Abstract
The neutralizing effect of homologous immune serum on the rabbit papilloma-virus protein is quantitatively reversible 1 by simple dilution over the whole range 2 of serum-virus relations accessible to study by infectivity-measurement. 3 Under proper conditions of serum-virus proportions, precipitates occur in the mixtures, consisting presumably of virus and specific antibody. In the present study the distribution of virus between the soluble and insoluble phases in one region of serum-virus quantities has been determined.
The results reported here were derived from 8 correlated experiments with papilloma-virus protein and an antipapilloma rabbit-serum designated as D. R. 496. The findings of 7 experiments with this serum have been tabulated in detail elsewhere. 1 , 2 An additional study made in the desired region of serum-virus relations is described here.
Papilloma-virus protein procured under standard conditions 3 by ultracentrifugation was mixed with undiluted immune serum D. R. 496 as previously reported 2 so that the final concentration of total virus was 24.4 γ per 0.1 cc (virus pI 4.6, serum pD 0). 1 , 2 After 11/2 hours the precipitate forming at room-temperature was sedimented in an ordinary horizontal International Centrifuge No. 2 at full speed for 30 minutes. The clear supernatant fluid was carefully pipetted from the pellet which was then suspended in 0.9% NaCl solution to the volume of the supernatant fluid (4.5 cc). The supernatant fluid and the pellet-suspension were inoculated 3 in successive twofold dilutions in a group of 32 rabbits, a number statistically adequate 3 for the problem at hand. Twofold dilutions of untreated viral protein were inoculated in the same animals for standardization.
With the serum-virus relations described, the free virus of the whole mixture without separation of the precipitate is 3 γ per 0.1 cc as previously reported, 2 indicating neutralization of 21.4 γ of the 24.4 γ initially present.
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