The observation that milkmaids are frequently infected with cowpox but rarely catch smallpox is generally credited to the English doctor Edward Jenner. Although Jenner might not have been the first person to notice the correlation, he was the first to make use of it: in 1796 he "vaccinated" children with material from cowpox blisters and showed that they became immune to smallpox. Jenner's work led directly to the development of a smallpox vaccine and less than 200 years later the disease was eradicated. Jenner's initial vaccine presumably came from an English strain of cowpox and it was generally assumed that commercial vaccines are derived from this. Recent findings from an international consortium including the group of Norbert Nowotny at the University of Veterinary Medicine, Vienna challenge this view and suggest that smallpox vaccines come instead from central or eastern Europe. The results have recently been published in the prestigious online journal PLoS One. The work is not merely of historical interest: since the cessation of smallpox vaccination there has been a rise in cases of related diseases and pox viruses once again represent a serious threat to public health.
The family of orthopox viruses is generally considered to comprise vaccinia virus, variola virus (which causes smallpox), cowpox virus and at least six other species. The various pox viruses are named after their usual hosts but this nomenclature may give rise to a false sense of security: most of them seem to have fairly catholic tastes and cowpox is able to infect not only cows but also a variety of other animals, ranging from mice to elephants as well as man.
Despite the importance of cowpox in human medicine the virus has attracted relatively little attention and how the many forms of cowpox are related was until recently a matter of conjecture. The issue has been clarified by a large international consortium headed by Darin Carroll at the Centers
|Contact: Beate Zoechmeister|
University of Veterinary Medicine -- Vienna