Fish Diseases and Management

5.4.5.1 BP Type baculoviruses

BP (Baculovirus penaei) causes significant disease in the larval, postlarval and early juvenile stages of many species of shrimps. The infections can be easily diagnosed by the demonstration of prominent tetrahedral occlusion bodies in unstained squash preparations of hepatopancreas, midgut or faeces and also in histological sections. In histological sections, occlusion bodies are found in single or multiple, eosinophilic, usually triangular within hypertrophied nuclei of hepatopancreatic tubular epithelial cells or in midgut epithelial cells. In hypertrophied nuclei, morphometric comparison of BP virions suggested the occurrence of 3 distinct strains of BP (Equator, Gulf of Mexico, Hawaii). BP is found to occur sporadically in hatchery, infecting larval stages. BP has not been reported outside of the Americas and Hawaii (?)