Systematic morphogenesis of the viral haemorrhagic disease virus in infected rabbits and in adapted cell culture.

The morphogenesis of viral haemorrhagic disease virus (VHDV) of rabbits in infected cell cultures and in tissues and cells from infected animals has been observed systematically by electron microscopy. Viral particles have been found to assemble through a condensation process within the nucleus of infected cells, having passed partially into the cytoplasm through disrupted nuclear membranes, enlarged nuclear pores or perinuclear space. Late in infection, both mature and immature virions are observed in the cytoplasm; these are often aggregated or interspersed and remain cell-associated long after infection. Release of the virus occurs when the cell finally lyses. In studies of the localisation and development of VHDV antigens, the viral antigens have been observed to appear first in the nucleus of infected cells and often thereafter in the cytoplasm. This finding is very similar to observations made by electron microscopy.