The Ultracentrifuge as an Aid in the Detection of Poliomyelitis Virus* by Joseph L. Melnick,, Ph.d

The ultracentrifuge has become a well established tool in virus research, because with this apparatus advantage can be taken of the size of viruses to permit the concentration and purification of these substances. The finding of Schultz and Raffel (1) that poliomyelitis virus from infected spinal cords can be sedimented in the ultracentrifuge has recently been confirmed (2, 3). I t has also recently been demonstrated that the analogous virus of mice discovered by Theiler (4) can also be concentrated and purified in this apparatus (5, 6). This paper presents an application of the ultracentrifuge to the preparation from stools of purified materials which can be inoculated intracerebrally into monkeys. The adequacy of this method has been compared with that of the intra-abdominal injection of etherized stool suspension in conjunction with the intranasal instillation of the untreated stool suspension. The former method will be referred to as the ultracentrifugal-intracerebral (or u.-i.c.) method; the latter, as the intra-abdominal-intranasal (or i.a.-i.n.) method. Eleven samples of human, monkey, and chimpanzee stools in which virus was suspected, have been tested by both methods, and two series of titrations with human stools have been carried out.