Disclosed herein are compounds, compositions, and methods to inactivate a virus and destroy tumor cells. The methods involve the addition into the cell of a compound containing a photosensitizing chemical and an energy donating chemical, optionally linked by a chemical tether. Also introduced into the cell are means to chemically activate the energy donating chemical which photoactivates the photosensitizing chemical which then destroys the tumor or virus. The photosensitizing chemical is preferably hypericin, porphyrin, or an analog and the energy donating chemical is preferably luciferin or an analog. Methods for synthesizing the chemicals are also disclosed. Further, the energy donating chemical is activated by an activating chemical. The expression of the activating chemical is regulated so as to target the virus-infected or tumor cells. Regulating the activating chemical is accomplished by a number of methods including construction of an expression plasmid containing a gene encoding the activating chemical under control of a promoter which is transactivated by replication of the virus or transactivated by elevated levels of proteins expressed in tumor cells.