Virus shedding by SV40-transformed human cells

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Simian virus 40 (SV40) is a DNA tumor virus known to infect human cells.
• SV40-transformed cells can exhibit various behaviors, including viral shedding.
• Understanding the mechanisms of viral shedding is crucial for controlling viral infections and understanding oncogenesis.

Purpose of the Study:

• To investigate the phenomenon of infectious virus shedding by SV40-transformed human cell cultures.
• To elucidate the factors influencing SV40 shedding, including viral replication and host cell DNA repair pathways.

Main Methods:

• Culturing SV40-transformed human cells and monitoring for infectious virus release over multiple passages.
• Utilizing anti-SV40 antiserum to assess the role of cell-to-cell virus propagation.
• Employing temperature-sensitive SV40 mutants (tsA30) to study the effect of viral gene function on shedding.
• Examining virus shedding in xeroderma pigmentosum cells, which have deficient DNA repair capabilities.

Main Results:

• SV40-transformed human cell cultures consistently released infectious SV40, even after extended in vitro passages.
• Virus shedding was not inhibited by antiserum that blocked cell-to-cell viral spread, indicating it's not solely dependent on propagation.
• Reduced virus shedding was observed when cells were infected with a temperature-sensitive mutant (tsA30) at the restrictive temperature.
• Xeroderma pigmentosum cells transformed by SV40 also shed infectious virus.

Conclusions:

• SV40-transformed cells release infectious virus independently of active viral replication and cell-to-cell spread.
• The shedding mechanism does not appear to involve host cell DNA excision and repair enzymes.
• These findings suggest a distinct molecular mechanism for SV40 release from transformed cells.