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Quantitative studies of integration of murine leukemia virus after exogenous infection
Abstract:
Using a [3H]DNA probe prepared from AKR murine leukemia virus, we determined the number of copies of the AKR virus genome integrated into the cellular DNA after exogenous infection of NIH mouse, AKR mouse, and rat cells in tissue culture. NIH mouse cells, which lack a portion of the viral genome (referred to as Gross-AKR specific sequences), incorporated three to four copies of these sequences per haploid genome. AKR cells, in which the Gross-AKR specific sequences are already present as three to four copies per haploid genome, did not shwo any distinct change in copy number after infection. Rat cells, which lack DNA sequences homologous to murine leukemia virus, incorporated one copy of the viral genome per haploid genome. It is inferred that the presence of viral sequences may affect the efficiency of integration of exogenous provirus, and that there may be a limit to the number of copies that can be inserted.
Insights
NIH mouse, AKR mouse, and rat cells were infected with AKR murine leukemia virus. Viral genome integration varied by cell type, suggesting host DNA influences proviral insertion efficiency and copy number limits.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Murine leukemia virus (MuLV) is a retrovirus known to integrate its genome into host DNA.
- Understanding retroviral integration is crucial for studying viral pathogenesis and gene therapy applications.
Purpose of the Study:
- To quantify the number of AKR murine leukemia virus (MuLV) genome copies integrated into cellular DNA.
- To investigate the influence of host cell genetic makeup on exogenous proviral DNA integration.
Main Methods:
- Utilized a [3H]DNA probe specific to the AKR MuLV genome.
- Performed exogenous infection of NIH mouse, AKR mouse, and rat cells in tissue culture.
- Quantified integrated viral genome copies per haploid genome using hybridization techniques.
Main Results:
- NIH mouse cells, lacking Gross-AKR specific sequences, integrated 3-4 copies of the viral genome per haploid genome.
- AKR mouse cells, already possessing 3-4 copies of Gross-AKR sequences, showed no significant change in copy number post-infection.
- Rat cells, lacking homologous sequences to MuLV, integrated one copy of the viral genome per haploid genome.
Conclusions:
- The presence of endogenous viral sequences in host cells may modulate the integration efficiency of exogenous provirus.
- A potential limit exists for the number of proviral copies that can be inserted into the host genome.