Abstract
This is a brief preliminary report of results indicating that we have been successful in sedimenting poliomyelitis virus, one of the smallest of the ultramicroscopic viruses, 1 from clear aqueous suspensions by means of ultracentrifugation in vacuum. The machine employed is similar in design to that recently described by Bauer and Pickels, 2
Thus far we have obtained complete results on 2 experiments. In both, the material subjected to ultracentrifugation consisted of a 25% suspension of glycerinated pooled virus cords in physiological saline. The lipoids in these suspensions were removed by ether extraction and the aqueous fraction was centrifuged in an Angle centrifuge at 3000 r.p.m. for at least an hour. In the first experiment the resultant fluid was water-clear to the eye; in the second, very slightly opalescent. Eight cc. of the clear suspension were placed in each of a series of celluloid tubes seated in the rotor.
In the first experiment, the rotor was in motion for a total of 4 hours. Stroboscopic determinations indicated that for 2 hours of this period, the speed was between 27,500 and 30,000 r.p.m. After centrifugation, all of the tubes contained a small membranous type of sediment which could not be completely dispersed by repeated pipetting. The thicker central portion of the sediment presented a pinkish tinge apparently due to sedimentation of hemoglobin present in the original cord suspension.
The supernatant was removed in 2 portions, the upper 6 cc. comprising the “top supernatant,” and the pooled bottom 1 cc. portions being the “bottom supernatant.” The sediment was resuspended in 6 cc. of saline. Monkeys were injected intracerebrally with 1 cc quantities of each of these fractions in varying dilutions. The results.
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