The pathological changes of hemocytes in the haemolymph and hepatopancreas were examined in experimentally and naturally WSSV(white spot syndrome virus) infected Fenneropenaeus chinensis. The results showed that the pathological manifesta-tions of hemocytes were similar among moribund shrimps infected via injection,feeding and by nature. Firstly,the total hemocyte counts(THCs) in WSSV-infected shrimp were significantly lower than those in healthy shrimp. Secondly,necrotic,broken and dis-integrated cells were often observed,and a typical hematolysis was present in the haemolymph smear of WSSV-infected shrimp. Thirdly,necrosis and typical apoptosis of hemocytes were detected with TEM in the peripheral haemolymph of WSSV-infected shrimp. Hyalinocytes and semi-granulocytes with masses of WSSVs in their nuclei often appeared,whereas no granular hemocytes with WSSV were found in the hepatopancreas of moribund infected shrimps. All our results supported that hemocytes were the main target cells of WSSV,and hyalinocytes and semigranular hemocytes seemed to be more favorable for WSSV infection in F. chinensis.
A pathogenic bacterium （S636）, identified as Streptococcus iniae, was isolated from turbot （Scophthalrnus maximus） in 2005. We immunized turbot with formalin-killed S. iniae four times （on days 1, 14, 21, and 28） by intraperitoneal inoculation. After each vaccination, we obtained serum samples and isolated the lymphocytes from the peripheral blood, spleen, pronephros, and mesonephros. We measured surface Ig-positive （sIg＋） lymphocytes and serum antibody levels from these organs using flow cytometry and enzyme-linked immunosorbent assay （ELISA）, respectively, using monoclonal antibodies against turbot immunoglohulin. We confirmed that the antibody reacted with both the surface and plasma Ig by confocal laser scanning microscopy and electron microscopy. The percentage of sIg＋ in the lymphocytes increased following each successive vaccination. The mean percentage increased from 31.96% （control） to 37.49%, 38.36%, 42.9%, and 51.63% in the peripheral blood; from 27.09% to 36.63%, 36.81%, 39.28%, and 46.0% in the spleen; from 22.2% to 28.99%, 29.21%, 32.83%, and 41.58% in pronephros; and from 18.12% to 22.17%, 22.45%, 25.69%, and 31.68% in the mesonephros. The ELISA results were consistent with these results. Both the total and specific antibody levels increased with each vaccination. The mean OD value of the specific antibody assay increased from 0.094, to 0.269, 0.283, 0.333, and 0.421; for total antibody the mean OD value increased from 0.133, to 0.292, 0.323, 0.413, and 0.527.
