The Effect of a Synthetic Lysine Polypeptide upon the Velocity of Precipitation of Tobacco Mosaic Virus by Its Antiserum

When small amounts of a basic synthetic lysine polypeptide preparation are added to tobacco mosaic virus along with its specific antiserum, both the antiserum and the polypeptide react simultaneously with the virus to cause an increase in the velocity of precipitate formation. However, when larger amounts are added to the virus before the antiserum, the polypeptide rapidly combines with the acidic surface of the virus and then at certain ratios of virus to polypeptide may interfere with subsequent combination with the antiserum and so decrease the velocity of precipitation. Precipitates are formed in the region of antigen excess in the presence of the polypeptide.