Evangelista Karen V, Lourdault Kristel, Matsunaga James, Haake David A
Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America.
Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
PLoS One. 2017 Jul 13;12(7):e0180004. doi: 10.1371/journal.pone.0180004. eCollection 2017.
Leptospirosis is the most widespread zoonosis and is considered a major public health problem worldwide. Currently, there is no widely available vaccine against leptospirosis for use in humans. A purified, recombinant subunit vaccine that includes the last six immunoglobulin-like (Ig-like) domains of the leptospiral protein LigA (LigA7'-13) protects against lethal infection but not renal colonization after challenge by Leptospira interrogans. In this study, we examined whether the addition of the first seven Ig-like domains of LigB (LigB0-7) to LigA7'-13, can enhance immune protection and confer sterilizing immunity in the Golden Syrian hamster model of acute leptospirosis. Hamsters were subcutaneously immunized with soluble, recombinant LigA7'-13, LigB0-7, or a combination of LigA7'-13 and LigB0-7 in Freund's adjuvant. Immunization with Lig proteins generated a strong humoral immune response with high titers of IgG that recognized homologous protein, and cross-reacted with the heterologous protein as assessed by ELISA. LigA7'-13 alone, or in combination with LigB0-7, protected all hamsters from intraperitoneal challenge with a lethal dose of L. interrogans serovar Copenhageni strain Fiocruz L1-130. However, bacteria were recovered from the kidneys of all animals. Of eight animals immunized with LigB0-7, only three survived Leptospira challenge, one of which lacked renal colonization and had antibodies to native LigB by immunoblot. In addition, sera from two of the three LigB0-7 immunized survivors cross-reacted with LigA11-13, a region of LigA that is sufficient for protection. In summary, we confirmed that LigA7'-13 protects hamsters from death but not infection, and immunization with LigB0-7, either alone or in combination with LigA7'-13, did not confer sterilizing immunity.
钩端螺旋体病是最广泛传播的人畜共患病，被认为是全球主要的公共卫生问题。目前，尚无广泛可用的用于人类的钩端螺旋体病疫苗。一种纯化的重组亚单位疫苗，包含钩端螺旋体蛋白LigA的最后六个免疫球蛋白样（Ig样）结构域（LigA7'-13），可预防致死性感染，但在受到问号钩端螺旋体攻击后不能预防肾脏定植。在本研究中，我们检测了将LigB的前七个Ig样结构域（LigB0-7）添加到LigA7'-13中，是否能增强免疫保护并在急性钩端螺旋体病的金黄叙利亚仓鼠模型中赋予无菌免疫。仓鼠用弗氏佐剂中的可溶性重组LigA7'-13、LigB0-7或LigA7'-13与LigB0-7的组合进行皮下免疫。用Lig蛋白免疫产生了强烈的体液免疫反应，IgG滴度高，可识别同源蛋白，并通过ELISA评估与异源蛋白发生交叉反应。单独的LigA7'-13或与LigB0-7组合，可保护所有仓鼠免受致死剂量的问号钩端螺旋体哥本哈根血清型Fiocruz L1-130腹腔攻击。然而，所有动物的肾脏中都能检测到细菌。在用LigB0-7免疫的八只动物中，只有三只在钩端螺旋体攻击后存活，其中一只没有肾脏定植，通过免疫印迹检测到对天然LigB的抗体。此外，三只LigB0-7免疫存活者中的两只血清与LigA11-13发生交叉反应，LigA11-13是LigA中足以提供保护的区域。总之，我们证实LigA7'-13可保护仓鼠免于死亡，但不能预防感染；单独或与LigA7'-13联合用LigB0-7免疫均不能赋予无菌免疫。
