Detection and tissue tropism of white spot syndrome baculovirus (WSBV) in captured brooders of Penaeus monodon with a special emphasis on reproductive organs

Abstract

In cultured shrimp, w h ~t e spot syndrome 'baculovirus' (WSBV) Infection IS characterized by a wide range of target tissues, rapid disease onset and high mortality Dunng the viremic phase of infection, the virus is present in many organs However, the s~tuation in the natural environment remalns unclear To identify the pattern of the t ~s s u e t r o p ~s m of WSBV infection in adult Penaeus monodon (black tiger shnmp) of wild ongin, w e conducted a c o m b ~n e d study using currently available nucleic acid diagnostic tools and conventional histological observat~ons uslng light (LM) and transnxssion electron (TEM) mlcroscopy to examine the sites for virus mult~plication S ~x t e e n parts excised from shnmp specimens were examined pleopods, gills, stomach, abdominal muscle, hemolymph. m ~d g u t , heart, pereiopods lymphoid organs, integument, nervous tissue, hepatopancreas, testes, ovaries, spermatophores, and eye stalks All these tissues/organs were found to support WSBV replic a t ~o n For the f ~r s t t ~m e in s ~t u hybridization and TEM showed evidence of WSBV in reproduct~ve organs of black tiger shrlmp In testes, WSBV-positive cells were located in the connective Ussue layer surrounding the seminiferous tubules and no germ cells were found to b e infected In the spermatophore only muscle and connective t ~s s u e cells were WSBV posltive In the ovary, foll~cle cells oogonla oocytes and connective tissue cells were WSBV positlve However, the fact that w e were unable to find any Infected mature eggs suggested that infected e g g cells were killed by the virus before maturation