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Feline oncornavirus-associated cell membrane antigen: evidence for an immunologically crossreactive feline sarcoma
Abstract:
The feline oncornavirus-associated cell membrane antigen (FOCMA) acts as a target for natural immuno-surveillance against tumor development in the cat. In the present study, mink and rat cells nonproductively transformed by feline sarcoma virus (FeSV) were shown to express FOCMA as well as 5'-terminal feline leukemia virus (FeLV) gag gene proteins, p15 and p12. In contrast, such cells lack detectable levels of other FeLV gag gene-coded proteins or the env gene product, gp70. FOCMA, p15, and p12 antigen expression is initially in the form of an 80,000-100,000 molecular weight precursor which, upon post-translational cleavage, gives rise to a 65,000 molecular weight component that contains FOCMA and a 25,000 molecular weight component containing p15 and p12. Feline lymphoma cells, including those from several tumors that lacked detectable levels of FeLV structural protein expression, were shown to be FOCMA-positive. These findings strongly suggest that FOCMA represents an FeSV-coded transformation specific protein and provide preliminary information regarding the position within the FeSV genome coding for its synthesis.
Insights
The feline oncornavirus-associated cell membrane antigen (FOCMA) is a transformation-specific protein coded by the feline sarcoma virus (FeSV). This antigen is crucial for immune surveillance against feline tumors.
Area of Science:
- Oncology
- Virology
- Immunology
Background:
- Feline oncornavirus-associated cell membrane antigen (FOCMA) is a key target for immune surveillance against feline tumors.
- Feline sarcoma virus (FeSV) and feline leukemia virus (FeLV) are implicated in feline cancers.
Purpose of the Study:
- To investigate the expression and nature of FOCMA in FeSV-transformed cells.
- To determine if FOCMA is a transformation-specific protein coded by FeSV.
Main Methods:
- Analysis of FOCMA expression in mink and rat cells transformed by FeSV.
- Detection of viral gag and env gene products using specific antibodies.
- Characterization of FOCMA precursor and mature forms through molecular weight analysis.
Main Results:
- FeSV-transformed cells expressed FOCMA, p15, and p12 gag proteins, but not other FeLV gag proteins or gp70.
- FOCMA, p15, and p12 are derived from a common precursor (80,000-100,000 MW).
- Feline lymphoma cells, even without detectable FeLV structural proteins, were FOCMA-positive.
Conclusions:
- FOCMA is likely an FeSV-coded transformation-specific protein.
- Findings provide insights into the genomic location responsible for FOCMA synthesis.
- FOCMA expression is independent of detectable FeLV structural protein expression in feline lymphomas.