Ultrastructure analysis of white spot syndrome virus (WSSV)

In this study, two aspects of the ultrastructure of white spot syndrome virus (WSSV) were identified: (i) The virus nucleocapsids were disassembled, and transmission electron microscopy (TEM) image analysis confirmed that the nucleocapsids were composed of stacked ring segments rather than the usual helix system, with each ring segment consisting of three rows of subunits linked by filaments. (ii) In addition, the morphological characteristics of virus self-assembly at different stages were observed, and two different enveloping morphologies were found, implying that the virion matures through two distinct envelopments. Thus, we propose a viral membrane assembly process for WSSV virion.