Molecular mechanism of persistent infection of SSPE virus

亚急性硬化性泛脑炎(SSPE)是一种由麻疹病毒变种(SSPE病毒)持续感染引起的慢性进行性中枢神经系统疾病。本研究采用RT-PCR和CDNA克隆技术，对一例SSPE患者脑和淋巴结组织中的SSPE病毒结构蛋白基因进行了检测。本病例在脑和淋巴结中均检测到6个主要结构蛋白基因(NP、P、M、F、HA和L)。在脑检查中，对这些基因编码区全长的多个独立克隆进行了测序，发现这些基因与埃德蒙斯顿株麻疹病毒具有相同的多个突变。淋巴结克隆与脑克隆有相同的突变，并有多个额外的突变，表明病毒基因仍处于超突变机制的影响下。这些发现提示，除中枢神经系统外，淋巴结也可能在SSPE的进展中起作用。这些突变中93%是转换(U到C)。这种偏向的超突变被认为是SSPE病毒所特有的。在我们的病例中没有发现易位或染色体异常。CDNA消减方法未在脑和淋巴结中检测到差异表达的独特基因。

Subacute sclerosing panericephalitis (SSPE) is a chronic progressive disease of the central nervous system caused by a persistent infection of a variant of measles virus (SSPE virus). In this study, RT-PCR and CDNA cloning were used to examine the structural protein genes of SSPE virus in the brain and lymph node from a case ofSSPE. Six major structural protein genes (NP, P, M, F, HA and L) were detected in both brain and lymph node in our case. In the examination of the brain, multiple independent clones of the entire length of the coding region of the genes were sequenced.The identical multiple mutations were revealed in the genes in comparison with Edmonston strain of measles virus. The lymph node clones had identical mutations with brain clones and had multiple additional mutations, indicating that the viral genes were still under the influence of the hypermutation mechanism. These findings suggest mat in addition to the central nervous system, the lymph node may also have a role in the progression of SSPE. Ninety-three percent of these mutations was transition (U to C). This biased hypermutation was considered to be specific for SSPE virus.Translocations or chromosomal aberrations were not found in our case. Differentially expressed unique genes were not detected in the brain and lymph node by CDNA subtraction methods.