| 研究開始時の研究の概要 |
The largest obstacle in vaccine development for aquaculture is that the mechanism of cell-mediated immunity (CMI) has not been fully understood in fish. Fish has two types of CD4: CD4-1 resembles the mammalian CD4 while CD4-2 is a unique CD4 homolog. Fish CD4-1 cells play an important role in humoral immunity, but not in the CMI. Hence, CD4-2 cells may include the CMI of fish. Hence, a monoclonal antibody against fish CD4-2 was developed to study the unique CD4-2 cells from different perspectives:(1) morphological characteristics; (2) tissue distribution; and (3) roles in CMI of fish.
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| 研究実績の概要 |
In fiscal year (FY) 2023, in vivo transplantation of stimulated leukocytes from donor fish into recipient fish, and in vitro cytotoxicity assay of effector cells were studied using ginbuna as a model fish species. Through in vivo transplantation studies, I found that naive recipients who received stimulated leukocytes from peripheral blood and spleen of vaccinated donors tend to have a higher survival rate (90%) than those who received stimulated leukocytes from trunk-kidney and head-kidney (40%). These findings indicated that the majority of memory cells moved to a major secondary lymphoid organ such as the spleen and circulated in the systemic blood of ginbuna. Through in vitro cytotoxicity studies, regardless of stimulated or non-stimulated leukocytes, I realized that the cytotoxic activities of naive recipients who received donor cells with CD4-1 positive cells were higher than those of fish who received donor cells with CD4-2 positive cells. These results suggested that the adoptive transfer of stimulated leukocytes with CD4-1 positive cells rather than CD4-2 positive cells provided naive recipients efficient cytotoxic activity against virus-infected cells. However, naive recipients that received unsorted leukocytes from vaccinated donors following a secondary virus infection showed higher cytotoxic activities than those aforementioned treatment groups. These results suggested that secondary cell-mediated immunity is probably enhanced by CD4-1 and CD4-2 positive cells in ginbuna against a virus infection.
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