The Simultaneous Occurrence of the Viruses of Canine Distemper and Lymphocytic Choriomeningitis* a Correction of "canine Distemper in the Rhesus Monkey" by Gilbert Dalldorf, M.d

The injection of suspensions of dog and ferret spleens from various generations of a particular serial passage of canine distemper was found to regularly produce a disease in rhesus monkeys which we believed to be distemper (1). Further work has shown this identification to be incorrect. The response in monkeys is not due to Carr6's virus but to lymphocytic choriomeningitis which has been simultaneously present with canine distemper virus in all of the samples of the source material tested. In a preliminary correction of the original report it was shown that each of two generations of the source material was capable of producing the clinical responses and lesions of lymphocytic choriomeningitis in mice and guinea pigs. I t was also shown that mice which had received suspensions of the material intravenously and recovered were subsequently resistant to a known strain of lymphocytic choriomeningitis virus injected intracerebrally, and conversely that monkeys convalescent from infection with a known strain of virus were resistant to the same dog spleen suspensions which were pathogenic for normal monkeys (2). Having failed at that time to identify the second virus serologically and because it seemed of particular importance that its presence in the source material be thoroughly established, two other samples were examined. The study of these forms the substance of the present report. Certain observations which seem to explain some of the circumstances which led to the original error are also included.