| Summary: | 碩士 === 國立高雄海洋科技大學 === 海洋生物技術研究所 === 99 === White spot syndrome virus (WSSV) is the viral pathogen of shrimp white spot disease and causes large economic losses to global shrimp farming. In this study, Escherichia coli system was chose to express two WSSV envelope proteins, VP28 and VP36B, inoculated white shrimp (Litopenaeus vannamei) as subunit vaccine. Shrimps were divided into 3 groups and intramuscularly injected rVP28, rVP36B or PBS two times at intervals of 3 days. After vaccination, sampling of hemolymph on the 3rd, 5th and 7th day, total haemocyte counts, activities of phenoloxidase (PO) and superoxide dismutase (SOD) were analyzed. mRNA expression of prophenoloxidase (proPO) and superoxide dismutase was also evaluated on the 3rd day by relative real-time qPCR.
The result indicated that the total haemocyte counts was significantly higher in PBS group when compared to vaccinated groups. In contrast to total haemocyte counts, the other immune parameters analyzed among 3 groups revealed that the rVP28 vaccinated shrimp showed significantly highest level of PO and SOD activity. However, no significant differences in PO or SOD mRNA expression of shrimp were observed among all groups. In the in vivo saturation experiment, both rVP28 and rVP36B could not promote the survival rate of shrimp which were challenged by WSSV.
It was concluded that the innate immunity was elevated in VP28 vaccinated shrimp. Yet the clear mechanism responsible for developing protection against virus in vaccinated shrimp is still in searching.
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