Potency of Nannochloropsis oculata as Antibacterial, Antioxidant and Antiviral on Humpback Grouper Infected by Vibrio alginolyticus and Viral Nervous Necrotic

The aim of this study was to explore the potency of N. oculata extracts as antibacterial, antioxidant and antiviral on grouper Cromileptes altivelis （C. altivelis） infected by Vibrio alginolyticus （V. alginolyticus） and Viral Nervous Necrotic （VNN）. Dilution test was used to measure antibacterial activity of N. oculata extracts. Antioxidant activity of extracts was expressed by levels of MDA （Malondialdehyde） and SOD （superoxide dismutase） in the brain and kidneys of fish. Antiviral capability of N. oculata was determined by the expression of cellular immune cells Major Histocompatibility Complex （MHC） Class I for proliferation and inhibition of VNN in blood cells with immunocytochemistry. The results showed that N. oculata extract was able to suppress the growth of V. alginolyticus at a concentration of 40%. Increasing levels of SOD and reducing level of MDA indicated that N. oculata extracts may serve as an antibacterial and antioxidant. Providing cellular response of MHC class I cell expressed on C. altive/is blood cells, N. oculata demonstrated its antiviral activity.

Localization and Dynamic Expression of a 27.8kDa Receptor Protein for Lymphocystis Disease Virus Infection in Sea Bass(Lateolabrax japonicus) Tissues

Lymphocystis disease virus(LCDV) infects target cells by attaching to a 27.8 k Da receptor(27.8R) protein in flounder Paralichthys olivaceus, and anti-27.8R monoclonal antibodies(MAbs) have been developed. However, the 27.8R existence in tissues of sea bass(Lateolabrax japonicus) and its role in LCDV infection have remained unclear. In this study, the results of western blotting demonstrated that the same 27.8R was shared by flounder and sea bass. LCDV-free sea bass individuals were intramuscularly injected with LCDV, and viral copies were detected in tissues from 3 h post infection and showed a time-dependent increase during 9 days infection. Distribution and synthesis of 27.8R in sea bass tissues were investigated by using anti-27.8R MAbs as probes. It was found that 27.8R was distributed in all the tested tissues. The levels of 27.8R protein were highest in gill and skin, then a bit lowly in stomach, head kidney and heart, followed by spleen, intestine, blood cells, gonad and liver, and least in kidney and brain in healthy sea bass. Upon LCDV infection, 27.8R synthesis was up-regulated in each tissue, and higher in the tissues with higher LCDV copies. The 27.8R and LCDV were detected in some peripheral blood leukocytes but not in red blood cells. These results suggested that 27.8R was widely distributed in sea bass tissues, and it served as a receptor and correlated with tissue tropism of LCDV infection. Furthermore, leukocytes had the potential of being a LCDV carrier and were responsible for a systemic infection of LCDV in sea bass.

Proteomic aspects of infection by lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus)

To reveal the key factor in self-healing from LCDV （lymphocystis disease virus）-infected Japanese flounder （Paralichthys olivaceus）, serum proteins from self-healing and sick Japanese flounder were separated by two-dimensional electrophoresis to screen differentially expressed proteins. Protein spots demonstrating changes greater than two-fold in the expression level were digested and further identified in capillary liquid chromatography tandem mass spectrometry （LC-MS/MS）. Two immunityrelevant proteins were thus identified as transferrin and the complement component C3 of Japanese flounder. These findings suggest that the two proteins may play important roles in the self-healing of lymphocystis in Japanese flounder. This is an important theoretical foundation to promote self-healing in LCDV-infected Japanese flounder by improving their innate immunity.