Monodon baculovirus (MBV) of penaeid shrimp has been associated with high mortalities in hatchery-reared larval, post-larval and early juvenile stages of Penaeus monodon and is thought to have originated from Taiwan (Lightner, Redman & Bell 1983). MBV is pathogenic to several species of shrimp such as P. monodon Fabricius, P. penicillatus Alcock and Metapenaeus ensis De Haan (Chen, Chang, Kou & Lightner 1989). The principal clinical sign of MBV is the presence of single or multiple, generally spherical occlusion bodies in the hepatopancreas and midgut epithelial cells. In India, the prevalence of MBV and mortalities in hatcheries and farms associated with the virus has been reported (Ramasamy, Brennan & Jayakumar 1995; Karunasagar, Otta & Karunasagar 1998). The virus can be transmitted via horizontal transmission directly through the water column (Paynter, Vickers & Lester 1992), or through cannibalism and it is believed, but not proven, that transmission can also be vertical from brood stock to offspring. Infection can result in substantial economic loss due to poor growth and reduced survival of post-larvae of up to 90% at high densities. Furthermore, stress and overcrowding are predisposing factors that may increase the severity of MBV infection (Lightner et al. 1983). The MBV particles are rod shaped and replicate in the nucleus. They appear either free or within proteinaceous polyhedral occlusion bodies, and contain DNA. However, little is known about the mechanism of MBV production in the host cell (Lu, Tang, Kou & Chen 1995). Diagnosis of MBV depends upon the demonstration of MBV occlusion bodies in hypertrophied nuclei of the anterior midgut epithelium and hepatopancreatic cells by direct light microscopy or standard HE Muroga, Higashi & Keitiku 1989; Nicolas, Robic & Ansquer 1989) and viruses, such as infectious pancreatic necrosis virus (IPNV), Macrobrachium rosenbergii nodavirus and fish nodavirus (Mortensen, Evensen, Rodseth & Hjeltnes 1993; Skliris & Richards 1998; Sudhakaran, YogJournal of Fish Diseases 2008, 31, 631–636 doi:10.1111/j.1365-2761.2008.00926.x