Biomedical subjects
Publications and source records attributed to Y C Zee.
A viral agent was isolated from lung tissue obtained upon necropsy of an Arabian foal which had exhibited clinical signs of pneumonia. The virus is 75 nm in diameter, cubic in symmetry, and resistant to chloroform and low pH (3.0). It contains deoxyribonucleic acid and has a buoyant density of 1.31 g/cm(3) in cesium chloride. These findings indicate that the virus is a member of the adenovirus group.
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Cellular immunity to Listeria monocytogenes infection was studied by assaying for antibacterial activity in fractions of leukocytes collected from the peritoneal cavity, lungs, and mammary glands of immunized sheep. The cells were collected in populations that were largely either macrophages or neutrophils. Mechanically disrupted cells were divided into nuclear, lysosomal, and supernatant fluid fractions and then subjected to freezing and thawing. Comparison with similarly treated rabbit cells showed that greater fragility exists in the lysosomes of sheep cells, as indicated by the amount of acid phosphatase activity released. Inhibition of bacterial growth was assayed in a broth medium at pH 4.6. As expected, nuclear and lysosomal fractions from neutrophils were inhibitory. Some antibacterial activity was found in nuclear fractions of macrophages. The lysosomes of macrophages collected from the peritoneal cavity and the mammary gland did not inhibit the growth of L. monocytogenes. Peritoneal macrophages were allowed to interact with sensitized lymphocytes and an avirulent strain of L. monocytogenes for 4 hr prior to disruption and fractionation, but antibacterial activity was not detected. Pulmonary alveolar macrophages from 5 out of 16 sheep contained Listeria inhibitory activity in their lysosomes. The mechanism was inhibitory but not bactericidal.
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Except for the rate, vesicular stomatitis virus (VSV) grows as well at 25 C as at 37 C in primary chick embryo fibroblast cells and in a pig kidney cell line [PK(H13)]. Maximal yields were reached at about 28 hr at 25 C and 10 hr at 37 C in these cells. Morphogenesis, as observed by electron microscopy, was similar at the two temperatures. The main feature was accumulation of virus in intracytoplasmic vacuoles. Mode of release of VSV has been controversial; both budding (as displayed by myxoviruses) and maturation at membranes of cytoplasmic vacuoles (as with arboviruses) have been claimed. Our observations support the latter view, and the apparent dichotomy in interpretation is discussed.
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