Fibrils, Tubules, and Crystals in Cells Infected with Epizootic Hemorrhagic Disease Virus

Epizootic hemorrhagic disease virus (EHDV), an orbivirus taxonomically and an arbovirus epidemiologically, replicated in cytoplasmic matrixes of infected cells.1-3 Filaments and macrotubules were observed in the cytoplasm and in association with viroplasms in EHDV-infected cells.1-3 In two studies,2,3 the diameters of the macrotubules were similar to that of the virion, i.e., 53 and 62 nm. One study1 reported that the outer and inner diameters of macrotubules were 40-50 and 35-40 nm and the diameter of the virions was 59 nm with an electron-dense core of 40 nm. Another report4 gave macrotubule outer and inner diameters of ca 35 and 25 nm and a virus diameter of ca 60 nm with an RNA core of 30 nm. Many tubules contained dark-staining centers similar in diameters to that of the interiors of the macrotubules and the EHDV RNA cores.4 This report describes additional morphological features associated with EHDV-infected cells.