A technology that shows great promise in treating human disease is the use of viruses as vectors (or carriers) to insert and replicate new genetic material into the genome of a diseased cell. Parvoviruses are suitable candidates for use as vectors, including the parvovirus known as MVM (minute virus of mice). These viruses have been successfully tested in many preclinical models of human diseases, including cancer. As part of its replication cycle, the genome of MVM must enter the nucleus of its host cell. How MVM accomplishes this is unknown, but studies suggest that the way it breaches the nuclear membrane is unlike that of any other known virus. Sarah Cohen is using electron microscopy, combined with biochemical and genetic approaches, to investigate the mechanisms employed by MVM to enter the nucleus of a host cell. Gaining a more developed understanding of these entry mechanisms will aid in the development of MVM as a therapeutic vector, helping to bring MVM-based vectors into clinical trials. A successful vector for gene therapy could ultimately deliver healthy genes to patients for the treatment of a wide variety of genetic diseases.