It was shown in this work that the electrophoretic mobility of the MEF1 strain of poliovirus was increased approximately 25% after interrupted inactivation with formaldehyde. This is in accordance with past observations on the behaviour of formaldehyde-treated proteins. The residual live virus had the same mobility as the ‘killed’ virus, thus indicating that the surfaces of all the virus particles have been affected to the same degree by the inactivating agent.
Gel precipitin tests performed on the different samples obtained by zone electro-phoresis showed, in addition to the main antigen, the presence of a small amount of a second component of slightly higher mobility, and, as it occurs in the main fraction and the sample thereafter it probably has a slightly higher mobility than the main component.
The antigenic properties of the different fractions as shown by the production of antibodies in guinea-pigs correspond with the presence of precipitating antigen in the samples in the region of highest antigen concentration. The faint antigenicities of the fractions obtained from the regions higher up in the zone electrophoresis column are due to small amounts of virus antigen similar to that found in the column on electrophoresis of untreated MEF1 virus, bearing in mind that the inactivated virus was concentrated approximately 2000 times for zone electrophoresis.