Randall, Charles C. (University of Mississippi, Jackson), Lanelle G. Gafford, Richard L. Soehner, and James M. Hyde. Physicochemical properties of fowlpox virus deoxyribonucleic acid and its anomalous infectious behavior. J. Bacteriol. 91:95-100. 1966.-Deoxyribonucleic acid (DNA) was extracted from fowlpox virus-infected tissue, purified inclusions, and purified virus by five variations of detergent and phenol methods. Phenol methods gave a poor yield, whereas detergent techniques extracted up to 78% of the DNA. The buoyant density was 1.695 g/ml, and the melting temperature in 7.2 m NaClO(4) was 39 C, both approximately equivalent to a guanine plus cytosine content of 35 moles per cent. Further proof of the double-stranded nature of the DNA was shown by the characteristic behavior toward deoxyribonuclease, formaldehyde, and heat. Infectious DNA was obtained by the various methods described, but this manifestation of biological activity was capricious and for unknown reasons was often not evident. The infectivity could not be related quantitatively to the amount of DNA employed. Furthermore, the infectious nature of fowlpox virus DNA was demonstrable only when the route of infection was the chorioallantoic membrane. In contrast, whole virus infected both membrane and chick skin with equal efficiency.