嗜肺军团菌致病性与效应蛋白的研究进展

嗜肺军团菌是一种可以引起军团菌肺炎和庞蒂亚克热的兼性胞内病原菌，主要侵染阿米巴原虫和人类巨噬细胞。该菌在宿主胞内能依靠Dot/Icm IVB型分泌系统产生的效应蛋白成功逃避溶酶体的降解。本文主要对嗜肺军团菌的致病物质、胞内存活与增殖机制及其效应蛋白的生物学功能进行综述，详细介绍嗜肺军团菌的毒力因子与致病机制，为军团病防治的研究提供新思路，也为其他胞内病原菌所致感染性疾病的研究提供重要的借鉴意义。     

Legionella longbeachae pneumonia: A case report and literature review in Japan

Herein, we report the case of a 74-year-old man diagnosed with Legionella pneumonia detected by Loop-Mediated Isothermal Amplification (LAMP) method, which was suspected to have been transmitted from the potting soil. Legionella longbeachae was identified in the sputum culture. The patient was intubated and maintained on mechanical ventilation. Antimicrobial therapy with azithromycin was also administered. His symptoms were resolved and he was discharged after 26 days of hospitalization. Legionella longbeachae pneumonia rarely occurs in Japan, and published literature of Legionella longbeachae pneumonia cases in Japan was reviewed. Patients with severe pneumonia exposed to potting soils, but with negative urinary antigen test results, should be examined by LAMP method.     

The first recognized patient withLegionella pneumophila serogroup 9 pneumonia in Japan

A 77-year-old female was admitted because of high fever, cough and sputum. She had been receiving corticosteroid therapy for 4 years for multiple myeloma and was immunosuppressed. A physical examination on admission showed coarse crackles in the right lower lung field, a chest radiograph showed consolidation in the right middle and lower lung fields, and a blood gas analysis revealed marked hypoxemia. The patient was diagnosed as having refractory pneumonia associated with acute respiratory failure and treated with intravenous cefmetazole followed by imipenem. On hospital day 5, erythromycin therapy was started because of a poor response to the previous antibiotics. The patient became afebrile on the tenth day and was in good health on day 15. A sputum culture on day 4 revealed aLegionella organism on Wadowsky-Yee-Okuda medium, which was subsequently confirmed to beLegionella pneumophila by a DNA hybridization test. This strain was identified at the Centers for Disease Control (Atlanta, GA, USA) by slide agglutination asL. pneumophila serogroup 9. Although our patient's symptoms are not apparently different from those caused by other serogroup strains ofL. pneumophila, this is the first recognized patient with culture-provenL. pneumophila serogroup 9 pneumonia in Japan. The clinical course of the disease and the diagnostic difficulties in identifying this type of pneumonia are discussed.     

Phase-variable Expression of Lipopolysaccharide Contributes to the Virulence of Legionella pneumophila

The mechanisms that maintain memory in T cells are not completely understood. We have investigated the role of antigen and interleukin (IL)-2 in the growth and maintenance of CD8⁺ T cells using a cytolytic T cell line specific for ovalbumin (OVA)_257-264 presented by H-2K^b. This line does not secrete IL-4 or IL-2; hence, stimulation with the OVA-transfected EL4 line (E.G7-OVA) does not induce proliferation without addition of exogenous growth factors. Furthermore, this line can be maintained continuously by weekly addition of irradiated, splenic filler cells and IL-2, with or without E.G7-OVA. Although IL-2 induced proliferation of these cytotoxic T lymphocytes (CTLs), production of interferon γ and tumor necrosis factor α required stimulation of the CTL with E.G7-OVA. The kinetics of lymphokine secretion after stimulation by E.G7-OVA were the same whether the CTL had been maintained with or without antigen (Ag). In addition, both CTL lines killed E.G7-OVA target cells within 4 h. Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy. CTLs cultured with or without Ag also served as memory T cells when parked for 100 d in unirradiated, syngeneic recipients without OVA. In the absence of OVA, the precursor frequency was identical in spleens of normal and β₂-microglobulin knockout recipients, but significantly less in IL-2 knockout mice. The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8⁺ T cell memory. These data also suggest that stimulation of OVA-specific CTLs by lymphokines seems to be more important to maintaining memory than stimulation of TCRs by cross-reactive peptides complexed to class I molecules.Memory is a hallmark of the immune response to T cell–dependent antigens. Memory, in both B and T cells, is manifest by stronger and quicker responses upon secondary exposure to antigen. The mechanisms that maintain memory are not completely understood. In part, T cell memory reflects an increase in the frequency of precursor cells. Memory T cells are also qualitatively distinct from naive T cells in that they have less stringent requirements for activation and respond more rapidly than naive T cells (for review see reference 1). Naive and memory T cells are distinct from effector T cells in that the latter are actively engaged in lymphokine secretion and lytic function in the case of CD8⁺ T cells. By contrast, both naive and memory T cells must be stimulated with antigen to express these effector functions. Naive T cells can be distinguished from effector T cells by differences in the expression of several cell-surface antigens. However, effector T cells cannot be easily distinguished from memory T cells because they both express activation antigens and increased density of adhesion molecules.Several important questions remain concerning the maintenance of memory T cells. The question of whether antigen is required for memory T cell persistence has been the subject of considerable debate. The majority of studies on the requirement for antigen in maintaining CD8⁺ memory T cells have been performed using polyclonal T cells activated by viruses such as lymphocytic choriomeningitis virus (LCMV), Sendai virus, or influenza. One of the major obstacles in studying memory in virus-specific, CD8⁺ T cells is ruling out restimulation by persisting Ags. However, transfer of CD8⁺ T cells from infected mice into irradiated, syngeneic recipients showed that memory persisted in the absence of virus, as measured by PCR (2–4). Another important issue is the relationship between effector and memory T cells. Whether memory T cells are derived from effector T cells in a linear fashion or whether they differentiate along separate pathways is not known. Signals that regulate development of memory T cells have not been identified.We have recently demonstrated that soluble OVA emulsified in CFA (5) or nonionic block copolymer adjuvants primed CD8⁺ CTL precursors in mice (6). These OVA-specific CTLs (OVA-CTLs) produced IFN-γ and TNF-α upon stimulation with E.G7-OVA or with OVA_257-264 in association with H-2K^b (6). However, these OVA-CTL cells do not produce IL-2 or -4. We reasoned that such CD8⁺ T cells would provide a good model for studying the memory function of CTLs because persistence of Ags would not be a problem. The results presented below compare the requirements for activation of CTLs versus maintenance of memory CTLs in vitro and in vivo. Our results show that CD8⁺ CTLs specific for the exogenous Ag, OVA, have the same potential to persist as memory T cells specific for viruses and tumors. Moreover, persistence of memory T cells was more dependent upon IL-2 than cross-reactive complexes of peptides and MHC class I antigens.     

一种复方季铵盐类消毒液杀灭嗜肺军团菌效果的研究

目的研究一种复方季铵盐消毒剂对嗜肺军团菌杀灭效果及其影响因素。方法应用悬液定量杀菌试验方法,对以二癸基二甲基氯化铵为杀菌成分的复方季铵盐消毒液杀灭嗜肺军团菌的效果及其影响因素进行了观察。结果以活性物含量为59.2 mg/L的该复方季铵盐消毒剂对悬液内嗜肺军团菌作用5 min,平均杀灭对数值>5.0。该复方季铵盐消毒剂随浓度增加和作用时间延长,其杀菌作用增强;但其随消毒液pH值降低,杀菌作用减弱。结论该复方季铵盐消毒剂在较低浓度下对嗜肺军团杆菌杀灭效果较好,但消毒液pH值偏酸性会降低其杀菌效果。     

碘伏消毒液对龟分枝杆菌的杀灭效果观察

目的观察聚维酮碘消毒液对龟分枝杆菌的杀灭效果。方法采用悬液定量杀菌试验方法进行了实验室检测,同时与杀灭嗜肺军团菌的效果作比较。结果用含有效碘250 mg/L的聚维酮碘消毒液作用5 min或有效碘1 000 mg/L该消毒液作用1 min,对龟分枝杆菌平均杀灭对数值大于5.00。用含有效碘100 mg/L的聚维酮碘消毒液作用2.5 min,对嗜肺军团菌平均杀灭对数值大于5.00。结论聚维酮碘消毒液对龟分枝杆菌具有良好杀菌作用,龟分枝杆菌对碘伏消毒液的抵抗力明显高于嗜肺军团菌。     

脉冲场凝胶电泳用于军团菌分型能力的评价

目的 评价脉冲场凝胶电泳(PFGE)技术用于军团菌属不同种(Legionella species)以及不同血清型菌株的分型能力.方法 选用117株10个嗜肺军闭菌血清型,30种非嗜肺军团菌的参考菌株和我国环境分离菌株,采用Asc Ⅰ内切酶酶切,进行PFGE.从电泳条带的数量和分布、PFGE的分型力、分辨率和与流行病学资...