Black B L, Lyles D S
Department of Microbiology and Immunology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157.
J Virol. 1992 Jul;66(7):4058-64. doi: 10.1128/JVI.66.7.4058-4064.1992.
Infection by vesicular stomatitis virus (VSV) results in a rapid inhibition of host cell transcription and translation. To determine whether the viral matrix (M) protein was involved in this inhibition of host cell gene expression, an M protein expression vector was cotransfected with a target gene vector, encoding the target gene, encoding chloramphenicol acetyltransferase (CAT). Expression of M protein caused a decrease in CAT activity in a gene dosage-dependent manner, and inhibition was apparent by 12 h posttransfection. The inhibitory effect of M protein was quite potent. The level of M protein required for a 10-fold inhibition of CAT activity was less than 1% of the level of M protein produced during the sixth hour of VSV infection. Northern (RNA) analysis of cotransfected cells showed that expression of M protein caused a reduction in the steady-state level of the vector-encoded mRNAs. Expression of both CAT and M mRNAs was reduced in cells cotransfected with a plasmid encoding M protein, indicating that expression of small amounts of M protein from plasmid DNA inhibits further expression of both M and CAT mRNAs. Nuclear runoff transcription analysis demonstrated that expression of M protein inhibited transcription of the target genes. This is the first report of a viral gene product which is capable of inhibiting transcription in vivo in the absence of any other viral component.
水泡性口炎病毒（VSV）感染会导致宿主细胞转录和翻译迅速受到抑制。为了确定病毒基质（M）蛋白是否参与了对宿主细胞基因表达的这种抑制作用，将一个M蛋白表达载体与一个编码氯霉素乙酰转移酶（CAT）的靶基因载体共转染。M蛋白的表达导致CAT活性呈基因剂量依赖性降低，且在转染后12小时抑制作用明显。M蛋白的抑制作用相当有效。使CAT活性降低10倍所需的M蛋白水平不到VSV感染后第6小时产生的M蛋白水平的1%。对共转染细胞的Northern（RNA）分析表明，M蛋白的表达导致载体编码的mRNA稳态水平降低。在与编码M蛋白的质粒共转染的细胞中，CAT和M mRNA的表达均降低，这表明从质粒DNA表达少量M蛋白会抑制M和CAT mRNA的进一步表达。核转录分析表明，M蛋白的表达抑制了靶基因的转录。这是关于一种病毒基因产物能够在没有任何其他病毒成分的情况下在体内抑制转录的首次报道。
