Akhvlediani T, Gochitashvili N, Tsertsvadze T
Department of Infectious Diseases, Faculty of Medicine, I. Javakhishvili Tbilisi State University, Tbilisi, Georgia.
Georgian Med News. 2007 May(146):38-42.
The group of persistent viral infections includes latent, chronic and slow infections. The latter can be caused by: conventional viruses (e.g. polyomavirus JC - causative agent of the Progressive Multifocal Leucoencephalopathy (PML)); defective forms of conventional viruses (e.g. defective measles virus, causing Subacute Sclerosing Panencephalitis (SSPE)) and non-conventional infectious agents - prions (proteinaceous infectious particles), causative agents of transmissible spongiform encephalopathies of humans and different animal species. Prion Diseases are unique in that the same pathologic substrate may cause infectious , genetic and sporadic disease. The primary signs of prion diseases are cognitive impairment and ataxia. On histologic analysis of tissue, spongiform degeneration of the brain accompanied by activated astrocytes and microglia is observed. Prion diseases are the least frequent of all persistent infections. However, there is a big scientific interest in these diseases aimed to solve many open questions related to these mysterious diseases. Emergence of the variant Creutzfeldt-Jakob disease in 1996 in Europe manifested a new threat - prions may cross a species barrier, humans may get infection from diseased animals. According to some authors, the list of prion diseases may grow to include several neurodegenerative disorders. The present review discusses current scientific concepts and peculiarities of prion diseases.
持续性病毒感染包括潜伏感染、慢性感染和慢感染。慢感染可由以下原因引起：传统病毒（如多瘤病毒JC——进行性多灶性白质脑病（PML）的病原体）；传统病毒的缺陷形式（如缺陷麻疹病毒，可引起亚急性硬化性全脑炎（SSPE））以及非传统感染因子——朊病毒（蛋白质感染颗粒），它是人类和不同动物物种可传播性海绵状脑病的病原体。朊病毒疾病的独特之处在于，相同的病理底物可导致传染性、遗传性和散发性疾病。朊病毒疾病的主要症状是认知障碍和共济失调。在对组织进行组织学分析时，可观察到大脑的海绵状变性，并伴有星形胶质细胞和小胶质细胞的激活。朊病毒疾病是所有持续性感染中最不常见的。然而，科学界对这些疾病有着浓厚的兴趣，旨在解决与这些神秘疾病相关的许多悬而未决的问题。1996年欧洲出现的变异型克雅氏病表明了一种新的威胁——朊病毒可能跨越物种屏障，人类可能从患病动物身上感染。据一些作者称，朊病毒疾病的名单可能会增加，包括几种神经退行性疾病。本综述讨论了朊病毒疾病的当前科学概念和特点。
