Montana State University, Bozeman, 59717-3610, USA.
BMC Immunol. 2010 Jul 7;11:36. doi: 10.1186/1471-2172-11-36.
Immunization with recombinant carboxyl-terminal domain of the heavy chain (Hc domain) of botulinum neurotoxin (BoNT) stimulates protective immunity against native BoNT challenge. Most studies developing a botulism vaccine have focused on the whole Hc; however, since the principal protective epitopes are located within beta-trefoil domain (Hcbetatre), we hypothesize that immunization with the Hcbetatre domain is sufficient to confer protective immunity. In addition, enhancing its uptake subsequent to nasal delivery prompted development of an alternative vaccine strategy, and we hypothesize that the addition of targeting moiety adenovirus 2 fiber protein (Ad2F) may enhance such uptake during vaccination.
The Hcbetatre serotype B immunogen was genetically fused to Ad2F (Hcbetatre/B-Ad2F), and its immunogenicity was tested in mice. In combination with the mucosal adjuvant, cholera toxin (CT), enhanced mucosal IgA and serum IgG Ab titers were induced by nasal Hcbetatre-Ad2F relative to Hcbetatre alone; however, similar Ab titers were obtained upon intramuscular immunization. These BoNT/B-specific Abs induced by nasal immunization were generally supported in large part by Th2 cells, as opposed to Hcbetatre-immunized mice that showed more mixed Th1 and Th2 cells. Using a mouse neutralization assay, sera from animals immunized with Hcbetatre and Hcbetatre-Ad2F protected mice against 2.0 LD50.
These results demonstrate that Hcbetatre-based immunogens are highly immunogenic, especially when genetically fused to Ad2F, and Ad2F can be exploited as a vaccine delivery platform to the mucosa.
用重组肉毒神经毒素（BoNT）重链羧基末端域（Hc 域）免疫可刺激针对天然 BoNT 攻击的保护性免疫。大多数开发肉毒杆菌毒素疫苗的研究都集中在整个 Hc 上；然而，由于主要的保护性表位位于β三叶形域（Hcbetatre）内，我们假设用 Hcbetatre 域免疫足以赋予保护性免疫。此外，增强其在鼻内给药后的摄取促使开发了另一种疫苗策略，我们假设添加靶向部分腺病毒 2 纤维蛋白（Ad2F）可能会在接种疫苗期间增强这种摄取。
Hcbetatre 血清型 B 免疫原与 Ad2F （Hcbetatre/B-Ad2F） 遗传融合，并在小鼠中测试其免疫原性。与粘膜佐剂霍乱毒素（CT）结合，与单独的 Hcbetatre 相比，鼻内 Hcbetatre-Ad2F 诱导增强的粘膜 IgA 和血清 IgG Ab 滴度；然而，肌肉内免疫获得了类似的 Ab 滴度。这些由鼻内免疫引起的 BoNT/B 特异性 Ab 主要由 Th2 细胞支持，而不是由 Hcbetatre 免疫的小鼠产生的 Th1 和 Th2 细胞混合支持。使用小鼠中和测定法，用 Hcbetatre 和 Hcbetatre-Ad2F 免疫的动物的血清可保护小鼠免受 2.0 LD50 的攻击。
这些结果表明，基于 Hcbetatre 的免疫原具有高度的免疫原性，特别是当与 Ad2F 遗传融合时，并且可以利用 Ad2F 作为粘膜疫苗的传递平台。
