Immunity to coccidia in chickens: adoptive transfer with peripheral blood lymphocytes and spleen cells

Suspensions of cells prepared from the caecal tonsils and spleen, and the peripheral blood lymphocytes of chickens immune to Eimeria maxima , were tested for their ability to transfer resistance to syngeneic recipients. The intravenous injection of approximately 6 × 10⁸ spleen cells or peripheral blood lymphocytes caused a significant reduction of oocyst production by the challenged recipients, in comparison with controls which were uninjected or given cells from birds susceptible to E. maxima. Peripheral blood lymphocytes appeared to be most effective when obtained 10–15 days after a primary, or 3–10 days after a secondary inoculation of oocysts. The peripheral blood lymphocytes which participate in the early response to challenge of immune birds were not found to be protective. When given intraperitoneally, greater numbers of spleen cells were required to reduce oocyst production, and small numbers of caecal tonsil cells were ineffective. The ability of the various cell suspensions to transfer antibody and cell-mediated responses was monitored with 'marker' antigens. There was some indication that both types of response were involved in protection.     

Conduction Defects and Arrhythmias in Chagas' Disease:

Gap Junctions and Humoral Factors in Chagas' Disease. The protozoan parasite Trypanosoma cruzi causes Chagas' disease, a major cause of cardiac dysfunction in Latin Americans. Chagas' disease exhibits both acute and chronic phases, and each may be characterized by cardiac conduction disturbances. In acutely infected cultures of rodent heart cells, synchronized spontaneous beating becomes less regular, and coupling between cells is reduced. The basis of this decreased conduction is apparently in localization of the gap junction protein (Cx43) inside infected cells. Although total Cx43 is normal in infected cells, little is recognizable at appositional membranes. Electrophysiological properties are also altered by this infection. Action potentials are shortened, resting Ca²⁺ levels are elevated, and response to α-adrenergic agonists was altered, compared to controls. Humoral factors may contribute to the conduction defects in chronic Chagas' disease. Sera from chronically infected rabbits produced KC(J abnormalities in Langendorff-perfused rabbit hearts. These findings indicate that chagasic infection may modify ion channel function in the heart, and we suggest that these changes may be manifested in the conduction disturbances that characterize this disease.     

青海省湟源县人体肠道寄生虫分布调查报告

湟源县为我省海东地区管辖的农业县之一，是青海省农、牧区之间的过渡地段。该县属高原大陆性气候，日照强，多风干燥，地势复杂，是青藏公路沿线的重镇。按全国人体寄生虫分布调查实施细则的要求，确定日月，大华两乡各１个调查点。共检查１０３９人，查见寄生虫感染者４２９例，人群的寄生虫总感染率为４１．３％。日月点和大华点人群寄生虫感染率（感染者）分别为４５．４％（２３５／５１８）和３７．０％（１９３／５２１）。共查见寄生虫９种，各种寄生虫感染率分别为：蛔虫２９％（３０１例），蛲虫（１２岁以下儿童）３８．７％（９１例），结肠内阿米巴８．１％（８４例），微小内蜒阿米巴４．３％（４５例），布氏嗜碘阿米巴２．２％（２３例），哈氏内阿米巴０．９％（９例），溶组织内阿米巴０．５％（５例），贾第虫１．７％（１８例），人芽囊原虫１．４％（１４例）。两个点的调查结果表明，在不同性别、年龄和职业寄生虫感染率间的差别，均具有显著意义（其χ２值依次为８．３８７６、２８．６０２８和３２．４８，其Ｐ值均＜０．０５）。     

Trypanosoma cruzi: binding of parasite antigens to mammalian cell membranes

Summary Muscle and neuronal cell lines were infected with Trypanosoma cruzi and stained for the presence of parasite antigens by immunofluorescence. Up to 72 h post infection, fluorescence was limited to the intracellular amastigote stages. After the release of parasites, at about 96 h, fluorescence was also associated with the membranes of normal and infected cells. This finding was reproduced by passive sensitization of uninfected cells using amastigote antigens at protein concentrations as low as 10 μg ml^-1. Intriguingly, although both normal and transformed cells of muscle and nervous tissue origin adsorbed significant quantities of antigen, lymphocytes and erythrocytes failed to show any detectible uptake.     

Parasites as aetiological agents in chronic diseases. Epidemiological associations and potential mechanisms of pathogenesis

The aetiological role of parasitic infection has been well established, through epidemiological studies, for many chronic diseases prevalent in the tropics. Examples include Schistosoma mansoni infection leading to portal hypertension, Schistosoma haematobium infection leading to obstructive uropathy and squamous cell carcinoma of the bladder, Clonorchis sinensis leading to cholangiocarcinoma, and Taenia solium infection leading to epilepsy. Our understanding of the pathogenesis of these associations, however, continues to evolve, with new insights from many fertile avenues in chronic disease research. There are also tenuous associations such as schizophrenia with toxoplasmosis, and the findings from observational studies that link malignancy and epilepsy with a range of helminthic infections. Imprecise case definitions, and the lack of good animal models, are limitations to the evidence for a causal role of parasitic infection in these diseases.     

第五期国际计划生育合作项目寄生虫病防治效果评价

目的　评价 1996～ 1998年第五期国际计划生育合作项目寄生虫病防治的效果。　方法　采用以定性为主 ,同时与定量相结合的方法对寄生虫病防治效果进行评价。　结果　项目实施后 ,通过宣传教育、粪检和集体驱虫 ,学生寄生虫感染的总阳性率下降了 33%～ 5 5 % ;蛔虫卵的阳性率下降了 32 %～ 5 2 %。人们的卫生观念和生活质量得到了明显提高。　结论　宣传教育及有效的检测和治疗手段相结合是农村贫困地区人群寄生虫防治的有效方法。     

Failure of nude (athymic) rats to become resistant to reinfection with the intestinal coccidian parasite Eimeria nieschulzi or the nematode Nippostrongylus brasiliensis

The course of each of three successive infections with Eimeria nieschulzi in nude (athymic) rats was the same as the primary infection in nu/+ animals, with the production of more oocysts. This indicates that resistance to reinfection with this parasite is mediated by T lymphocytes but that these cells do not control the duration of the life cycle, since oocyst production was not prolonged in the nu/nu rats. After the three infections with E. nieschulzi, the rats were exposed twice to the intestinal nematode Nippostrongylus brasiliensis, and the nu/nu were completely susceptible even to the second infection. Egg production by both infections in the nu/nu animals was similar and continued at a high plateau level for 28 days before falling to a low level. It appears that the strain of N. brasiliensis used in this study is unable to sustain high egg production for more than 4 weeks in T cell deficient rats.     

Evaluation of IgG4 response in ascariasis by ELISA for serodiagnosis

The excretory/secretory (ES) antigen(s) of Ascaris lumbricoides was fractionated into 10 fractions by gel chromatography on a Suparose 12 column in FPLC. Of these, the third fraction (Al III), showing binding activity with both IgE and IgG antibodies of A. lumbricoides infected patients' sera, was further resolved into 2 fractions (Al IIIa and Al IIIb) on passage through a Mono Q column. Al IIIb was found to be the most potent antigen due to its high binding affinity with IgE and IgG antibodies of Ascaris infected patients as evidenced by ELISA inhibition. Although a two to five-fold increase of serum IgE level was observed in all helminthic parasite infected patients studied compared to control subjects, Al IIIb specific IgE was detected in sera of all Ascaris infected and only 40% of hookworm infected patients. When Al IIIb was tested by ELISA with sera of control subjects, Ascaris, hookworm, Strongyloides and Trichuris infected patients, strong binding was observed with the IgE and also IgG of all the Ascaris infected patients; however, it cross-reacted with IgG in 50% of hookworm, 28.6% of Trichuris trichura and 22.2% of Strongyloides infected patients' sera; but with IgE only in 40% of hookworm infected patients' sera. Further study showed specific detection of IgG₄ in all the serum samples of 65 Ascaris infected patients when Al IIIb antigen was allowed to react with different subclasses of IgG by ELISA, giving a sensitivity of 100%. Reactivities of Al IIIb with IgG₁, and IgG₃, were only 47.6 and 11.8% respectively and there was no reactivity with IgG₂, subclass. No IgG₄ reactivity against Al IIIb was observed in the sera of hookworm, Trichuris or Strongyloides infected patients and was similar to that observed with control subjects showing the 100% specificity of the test system. This study may therefore be regarded as a novel technique for serodiagnosis of ascariasis by measuring Ascaris specific IgG₄.     

Antibody isotype responses to Trichuris infection in humanized SCID mice

We have developed a humanized SCID mouse model of trichuriasis involving the injection of peripheral blood lymphocytes (PBLs) from normal healthy donors into C. B.-17 severe combined immunodeficiency (SCID) mice followed by vaccination and infection of these mice with the murine species of Trichuris, Trichuris muris . Optimal results with respect to parasite specific antibody production and peripheral engraftment were achieved by injecting intraperitoneally 2 × 10⁷ PBLs which had been incubated overnight on anti-human CD3 coated plates. Mice were immunized three weeks post reconstitution with parasite antigen in Freund's Incomplete Adjuvant and infected two weeks later. At autopsy human T cells could be detected in the spleens of engrafted animals and anti- T. muris antibody detected. The dominant IgG isotype responses were shown to be IgG1 and IgG2, providing a similar IgG isotype profile to that seen in humans infected with T. trichiura in the field. In several cases engrafted animals showed the remarkable ability to expel their parasite load. The model will thus be useful for analysing human immune responses to trichuriasis under highly controlled laboratory conditions impossible to achieve in the field .