Novel Semliki Forest virus vectors with reduced cytotoxicity and temperature sensitivity for long-term enhancement of transgene expression

Mol Ther. 2003 Feb;7(2):202-9. doi: 10.1016/s1525-0016(02)00056-4.


Alphaviral vectors inhibit host cell protein synthesis and are cytotoxic. To overcome these limitations, we modified the nonstructural protein-2 (nsP2) gene in the Semliki Forest virus (SFV) vector, pSFV1. Packaging of SFV replicons with two point mutations in nsP2 resulted in high-titer recombinant SFV(PD) particles. SFV(PD) led to more efficient host cell protein synthesis, exhibited reduced cytotoxicity and improved cell survival, and allowed greater and prolonged transgene expression than the original vector, SFV. In dissociated hippocampal neurons and organotypic rat hippocampal slices, SFV(PD) infection preserved neuronal morphology and synaptic function more efficiently than SFV. Combination of the two point mutations with a replication-persistent mutation in nsP2 resulted in a highly temperature-sensitive vector, SFV(PD713P), which efficiently transduced neurons in hippocampal slice cultures. At 31 degrees C, SFV(PD713P) allowed continuous transgene expression in BHK cells, at amounts comparable to SFV(PD). These new SFV mutants are expected to substantially broaden the application of alphaviral vectors in neurons and other mammalian cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Cell Line
  • Cell Survival
  • Cricetinae
  • Electrophoresis, Polyacrylamide Gel
  • Gene Transfer Techniques
  • Genetic Therapy / methods*
  • Genetic Vectors*
  • Green Fluorescent Proteins
  • Hippocampus / pathology
  • Hippocampus / virology
  • Humans
  • Immunohistochemistry
  • Luminescent Proteins / metabolism
  • Microscopy, Fluorescence
  • Mutagenesis, Site-Directed
  • Neurons / metabolism
  • Neurons / virology
  • Point Mutation
  • Rats
  • Semliki forest virus / genetics*
  • Temperature
  • Time Factors
  • Transgenes*


  • Luminescent Proteins
  • Green Fluorescent Proteins