THE ENHANCING EFFECT OF MURINE HEPATITIS VIRUS ON THE CEREBRAL ACTIVITY OF PLEUROPNEUMONIA-LIKE ORGANISMS IN MICE

Nelson, John B.

Twenty of the 40 mice in this series of passages died, 14 on the 3rd day and 6 on the 4th. The 20 survivors were acutely ill when killed for autopsy. They regularly showed a marked loss in weight, up to 4 grn. per mouse. Roughening of the hair was a variable finding. Many of the mice were inactive and some were prone. Convulsive movements were irregularly observed and a tendency to roll was seen in 3. At autopsy the livers commonly showed a normal red color but were regularly spotted with small white loci. These areas were often few in number, 10 or less, and in some instances were visible only on low power magnification. The Gram-stained films regularly showed leukocytes in considerable numbers. In some films extra-and intracellular groupings of PPLO were clearly demonstrable. Areas of inflammation with innumerable leukocytes were observed in the brain sections. A pure growth of PPLO colonies, varying from several thousand to innumerable, was obtained on the plate cultures from 7 of the passages. The growth from the brains of the first passage, which had been made with a previously frozen suspension, was relatively meagre. A culture made from the pooled livers of the 2 survivors in the second passage was bacteriologically sterile.