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In cell-related experimental operations, for some cells that are difficult or even impossible to transfect by conventional methods, virus-mediated transfection (also known as transduction) can greatly improve the transient expression or knockout of their target genes, which is one of the most used methods of nucleic acid drug delivery in clinical research.

Viral transfection features

Unlike transfecting cells with foreign DNA or RNA, virus transfection does not require transfection reagents. The viral vector itself, also known as virion, can infect cells and transport DNA directly to the nucleus, regardless of other functions. After the DNA is released into the nucleus, the cell's own mechanism is used to produce the target protein.

Typical transduction protocols include engineering of recombinant viruses carrying transgenes, amplification of recombinant virus particles in packaging cell lines, purification and titration of amplified virus particles, and subsequent infection of target cells. Although the transduction efficiency achieved in primary cells and cell lines is high (about 90-100%), only cells with virus-specific receptors can be infected by the virus. It is also important to note that packaging cell lines used for viral amplification need to be transfected with non-viral transfection methods.

Viral transfection workflow

Figure 1: Viral transfection workflow.

Commonly used viruses

• RNA virus (Retrovirus)

  This is a type of virus that produces double-stranded DNA copies of its RNA genome, and these copies can be integrated into the chromosomes of the host cell. Examples include:

  • Murine Leukemia Virus (MuLV)
  • Human Immunodeficiency Virus (HIV)
  • Human T cell lymphovirus (HTLV)
• DNA virus
  • Adenovirus

  It is a type of virus with a double-stranded DNA genome that can cause infections in the human respiratory tract, intestinal tract, and eyes. The virus that causes the common cold is adenovirus

  • Adeno-associated virus

  It is a small single-stranded DNA virus that can insert its genetic material into a specific site on chromosome 19

  • Herpes simplex virus

  It is a type of double-stranded DNA virus that infects specific cell types (neurons). Herpes simplex virus type 1 is a common human pathogen that causes cold sores

Comparison of different virus-mediated methods

Use safety precautions

• It is best to use a biological safety cabinet for virus handling. If you use an ordinary ultra-clean workbench to operate the virus, please do not open the exhaust fan.
• Please wear lab coat, mask, and gloves when handling the virus.
• Be especially careful not to generate mist or splashes when handling viruses. If the ultra-clean workbench is contaminated with virus during operation, please wipe it clean with 70% ethanol and 1% SDS solution immediately. The pipette tips, centrifuge tubes, culture plates, culture medium, etc. that have been in contact with the virus should be soaked in 84 disinfectant or 1% SDS overnight and then discarded.
• The following steps should be followed when observing cell infection with a microscope: Tighten the culture flask or cap the culture plate. Clean the outer wall of the culture flask with 70% ethanol, observe and take pictures under a microscope. Before leaving the microscope bench, clean the microscope bench with 70% ethanol.
• If centrifugation is required, use a centrifuge tube with a good seal, or seal it with a parafilm and centrifuge, and use a centrifuge in the tissue culture room as much as possible.
• After taking off the gloves, wash your hands with soap and water.

Related Sections:

• Introduction to Transfection
• DNA, RNA, and Protein as Transfection Substrates
• Something About siRNA Transfection
• Electroporation
• RNAi and siRNA Transfection
• CRISPR/Cas9 Transfection