Liu Wangta, Hsu Chi-Hsin, Chang Chiung-Yin, Chen Hsin-Hong, Lin Chan-Shing
Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung 804, Taiwan.
Vaccine. 2006 Sep 11;24(37-39):6282-7. doi: 10.1016/j.vaccine.2006.05.073. Epub 2006 Jun 9.
The grouper is a high-value fish in the seafood market. Grouper nervous necrosis virus (GNNV) causes mass mortality, near 100% in larvae and juveniles, which has great economic impact on the aquaculture of the marine fish. Since vaccination is one of the best methods against viral diseases, grouper Epinephelus lanceolatus was injected with virus-like particles (VLPs) of GNNV at different dosages and injection frequencies. The anti-sera of vaccinated fish were analyzed with antigen-capture ELISA to quantify immunization titer. The antibody titers in the vaccinated fish increased remarkably within 4 weeks, during which time the antibody was definitely capable to neutralize the native virus. With one shot of 10-250 microg VLPs, the stimulated antibody titer reached a steady saturation level in 1 month, among which the titers by one shot of 100 and 250 microg VLPs were 13% higher than by 10 microg. Two shots of 10 and 100 microg VLPs increased to maximum titer, which was 29% higher than one shot, whereas two shots of 250 microg VLPs and four shots of 100 microg VLPs dramatically downgraded the titers by -23% and -44%, respectively. These results imply that the overdose effects occurred in total dosages higher than 200 microg VLPs. The experiments of VLP vaccine with adjuvant revealed that the adjuvant is not required for increasing the efficacy of the VLP vaccine. Immunization with the VLPs can also stimulate fish to produce high antibody titer for more than 5 months, which can be correlated to long-term protection. When VLPs are used as vaccine agent, a dosage at 1 microg/g of fish body weight is enough to stimulate a full-scale immune response.
石斑鱼是海鲜市场上的高价值鱼类。石斑鱼神经坏死病毒（GNNV）会导致大规模死亡，在幼鱼和稚鱼中死亡率接近100%，这对海水鱼类养殖造成了巨大的经济影响。由于疫苗接种是对抗病毒性疾病的最佳方法之一，因此对鞍带石斑鱼注射了不同剂量和注射频率的GNNV病毒样颗粒（VLPs）。用抗原捕获ELISA分析接种疫苗鱼的抗血清以定量免疫效价。接种疫苗的鱼体内抗体效价在4周内显著升高，在此期间抗体肯定能够中和天然病毒。注射一次10 - 250微克VLPs，刺激的抗体效价在1个月内达到稳定饱和水平，其中注射一次100微克和250微克VLPs的效价比10微克的高13%。注射两次10微克和100微克VLPs效价升至最高，比注射一次高29%，而注射两次250微克VLPs和注射四次100微克VLPs效价分别显著降低了23%和44%。这些结果表明，总剂量高于200微克VLPs时会出现过量效应。含佐剂的VLP疫苗实验表明，增加VLP疫苗效力不需要佐剂。用VLPs免疫也能刺激鱼产生高抗体效价超过5个月，这与长期保护相关。当VLPs用作疫苗剂时，鱼体重1微克/克的剂量足以刺激全面的免疫反应。
