Spillover: Zika, Ebola & Beyond

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The proteins that make up the icosahedral capsid structure of the virus are shown.

Papillomavirus Cross Section

A. DNA genome; B. Histone; C. Capsid proteins

Replication Cycle Content


  • Papillomaviridae family
  • ~55-nm naked particles with icosahedral structure
  • Circular, ds DNA genome of ~8,000 bp
  • Infects many different organisms including humans, cattle, and other mammals; birds; fish; reptiles; and amphibians
  • Human vaccine protects against several sexually transmitted strains

Show Relative Size

Papillomaviruses are numerous—as of 2015, there were over 100 recognized species. Many of these infect humans and can cause symptoms ranging from benign growths (called warts, or papillomas) on the skin, respiratory tract, or genitals, to several types of cancer. In 2006 the first vaccines became available against strains of human papilloma viruses (HPV) that can cause genital warts and cancer.


Relative Sizes

Chart showing size comparison of different viruses.

The white line represents 100 nanometers (nm). For comparison, the width of a human hair is about 75,000 nm, so it would be 750 times as long!