Silverstein P S, Bird R C, van Santen V L, Nusbaum K E
Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama 36849-5519, USA.
J Virol. 1995 May;69(5):3161-6. doi: 10.1128/JVI.69.5.3161-3166.1995.
With cDNA probes and by Northern (RNA) blot analysis, a region containing immediate-early (IE) genes in the channel catfish virus (CCV) genome was identified. IE transcription in CCV-infected cells appears to be restricted to the terminal repeat region, suggesting that CCV is most closely related to the alpha subfamily of herpesviruses. CCV DNA fragments from this region encoding IE transcripts were cloned. Northern analysis with one of these cloned fragments, a 3,927-bp EcoRI-XbaI fragment, indicates that it encodes two IE transcripts. Both transcripts (ie1 and ie2) were characterized by S1 nuclease analysis, primer extension analysis, and analysis of cDNAs. The ie2 transcript is a 1.3-kb bicistronic mRNA containing open reading frame (ORF) 8a and ORF 9. ORF 8a is a 5'-truncated version of ORF 8 which, along with ORF 9, was previously identified (A. J. Davison, Virology 186:9-14, 1992). The ie1 transcript is 0.6 kb in size, contains only ORF 9, and is expressed at a level approximately six times that of ie2 in cycloheximide-treated cells. The putative product of ORF 9 is predicted to have a basic pI and contains a potential zinc-binding domain, making it a probable transcription factor. ORF 8a encodes a putative product which is very hydrophobic, an unusual characteristic for an IE protein.
利用cDNA探针并通过Northern（RNA）印迹分析，在斑点叉尾鮰病毒（CCV）基因组中鉴定出一个包含立即早期（IE）基因的区域。CCV感染细胞中的IE转录似乎局限于末端重复区域，这表明CCV与疱疹病毒的α亚科关系最为密切。克隆了该区域编码IE转录本的CCV DNA片段。用其中一个克隆片段，即一个3927 bp的EcoRI - XbaI片段进行Northern分析，表明它编码两种IE转录本。通过S1核酸酶分析、引物延伸分析和cDNA分析对这两种转录本（ie1和ie2）进行了表征。ie2转录本是一个1.3 kb的双顺反子mRNA，包含开放阅读框（ORF）8a和ORF 9。ORF 8a是ORF 8的5'截短版本，ORF 8与ORF 9先前已被鉴定（A. J. Davison，Virology 186:9-14，1992）。ie1转录本大小为0.6 kb，仅包含ORF 9，在环己酰亚胺处理的细胞中其表达水平约为ie2的六倍。ORF 9的推定产物预计具有碱性pI，并包含一个潜在的锌结合结构域，使其可能是一种转录因子。ORF 8a编码一种推定产物，该产物非常疏水，这是IE蛋白不寻常的特征。
