| Abstract: | Tissues from mink infected with aleutian disease virus were examined by the electron microscope for the presence of virus particles. Virus-like particles, measuring 22 nm in diameter, were observed in macrophages of spleen, mesenteric lymph node and in Kupffer cells in liver of mink ten to 13 days after infection. The virus-like particles were usually present in vacuoles inside the cytoplasm of macrophages and Kupffer cells and, occasionally, similar particles were observed inside the nucleus. Cells from uninfected mink did not contain such patricles. To correlate the existence of these virus-like particles with the presence of aleutian disease virus antigen in infected cells, tissues were processed for immunoferritin technique. It was found that aleutian disease virus antigen was present in vacuoles inside the cytoplasm of cells from the infected spleen, lymph node and liver, and that the location was similar to that of the 22 nm virus-like particles. In addition, some viral antigen was also detected as cytoplasmic granular material. The nuclei of some cells also contained aleutian disease virus antigen. The pattern of aleutian disease virus antigen was similar to the distribution of virus-like particles in cells of infected tissue. It is suggested that virus replication occurs inside the nucleus with subsequent accumulation of virus in the vacuoles of the cytoplasm. |
