Frequently asked questions

Will the VVCC provide a letter of support for my grant application? Absolutely! Dr. Wickman can work with you to develop a project-specific letter that can be included with your grant application.

Why does viral titer vary from project-to-project? Project-specific shuttle vectors are the main variable in packaging projects. When viral production fails or titer is low, therefore, the problem can typically be traced back to the shuttle vector. Expression of genes in virus-producing cells may inhibit viral production as this process depends on host cellular infrastructure and overall health. Typically, highest titers are obtained when vectors encode “innocuous” genes or when the promoter is weak in virus-producing cells.

How should I store my viral vector? AAV vectors are stable if stored at -80oC. Viruses with a lipid membrane (e.g., lentiviruses), however, can experience a ~10-fold reduction in titer for every 6 months of storage at -80oC. Accordingly, the VVCC recommends that lentiviral vectors are used within 2-3 months of production unless the titer far exceeds what is required for the project. In addition, it may be better to order smaller lots of virus repeatedly rather than one large lot.

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