HIV感染伴发溶组织内阿米巴感染概况

溶组织内阿米巴是侵袭性阿米巴病的病原体,据估计每年全世界约有5000万人感染。同时据已报道的为数不多的流行病学调查数据显示,溶组织内阿米巴感染在HIV感染者这一特殊人群中正呈上升趋势。尽管溶组织内阿米巴并未归入机会致病寄生虫,但其和HIV感染的相关性越来越受到关注。本文就溶组织内阿米巴在HIV感染者中流行情况、感染的危险因素、临床表现、诊断及治疗方面进行综述。     

Antigenicity and immunogenicity of phage library-selected peptide mimics of the major surface proteophosphoglycan antigens of Entamoeba histolytica

Entamoeba histolytica is the protozoan parasite responsible for intestinal amoebiasis and amoebic liver abscess, which cause significant morbidity and mortality in many countries of the world. Proteophosphoglycans (PPGs, also known as lipophosphoglycans, LPGs, or lipopeptidophosphoglycans, LPPGs) represent dominant surface components of E. histolytica. Passive immunization with a monoclonal antibody (EH5) directed against these components protected SCID mice from amoebic liver abscess, so PPGs might be regarded as vaccine candidates; however, their structure is very complex and only known in part. They are glycosylphosphatidylinositol-linked polypeptides of unknown sequence carrying glycan side-chains linked to serine residues via phosphodiester bonds. In order to identify peptide mimics of the E. histolytica PPG antigens, we screened six different phage-displayed random peptide libraries with the antibody EH5. Various peptide mimics of different length were identified and, in all the peptides, a distinct consensus sequence Gly-Thr-His-Pro-X-Leu could be identified. The phages strongly bound to the antibody, and the natural antigen inhibited binding of the phages to antibody EH5. In addition, several of the phages induced a significant immunoglobulin G response against amoebic antigens in immunized mice.     

齿龈内阿米巴引起牙周炎的实验研究

目的　探讨齿龈内阿米巴 (Entamoeba ,gingivalis ,E .g .)的致病性及其与牙周炎之间的关系。方法　大白鼠用免疫抑制剂处理 1周 ,其下颌中切牙颈部用不锈钢丝栓扎后 ,随机分为 3组 ,分别于牙龈涂拭E .g .,共生菌 (Symbioticbacteria ,S .b .)及生理盐水 ,观察各组大白鼠发生牙周炎状况 ,同时检查脓液中有无活的病原体 ,实验结果进行病理学分析。结果　E .g .组大白鼠牙周炎发病率高于S .b .组和对照组 (P <0 .0 5 ) ,S .b组大白鼠牙周炎发病率高于对照组 (P <0 .0 5 ) ;脓液镜检或培养均查见相应的病原体 ;病理证实E .g .可引发牙周炎。结论　E .g .是条件致病病原体 ,当宿主免疫力低下时 ,在口腔内细菌协同作用下可使宿主发生牙周炎。     

药物牙膏对齿龈内阿米巴的体外抑制作用

目的 研究药物牙膏对齿龈内阿米巴的体外抑制作用.方法 从牙龈炎患者口腔中取得齿龈内阿米巴体外培养,加入不同浓度的牙膏A、B、C和高露洁48h后,显微镜下观察齿龈内阿米巴形态和数目的 变化.结果 牙膏A、B、C和高露洁均可以抑制口腔齿龈内阿米巴,其IC50值分别为3.58、3.93、3.72和3.56mg/ml.结论 4...     

Averting transmission: A pivotal target to manage amoebiasis

Amoebiasis is a parasitic infectious disease caused by the enteric protozoan Entamoeba histolytica, a leading basis of deaths accounted to parasites, succeeding malaria and schistosomiasis. Conventional treatment methodologies used to deal with amoebiasis mainly rely on the administration of anti‐amoebic compounds and vaccines but are often linked with substantial side‐effects on the patient. Besides, cases of development of drug resistance in protozoans have been recorded, contributing further to the reduction in the efficiency of the treatment. Loopholes in the efficacious management of the disease call for the development of novel methodologies to manage amoebiasis. A way to achieve this is by targeting the essential metabolic processes of ‘encystation’ and ‘excystation’, and the associated biomolecules, thus interrupting the biphasic life cycle of the parasite. Technologies like the CRISPR‐Cas9 system can efficiently be exploited to discover novel and essential molecules that regulate the protozoan's metabolism, while efficiently manipulating and managing the known drug targets, leading to an effective halt and forestall to the enteric infection. This review presents a perspective on these essential metabolic processes and the associated molecules that can be targeted efficaciously to prevent the transmission of amoebiasis, thus managing the disease and proving to be a fruitful endeavour.     

齿龈内阿米巴对大白鼠牙龈组织的致病作用

目的观察齿龈内阿米巴(Eg)对实验动物的致病作用,了解其发病机制,研究Eg感染与牙周病的关系。方法从牙周病患者的牙周袋内容物分离Eg虫株并培养,分组人工感染大白鼠,观察Eg、共生菌(sb)和生理盐水的致病作用以及组织病理改变。结果Eg组s、b组及生理盐水对照组大白鼠牙周组织炎症发病率分别为87.50%、68.75%和12.50%,差异有统计学意义(P<0.01)。结论宿主免疫力低下时,Eg感染可导致牙龈组织炎症发生。     

Non-pathogenic Entamoeba histolytica: functional and biochemical characterization of a monoxenic strain

We have cultured under monoxenic conditions and characterized an Entamoeba histolytica clone, MAV-I CINVESTAV (MAV-I), obtained from feces from an asymptomatic carrier. The clone shows the non-pathogenic E. histolytica zymodeme type I, which did not change through the process of monoxenization. Clone MAV-I was non-pathogenic in both in vivo and in vitro tests, and it did not have a functional 112-kDa adhesin. As far as we know, this is the first non-pathogenic monoxenic strain reported. Clone A (strain HM1:IMSS), a highly virulent clone with pathogenic zymodeme type II, and which has the 112-kDa adhesin, was used as a control. Protein patterns from both clones were almost identical in one-dimensional gels. In two-dimensional gels, differences in high-molecular-weight proteins were detected. Clone MAV-I adhered and phagocytosed only 12% of the red blood cells adhered and phagocytosed by clone A. MAV-I trophozoites did not destroy cell culture monolayers and did not produce hepatic abscesses in hamsters. They also showed deficiency in protease activity. The absence of virulence in clone MAV-I correlated directly with the absence of a functional 112-kDa adhesin, supporting the role that this protein plays in virulence.     

Diagnostic methods for differentiation of Entamoeba histolytica and Entamoeba dispar in carriers: performance and clinical implications in a non-endemic setting

Unpreserved faecal samples, suspected to contain Entamoeba histolytica/Entamoeba dispar cysts or trophozoites on the basis of microscopic examination, and serum samples from 416 patients were collected in a prospective study to determine whether stool antigen assays and detection of antibodies in serum are reliable methods to distinguish between carriers of E. histolytica and E. dispar in comparison to the reference test: real-time PCR. In 283 patients (68%) DNA of E. histolytica or E. dispar was amplified by real-time PCR: 6 patients with amoebic colitis (2%), 19 carriers of E. histolytica (6.7%), and 258 carriers of E. dispar (91.2%). In 133 patients (31%) no DNA of E. histolytica or E. dispar could be amplified in the stool samples. This patient group was used as control for the evaluation of diagnostic tests. Using real-time PCR as a reference test, the sensitivity and specificity of (1) the Entamoeba test for the diagnosis of E. histolytica/E. dispar carrier were 59% and 98%, (2) E. histolytica II for the diagnosis of E. histolytica carrier was 71% and 100%, and (3) serology for the diagnosis of E. histolytica infection was 83.3% and 95.2%, respectively. Applied to carriers that did not originate from an endemic country the sensitivity of serology for E. histolytica infection was 90% and specificity was 98.8%. In comparison to real-time PCR the performances of Entamoeba test and E. histolytica II lacked sensitivity for a reliable diagnosis of E. histolytica/E. dispar infection in a non-endemic setting. In carriers of E. histolytica/E. dispar from non-endemic countries the high specificity of serology can be used to establish the diagnosis of E. histolytica infection if antibodies are present.     

齿龈内阿米巴的致病作用与致病机制的研究

在注射免疫抑制剂 1周后的大白鼠龈缘涂抹齿龈内阿米巴 (Emtamoebagingivalis ,E .g .) ,5天后 ,牙龈组织出现溃疡、牙周脓肿形成、脓液查见活E .g .、牙槽骨吸收等牙周炎病症。电镜术与生化分析发现 :E .g .伪足活跃、有丰富的溶酶体 ,所含水解酶与ACP显著较健康组高 (P <0 0 1) ,可使牙周组织溶解与受损。SOD较健康组显著性低 (P <0 0 1) ,MDA显著性增高 (P <0 0 1) ,说明E .g .感染产生较多氧自由基可使细胞膜受损 ,加上口腔共生菌的协同作用使免疫力低下的宿主发生牙周炎。     

性激素对溶组织内阿米巴致病力的影响

为进一步探索性激素在阿米巴致病中的影响,用加性激素培养的阿米巴进行了白细胞触杀实验,观察其毒性的改变.结果,雄性激素可以增强阿米巴对白细胞的触杀作用,而雌性激素无明显的增毒作用.另以肌注性激素的大白鼠进行了肝脏阿米巴接种实验,观察其对阿米巴肝脓肿形成的影响.结果提示两种性激素均能促进大白鼠阿米巴肝脓肿的形成,尤以雄性激素作用更明显.