Baculoviral Midgut-gland Necrosis (BMN) of Penaeid Shrimp

Category

Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Baculovirus midgut (hepatopancreas) gland necrosis (BMN), Midgut gland cloudy disease, White turbid liver disease, White turbidity disease.

Scientific name or taxonomic affiliation

PjNOB I, a non-occluded gut-infesting baculovirus. The acronym PjNOB I represents: Pj = P. japonicus, the first species in which the agent was described; NOB = non occluded baculovirus; I = first reported type of this genus of virus. The former classification of type C non-occluded baculovirus has been discontinued.

Geographic distribution

a) Southern Japan and Korea.
b) East and southeast Asia and in Australia

Host species

a) Penaeus japonicus and experimentally in Penaeus monodon, Penaeus chinensis, Penaeus semisulcatus.
b) Penaeus monodon and Penaeus plebejus.

Impact on the host

Generally infects larvae and early postlarval stages in which it can cause high mortalities. The apparent white turbidity of the hepatopancreas is caused by necrosis of hepatopancreas tubule epithelium and possibly also the mucosal epithelium. Larvae float inactively but later stages (late postlarvae) tend to show resistance to the disease. Source of infection is documented to be wild-caught female spawners.

Diagnostic techniques

Gross Observations: Sudden onset of white turbid midgut gland (hepatopancreas) in larvae and postlarvae with associated high mortality. Larvae float inactively on the surface and exhibit a white midgut line through the abdomen.

Smear: Hepatopancreas of postlarvae with no polyhedral or spherical occlusion bodies, but with hypertrophied nuclei in midgut gland epithelial cells as viewed under dark field illumination equipped with a wet-type condenser. Infected nuclei appear white against the dark background due to the increased reflected and diffracted rays produced by numerous virus particles in the nucleus. Feulgen stain makes the difference between normal nuclei (about 10 µm in diameter) and infected hypertrophied nuclei (about 20-30 µm in diameter) clearer. Usually has abundant Gram negative bacteria from a secondary infection.

Histology: Hepatopancreatic tubule epithelial cells undergoing necrosis have markedly hypertrophic nuclei that are characterized by marginated chromatin, diminished nuclear chromatin, nucleolar dissociation and the absence of occlusion bodies that characterize infections by the occluded (SNPV-type or type A) baculoviruses.

Electron Microscopy: Numerous rod-shaped virions (72 x310 nm) of BMN in hypertophied nucleus of infected hepatopancreatic epithelial cells. The nucleocapsid measures 36 by 250 nm with enveloped virons measuring about 72 by about 310 nm.

Immunological Assay: A direct fluorescent antibody diagnostic procedure using labeled polyclonal antibody has been developed (Sano et al. 1984). However, anti-BMN antibody is not yet commercially available.

Bioassay: BMN from asymptomatic carriers was detected by the smear technique in mysis stage larvae or early post larvae within 2 to 4 days post-inoculation.

DNA Probes: Fragements of the genomic DNA of PjNOB from Penaeus japonicus were partially cloned and successfully used as a probe for Southern blot analysis (Arimoto et al. 1995).

Methods of control

No known treatment. Destroy infected stocks and disinfect equipment and tanks. Avoid use of BMN-infected broodstock. A prophylactic effect can be achieved by washing the fertilized eggs in clean sea water.

References

Arimoto, M., T. Yamazaki, Y. Mizuta and I. Furusawa. 1995. Characterization and partial cloning of the genomic DNA of a baculovirus from Penaeus japonicus (PjNOB = BMNV). Aquaculture 132: 213-220.

Brock, J.A. and D.V. Lightner. 1990. Diseases of Crustacea. Diseases caused by microorganisms. In: O. Kinne (ed.). Diseases of Marine Animals. Volume III: Introduction, Cephalopoda, Annelida, Crustacea, Chaetognatha, Echinodermata, Urochordata. Biologische Anstalt Helgoland, Hamburg, p. 258-260.

Lightner, D.V. 1988. Baculoviral Midgut Gland Necrosis (BMN) Disease of Penaeus japonicus. In: C.J. Sindermann and D.V. Lightner (eds.). Disease Diagnosis and Control in North American Aquaculture. Developments in Aquaculture and Fisheries Science 17. Elsevier, Amsterdam, p. 26-29.

Lightner, D.V. (ed.). 1996. A Handbook of Shrimp Pathology and Diagnostic Procedures for Disease of Cultured Penaeid Shrimp. World Aquaculture Society, Baton Rouge.

Lightner, D.V., T.A. Bell, R.M. Redman, L.L. Mohney, J.M. Natividad, A. Rukyani and A. Poernomo. 1992. A review of some major diseases of economic significance in penaeid prawns/shrimp of the Americas and Indopacific. In: M. Shariff, R.P. Subasinghe and J.R. Arthur (eds.). Diseases in Asian Aquaculture. I. Fish Health Section, Asian Fisheries Society. Manila, Philippines, p. 57-80.

Momoyama, K. 1992. Viral diseases of cultured penaeid shrimp in Japan. In: W. Fulks and K.L. Main (eds.). Diseases of Cultured Penaeid Shrimp in Asia and the United States. The Oceanic Institute, Honolulu, p. 185-192.

Natividad, J.M. and D.V. Lightner. 1992. Prevalence and geographic distribution of MBV and other diseases in cultured giant tiger prawns (Penaeus monodon) in the Philippines. In: W. Fulks and K.L. Main (eds.). Diseases of Cultured Penaeid Shrimp in Asia and the United States. The Oceanic Institute, Honolulu, p. 139-160.

Park, M.A. 1992. The status of culture and diseases of penaeid shrimp in Korea. In: W. Fulks and K.L. Main (eds.). Diseases of Cultured Penaeid Shrimp in Asia and the United States. The Oceanic Institute, Honolulu, p. 161-167.

Sano, T. and K. Momoyama. 1992. Baculovirus infection of penaeid shrimp in Japan. In: W. Fulks and K.L. Main (eds.). Diseases of Cultured Penaeid Shrimp in Asia and the United States. The Oceanic Institute, Honolulu, p. 169-174.

Sano, T., T. Nishimura, H. Fukuda and T. Hayashida. 1984. Baculo-virus midgut gland necrosis (BMN) of the Kuruma shrimp (Penaeus japonicus) larvae in intensive culture systems. Helgoländer Meeresuntersuchungen 37: 255-264.

Sano, T., T. Nishimura, K. Oguma, K. Momoyama and N. Takeno. 1981. Baculovirus of cultured shrimp, Kuruma shrimp, Penaeus japonicus in Japan. Fish Pathology 15: 185-191.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Baculoviral Midgut-gland Necrosis (BMN) of Penaeid Shrimp

Date last revised: September 1996
Comments to Susan Bower

Date modified: