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Hyde, James M. (University of Mississippi School of Medicine, Jackson), Lanelle G. Gafford, and Charles C. Randall. Fine structure of the coat and nucleoid material of fowlpox virus. J. Bacteriol. 89:1557-1569. 1965.-Several morphological forms characteristic of the poxvirus group were demonstrated for fowlpox virus with neutral phosphotungstic acid (PTA). Viral particles (purified from viral inclusion bodies) stained with uranyl acetate (UA) and shadowed with platinum were shown to have an external knobby surface not evident with PTA. The external coat of freshly purified viral particles seemed intact, but as the preparation aged, it appeared to unwind, resulting in twisted "rope-like" structures. This process was facilitated by use of 1% trypsin, and three dense fibrils were identified with UA within the partially detached viral coat. Studies with alkaline PTA (pH 9) were interpreted as revealing a complex nucleoid, but solutions above this pH damaged the particles. The morphology of the nucleoid was better depicted in ultrathin sections of whole virus which, when stained with UA, revealed dense coiled threads. Treatment of virus with sodium lauryl sulfate exposed an underlying coat consisting of small subunits approximately 40 A in diameter. Of great interest was the demonstration that the detergent removed strands of deoxyribonucleic acid (DNA) from the virus without destroying the contour of the particle. The origin of the strands was definitely the fine uranophilic, coiled threads of the nucleoid, which probably represent the DNA molecule(s). That the extracted material was largely DNA was proved by digestion with deoxyribonuclease and resistance to ribonuclease and trypsin. These studies illustrate how a variety of electron microscopic techniques may be utilized alone or in combination to reveal hitherto undescribed fine structure of viral particles.

Randall, Charles C. (University of Mississippi School of Medicine, Jackson), Lanelle G. Gafford, Robert W. Darlington, and James M. Hyde. Composition of fowlpox virus and inclusion matrix. J. Bacteriol. 87:939-944. 1964.-Inclusion bodies of fowlpox virus infection are especially favorable starting material for the isolation of virus and inclusion matrix. Electron micrographs of viral particles and matrix indicated a high degree of purification. Density-gradient centrifugation of virus in cesium chloride and potassium tartrate was unsatisfactory because of inactivation, and clumping or disintegration. Chemical analyses of virus and matrix revealed significant amounts of lipid, protein, and deoxyribonucleic acid, but no ribonucleic acid or carbohydrate. Approximately 47% of the weight of the virus and 83% of the matrix were extractable in chloroform-methanol. The lipid partitions of the petroleum ether extracts were similar, except that the phospholipid content of the matrix was 2.2 times that of the virus. Viral particles were sensitive to diethyl ether and chloroform.