Part of the "Branches on the Tree of Life" series. Describes the discovery of viruses and their structure, how viruses are studied, how they infect their hosts, and how they replicate. Provides details on the T-4 bacteriophage and retroviruses, such as HIV. Accessibility options on the DVD are: (1) expanded description, (2) English subtitles in a black box, (3) subtitled description.
