DIRECT QUANTIFICATION OF UNADSORBED VIRUSES IN SUSPENSIONS OF ADSORBING COLLOIDS WITH THE ENZYME-LINKED-IMMUNOSORBENT-ASSAY

Quantification of two plant viruses in suspensions of homoionic Ca-ben tonite was conducted by applying to the enzyme-linked immunosorbent as say plates either the virus-clay mixture (direct method) or the supern atant obtained after the clay was allowed to settle (classic method). Both methods showed a similar dependence of free virus content on clay concentration. A higher content at equilibrium was measured for both viruses by the direct method. The advantage of using the direct over t he classic method is discussed.