Measurement of the electrokinetic properties of vaccinia and reovirus by laser-illuminated whole-particle microelectrophoresis

The electrokinetics of vaccinia virus and reovirus type 3 were studied in dilute electrolyte solutions by whole-particle microelectrophoresis with dark-field laser illumination. The electrophoretic mobilities were dependent upon pH and electrolyte composition. The isoelectric point of vaccinia virus in dilute NaCl was 4.8 +/- 0.1; that of reovirus was 3.8 +/- 0.1. The mobility of reovirus was -2.65 +/- 0.30 micrometer . S-1 . V-1 . cm-1. Treatments known to cause irreversible changes in the structure of vaccinia, such as heating to 90 degrees C or exposure to pH 10, altered the virus's mobility under the reference conditions. The practical range of whole-particle microelectrophoresis thus extends to microorganisms as small as reovirus, allowing their electrokinetic and related surface properties to be studied.