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Inability of Kaplan radiation leukemia virus to replicate on mouse fibroblasts is conferred by its long terminal
E Rassart1, Y Paquette, P Jolicoeur
1Laboratory of Molecular Biology, Clinical Research Institute of Montreal, Quebec, Canada.
Abstract:
The molecularly cloned infectious Kaplan radiation leukemia virus has previously been shown to be unable to replicate on mouse fibroblasts (E. Rassart, M. Shang, Y. Boie, and P. Jolicoeur, J. Virol. 58:96-106, 1986). To map the viral sequences responsible for this, we constructed chimeric viral DNA genomes in vitro with parental cloned infectious viral DNAs from the nonfibrotropic (F-) BL/VL3 V-13 radiation leukemia virus and the fibrotropic (F+) endogenous BALB/c or Moloney murine leukemia viruses (MuLV). Infectious chimeric MuLVs, recovered after transfection of Ti-6 lymphocytes with these recombinant DNAs, were tested for capacity to replicate on mouse fibroblasts in vitro. We found that chimeric MuLVs harboring the long terminal repeat (LTR) of a fibrotropic MuLV replicated well on mouse fibroblasts. Conversely, chimeric MuLVs harboring the LTR of a nonfibrotropic MuLV were restricted on mouse fibroblasts. These results indicate that the LTR of BL/VL3 radiation leukemia virus harbors the primary determinant responsible for its inability to replicate on mouse fibroblasts in vitro. Our results also show that the primary determinant allowing F+ MuLVs (endogenous BALB/c and Moloney MuLVs) to replicate on mouse fibroblasts in vitro resides within the LTR.
Insights
The long terminal repeat (LTR) of radiation leukemia virus primarily determines its inability to replicate on mouse fibroblasts. Fibrotropic murine leukemia viruses (MuLVs) with a functional LTR efficiently replicate on these cells.
Area of Science:
- Virology
- Molecular Biology
- Retroviral Research
Background:
- Kaplan radiation leukemia virus (Rauscher MuLV) is non-fibrotropic, failing to replicate on mouse fibroblasts.
- Understanding the genetic basis for tropism is crucial for retroviral vector development and pathogenesis studies.
Purpose of the Study:
- To identify the specific viral sequences responsible for the replication tropism of radiation leukemia virus on mouse fibroblasts.
- To determine the role of the long terminal repeat (LTR) in mediating fibroblast tropism for different murine leukemia viruses (MuLVs).
Main Methods:
- Construction of chimeric viral DNA genomes by combining sequences from non-fibrotropic (F-) and fibrotropic (F+) MuLVs in vitro.
- Transfection of Ti-6 lymphocytes with recombinant DNA to generate infectious chimeric MuLVs.
- Assessment of the replication capacity of chimeric MuLVs on mouse fibroblasts in vitro.
Main Results:
- Chimeric MuLVs containing the LTR from a fibrotropic MuLV demonstrated efficient replication on mouse fibroblasts.
- Chimeric MuLVs with the LTR from the non-fibrotropic radiation leukemia virus showed restricted replication on mouse fibroblasts.
- The LTR sequence of BL/VL3 radiation leukemia virus contains the primary determinant for its lack of fibroblast replication.
Conclusions:
- The long terminal repeat (LTR) is the primary determinant of fibroblast tropism for radiation leukemia virus.
- The LTR also contains the key determinant enabling fibrotropic MuLVs (BALB/c and Moloney MuLVs) to replicate on mouse fibroblasts.