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

Nelson, John B.

Unusually acute signs of illness appeared in Swiss mice during the first cranial passage series. By the 3rd transfer, leukocytes were demonstrable in direct films 179 and later in sections from the brain. A cerebral suspension prepared from the mice of the 5th transfer yielded a pure growth of PPLO. The passage series was continued with a Coors filtrate of the contaminated suspension and subsequently maintained in the absence of PPLO. In 1938, Sabin (2) described a nervous disorder of mice that appeared during the cerebral passage of toxoplasma. The characteristic sign was a rolling motion on the long axis of the body. It was also observed after intraabdominal and intrathoracic injection. The incidence was 20 to 40 per cent. Two kinds of brain lesions were found in sections. The first one was indicated by destruction of the periventricular tissue and extensive leukocytic infiltration. It was present in all mice. The second lesion, consisting of almost complete necrosis and lysis of the posterior pole of the cerebellum, occurred only in mice with rolling signs.