Microinjected simian virus 40 cRNA is spliced, as evidenced by electron microscopy

Area of Science:

• Molecular Biology
• Virology
• Cell Biology

Background:

• Simian virus 40 (SV40) is a DNA tumor virus.
• Understanding viral gene expression is crucial for virology research.
• The early region of SV40 encodes the large T antigen.

Purpose of the Study:

• To investigate the in vitro transcription and processing of Simian virus 40 (SV40) cRNA.
• To analyze the structural features of processed SV40 cRNA within host cell nuclei.

Main Methods:

• In vitro transcription of SV40 cRNA from viral DNA.
• Microinjection of cRNA into monkey cell nuclei.
• RNA extraction and hybridization to SV40 DNA sequences.
• Electron microscopy for structural analysis.

Main Results:

• Processed SV40 cRNAs were observed within the nuclei of injected monkey cells.
• Electron microscopy revealed the presence of splice loops in the processed cRNAs.
• These splice loops were located in the region corresponding to the intron of the large T antigen.

Conclusions:

• SV40 cRNA undergoes processing, including intron removal, within the host cell nucleus.
• This processing is essential for the expression of viral proteins like large T antigen.
• The findings provide insights into the molecular mechanisms of SV40 gene expression.