DISTRIBUTION OF YELLOW-HEAD VIRUS IN SELECTED TISSUES AND ORGANS OF PENAEID SHRIMP PENAEUS-VANNAMEI

The distribution of yellow-head virus (YHV) in 9 different tissues and organs including the branchial portion of the gill, nerve cord, lymph oid organ (Oka), heart, midgut, hepatopancreas, head soft tissues (HST ), abdominal muscle, and eyestalk of experimentally infected moribund white shrimp Penaeus vannamei (Boone) was examined by bioassay using p enaeid shrimp indicators and by quantal assay (TCID50) in primary shri mp Oka organ cell cultures. Infectious YHV was demonstrated in all the tissues and organs tested; inoculation of each of the tissue and orga n filtrates into experimental shrimp resulted in 100% mortality within 6 to 9 d postinfection. The TCID50 assay in primary Oka organ cells r evealed that Oka, gill and HST contained 10- to 800-fold higher titers of YHV than the other tissues and organs tested and suggested that th ey are apparently the primary target tissues and organs for YHV infect ion.