Flu Virus

Travelling easily through the air, flu viruses rapidly spreading infection. As tightly coiled strands of genetic material unwind and make duplicates, mistakes in the reproductive process result in genetically changed offspring-one reason why new viral strains emerge so often.

Hepatitis B Virus

One virus may take different forms and invade various kinds of cells. For example, particles of hepatitis B virus may be are found in the bloodstream of infected people. However, one of hepatitis B's distinguishing traits is that numerous viral particles never become full viruses. A more complete form of the virus infects liver cells, sometimes causing cirrhosis.