Type C viruses are retroviruses known to infect various animal species.
Kirsten sarcoma virus (Ki-MSV) is a type C retrovirus implicated in tumor formation.
Understanding the origin of viral genetic material is crucial for retrovirology research.
Purpose of the Study:
To investigate the origin of sarcoma-specific nucleic acid sequences in Kirsten sarcoma virus.
To determine the relationship between viral RNA subunits and host cell RNA.
To elucidate the mechanism of Ki-MSV evolution during in vivo passage.
Main Methods:
Isolation and characterization of type C viruses from rat cell lines (NRK).
Analysis of viral RNA subunit sizes using sedimentation techniques (35S and 30S).
Hybridization assays using a DNA transcript specific for Ki-MSV to identify homologous RNA sequences in normal and virus-producing rat cells.
Main Results:
Rat type C virus activated from NRK cells exhibited two major RNA subunits (35S and 30S).
Normal rat cells contained primarily virus-specific 30S RNA species.
A Ki-MSV-specific DNA transcript hybridized exclusively with the 30S RNA species in both normal and virus-producing rat cells, suggesting its origin from rat cellular RNA.
Conclusions:
Sarcoma-specific sequences in Ki-MSV likely arose from the incorporation of rat cell 30S RNA into Kirsten leukemia virus during in vivo passage.
The 30S RNA subunit appears to carry sarcoma-virus-specific information in both rats and mice.
This study provides insights into the retroviral recombination and oncogene acquisition mechanisms.