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Nonreciprocal pseudotyping: murine leukemia virus proteins cannot efficiently package spleen necrosis virus-based
J L Certo1, B F Shook, P D Yin
1Department of Genetics and Developmental Biology, West Virginia University, Morgantown, West Virginia 26506, USA.
Journal of Virology
|June 17, 1998
Summary
Spleen necrosis virus (SNV) proteins can package murine leukemia virus (MLV) RNA, but MLV proteins cannot package SNV RNA. This study reveals a striking nonreciprocal retroviral packaging specificity.
Area of Science:
- Retroviral biology
- Molecular virology
- Gene therapy vectors
Background:
- Spleen necrosis virus (SNV) and murine leukemia virus (MLV) are retroviruses with distinct packaging signals (E and Psi, respectively).
- Previous studies suggested potential for cross-packaging due to similar predicted RNA structures, despite low sequence homology.
Purpose of the Study:
- To investigate whether MLV proteins can package SNV RNA.
- To determine the packaging specificity of MLV proteins compared to SNV proteins.
Main Methods:
- Modification of an SNV vector for expression in an MLV-based murine helper cell line.
- Quantification of retroviral vector titers.
- RNA analysis using RNA hybridization to assess packaging efficiency.
Main Results:
- MLV proteins failed to support SNV vector replication, resulting in a 2,000- to 20,000-fold decrease in titer.
- SNV RNA was packaged at least 25-fold less efficiently by MLV proteins compared to MLV RNA.
- SNV proteins demonstrated broad packaging specificity, recognizing both SNV E and MLV Psi signals.
Conclusions:
- MLV proteins exhibit a strict packaging specificity, recognizing only MLV Psi.
- SNV proteins display a broader packaging specificity than MLV proteins.
- This study demonstrates nonreciprocal packaging specificities between SNV and MLV for the first time.