肠杆菌科新种细菌的分离鉴定及致病性研究

报告了从辽宁省部分地区腹泻和感染标本中检出的成团肠杆菌、非脱羧勒克氏菌、克吕沃尔氏菌、彭氏变形菌、霍堆氏肠杆菌的分离、鉴定，药敏试验及致病性研究结果．部分菌株可引起动物、生物模型病变，证明有致病力．与人的腹泻和感染有关．致病性研究中，溶血性阳性率最高，依次为乳鼠灌胃，ＨｅＰ—２细胞、Ｖｅｒｏ细胞病变，兔肠袢结扎．豚鼠角膜侵袭试验无阳性．药敏试验证实，５组细菌抗药谱已很广，临床可用的敏感药物不多，一旦发生感染，治疗将十分困难．     

HCV HVR1准种在不同基因型丙型肝炎患者中的分布

目的:通过研究丙型肝炎病毒高变区1(HCV HVR1)准种复杂性与基因型之间的关系,探讨不同基因型HCV致病性差异的机制.方法:采用C区型特异性引物PCR法进行HCV基因分型,采用单链构象多态性聚合酶链反应法(SSCP法)检测HCV HVR1准种.结果:68例丙型肝炎患者中,Ⅱ型49例(72%),Ⅲ型13例(19%),Ⅱ、Ⅲ混合型6例(9%).Ⅱ型和Ⅱ、Ⅲ混合型HCV感染患者的HCV HVR1准种复杂性(SSCP条带数)明显高于Ⅲ型感染的患者,且与疾病严重程度关系密切.结论:HCV HVR1准种复杂性的差异可能是导致不同基因型HCV致病性差异的因素之一.     

着色真菌蟾蜍分离株小鼠致病试验研究

目的：观察着色真菌蟾蜍分离株的致病性。方法：抽样取着色真菌蟾蜍分离株与标准人分离株对照，制成菌悬液，做小鼠腹腔接种，观察接种后小鼠的外观表现，做菌种逆培养和观察内脏病理变化。结果：蟾蜍分离株卡氏枝孢霉、疣状瓶霉、裴氏着色霉和甄氏外瓶霉与病人分离株一样，在接种28天后，均可从小鼠脏器逆培养出接种的菌种，并引起内脏病变，形成结核样肉芽肿，肉芽肿内均可查见棕黄色硬壳小体。而瓶霉和外瓶霉属菌种逆培养结果均阴性。结论：从野生蟾蜍分离出的卡氏枝孢霉、疣状瓶霉，裴氏着色霉和甄氏外瓶霉与病人分离株一样，对小鼠有致病性，故可能是人着色芽生菌病的致病菌。     

Understanding how Listeria monocytogenes targets and crosses host barriers

Human listeriosis is caused by the Gram-positive bacterium Listeria monocytogenes. In humans, this pathogen has the ability to cross the intestinal, placental and blood-brain barriers, leading to gastroenteritis, maternofetal infections and meningoencephalitis, respectively. The entry of L. monocytogenes into cultured human epithelial cells is mediated by the interaction of an L. monocytogenes surface protein, internalin, with its human receptor, E-cadherin. The internalin-E-cadherin interaction is species-specific, and relies on the nature of a single amino-acid in the E-cadherin molecule, which is proline in permissive species such as humans, and glutamic acid in non-permissive species such as the mouse. In a transgenic mouse model that expresses human E-cadherin in enterocytes, internalin allows L. monocytogenes to cross the intestinal barrier. Epidemiological evidence also supports a role for internalin in human listeriosis, not only for crossing the intestinal barrier, but also for targeting and crossing the placental and blood-brain barriers. Consistent with these epidemiological data, infection with L. monocytogenes of trophoblastic cell lines, primary trophoblast cultures and human placental villous explants demonstrates that bacterial invasion of the syncytiotrophoblast barrier is mediated by the internalin-E-cadherin interaction, leading to histopathological lesions that mimic those seen in the placentas of women with listeriosis. Thus, the internalin-E-cadherin interaction that plays a key role in the crossing of the intestinal barrier in humans is also exploited by L. monocytogenes to target and cross the placental barrier. Further investigations are currently focusing on the molecular mechanisms by which L. monocytogenes targets and crosses the blood-brain barrier.     

SARS coronavirus induces apoptosis in Vero E6 cells

Severe acute respiratory syndrome (SARS) is an emerging infectious disease. Its etiological agent has been convincingly identified as a new member of family Coronaviridae (SARS-CoV). It causes serious damage to the respiratory system yet the mechanism is not clear. Infection-induced apoptosis or necrosis is suspected but no direct evidence for this yet exists. To date, Vero E6 cells are the only cell line that could be used to replicate the virus with obvious CPE (cytopathic effect) in vitro. It is known for some viruses (including members of family Coronaviridae) that CPE can be caused either by virus-induced apoptosis (active death) or cell necrosis (passive death). In this study, we examined the apoptosis in the SARS-CoV infected Vero E6 cells. Indeed, the results do show that the CPE was induced by apoptosis rather than necrosis, shown by typical DNA fragmentation, through the existence of apoptotic bodies and swollen mitochondria. This observation has some implications for the SARS-CoV pathogenicity: SARS-CoV does induce apoptosis in cell cultures and might have the same effect in vivo, responsible for the severe damage of the respiratory system.     

HPI毒力岛缺失的EAggEC17-2突变菌株的构建及其功能研究

目的 构建HPI毒力岛缺失的EAggEC17-2突变株，初步研究EAggEC菌株携带的耶尔森菌HPI毒力岛合成铁载体Ybt的功能。方法以EAggEC17-2为出发菌株，irp8基因部分序列作为同源重组的一侧序列，irp5基因序列作为同源重组的另一侧序列，中间插入有氯霉素（Can）抗性基因（cat基因）标记。通过接合转移和同源重组，构建了缺失约24kb的HPI毒力岛功能核心区区域EAggEC17-2的仝岛缺失株EA85。应用流式细胞技术（FACS）检测指示菌株WA-CS irp1：：KN（pC3G3．3N）荧光强度的变化情况，对EA85缺失株和出发菌株进行了合成Ybt的功能比较研究。结果成功构建了EAggEC17-2HPI全岛缺失株EA85。EAggEC17-2菌株具有表达Ybt的功能，而缺失株EA85丧失了合成Ybt的能力。结论EAggEC17-2HPI毒力岛的缺失，使Ybt的合成彻底阻断。EAggEC17-2具有的合成Ybt的功能是由其染色体携带的HPI毒力岛所决定的。     

桑褐刺蛾幼虫致病物质成份的实验研究

为研究刺蛾幼虫致病性物质成分, 以探讨刺蛾幼虫皮炎的致病机理及其治疗。采用 “ Ｏ”号毛笔刺激刺蛾幼虫释放毒素, 再用０℃蒸馏水制备毒素洗脱液,并用考马氏亮蓝 Ｇ—２５０ 染色法检测该毒素洗脱液成分;然后用该洗脱液接种人体皮肤进行致病性研究。结果, 测得毒素洗脱液中有蛋白质存在; 该毒素洗脱液直接接种人体皮肤可致皮炎,若将其加热后再接种人体无致病作用,从而进一步证实该毒素洗脱液的致病物质为蛋白质类毒素。     

庚型肝炎病毒感染的致病性与临床意义

为探讨庚型肝炎病毒(HGV)感染的致病性及临床意义,本文从5927例各型肝病人中筛选出抗—HGV阳性的173例病人与抗—HGV阴性的肝炎患者30例(对照组)进行观察比较。结果显示,抗—HGV阳性组与对照组部分血清ALT、BIL水平有显著性差异。173例抗—HGV阳性病人中,单独感染者31例,有70.79％(23/31)的病人迁延不愈,其中死亡2例,而30例对照组中,56.67％(17/30)迁延不愈,无1例死亡,重叠感染组142例有81.69％(116/142)迁延不愈,与对照组相比P<0.01有高度显著性差异,其中死亡3例。提示HGV的感染是病毒性肝炎的病原之一,它能造成各种不同程度的肝损害,在临床上可引起各型肝炎,病情趋于迁延,病死率较高,重叠感染可加重病情。由此可见,HGV具有致病性。HGV的感染在病毒性肝炎中具有重要的临床意义。