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Analysis of the unique hamster cell tropism of ecotropic murine leukemia virus PVC-211
M Masuda1, M Masuda, C A Hanson
1Laboratory of Molecular Oncology, National Cancer Institute, Frederick, Maryland 21702-1201, USA.
Abstract:
PVC-211 murine leukemia virus (MuLV) is a neuropathogenic variant of Friend MuLV (F-MuLV). Previous studies from our laboratory demonstrated that unlike the parental F-MuLV, PVC-211 MuLV can infect rat brain capillary endothelial cells efficiently and that it has acquired genetic changes responsible for its expanded cellular tropism. To determine if PVC-211 MuLV also has expanded its host range, we tested its infectivity on Chinese hamster ovary-derived CHO-K1 cells, which are generally resistant to ecotropic MuLV. The results indicated that PVC-211 MuLV, but not F-MuLV, was highly infectious for CHO-K1 cells. Studies using glycosylation inhibitors and glycosylation mutants of CHO-K1 cells, as well as interference studies, suggested that PVC-211 MuLV has acquired the ability to interact with the ecotropic MuLV receptor on CHO-K1 cells that has undergone glycosylation-dependent modification. Using chimeric viruses between PVC-211 MuLV and F-MuLV, we were able to localize the viral genetic element crucial for CHO-K1 cell tropism within the env gene of PVC-211 MuLV and show that glycine at position 116 and lysine at position 129 of the envelope glycoprotein SU were important. These viral determinants also appear to confer tropism for other hamster cells resistant to ordinary ecotropic MuLVs. Further studies on the interaction between PVC-211 MuLV and the receptor on hamster cells may provide novel insights into the molecular mechanisms for receptor recognition and binding by viral envelope glycoproteins.
Insights
PVC-211 murine leukemia virus (MuLV) shows expanded host range, efficiently infecting Chinese hamster ovary-K1 cells. This tropism is linked to specific amino acids in the viral envelope glycoprotein SU, suggesting novel receptor interactions.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- PVC-211 murine leukemia virus (MuLV) is a neuropathogenic variant of Friend MuLV (F-MuLV).
- Previous studies showed PVC-211 MuLV infects rat brain capillary endothelial cells, indicating expanded cellular tropism.
- The genetic basis for this expanded tropism was not fully understood.
Purpose of the Study:
- To determine if PVC-211 MuLV has an expanded host range beyond rat cells.
- To investigate the molecular mechanisms underlying PVC-211 MuLV's infectivity in resistant cell lines.
- To identify the specific viral genetic elements responsible for altered tropism.
Main Methods:
- Infectivity assays on Chinese hamster ovary-K1 (CHO-K1) cells using PVC-211 MuLV and F-MuLV.
- Studies involving glycosylation inhibitors and mutants of CHO-K1 cells.
- Interference studies to assess receptor usage.
- Construction and analysis of chimeric viruses between PVC-211 MuLV and F-MuLV.
Main Results:
- PVC-211 MuLV, but not F-MuLV, efficiently infected CHO-K1 cells.
- Infectivity correlated with a glycosylation-dependent modification of the ecotropic MuLV receptor on CHO-K1 cells.
- Chimeric virus studies localized the tropism determinant to the env gene of PVC-211 MuLV.
- Glycine at position 116 and lysine at position 129 of the envelope glycoprotein SU were identified as crucial for CHO-K1 cell tropism.
Conclusions:
- PVC-211 MuLV exhibits an expanded host range, infecting hamster cells resistant to standard ecotropic MuLVs.
- The env gene, specifically amino acids in the SU glycoprotein, dictates this altered tropism.
- These findings offer insights into viral envelope glycoprotein-receptor interactions and molecular mechanisms of viral entry.