Optical Imaging To Track Ligands

Determining where ligands and viruses distribute in vivo is normally an exhaustive process requiring that the animals be sacrificed and their tissues and organs be extracted for enzymatic assays or sectioned to identify the specific cell types that were transduced. These assays are quite laborious requiring that one actually sections the whole animal to be certain of the tissue localization of the vector and to ensure that ligand or vector delivery into very unexpected sites is not missed.

Given the labor involved in these traditional assays, the Virology, Vector and Vaccine Engineering Lab has recently optimized fluorescence and luciferase luminescence imaging to track ligands, vector particles and gene delivery in vivo. While luciferase imaging is now accepted as an excellent approach to track vector delivery or to assess tumor burden noninvasively from luciferase-expressing cancer cells, this technology cannot track the targeting ligands the lab is interested in, as the ligands do not carry transgenes. Likewise, even in vectors, luciferase imaging only allows the identification of cells that were successfully transduced by the vector.

Unfortunately, this provides zero information toward knowing where all the virions actually went, where the unsuccessful vectors are located and if any of the vectors actually made it to the tumor without transducing it. To learn more, the team is applying near infrared fluorescence imaging to track ligands and vectors in vivo and combining this research with luciferase imaging to track successful virus and vector delivery in small animals. These imaging approaches are being applied for all of the gene therapy, vaccine and cancer projects in the lab.