Abstract
A modified technique using protein A in the serum-in-agar (SIA) method for immune electron microscopy (IEM) was presented. Grids coated with staphylococcal protein A were floated on samples mounted on agar containing 2%, antiserum and incubated at 37C, for 60min. After washing and staining, the grids were observed in an electron microscope. The effects of protein A on virus detection were evaluated using poliovirus and bovine rotavirus infected cell culture fluids. The results showed that the technique using protein A (PA-SIA) had at least 10-fold higher sensitivity for virus detection than the original SIA. The optimal concentration of protein A was 1 to 10μg/ml for coating the grids to trap virus particles. The PA-SIA method was also compared with immunosorbent electron microscopy (ISEM). The former showed higher or at least the same sensitivity and some advantages in detecting antigen-antibody reaction than the latter method. These results indicate that our PA-SIA method may be superior to other IEM techniques presented previously for the detection and identification of viruses.
