Cowpox virus: Old friend but new foe
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...