Figure 1 Morphology of ascovirus virions. (A) Schematic illustration of the structure of a typical ascovirus virion. The virion consists of an inner particle and an outer envelope. The inner particle is complex and contains a DNA/protein core surrounded by an apparent unit membrane, the external surface of which bears a layer of distinctive protein subunits. (B, C) Respectively, ultrathin longitudinal and cross sections through typical ascovirus virions. The dense inner layer corresponds with the distinctive layer of subunits shown in A. (D-F) Negative contrast electron micrographs of virions from three different ascovirus species: D, Spodoptera frugiperda ascovirus 1a (SfAV-1a); E, Trichoplusia ni ascovirus 2a (TnAV-2a) and F, Heliothis virescens ascovirus 3a (ApAV-3a). The reticulate appearance of the virions is thought to be due to the superimposition of top and bottom layers of the inner particle and outer envelope.
Figure 2 Cladogram based on genetic distances between amino acid sequences derived from the DNA polymerase gene of several ascoviruses.
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