Human papilloma viruses. Computer artwork of human papilloma virus (HPV) particles (virions, green and blue) surrounding a raised wart (centre). This virus consists of a protein capsid enclosing DNA (deoxyribonucleic acid), the virus' genetic material. Attached to the capsid (green) are numerous surface proteins (spikes, blue). HPV causes warts, which mostly occur on the hands and feet. Certain strains also infect the genitals. Although most warts are non-malignant (not cancerous), some strains of HPV have been associated with cancers, especially cervical cancer.