Comparative genomic analysis of three white spot syndrome virus isolates of different virulence.

Three white spot syndrome virus (WSSV) isolates of different virulence were identified in our previous study, the high-virulent strain WSSV-CN01, the moderate-virulent strain WSSV-CN02 and the low-virulent strain WSSV-CN03. In this study, the genomes of these three WSSV isolates were sequenced, annotated and compared. The genome sizes for WSSV-CN01, WSSV-CN02, and WSSV-CN03 are 309,286, 294,261, and 284,148 bp, bearing 177, 164, and 154 putative protein-coding genes, respectively. The genomic variations including insertions, deletions, and substitutions were investigated. Thirty four genes show >20% variation in their sequences in WSSV-CN02 or WSSV-CN03, in comparison with WSSV-CN01, including six envelope protein genes (wsv237/vp41A, wsv238/vp52A, wsv338/vp62, wsv339/vp39, wsv077/vp36A, and wsv242/vp41B), and two immediate-early genes (wsv108 and wsv178). The genomic variations among WSSV isolates of different virulence, especially those in the coding regions, certainly provide new insight into the understanding of the molecular basis of WSSV pathogenesis.