The cowpox virus contains 222 thousand base pairs of DNA, which contains the information for about 203-204 genes. This makes cowpox one of the most complicated viruses known. A significant number of these genes give instructions for key parts of the human immune system, giving a clue as to why the closely related smallpox is so lethal. The vaccinia virus now used for smallpox vaccination is sufficiently different from the cowpox virus found in the wild as to be considered a separate virus.
The cowpox virus contains 222 thousand base pairs of DNA, which contains the information for about 203-204 genes. This makes cowpox one of the most complicated viruses known. A significant number of these genes give instructions for key parts of the human immune system, giving a clue as to why the closely related smallpox is so lethal. The vaccinia virus now used for smallpox vaccination is sufficiently different from the cowpox virus found in the wild as to be considered a separate virus.