Study of the Virus of the Common Cold and Its Cultivation in Tissue Medium.

In previous papers we reported the evidence which supports our belief that the common cold in man is caused by a filterable virus. This view is strengthened by recent work published by Long and Doull. In addition to the effort to decide the question of etiology one of the objects of this investigation has been to explore the possibility of developing a specific prophylaxis for this disease. The first steps in the successful carrying out of such a procedure must naturally be directed toward an attempt to preserve the virus in an active form outside the animal body and an effort to cause this agent to reproduce itself in vitro. In order to test survival of the virus after removal from the human body, naso-pharyngeal washings were obtained in the manner previously described, from individuals within the first 24 hours of a typical attack of common cold. The material was quickly passed through a Seitz filter and the filtrate was subsequently tested for its capacity to induce the symptoms of the common cold in chimpanzees and in human volunteers. The filtrates with cysteine hydrochloride added were preserved anaerobically under vaseline seal both at room and at ice-box temperature. In a few instances the filtrate was concentrated to approximately one-seventh its original volume by vacuum distillation. Of 12 inoculations of filtrates preserved in this manner 9 have produced in the inoculated subject typical symptoms of the common cold. The duration of time of preservation of active filtrates has ranged from 4 to 13 days. Tests of survival beyond the thirteenth day have not been made. Positive results have been obtained with filtrates kept at room temperature and with those kept at ice-box temperature, and with both the unconcentrated filtrate and with that concentrated by vacuum distillation.