The use of viruses to deliver genes and more specifically fluorescent markers to cells of the nervous system is known to work efficiently. However, different viral vectors are available to you that have different characteristics, and the decision to favor one or another virus should be based on numerous considerations, a few of which being:

• Size of the genetic material to be carried in the vector (gene of interest + regulatory sequences),
• Cells that are targeted (number, phenotype, mitotic status),
• Speed and duration of expression

Targeting virus entry specifically into neurons can be achieved, though not with any of the viral vectors described below in their present form. We are testing the possibility of also producing neuronotropic viruses like Semliki forest viruses, or pseudotyping some of our vectors with proteins from neuronotropic viruses: we will keep you informed of the developments. But it is certainly possible to restrict expression of the transgene to neurons by use of neuron-specific promoters like the synapsin I promoter.

We can help you choose the best tool for your experiment, so we suggest you contact us before ordering a viral vector.

View the list of viral vectors available at the Neurophotonics Centre.

For information about fluorescent proteins, you can visit FPbase.org (external link)

Your viral vector will arrive frozen, in 500ul Eppendorf tubes.

Keep the viral vector at -80C at all times, and consider the following for each type of viral vector:

1. Lentivirus-based vectors: very sensitive to freeze/thaw cycles, i.e. a significant drop in titer is expected after each cycle of freezing/thawing
2. Retrovirus-based vectors: very sensitive to freeze/thaw cycles
3. Adeno-associated virus/Self complementary adeno-associated virus vectors: can be thawed and refrozen multiple times without significant loss of titer.

We will provide you with a titer for your viral vector that is in TU (transducing units). This is the number of virions able to effectively cause expression of the viral transgene in a cell (from the particular cell line used for titration), following exposure of a near-confluent layer of these cells to a vector solution. Please keep in mind the units used for viral vector titers between different vector-producing labs are not always identical, and that the titer for a same sample can vary over several orders of magnitude depending on the titer unit used. The titer of your viral vector has been determined from a thawed sample of your vector and thus, should represent the titer to expect at the first thawing of your aliquots. When injecting your viral vector into an animal or exposing cells in culture, remember that most vectors are heat-labile: thaw the aliquots rapidly and then keep on ice until the last minute. If possible, use cold solutions and containers to dilute the samples.

Lentivirus and retrovirus-based vectors are sensitive to organic solvents like ethanol, to detergents, and should be diluted in isosmotic solutions. AAV vectors are resistant to ethanol and to low concentrations of Triton X-100 and other detergents, and remains integral in a wide range of osmolarities.

Always wear gloves, and decontaminate and dispose of waste appropriately (we recommend regular 5% bleach for decontamination and disposal).

Aliquot size

Aliquot of in stock virus:

• AAV
  100ul | 1E12GC/ml to 2E13 GC/ml (depending on the growth performance of the vector sequence and serotype)
• Lentivirus
  50ul | Concentrated virus 10E07 to 10E08 transducing units (depending on the growth performance of the vector sequence, FIV lower titer)

Some constructs will require a MTA, some others are covered by distribution agreements.

• We recommend you proceed with your order.
• We will contact you if one or more MTA are required.
• We will provide you with either the documents or the links to obtain the required MTA.