As a graduate student with Robert R. Wagner, in studies on vesicular stomatitis virus, she was the first to purify and characterize defective interfering (DI) viral particles. Her postulate that these mutants play a major role in viral pathogenesis stimulated work on many viral systems including plant viruses, and has led to the testing of these particles for the amelioration of viral diseases. Her postdoctoral work with David Baltimore and a graduate student Martha Stampfer, on vesicular stomatitis virus (VSV) uncovered a virion-associated RNA-dependent RNA polymerase that led the way to Baltimore's discovery of reverse transcriptase. Her overall research focused on the molecular characterization of VSV: its viral RNA species and regulatory mechanisms during replication as well as its glycoprotein and a derivative, soluble form, shed from infected cells. She was, also, the first to demonstrate that RNA and DNA enveloped viruses, including leukemia viruses, herpes viruses and human immunodeficiency virus, phenotypically mix their surface glycoproteins resulting in alterations of antigenicity and host range. These results led to the use of VSV as a vector to target specific cells. Her contributions to the early days of animal virus studies and the use of VSV as a model virus system have been widely recognized.
Subsequently, as Dean at NYU, she spearheaded interdisciplinary programs that resulted in the formation of "Silicon Alley, an entrepreneurial outgrowth from the collaboration of the Courant Institute of Mathematical Sciences, the Tisch School of the Arts, and Faculty of Arts & Sciences.