Vaccinia n. : Cowpox; vaccina. See Cowpox.

Example:
Which is larger in diameter, the “average” Chlamydia or the Vaccinia virus?

Taxonomy
Vaccinia virus, Vaccinia, smallpox, vaccine, virus, strains, infection, protein, free encyclopedia, vaccination, Modified vaccinia Ankara, cdc, virion, Cowpox virus, genome, IMV, CEV, EEV.

Defination from the web:
Vaccinia virus is well-known for its role as a vaccine that eradicated the smallpox disease, making it the first human disease to be successfully ... Post eradication of smallpox, scientists study Vaccinia virus to use as a tool for delivering genes into biological tissues (gene ...