Lymphoid Organ Vacuolization Virus (LOVV) of Penaeid Shrimp

Category

Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Lymphoid organ vacuolization virus, LOVV, Lymphoid organ vacuolization disease, LOVD.

Scientific name or taxonomic affiliation

A cytoplasmic, enveloped RNA virus belonging to the Togaviridae and contain four polypeptides of 70, 60, 38 and 37 kDa.

Geographic distribution

Presumed LOVD (based on histopathology of the lymphoid organ) has been observed everywhere P. vannamei is cultured in the Americas and in Hawaii.

Host species

Penaeus vannamei and possibly Penaeus stylirostris. Because LOVV is poorly understood, it is unknown if pathological conditions similar to LOVD in the lymphoid organ of other species of penaeids, especially Penaeus monodon in Asia, are caused by LOVV.

Impact on the host

No signs of disease or other abnormalities during 21 months that experimental P. vannamei, from an infected commercial source in Mazatlan, Sinaloa, Mexico, were cultured in a closed recirculating seawater system in Arizona. Nothing is known about the prevalence and pathogenicity of this virus in wild or cultured penaeid shrimp populations.

Diagnostic techniques

Histology: Cytoplasm of lymphoid organ cells with highly vacuolated cytoplasm and intracytoplasmic eosinophilic to pale basophilic (with haematoxylin and eosin stain), Feulgen negative, inclusion bodies. The nuclei of many affected cells were pyknotic or karyorrhectic. In some foci, affected lymphoid cells form large multicellular spherical structures, termed spheroids, that lacked a central vessel.

Electron Microscopy: Icosahedral nucleocapsids (30 - 31 nm in diameter) in dense cytoplasmic aggregates occasionally forming paracrystalline arrays, or as single rows of particles that were closely associated with host cell membranes where they acquired a host-membrane-derived envelope. Enveloped virons have a diameter of about 52 - 54 nm.

Methods of control

No known treatment.

References

Bonami, J.R., D.V. Lightner, R.M. Redman and B.T. Poulos. 1992. Partial characterization of a togavirus (LOVV) associated with histopathological changes of the lymphoid organ of penaeid shrimps. Diseases of Aquatic Organisms 14: 145-152.

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.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Lymphoid Organ Vacuolization Virus (LOVV) of Penaeid Shrimp.

Date last revised: Fall 1996
Comments to Susan Bower

Date modified: