Fig 1.
Hypertrophied virus-infected nuclei in surface epidermal cells of Adhesisagitta hispida.
A. Virus-infected nucleus located centrally within cell. B. Partially protruding virus-infected nucleus. C. Virus-infected nucleus protrudes above the rest of its epidermal cell. Arrowheads indicate locations of nuclear envelope; CF, aggregates of cytoplasmic filaments; CY cytoplasm; EDN, electron dense nucleoplasm; RM, reticulate mass; TEC, tonofilament-rich epidermal cells; UN, nucleus of uninfected surface gland cell; black arrow indicates full naked capsid in cytoplasm; white arrow indicates electron dense body. Scale bars = 2 μm.
Fig 2.
Meelsvirus, structure of mature virions.
A. Longitudinal section through entire virion, showing head (HD) and tail (TA). The envelope (EN) surrounds the capsid (CA) and extends over the surface of the tail. ECM, extracapsidular material in tail; GLM, glycocalyx-like material; ST, stem of tail; arrowheads indicate tail spikes. Scale bar = 0.2 μm. B. Cross section through head. The capsid wall varies in appearance depending on the exact plane of section through it. Area 1 is sectioned perpendicular to the surface; areas 2 and 3 have been somewhat obliquely cut. CM, central membrane of envelope; GLM, glycocalyx-like material. Scale bar = 0.1 μm. C-D. Details of capsid wall. RC, radial columns; CB, cross bridges; arrowheads indicate punctae. Scale = 0.05 μm. E. Tangential section through capsid wall showing patterned substructure. CC, capsid contents; CW, capsid wall; EN, envelope. Scale bar = 0.1 μm. F: Tangential longitudinal section of virion, showing ribs (RB). Scale bar = 0.2 μm.
Fig 3.
Details of infected nuclei and forming virions.
A. Basal edge of virus-infected nucleus. Numbers (1, 2, 3) show successive stages of virion assembly on the surface of the electron dense nucleoplasm (EDN). Note that the envelope and capsid wall self-assemble simultaneously. CW, capsid wall; CY, cytoplasm; ECM, extracapsidular material in a cross-sectioned tail; ELN, electron lucent nucleoplasm; EN, envelope; ST, stem of tail. B. Apical side of nucleus, showing single membrane of nuclear envelope (arrowheads) adjacent to plasma membrane (PM). C. Nuclear envelope in area where outer membrane becomes discontinuous. Arrowheads indicate membranes of the nuclear envelope. Scale bars = 0.2 μm.
Fig 4.
Successive stages of virion self-assembly.
A. During the earliest stages of virion formation, the envelope (EN) and capsid wall (CW) self-assemble on the inner surface of the electron dense nucleoplasm (EDN). B. Mid-stage of virion formation. Brackets indicate site of self-assembly of capsid wall and envelope. CM, central membrane of envelope; CW, capsid wall; EDN, electron dense nucleoplasm; PT, possible portal-like specialization of capsid wall; RL, reinforcing layer of forming tail stem; RB, ribs. C. Latest stage of virion formation that is associated with the inner surface of the electron dense nucleoplasm. The capsid wall (CW) and envelope (EN) are nearly closed. The envelope is separated from the capsid wall by a lucent extracapsidular space (ECS). PT, possible portal-like specialization of capsid wall. D. Detail of forming tail-end of virion. CC, capsid contents; CM, central membrane of envelope; CW, capsid wall; RL, reinforcing layer of forming tail stem. E. Longitudinal section of nearly-formed virion, showing envelope extended as a narrow tail (TA), but tail apparently not yet filled with extracapsidular material. Scale bars = 0.1 μm.