Functional analysis of Tumor necrosis Factor α(TNFα) on infections immunity.

冠状病毒表现出不同的细胞嗜性，如消化器官、呼吸器官、肝脏和中枢神经系统，不同毒株之间的毒力也不同，其机制因组织嗜性而异，毒力尚不清楚。小鼠肝炎病毒(MHV)感染可导致小鼠急性重型肝炎、慢性肝炎、急性脑炎和脱髓鞘，并一直在研究包括脊髓灰质炎在内的人类脱髓鞘疾病模型。提示宿主免疫，特别是炎症细胞因子α、IL-1和IL-6在…致重型肝炎、急性脑炎和脱髓鞘危象中起重要作用。为此，本研究通过RT-PCRRFLP分析，比较了疫苗、弱毒株和强毒株S糖蛋白基因3、3-1、4和7的序列，以探讨毒株间细胞嗜性和毒力差异的分子基础多为病毒(TGEV)9株。结果表明，日本1957~1995年间暴发的TGEV毒株分为两类。虽然ORF3、3-1、4区的缺失与病毒致病性有关，但我们的研究结果表明，ORF3、3-1、4区的缺失对病毒的致病性没有直接影响。我们分离到了一株存在S糖蛋白基因缺失的新毒株，该区域可能与致病性有关，但该毒株的血凝能力不足。鉴于肿瘤坏死因子α在体内感染小鼠冠状病毒中的作用尚不清楚，我们试图评价其在体内感染冠状病毒中的作用。诱导肿瘤坏死因子α缺陷的B6小鼠(肿瘤坏死因子α-/-鼠)感染MHV-3。结果表明，肿瘤坏死因子α-/-小鼠的存活率显著高于对照B6小鼠。另一方面，肿瘤坏死因子α-/-小鼠和对照6小鼠在肝脏中的病毒生长没有显著差异。这些结果表明，暴发型肝炎的主要原因不是病毒对肝细胞的直接损伤。同时，约40%的肿瘤坏死因子α-/-小鼠在感染MHV-3后死亡，但肿瘤坏死因子α-/-小鼠在MHV-3感染后的存活时间比对照B6小鼠要长。病理组织学观察两种品系小鼠均出现肝细胞凋亡性死亡。这些结果表明，肿瘤坏死因子α在重型肝炎的发生中起着重要作用，另一方面也提示病毒性肝炎还有其他因素。较少

Coronaviruses show different cell tropism , like the digestive organs, respiratory organs, liver and central nerve system, and virulence between different stains, and the mechanisms is of differences on tissue tropisms and virulence is not clear. Mouse hepatitis virus(MHV) infection lead to acute and fulmiant hepatitis, chronic hepatitis, acute encephalitis and demyelination in mice, and have been studying model of human demyelination diseases including polioencephalitis. It was suggested that the host immunity, especially inflammation cytokine like TNFα, IL-1 and IL-6, play a important role on the crisis of fulmiant hepatitis, acute encephalitis and demyelination induced by MHV.So, for the purpose of studing the molecular bases of the differences of cell tropism and virulent beween strains we have performed RT-PCR RFLP analysis and determination and comparison of sequence of S glycoprotein gene, ORF 3,3-1,4 and ORF 7 between vaccine, attenuated and virulent Transmissible gastroenterit … More is virus (TGEV) 9 strains. And it was shown that TGEV strains outbreaked in Japan between 1957 and 1995 were separated 2 gropes. Although a correlation between the presence of deletions of ORF3, 3-1, 4 region and viral pathogenicity has been reported, we had the results that the deletion of ORF3, 3-1, 4 region had no influence directly on pathogenicity. We have isolated new TGEV strain that have deletions on the regions of S glycoprotein gene, the region were expected to relate with pathogenicity, and the TGEV strain was deficient in the ability of hemagglutination.Since the role of TNFα in murine coronavirus infection in vivo uncertain, we attempted to evaluate its role in i.p. iduced MHV-3 infection of TNFα deficient B6 mice(TNFα-/- mice). It was shown that the survival rate of TNFα-/- mice was significantly higher than that of control B6 mice. On the other hand, there was no significant difference on viral growth in the liver between TNFα-/- mice and control 6 mice. These results show that the main causes of fulminant hepatitis was not the direct damage of hepatocytes by the virus. In the meantime, about 40% TNFα-/- mice were dead after MHV-3 infection, but thelength of survival after MHV-3 infection of TNFα-/- mice were longer than that of control B6 mice. And there were apoptotic hepatocyte death both strain mice by detail pathohistlogical observations. These results show that TNFα play a important role on the arisingof fulminant hepatitis, on the other hand it was indicated that there were another factors on the virul hepatitis. Less