The silkworm (Bombyx mori) and its pupae have been used for decades as nutritional additives and applied on the production of high-quality recombinant proteins via the baculovirus expression vector (BEV) system. The bio-capsule, the fat-rich body, and some body components of the silkworm pupae, which deliver antigens passing through the harsh environment of digestive tract and reaching the intestine, have been used as a vehicle for oral vaccines. In the present study, to develop a novel oral vaccine against porcine epidemic diarrhea virus (PEDV), the PEDV spike (S) protein was expressed in silkworm pupae and BmN cells using the BEV system. After three doses of oral administrations with 2-week intervals in pigs, neither PEDV S protein-specific humoral nor mucosal immune responses can be detected. The failure of eliciting the PEDV-specific immune response suggested that the BEV system using BmN cells or silkworm pupae as oral immunogen-expression vehicles was not able to overcome the immunological unresponsiveness, which was possibly due to gastrointestinal specific barriers and oral tolerance. Better strategies to enhance the delivery and immunogenicity of oral vaccines should be further investigated. Nevertheless, the PEDV S protein generated in the BmN cells and silkworm pupae herein provides an efficient tool to produce the recombinant antigen for future applications.

中文翻译：

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口服施用在express中表达的猪流行性腹泻病毒刺突蛋白未能引起猪的免疫反应。

蚕（Bombyx mori）及其p已作为营养添加剂使用了数十年，并通过杆状病毒表达载体（BEV）系统应用于生产高质量的重组蛋白。蚕p的生物胶囊，富含脂肪的身体和一些身体成分，可将抗原传递穿过恶劣的消化道环境并到达肠道，已被用作口服疫苗的载体。在本研究中，为了开发针对猪流行性腹泻病毒（PEDV）的新型口服疫苗，使用BEV系统在家蚕p和BmN细胞中表达PEDV刺突（S）蛋白。在猪中每两周间隔三剂口服给药后，无法检测到PEDV S蛋白特异性的体液和粘膜免疫反应。未能引起PEDV特异性免疫反应提示使用BmN细胞或家蚕p作为口服免疫原表达载体的BEV系统无法克服免疫学上的无反应性，这可能是由于胃肠道特异性屏障和口服耐受性所致。应该进一步研究提高口服疫苗的递送和免疫原性的更好策略。然而，本文的BmN细胞和家蚕p中产生的PEDV S蛋白提供了产生重组抗原用于未来应用的有效工具。应该进一步研究提高口服疫苗的递送和免疫原性的更好策略。然而，本文的BmN细胞和家蚕p中产生的PEDV S蛋白提供了产生重组抗原用于未来应用的有效工具。应该进一步研究更好的策略来增强口服疫苗的递送和免疫原性。然而，本文的BmN细胞和家蚕p中产生的PEDV S蛋白提供了产生重组抗原用于未来应用的有效工具。