Vaccinia

Vaccinia

Electron micrograph of the Vaccinia virus

Vaccinia is a virus that belongs to the Poxviridae family, which includes other notable viruses such as smallpox and cowpox. It is best known for its role in the smallpox vaccine, which led to the eradication of smallpox in 1980.

History

The use of vaccinia virus in vaccination dates back to the late 18th century when Edward Jenner discovered that milkmaids who had contracted cowpox were immune to smallpox. Jenner used material from cowpox lesions to inoculate people, a practice that eventually evolved into the use of vaccinia virus.

Characteristics

Vaccinia virus is a large, complex, enveloped virus with a linear double-stranded DNA genome. It replicates in the cytoplasm of host cells, unlike most DNA viruses that replicate in the nucleus.

Use in Vaccination

A smallpox vaccination site on the arm

Vaccinia virus is used in the smallpox vaccine because it provides immunity against smallpox without causing the disease itself. The vaccine is administered using a bifurcated needle that pricks the skin multiple times, creating a small lesion that heals over time.

Modern Applications

In addition to its historical use in smallpox vaccination, vaccinia virus is being explored as a vector for delivering genes in gene therapy and as a platform for developing vaccines against other infectious diseases.

Safety and Side Effects

While the smallpox vaccine is generally safe, it can cause side effects, particularly in individuals with weakened immune systems. Common side effects include mild fever and rash, while more serious complications are rare.

Related Pages

• Smallpox
• Edward Jenner
• Poxviridae

References

• Fenner, F., Henderson, D. A., Arita, I., Jezek, Z., & Ladnyi, I. D. (1988). Smallpox and its Eradication. Geneva: World Health Organization.
• Moss, B. (2001). "Poxviridae: The Viruses and Their Replication." In D. M. Knipe & P. M. Howley (Eds.), Fields Virology (4th ed., pp. 2849-2883). Philadelphia: Lippincott Williams & Wilkins.

Vial of smallpox vaccine