1. Introduction
The culture industry for black tiger shrimp Penaeus monodon in
Thailand has been affected by monodon slow growth syndrome
(MSGS) since 2003 (Chayaburakul et al., 2004; Flegel et al.,
2004). MSGS-affected shrimp reared in earthen ponds grow at a
greatly reduced rate compared to their unaffected counterparts,
leading to significant financial losses, comparable to those caused
by white-spot syndrome virus (WSSV) outbreaks (Flegel, 2001).
The aetiology of MSGS has not been fully elucidated, although multiple
infectious agents have been observed in several organs by histopathology,
transmission electron microscopy (TEM), and