Fig. 12.

Infectious myonecrosis (IMN) caused by IMNV. (a) TEM of a purified preparation of IMNV from naturally infected Litopenaeus vannamei from Brazil. Mostly full (and one empty) IMNV particles are shown. The 40 nm diameter virions are hexagonal in profile indicating their icosahedral shape. The most prominent gross signs presented by shrimp with IMN is opaque skeletal muscle shown in very young juvenile L. vannamei in (b) and in subadult L. vannamei in (c). The paired lymphoid organs in shrimp with IMN are typically hypertrophied to 2–4 times their normal size as in shown in the circle in (d).