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Sindbis Virus Gene Expression Vectors

3 types of Sindbis virus gene expression vectors Advantages of Sindbis virus vectors Bibliography of Sindbis virus vectors Molecular biology of Sindbis virus

  • 3 types of Sindbis virus gene expression vectors

    1. DI (defective-interfering genomes) vectors

      • They contain the essential cis-acting sequences for replication, with or without 1 or more promoters for expression of the foreign gene.
      • They require a source (e.g. wildtype helper virus) of the nonstructural proteins to be replicated and to express the foreign gene
      • They require a source of the structural proteins to be packaged into viral particles.

    2. Double-promoter vectors that are self-replicating, self-packaging

      • They contain the nonstructural and structural proteins, and are totally self-sufficient for replication and packaging.
      • Because of packaging size-constraints, the foreign gene to be packaged is limited to <2-3 kb in length. Beta-galactosidase (3 kb) is too large, tissue-type plasminogen activator (1.8kb) works fine.

    3. Self-replicating vectors, that require exogenous structural proteins to be packaged

      • They contain the nonstructural proteins, and are self-sufficient for replication and gene expression.
      • They lack the structural proteins, and a helper genome is needed to allow them to be packaged into infectious particles.
      • Removal of the structural proteins increases the cloning capacity of these vectors to more than 6kb (proteins that are >220 kdaltons). For example, the entire genome of hepatitis B virus was cloned and expressed using this type of vector.
      • The pSinRep5 vector and the DH-BB helper genome are available only from Washington University in St. Louis

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  • Advantages of Sindbis virus vectors

    1. High level of gene expression.
      Comparable to or better than vaccinia virus vectors.

    2. Rapid gene expression.
      Maximal expression within 12-15 hours at 37 degrees.

    3. Easy construction.
      Plasmid clones are easy to manipulate.

    4. Wide host range.
      Useful in many insect, avian, and mammalian cells.

    5. RNA genome.
      This is especially desirable for e.g. genetic immunization. DNA vectors (Robertson, J.S. 1994 Safety considerations for nucleic acid vaccines. Vaccine 12:1526-1528), pose the risks of cell transformation, immuno-modulation (ASM News 1996. 62:399-340), and persistent expression. RNA vectors should be less likely to transform cells. The Sindbis virus vectors give transient, not persistent gene expression.

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  • Bibliography of Sindbis virus vectors

    Journal articles reporting on the use of the Sindbis virus vectors.

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  • Molecular biology of Sindbis virus

    Sindbis virus genome, genes, proteins, mutations.

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