The organization of frog virus 3 as revealed by freeze-etching

Ultrastructure of lymphocystis disease virus (LDV) as compared to frog virus 3 (FV3) and chilo iridescent virus (CIV): effects of enzymatic digestions and detergent degradations

“…Although this arrangement could not be precisely measured, similar data have already been reported for LDV [3]. Moreover, for FV3, measurement of the angle between rows showed a deviation of 4 to 8 ° from the expected 60 or 90 ° angle with a P = 1 class of symmetry [5,9]. In such a case, rows of surface units would form an angle with the edge of the triangular facet of the icosahedron.…”

“…This was possible on FV 3 particles using the freeze-etching technique [9]. However, we already know that its periphery appeared different from its center, based on our PTA staining of the embedded virions, but the presence of the rod-like structures described by Berthiaume et al [3] and Madeley et al [17] needs to be confirmed.…”

“…On the other hand, FV3 has been more extensively investigated [8,9,10,22,26,27,28]. It was shown that its capsid is formed by surface protein units attached to an underlying membrane, composed of lipids and proteins, both structures surrounding the viral core [-8, 9, 10, 27].…”

Ranavirus Replication: Molecular, Cellular, and Immunological Events

“…Viral assembly sites contain viral DNA and a number of virus-encoded proteins and serve as the loci of virion formation. Newly synthesized virions are found free within the cytoplasm or within paracrystalline arrays, and, a minority, at least in vitro, bud from the plasma membrane and in the process acquire an envelope derived from the aforementioned plasma membrane and containing one or more virus-encoded proteins (Darcy-Tripier et al 1984 ). In appearance, ranavirus particles show marked similarity to the virions of African swine fever virus (ASFV) and members of the family Phycodnaviridae (Tulman et al 2009 ;Wilson et al 2009 ).…”

“…The factors that determine whether a given particle remains cell-associated or enveloped are not known. Freeze-fracture electron microscopy indicates that mature FV3 particles display a Russian doll-like structure with a knobby, spherical core composed of viral DNA and associated proteins enclosed within a capsid composed primarily of a 48 kDa MCP (Darcy-Tripier et al 1984 ;Devauchelle et al 1985 ). Electron microscopy of Chilo iridescent virus (genus Iridovirus ) has identifi ed at least three minor proteins (designated fi nger, zip, and anchor) associated with the virion, but has not linked them with specifi c viral ORFs (Yan et al 2009 ).…”