Variola virus

Variola virus is a virus that is responsible for causing smallpox, a highly contagious and deadly disease. It is a member of the Orthopoxvirus genus and the Poxviridae family of viruses. The virus is unique to humans and has two main types: Variola major and Variola minor.

History

The Variola virus has a long history, with evidence of smallpox found in ancient Egyptian mummies dating back to the 3rd century BCE. The disease was a major cause of death worldwide until the development of a vaccine by Edward Jenner in 1796. The World Health Organization (WHO) launched an intensive global smallpox eradication campaign in 1967, and the last known natural case of smallpox occurred in Somalia in 1977.

Structure and Genome

The Variola virus is a large, brick-shaped virus with a complex structure. It has a linear, double-stranded DNA genome that is approximately 186 kilobase pairs in length. The genome encodes for approximately 200 proteins, many of which are involved in evading the host's immune response.

Pathogenesis and Transmission

The Variola virus is transmitted from person to person primarily through respiratory droplets. After an incubation period of 7 to 17 days, the virus causes symptoms such as fever, fatigue, and a characteristic rash. The virus replicates in the lymph nodes before spreading to the bloodstream and skin.

Eradication and Current Status

The Variola virus is the only virus that has been eradicated in the wild through human effort. Since 1980, the WHO has declared the world free of smallpox. However, stocks of the virus are kept for research purposes in two WHO-designated repositories: the Centers for Disease Control and Prevention (CDC) in the United States and the State Research Centre of Virology and Biotechnology (VECTOR) in Russia.

See Also

• Smallpox
• Orthopoxvirus
• Poxviridae
• Edward Jenner
• World Health Organization