Experimental studies on transformation of the variola virus into the vaccinia virus

Abstract

The transformation of variola virus into vaccinia virus by means of passage through animal systems has been a subject of sei6ntific controversy for more than 100 years. The discussions centered around the question whether the vaeeinia virus represents 1) a separate member of the pox viruses which occur naturally; 2) a result of transformation of the variola virus, or 3) --an equally conceivable possibility, a transformed cowpox virus. The experimental research of the past and of recent time shows three stages. Evaluating the/irst period until 1890 we have, of course, to consider the low standard of microbiological research during this time. We find reports about viral transformation as well as reports about the absence of transformation. I~eferenees will be found in . There seems to be a preponderance of successful transformations, although it is doubtful whether all negative results had been reported.During that period a commission appointed by the medical association in Lyon investigated the problem under Chauveau (9), and emphatically disavowed the possibility of variola transformation into vaccinia. Other investigators, mainly the German research workers, looked upon transformation as a proven concept. This resulted in two scientific camps, the camp of the Unitarians and of the so called Dualists. The so called Unitarians "believed" in the transformation of the variola virus into vaccinia virus, in opposition to the Dualists, who favoured the concept of the independent occurrence of both viruses and denied any possible transformation. The second period lasts to the thirties of the 20th century and coincides with the peak of the bacteriologic research and the begin-39* A. Herrlich, A. Nayr, H. ~l~hnel, and E. 3lunz:

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