- Purified herpes simplex thymidine kinase Retrovector particles. I. In vitro characterization, in situ transduction efficiency, and histopathological analyses of gene therapy-treated brain tumors. Kruse, C.A., Roper, M.D., Kleinschmidt-DeMasters, B.K., Banuelos, S.J., Smiley, W.R., Robbins, J.M., Burrows, F.J. Cancer Gene Ther. (1997)