21: Viruses Last updated Save as PDF Page ID 12608 Boundless Boundless 21.1: Viral Evolution, Morphology, and Classification 21.1A: Discovery and Detection of Viruses 21.1B: Evolution of Viruses 21.1C: Viral Morphology 21.1D: Virus Classification 21.2: Virus Infections and Hosts 21.2A: Steps of Virus Infections 21.2B: The Lytic and Lysogenic Cycles of Bacteriophages 21.2C: Animal Viruses 21.2D: Plant Viruses 21.3: Prevention and Treatment of Viral Infections 21.3A: Vaccines and Immunity 21.3B: Vaccines and Anti-Viral Drugs for Treatment 21.4: Prions and Viroids 21.4.1: 21-4A- Prions and Viroids Thumbnail: Ebola virus. (Public Domain; CDC).