We have already looked into the different types of viral expression systems and when you might use one over another in my previous article. But why would you use viral transduction over similar techniques like plasmids?
Just a reminder: Transfection is a lab technique where nucleic acids or proteins may be introduced into cells. When viruses are used, it’s called viral transduction. A wide variety of viruses are used for this purpose, but the two most common ones are adenoviruses and lentiviruses.
There are many experiments for which viral transduction are useful, including gene knockdown/gene silencing, protein overexpression, stem cell reprogramming and differentiation, cell line generation, virus production, and gene knockout and knockin. Conveniently, this form of transfection is amenable to in vivo or in vitro applications.
Some advantages and disadvantages (a good resource can be found here):
Advantages of viral transduction:
- Gene delivery efficiency of 95-100% as they are designed to transport DNA into cell nuclei using intrinsic mechanisms for endosomal escape.
- Technically simple to use
- You have your choice of RNA or DNA viruses.*
- Can be cell-type specific
- Can be body region/part specific
- Can be chromosome specific
- Can infect dividing or senescent cells
- Can be stable or transient in expression
*RNA viruses or retroviruses make double-stranded DNA copies of their genome to allow for integration into a host cell’s DNA.
Disadvantages of viral transduction:
- Although they are replication incompetent, they still require biosafety level 2 facilities.
- Complicated synthesis process that is labor intensive*
- May disrupt tumor suppressor genes
- Limitation on gene size
*Complete kits are available, but transduction protocols require preparation of recombinant vectors in packaging cell lines and subsequent purification of viral particles. All of which is pretty labor intensive
When to use viral transduction:
Viral transfection is best served in the following circumstances:
- to introduce single cloned gene that you’d like to express in large amounts,
- to introduce shorter strands of nucleic acids,
- if your cells are refractory to CaCl2, lipofection, and/or electroporation,
- expression is weak
- you’re trying to deliver your DNA in vivo.
When considering which type of virus you should use for your experiment, you can follow this wonderful poster!
Featured image from Ralf Schulze.