The broad objective of Dr. Levin’s recent research has been to expand knowledge of HIV replication strategies and host defense mechanisms and thereby contribute to development of new treatments for AIDS patients. She has studied the effects of mutations in structural elements of the HIV-1 capsid protein on infectivity, viral core architecture, and reverse transcription. She has also had a long-standing interest and leadership role in research on the HIV-1 nucleocapsid protein (NC) and has made numerous contributions regarding the critical importance of NC function for specific and efficient reverse transcription. Her reviews on the nucleic acid chaperone activity of NC (i.e., the ability of NC to remodel nucleic acid structures to form the most thermodynamically stable conformations) continue to be cited widely in the retrovirus literature. Recently, Dr. Levin has undertaken studies of the human APOBEC3 (A3) proteins, a family of seven cellular cytidine deaminases, which function as DNA mutators and restrict HIV-1 and other pathogens. Her laboratory was one of the first to report biochemical studies of highly purified, catalytically active A3G. This work led to the proposal of a “roadblock” effect of A3G on reverse transcription, indicating that HIV-1 restriction can occur by deaminase-independent as well as deaminase-dependent mechanims. In other studies, Dr. Levin’s group has exploited a multi-disciplinary approach, targeting the molecular properties of A3A, A3H, and A3B (C-terminal catalytic domain) and their relation to biological activity and their three-dimensional NMR solution structure.