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May 12, 1945


JAMA. 1945;128(2):130. doi:10.1001/jama.1945.02860190066012

In medical literature the word virus is now used in a special sense to designate certain agents of infectious disease that are not subject to successful study by the usual bacteriologic procedures. The nature and properties of viruses so designated cannot be determined by the morphologic and cultural methods applied with such momentous results to bacteria. Viruses cannot be seen with the light microscope and so far they have not been cultivated outside of living tissue. Scarcely more than a decade ago they were demonstrable only by their power to cause disease. Special and new methods were required to gain some closer insight into their nature and properties. Recent and current results of intensive work with newer methods at Duke University are reviewed by Beard,1 with special reference to the viruses of vaccinia, equine encephalomyelitis, influenza and rabbit papilloma. By means of air driven, analytical centrifugation of virus infected materials,