Leptospirosis is a global zoonosis causing significant economic losses for cattle production. Current cattle vaccines against leptospirosis need improvement to provide efficacy against multiple serovars, reduce shedding in urine, and to induce earlier and more robust immune responses. In this study, Leptospira borgpetersenii serovar Hardjo strain 203 antigen was combined with novel adjuvants (a biodegradable polyanhydride compressed rod implant (VPEAR), poly(diaminosulfide) microparticles, a water-oil-water emulsion adjuvant, and aluminum hydroxide) to develop novel vaccines. Cattle were immunized twice, at a 4 week interval, with inoculums containing adjuvants alone or leptospira antigens and immune responses were compared to responses of cattle receiving a commercial monovalent leptospirosis vaccine (Spirovac). All animals were inoculated with a single dose of Spirovac at 20 weeks to assess antigen recall responses. Serum antibody responses were increased (P > 0.05) at 8 and 20 weeks after vaccination in cattle receiving inoculums containing leptospira antigens combined with water-oil-emulsion, poly(diaminosulfide) microparticles (PNSN-MP), or aluminum hydroxide and in cattle vaccinated with Spirovac. Humoral responses were predominantly IgG1 isotypes. Antigen-specific proliferative responses were detected after initial vaccination in cattle vaccinated with Spirovac, PNSN-MP and water-oil-water treatments. Most proliferative responses occurring within CD4+ and gamma delta T cell populations expressing CD45RO and CD25 markers, a response consistent with an effector memory phenotype. Antigen-specific immune responses were not detected in cattle vaccinated with VPEAR after initial inoculation, but were detected in the antigen recall responses. PBMCs from cattle vaccinated with Spirovac, oil-water-oil, or PNSN-MP treatments had increased (P < 0.05) IL-17A release after in vitro stimulation with leptospirosis antigens, whereas all groups produced IFN-γ and IL-17A after in vitro stimulation during the antigen recall response. Our data demonstrates that combining leptospirosis antigens with these adjuvants enhances immunogenicity in cattle.

Interpretative Summary: Vaccination of livestock is a key mechanism for minimizing transmission of leptospirosis, a zoonotic disease. Leptospirosis vaccines for cattle need to be improved to provide greater levels of protection from kidney colonization, better immune responses, and protection against multiple serovars. This could be accomplished using new vaccine adjuvants. In this study, several novel adjuvants were evaluated for their ability to induce effective immune responses in cattle to leptospira antigens as compared to currently available vaccines. Data suggested that vaccines containing biodegradable polymer microparticles and oil-emulsion adjuvants induced similar or greater immune responses as compared to a commercial vaccine. Our data suggest these new vaccine formulations warrant further investigation as new vaccine formulations for cattle and other livestock.

钩端螺旋体病是一种全球人畜共患病，给牛的生产造成重大的经济损失。当前的针对钩端螺旋体病的牛疫苗需要改进以提供针对多种血清型的功效，减少尿液脱落并诱导更早更强的免疫反应。在这项研究中，钩端螺旋体血清型Hardjo菌株203抗原与新型佐剂（可生物降解的聚酸酐压缩棒植入物（VPEAR），聚（二氨基硫醚）微粒，水-油-水乳液佐剂和氢氧化铝）组合以开发新型疫苗。用仅含佐剂或钩端螺旋体抗原的接种物以4周的间隔对牛进行两次免疫，并将免疫应答与接受商业单价钩端螺旋体病疫苗（Spirovac）的牛的应答进行比较。在20周时，给所有动物接种单剂量的Spirovac，以评估抗原召回反应。接种含钩端螺旋体抗原结合水油乳剂，聚（二氨基硫醚）微粒（PNSN-MP）的接种疫苗的牛在接种疫苗后8周和20周血清抗体应答增加（P> 0.05），或氢氧化铝，以及用Spirovac疫苗接种的牛。体液反应主要是IgG1同种型。在首次接种了Spirovac，PNSN-MP和水-油-水处理疫苗的牛中，初次接种疫苗后检测到抗原特异性增殖反应。大多数增殖反应发生在表达CD45RO和CD25标记的CD4 +和γT细胞群体中，该反应与效应记忆表型一致。初次接种疫苗后未在接种VPEAR的牛中检测到抗原特异性免疫反应，但在抗原召回反应中检测到了抗原特异性免疫反应。在体外用钩端螺旋体病抗原刺激后，用Spirovac，油-水-油或PNSN-MP处理疫苗接种的牛的PBMC增加（P <0.05）IL-17A释放，而所有组在抗原回忆反应期间在体外刺激后产生IFN-γ和IL-17A。我们的数据表明，钩端螺旋体抗原与这些佐剂结合可增强牛的免疫原性。

解释性摘要：牲畜接种疫苗是使钩端螺旋体病（一种人畜共患病）的传播最小化的关键机制。牛的钩端螺旋体病疫苗需要改进，以提供更高水平的肾脏定植保护，更好的免疫反应以及针对多种血清型的保护。这可以使用新的疫苗佐剂来完成。在这项研究中，与目前可用的疫苗相比，评估了几种新型佐剂在牛中对钩端螺旋体抗原诱导有效免疫应答的能力。数据表明，与商业疫苗相比，含有可生物降解的聚合物微粒和油乳剂佐剂的疫苗可诱导相似或更大的免疫反应。