Turbidimetric method for the assay of antiviral antibodies.

A rapid, simple assay method has been developed for antiviral antibodies. The technique has been applied to antisera, immune gamma-globulins, and immunospecifically purified antibody for two strains of influenza virus, Asian 305 and PR8, and to antisera to tobacco mosaic virus. Turbidity changes due to the specific interaction of a virus with its antibody were measured by the increase in optical density in a sensitive wavelength region, e.