A method of experimental infection of kuruma shrimp larvae, Penaeus japonicus Bate, with baculoviral mid‐gut gland necrosis (BMN) virus

Infectivity experiments were undertaken by water‐borne inoculation of kuruma shrimp, Penaeus japonicus Bate, larvae with BMN virus. Mysis stage larvae were inoculated with the virus by exposure for 2h in sea water containing a homogenized and filtered preparation (450nm) of naturally BMN virus‐infected shrimp stored for about 7 weeks at −80°C. Inoculated shrimp stocked in rearing jars were examined to determine whether nuclear hypertrophy of the mid‐gut gland epithelial cells characteristic for BMN virus infection could be observed in fresh squash preparations under dark field illumination equipped with a wet‐type condenser. Four days post‐inoculation at 25–30°C incubation temperature were considered to be satisfactory for the experimental trial.