Turbyfill K R, Hartman A B, Oaks E V
Department of Enteric Infections, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910-7500, USA.
Infect Immun. 2000 Dec;68(12):6624-32. doi: 10.1128/IAI.68.12.6624-6632.2000.
The invasiveness and virulence of Shigella spp. are largely due to the expression of plasmid-encoded virulence factors, among which are the invasion plasmid antigens (Ipa proteins). After infection, the host immune response is directed primarily against lipopolysaccharide (LPS) and the virulence proteins (IpaB, IpaC, and IpaD). Recent observations have indicated that the Ipa proteins (IpaB, IpaC, and possibly IpaD) form a multiprotein complex capable of inducing the phagocytic event which internalizes the bacterium. We have isolated a complex of invasins and LPS from water-extractable antigens of virulent shigellae by ion-exchange chromatography. Western blot analysis of the complex indicates that all of the major virulence antigens of Shigella, including IpaB, IpaC, and IpaD, and LPS are components of this macromolecular complex. Mice or guinea pigs immunized intranasally with purified invasin complex (invaplex), without any additional adjuvant, mounted a significant immunoglobulin G (IgG) and IgA antibody response against the Shigella virulence antigens and LPS. The virulence-specific response was very similar to that previously noted in primates infected with shigellae. Guinea pigs (keratoconjunctivitis model) or mice (lethal lung model) immunized intranasally on days 0, 14, and 28 and challenged 3 weeks later with virulent shigellae were protected from disease (P<0.01 for both animal models).
志贺氏菌属的侵袭性和毒力很大程度上归因于质粒编码的毒力因子的表达，其中包括侵袭质粒抗原（Ipa蛋白）。感染后，宿主免疫反应主要针对脂多糖（LPS）和毒力蛋白（IpaB、IpaC和IpaD）。最近的观察表明，Ipa蛋白（IpaB、IpaC以及可能的IpaD）形成一种多蛋白复合物，能够诱导吞噬事件，使细菌内化。我们通过离子交换色谱法从强毒性志贺氏菌的水可提取抗原中分离出了侵袭素和LPS复合物。对该复合物的蛋白质印迹分析表明，志贺氏菌的所有主要毒力抗原，包括IpaB、IpaC和IpaD以及LPS，都是这种大分子复合物的组成成分。用纯化的侵袭素复合物（invaplex）经鼻内免疫的小鼠或豚鼠，无需任何额外佐剂，就能对志贺氏菌毒力抗原和LPS产生显著的免疫球蛋白G（IgG）和IgA抗体反应。这种毒力特异性反应与先前在感染志贺氏菌的灵长类动物中观察到的反应非常相似。在第0、14和28天经鼻内免疫，3周后用强毒性志贺氏菌攻击的豚鼠（角结膜炎模型）或小鼠（致死性肺部模型）均受到疾病保护（两种动物模型的P均<0.01）。
