Sensitivity and specificity of virion and cell surface labeling using the unlabeled antibody-hemocyanin bridge method

The sensitivity and specificity of the unlabeled antibody-hemocyanin bridge method for immunoelectron microscopic localization of virion and cell surface antigens has been demonstrated using a hyperimmune serum to the Rauscher murine leukemia virus structural envelope glycoprotein (gp 70). The technique localized the gp70 on the viral envelope and on the infected cell surface at dilutions of greater than 10(-3) for the primary antiviral serum. Little or no nonspecific binding of hemocyanin was detected in control experiments using high concentrations of normal nonreacting or adequately absorbed antiviral primary sera and excess antibody bridge and marker; thus, the system is highly specific. Furthermore, sensitivity can be increased approximately fivefold by marked amplification steps whereby a specimen fixing only a slight amount of hemocyanin can be subsequently treated with antihemocyanin antibody, followed by hemocyanin.