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Fv-1 host restriction of Friend leukemia virus: analysis of unintegrated proviral DNA
Abstract:
The murine gene Fv-1 predominantly controls the outcome of infection by murine ecotropic retroviruses. The inhibition of virus replication by the Fv-1 gene product has been determined to be at an early stage in virus replication. Mechanistically, its effect appears to be on the accumulation of unintegrated proviral DNA or its integration or both. We investigated the synthesis of unintegrated proviral DNA, using several clones of B-, N-, or NB-tropic Friend murine leukemia virus. Our results indicate that the accumulation of B-tropic proviral DNA in NIH cells may be inhibited at either the level of linear (form III) or covalently closed circular DNA (form I), depending upon the degree of restriction of the clone of virus used. We confirmed that there is an effect of the Fv-1 gene on the accumulation of form I DNA of either B- or N-tropic Friend murine leukemia virus. However, the decrease in infectious centers effected by the Fv-1 gene did not correlate quantitatively with the effect on form I proviral DNA produced by N-tropic Friend murine leukemia virus in nonpermissive cells. Lastly, we demonstrated in nonpermissively infected NIH cells that a rapidly migrating doublet of viral DNA is formed.
Insights
The Fv-1 gene restricts murine leukemia virus replication early in infection. It impacts proviral DNA accumulation or integration, affecting linear and circular DNA forms.
Area of Science:
- Virology
- Genetics
- Molecular Biology
Background:
- The Fv-1 gene in mice controls susceptibility to ecotropic retroviruses.
- Fv-1 acts at an early stage of retroviral replication, influencing proviral DNA.
Purpose of the Study:
- To investigate the Fv-1 gene's mechanism of inhibiting murine leukemia virus replication.
- To determine the specific stage of unintegrated proviral DNA synthesis affected by Fv-1.
Main Methods:
- Utilized various clones of B-, N-, and NB-tropic Friend murine leukemia virus.
- Analyzed the accumulation of unintegrated proviral DNA (linear form III and circular form I).
- Assessed the impact of the Fv-1 gene on viral DNA forms in NIH cells.
Main Results:
- Fv-1 inhibition affected B-tropic proviral DNA accumulation at linear or circular DNA stages.
- Confirmed Fv-1's effect on form I DNA for both B- and N-tropic viruses.
- Observed a rapidly migrating viral DNA doublet in nonpermissive cells.
Conclusions:
- The Fv-1 gene's restriction mechanism involves modulating proviral DNA accumulation or integration.
- Fv-1's effect on DNA forms may vary depending on the specific viral clone and host cell.
- Further research is needed to fully elucidate the Fv-1 restriction pathway.