A small particle that contains certain proteins from the outer coat of a virus. Virus-like particles do not contain any genetic material from the virus and cannot cause an infection. They are used to make vaccines that can help the body?s immune system kill microorganisms and certain cancer cells. Virus-like particles were used to make vaccines that prevent cervical cancer caused by human papilloma viruses (HPV). They were also used to make vaccines that prevent liver cancer caused by infection with the hepatitis B virus.