Kim B, Bowersock T, Griebel P, Kidane A, Babiuk L A, Sanchez M, Attah-Poku S, Kaushik R S, Mutwiri G K
Veterinary Infectious Disease Organization, University of Saskatchewan, 120 Veterinary Road, Saskatchewan, Saskatoon, Canada S7N 5E3.
J Control Release. 2002 Dec 13;85(1-3):191-202. doi: 10.1016/s0168-3659(02)00280-8.
Availability of effective oral vaccine delivery vehicles should contribute to the success of oral immunization in domestic animals. To achieve this goal, we evaluated alginate microspheres for their capacity to induce mucosal immune responses following oral and enteric immunizations. Mice were immunized with either live porcine rotavirus (PRV) or its recombinant VP6 protein, encapsulated in alginate microspheres or unencapsulated. VP6-specific IgG (but no IgA) antibodies were detected in the sera of mice after a single intraperitoneal (i.p.) immunization with either VP6 in Incomplete Freund's adjuvant (VP6-IFA), VP6 in alginate microspheres (VP6-MS) or with live PRV in incomplete Freund's adjuvant (PRV-IFA). In contrast, VP6-specific IgA (but no IgG) was detected in culture supernatants of mesenteric lymph nodes from mice immunized i.p. with either VP6-IFA or with PRV-IFA. Oral immunization with VP6-MS induced the highest level of VP6-specific fecal IgA antibody, similar to responses induced by oral immunization with live PRV. Furthermore, the VP6-specific fecal IgA could be boosted by a secondary i.p. immunization with VP6. Further experiments were performed in a sheep intestinal 'loop' model to evaluate uptake of microspheres by Peyer's patches. Microspheres containing colloidal carbon were specifically bound and transported by follicle-associated epithelium of Peyer's patches. Additionally, mucosal immune responses were detected following enteric immunization with porcine serum albumin (PSA) encapsulated in alginate microspheres. Our results confirm that alginate microspheres are an effective oral delivery vehicle for protein antigens and intestinal IgA antibody responses are induced by antigens encapsulated in alginate microspheres without any additional mucosal adjuvant. These investigations confirm that alginate microspheres have the potential as an effective delivery vehicle for oral immunization of ruminants.
有效的口服疫苗递送载体的可得性应有助于家畜口服免疫的成功。为实现这一目标，我们评估了藻酸盐微球在口服和肠道免疫后诱导黏膜免疫反应的能力。用包裹在藻酸盐微球中的或未包裹的活猪轮状病毒（PRV）或其重组VP6蛋白对小鼠进行免疫。在用弗氏不完全佐剂中的VP6（VP6-IFA）、藻酸盐微球中的VP6（VP6-MS）或弗氏不完全佐剂中的活PRV（PRV-IFA）进行单次腹腔内（i.p.）免疫后，在小鼠血清中检测到VP6特异性IgG（但无IgA）抗体。相比之下，在用VP6-IFA或PRV-IFA进行腹腔内免疫的小鼠肠系膜淋巴结培养上清液中检测到VP6特异性IgA（但无IgG）。用VP6-MS进行口服免疫诱导出最高水平的VP6特异性粪便IgA抗体，类似于用活PRV进行口服免疫诱导的反应。此外，VP6特异性粪便IgA可通过用VP6进行二次腹腔内免疫来增强。在绵羊肠“袢”模型中进行了进一步实验，以评估派尔集合淋巴结对微球的摄取。含有胶体碳的微球被派尔集合淋巴结的滤泡相关上皮特异性结合并转运。此外，在用包裹在藻酸盐微球中的猪血清白蛋白（PSA）进行肠道免疫后检测到黏膜免疫反应。我们的结果证实，藻酸盐微球是一种有效的蛋白质抗原口服递送载体，并且在没有任何额外黏膜佐剂的情况下，包裹在藻酸盐微球中的抗原可诱导肠道IgA抗体反应。这些研究证实，藻酸盐微球有潜力作为反刍动物口服免疫的有效递送载体。
