The innate immune response against Brucella in humans

Pathogens have developed different strategies to survive and multiply within their host. Among them is the ability to control phagocyte apoptosis while another is to affect the expression of cytokines which is necessary for a normal protective function of the immune response. To establish themselves and cause chronic disease in humans and animals, Brucella spp. invade and proliferate within monocytic phagocytes. We have established that in humans, Brucella suis impairs the apoptosis of monocytes and macrophages, thus preventing its host cell elimination. In mice, which are not naturally colonized by the bacteria, Brucella infection results in Type1 (Th1) cellular immune response which promotes a clearance of the bacterial organism. The development of this response is under the control of major cytokines like TNF-alpha, IFN-gamma and IL-12 produced at the onset of infection. We have observed that in humans, B. suis-infected macrophages which produce IL-1, IL-6, IL-10 and several chemokines including IL-8, do not secrete TNF-alpha. By constructing null mutants, we demonstrated that this inhibition involves the outer membrane protein Omp25 of Brucella, however the mechanism regulating the inhibition has not yet been clearly defined. It is likely that the Omp25-induced effect on TNF-alpha production assists bacterial evasion of antimicrobial defences at different levels. Firstly, by preventing the autocrine activation of macrophages thus inhibiting innate immunity and secondly by impairing the production of IL-12 and the development of a Th1 type specific immunity. In addition to the central role of the macrophage in Brucella infection, others cells of the innate immune response are recruited and influenced by the interactions between bacteria and host. For instance, human Vgamma9Vdelta2 T-cells play an important role in the early response to infection with intracellular pathogens. Evidence has been presented that their number dramatically increased in the peripheral blood of patients with acute brucellosis. We have shown that human Vgamma9Vdelta2 T-cells can be specifically activated by non-peptidic low molecular weight compound(s) from B. suis lysate or by soluble factors produced by B. suis-infected macrophages. Under these conditions, they produce TNF-alpha and IFN-gamma and reduce the bacterial multiplication inside infected autologous macrophages. This impairment of B. suis multiplication is due to both soluble factors released from activated gammadeltaT-cells (including TNF-alpha and IFN-gamma) and to a contact-dependent cytotoxicity directed against the infected cells. The interactions between the bacteria and these cells can counteract the intramacrophagic development of the bacteria and finally influence the further development of the host defense. We hypothesize that the chronicity or the elimination of the infection will depend on the balance between contradictory effects induced by the bacteria which favor either the host or the pathogen. Moreover, the interrelationship between the different cells must be taken into account in the analysis of the virulence of the bacteria and in the development of in vitro models of human macrophage infection.     

Effect of Immunization with Plasmid DNA Encoding for Rinderpest Virus Matrix Protein on Systemic Rinderpest Virus Infection in Rabbits

Plasmid vaccine pBK-CMVMP1LC113 expressing the matrix (M) gene of rinderpest virus was assessed for its potential to protect rabbits against a lethal viral challenge. Rabbits immunized with plasmids expressing the M gene were not protected when challenged with lapinized rinderpest virus, despite the production of anti-M antibodies, while rabbits immunized with rinderpest tissue culture vaccine were completely protected from a lethal challenge with lapinized rinderpest virus. The plasmid vaccine also had no significant effect on the lymphopenia in challenged rabbits. The results indicate that rinderpest M protein does not have a protective role in rinderpest infection.     

Orientation of bovine CTL responses towards PIM, an antibody-inducing surface molecule of Theileria parva, by DNA subunit immunization

East Coast fever, an acute lymphoproliferative disease of cattle, is caused by the apicomplexan parasite Theileria parva. Protective immunity is mediated by CD8(+) cytotoxic T lymphocytes directed against schizont-infected cells. The polymorphic immunodominant molecule, although an antibody-inducing surface molecule of the schizont, has been hypothesized to play a role in protective immunity. In order to evaluate the immunogenicity of PIM for inducing CTL, cattle were immunized with PIM in isolation from other T. parva antigens, forcing the presentation of PIM-derived epitopes on the MHC class I molecules. Although parasite-specific cytotoxicity was induced in both vaccinated animals, their immune response was clearly different. One animal generated MHC-restricted parasite-specific CTL against PIM while the other calf exhibited a strong PIM-specific proliferative response but non-MHC-restricted parasite-specific cytotoxicity. Only calf 1 survived a lethal sporozoite challenge. This DNA immunization technique with an antigen in isolation of CTL-immunodominant antigens might open possibilities for directing CTL responses against predefined antigens, such as strain cross-reacting CTL antigens.     

HBV转基因小鼠T细胞免疫状态

以正常非转基因 ICR小鼠为对照 ,用 3H-Td R掺入法和 ELISA分别测定了 HBV转基因 ICR小鼠脾淋巴细胞针对 HBe Ag的特异性增殖功能及其培养液上清中 Th1、Th2相关细胞因子 m IFN-γ、m IL-2、m IL-6、m IL-1 0含量。结果 ,HBV转基因小鼠脾淋巴细胞对 HBe Ag刺激引起的增殖反应、HBe Ag与 Con A共同刺激引起的增殖反应及其培养液上清中 4种细胞因子含量均明显低于对照组。以上结果表明 ,HBV转基因小鼠 Th1、Th2淋巴细胞所介导的特异性免疫功能均受到抑制     

犬淋巴细胞转化增殖试验最佳条件的确定

本试验选择杂种牧羊犬作为实验犬,用MTT法检探讨了不同浓度犊牛血清（FCS）、淋巴细胞、植物血凝素P（PHA-P）和刀豆蛋白A（ConA）对犬淋巴细胞增殖的影响。确定了犊牛血清含量为10%,淋巴细胞浓度为5×106个/mL,用丝裂原PHA-P 刺激的最佳浓度为12.5ug/mL时,MTT法测定能够刺激犬淋巴细胞转化增殖,但t检验分析表明其促进淋巴细胞增殖的效果并不显著;当其它条件不变,所用的丝裂原为Con A时,它在浓度为0.5～2.5μg/mL范围内均可以显著刺激T细胞的增殖（P<0.05）,且在浓度为2.5μg/mL时刺激效果最佳     

The effect of feeding the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) on cell-mediated immunity and protection against Yersinia ruckeri in pikeperch (Sander lucioperca)

The present study examined the influence of leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB), a natural product HMB, on nonspecific cell‐mediated defence mechanisms and protection against enteric redmouth disease (ERM) in pikeperch (Sander lucioperca). β‐hydroxy‐β‐methylbutyrate was fed in a pelletted ration at 50 mg kg^?1 of the feed for 8 weeks. The phagocytic ability and potential killing activity of blood and pronephric phagocytes were examined in HMB‐ and control‐fed fish before and after 8 weeks of feeding HMB. Simultaneously, the proliferative response of blood and pronephric lymphocytes stimulated by mitogens concanavaline A and lipopolisaccharide were examined in experimental and control groups. Following 8 weeks of HMB feeding, a challenge test was performed by injecting the fish with live pathogenic bacteria Yersinia ruckeri. β‐hydroxy‐β‐methylbutyrate applied in the diet for 8 weeks prompted a statistically significant (P<0.05) increase in phagocytic ability and potential killing activity of the blood and pronephric phagocytes and the proliferative response of blood and pronephric lymphocytes. The changes in these mechanisms correlated with protection against Y. ruckeri, the ERM pathogen. The results showed that feeding HMB increased the nonspecific cell‐mediated defence mechanisms and protection against ERM by reducing cumulative mortality (30%) following the challenge with pathogenic bacteria. Future studies will include determination of optimal doses and protocols of oral application of HMB to maximize the immunomodulatory effects and protection against viral diseases in intensive pikeperch culture.     

鲫、草鱼外周血中淋巴细胞和单核细胞对鲤血管内皮细胞的粘附

借鉴哺乳动物内皮细胞体外培养技术，结合鱼类细胞自身特点，纯化培养鲤血管内皮细胞并传至3代，以此作为粘附材料。应用淋巴细胞分离液离心技术并结合玻璃粘附法分离纯化鲫、草鱼外周血中淋巴细胞、单核细胞，并与上述3代内皮细胞进行免疫粘附试验，同时进行免疫粘附动力学观察。结果显示，鲫、草鱼两类细胞对内皮细胞的粘附率分别为0.09±0.013，0.20±0.018；0.11±0.015，0.21±0.023。表明鲤科鱼类不同种的同类细胞粘附率差异不大，而同种不同类细胞则差异显著。动力学观察分析表明，淋巴细胞粘附较快，60min进入平台期；单核细胞粘附慢，120min进入平台期。初步证明鱼类内皮细胞具有免疫介导作用。     

左旋咪唑党参多糖对雏鸡免疫调节效果的研究

210羽7日龄蛋公鸡随机均分成7组,每组30只,1～3组口服高、中、低浓度的左旋咪唑党参多糖水溶液,4～6组口服高、中、低浓度的党参多糖水溶液,7组为对照组,口服生理盐水。用2羽份的新支二联弱毒苗点眼、滴鼻,并用新城疫油乳灭活苗皮下注射。用微量法测定新城疫血凝抑制（HI）抗体效价,用MTT法测定淋巴细胞增殖的动态变化,称取体重和胸腺、脾脏、法氏囊的质量,计算器官指数。结果表明,左旋咪唑党参多糖组和党参多糖组的抗体效价均显著高于对照组,左旋咪唑党参多糖组的抗体效价显著高于党参多糖组。试验组的OD值显著高于对照组,左旋咪唑党参多糖组的OD值显著高于党参多糖组。左旋咪唑党参多糖和党参多糖都可以提高胸腺、法氏囊和肾脏指数,但是以左旋咪唑党参多糖组效果好,尤其高剂量组更为明显。     

H5N1亚型禽流感病毒感染SPF雏鸡的外周血液免疫病理变化

以7日龄SPF雏鸡为试验动物,应用细胞培养和免疫酶技术,通过对外周血液免疫球蛋白含量、T和B淋巴细胞数量及其功能的检测,较全面系统地研究了鹅源H5N1亚型中强毒禽流感病毒(AIV)感染SPF雏鸡后,其外周血液上述指标的动态变化。结果发现,SPF雏鸡感染鹅源H5N1亚型AIV后,血清IgG和IgA含量在1~4d显著或极显著低于对照雏鸡(P<0.05或P<0.01),而IgM在病毒感染早期未见显著性差异,随后3种免疫球蛋白含量逐渐回升;血液T淋巴细胞数量显著低于对照雏鸡(P<0.05或P<0.01),而B淋巴细胞在1~5d明显降低(P<0.05或P<0.01);T、B淋巴细胞对ConA或PMA的增殖反应分别于1~8d、1~4d明显低于对照雏鸡(P<0.05或P<0.01)。上述结果表明,AIV感染SPF雏鸡外周血液无论是细胞免疫还是体液免疫功能均呈现一定抑制。