Infection of white-spot baculovirus-like virus (WSBV) in two species of penaeid shrimp Penaeus stylirostris (Stimpson) and P. vannamei (Boone).

Tayap, L.M., Yu, Y., Gose, R.B., Brock, J.A. & Loh, P.C.
In: Diseases in Asian aquaculture III. (Eds. Flegel, T.W. & MacRae, I.H.), Fish Health Section, Asian Fisheries Society, Manila, Philippines.
White-spot baculovirus (WSBV), also known as Chinese baculovirus-like virus (CBV), is one of the most virulent viruses reported to infect Penaeus monodon and P. japonicus. It has been demonstrated to be similarly pathogenic and highly infectious for P. stylirostris (blue shrimp) and P. vannamei (white shrimp), the two penaeid species which are commercially cultivated in Hawaii and the Western Hemisphere. Experimental CBV infection resulted in 100% cumulative mortalities in both species within 4 days post infection. Histopathological examination of animals infected with CBV revealed extensive cellular necrosis in the cuticular epidermis and mesodermal tissues. Endoderm-derived cells were spared by CBV. Electron microscopic examination of thin sections of the gill tissues from infected shrimp revealed rod-shaped, enveloped and non-occluded particles in the nuclei of affected gill cells. Affected nulcei were markedly enlarged an exhibited conspicuous loss of integrity in the marginated chromatin material. Complete viral particles possessing double laminar enveloped had an average size of 265 +/- 20 = 20 x 120 +/- 10 nm. They occurred freely and singly (occasionally in pairs within a single envelope) in the nuclei of infected cells. The above data strongly indicate that CBV may pose a potential threat to shrimp farmed in the Western Hemisphere.

Unspecified source