Cold and Flu
Microbiology
Infectious Diseases
Conditions and Diseases
Rabies
Swine Flu (H1N1/09)
Biology
Ebola Hemorrhagic Fever
Genetics
Health
Bacteria
Computer Viruses
Vaccinations
Science
Cell Biology (cytology)
HIV and AIDS

Viruses (biological)

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses display a wide diversity of shapes and sizes, called morphologies. Generally viruses are much smaller than bacteria. Most viruses that have been studied have a diameter between 10 and 300 nanometres.