Viruses Viruses contain DNA or RNA 。And a protein coat Some are enclosed by an envelope 。 Some viruses have spikes Most viruses infect only specific types of cells in one host Host range is determined by specific host attachment sites and cellular factors Viruses • Viruses contain DNA or RNA • And a protein coat • Some are enclosed by an envelope • Some viruses have spikes • Most viruses infect only specific types of cells in one host • Host range is determined by specific host attachment sites and cellular factors