English: Virion factory (VF) formation of cotonvirus japonicus in Acanthamoeba castellanii.
(a) Development of cotonvirus VF. First, the inner materials of cotonvirus particles are released and engulfed by amoeba cells into the host cytoplasm at 2 hpi (hours past infection). The cotonvirus core and membrane-like structures surrounding it are visualized at 4 hpi. Early VFs are visible at both 8 and 12 hpi, and Golgi apparatus-like structures are found around early VFs. Mature VF is formed, and the production of viral particles is initiated at 16 hpi. New virions are then produced and accumulate in the host cytoplasm at 20 hpi and 24 hpi, respectively. VF release by cell lysis is observed at 28 hpi. Scale bars:

2 hpi, 4 hpi, 500 nm; 8 hpi to 16 hpi, 28 hpi, 1 µm;

20 hpi, 24 hpi, 5 µm.
(b) Four other views of early VFs surrounded by Golgi apparatus-like structures at 12 hpi.