Among shrimp viral pathogens, white spot syndrome virus (WSSV) and yellow head virus (YHV) are the most lethal agents, causing serious problems for both the whiteleg shrimp, Penaeus (Litopenaeus) vannamei , and the black tiger shrimp, Penaeus (Penaeus) monodon . Another important virus that infects P. vannamei is infectious myonecrosis virus (IMNV), which induces the white discoloration of affected muscle. In