The detection of intracellular bluetongue virus particles within ovine erythrocytes.

1. We report here a simplified method for detecting viruses and other antigenic agents in red blood cells (RBCs). Using a nonionic detergent to prepare cytoskeletons, the interior of RBCs can be scanned rapidly using immunoelectron microscopy. 2. In this study, RBCs from bluetongue (BLU) virus-infected sheep were adsorbed directly onto Formvar-coated, gold electron microscope grids. 3. Cytoskeletons were prepared and then probed using a monoclonal antibody to VP 7, a structural BLU-virus protein and Protein-A gold. 4. Of the ca 32,000 RBCs that were examined from BLU virus-infected sheep, 34 (0.106%) contained labelled BLU virus particles. 5. No labelled particles were observed in any of ca 8000 RBCs taken prior to BLU virus inoculation of sheep. 6. If the antigenic BLU virus particles (which may be viral cores) are in fact infectious, this method of sequestration of virus within RBCs could contribute to the prolonged viremia typical of this arboviral disease, which is known to occur concurrently with circulating neutralizing antibody.