Abstract：
Largemouth bass ranavirus (LMBV) infects largemouth bass, leading to significant mortality and economic losses. There are no safe and effective drugs against this disease. Oral vaccines that directly target the intestinal mucosal immune system play an important role in resisting pathogens. Herein, the B subunit of Escherichia coli heat-labile enterotoxin (LTB, a mucosal immune adjuvant) and the LMBV main capsid protein (MCP) were expressed using Saccharomyces cerevisiae surface display technology. The yeast-prepared oral vaccines were named EBY100-OMCP and EBY100-LTB-OMCP. The candidate vaccines could resist the acidic intestinal environment. After 7 days of continuous oral immunization, indicators of innate and adaptive immunity were measured on days 1, 7, 14, 21, 28, 35, and 42. High activities of immune enzymes (T-SOD, AKP, ACP, and LZM) in serum and intestinal mucus were detected. IgM in the head kidney was significantly upregulated (EBY100-OMCP group: 3.8-fold; BY100-LTB-OMCP group: 4.3-fold). IgT was upregulated in the intestines (EBY100-OMCP group: 5.6-fold; EBY100-LTB-OMCP group: 6.7-fold). Serum neutralizing antibody titers of the two groups reached 1:85. Oral vaccination protected against LMBV infection. The relative percent survival was 52.1% (EBY100-OMCP) and 66.7% (EBY100-LTB-OMCP). Thus, EBY100-OMCP and EBY100-LTB-OMCP are promising and effective candidate vaccines against LMBV infection.
摘要：
大口鲈鱼病毒（LMBV）感染大口鲈鱼，导致重大的死亡率和经济损失。目前还没有针对这种疾病的安全有效的药物。直接靶向肠道粘膜免疫系统的口服疫苗在抵抗病原体中起着重要作用。在这里，大肠杆菌不耐热肠毒素的B亚基(LTB，粘膜免疫佐剂）和LMBV主衣壳蛋白（MCP）使用酿酒酵母表面展示技术表达。酵母制备的口服疫苗命名为EBY100-OMCP和EBY100-LTB-OMCP。候选疫苗可以抵抗酸性肠道环境。连续口服免疫7天后，在第1,7,14,21,28,35和42天测量先天免疫和适应性免疫指标.高活性的免疫酶（T-SOD，AKP,ACP,和LZM）在血清和肠粘液中检测到。头肾中的IgM显著上调(EBY100-OMCP组:3.8倍;BY100-LTB-OMCP组:4.3倍)。IgT在肠中上调(EBY100-OMCP组:5.6倍;EBY100-LTB-OMCP组:6.7倍)。两组血清中和抗体滴度均达到1：85。口服疫苗预防LMBV感染。相对存活率为52.1%(EBY100-OMCP)和66.7%(EBY100-LTB-OMCP)。因此，EBY100-OMCP和EBY100-LTB-OMCP是针对LMBV感染的有希望且有效的候选疫苗。
