Teiichi Nishimura

Baculoviral mid-gut gland necrosis (BMN) of kuruma shrimp(Penaeus japonicus) larvae in Japanese intensive culture systems

In many shrimp farms in the Kyushu and Chugoku areas of Japan, the so-called mid-gut gland cloudy disease of kuruma shrimp larvae(Penaeus japonicus) has occurred since 1971. The pathological changes associated with this baculoviral mid-gut gland necrosis (BMN) are extensive cellular necrosis, collapse of mid-gut gland cells, nuclear hypertrophy and finally karyorrhexis. Electron microscopic examination revealed the presence of virions and virogenic stages in the affected nuclei. Average length and diameter of the virions detected was 310 and 72 nm, respectively; nucleocapsids were 250 nm in size. Virions enclosing 2 nucleocapsids within a single envelope were rarely found. The spirally arranged capsomeres were at an angle of 37 to 38° to a horizontal line meeting at right angles with the long axis of the virion. Infectivity trials resulted in high mortality of healthy mysis and juveniles (2nd post-larval stage). Juveniles at the 9th post-larval stage showed no mortality, although they could be infected easily by the agent. Hypertrophied nuclei in squashed and stained preparations of the affected gland cells can be considered to be of reliable presumptive diagnostic character, and fluorescent antibody staining can be employed to confirm the diagnosis of BMN.

Comparison between EPC and FHM cell lines on IHN virus susceptivility and effect of fetal bovine serum concentration on IHNV-CPE appearance

牛胎児血清濃度を1,2,5％としたMEMでEPCとFHM細胞をマイクロプレートに調整し, IHNV長野分離株のウイルス力価を測定したところ, 高い血清濃度はCPEの発現を遅らせ, 力価を緩慢に上昇させ, 最終力価に達するまでにより長期間を要した。最終力価では血清濃度による明瞭な差は生じなかった。FHM細胞ではCPEぼ発現も遅く, MEM-2で調整した両細胞により多数の試料を測定して比較したところ, IHNV長野分離株に対し, FHM細胞はEPC細胞よりも明らかに低感受性であった。