase activity.
• Mycoplasmas are widespread contaminants in cell cultures.
• Mycoplasmas can significantly alter cellular physiology and experimental results.