Figure 8

Schematic representation of the Cedratvirus getuliensis replication cycle. Infectious particles enter their host cells by phagocytosis (1). Following entry, one cork is expelled and the fusion of the internal membrane with the phagosome membrane occurs with the release of the genome into the cytoplasm, as demonstrated by Andreani et al. (2016) and Bertelli et al. (2017) (2–3). The precise mechanism that triggers the cork expelling and membrane fusion remains unknown, but it may be related to the low pH environment of phagosome. After an eclipse phase, a large electron-lucent viral factory is formed, wherein the virion morphogenesis occurs (4). This process is complex and involves sequential structures starting with crescent-shaped precursors, followed by longitudinal-elongation, first cork acquisition, and the presence of structures with a horseshoe-like and rectangular shape (4). Next, a progressive filling of the capsid is observed, followed by the complete closure of the capsid and the emergence of the second cork (4). Thickening of the capsid wall (5) also occurs, and new viral particles are observed dispersed throughout the cytoplasm (6) or taken up by vesicles with one or two membranes (7). The viral progeny are primarily released through cell lysis (8), but exocytosis is also likely to occur.