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Post Larva Acclimitation


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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.




Variables to be used in health evaluation

Health evaluation tests
Wet Mount Procedure . PL visual examination . Stress test for post larva . Gill examination . Mid-gut Examination . Stomach Contents Analysis

Shrimp Diseases
Hepatopancreatic parvo-like virus (HPV) . Reo-like virus (REO) . You are here . Taura Syndrome Virus (TSV) . Rhabdovirus of Penaeid Shrimp (RPS) . White Spot Syndrome Virus (WSSV) . Infectious hypodermal and hematopoietic virus (IHHNV) . Baculovirus penaei (BP)
Bacterial Diseases
Vibriosis . Epicommensal fouling disease (filementous bacteria) . Necrotizing Hepatopancreatitis (NHP) . Black spot disease (BSD) . Mycobacteriosis
Fungal Diseases
Larval mycosis . Fusariosis
Haplosporidia . Gregarines . Cotton Disease
Black Gill Disease (BGD) Dissolved Oxygen Crisis Nitrogen Gas Bubble Disease

Disease control
Decreasing density, partial or early harvests . Drugs, chemicals and treatments . Sanitation