Chang Kyung-Soo, Ohashi Kazuhiko, Onuma Misao
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
J Vet Med Sci. 2002 Dec;64(12):1097-101. doi: 10.1292/jvms.64.1097.
The meq gene encoding a 339-amino-acid bZIP transactivator protein has been identified as a candidate oncogene of Marek's disease virus serotype 1 (MDV1), which induces malignant lymphomas in chickens. We have previously reported that, in addition to meq, L-meq, in which a 180-bp sequence is inserted into the region encoding the transactivation domain of meq, is also detected in chickens experimentally infected with MDV. To further analyze the diversity in meq, PCR was performed using a primer set which specifically amplify the proline-rich repeat (PRR) region in the transactivation domain of meq. In CVI988/R6, a vaccine strain of MDV1, and JM, an MDV1 strain attenuated by prolonged passage in vitro, a major band of a 0.8 kb corresponding to L-meq as well as a minor band of 0.6 kb corresponding to meq was detected by PCR. Furthermore, extra 0.5- and 0.3-kb bands, corresponding to genes termed as short meq (S-meq), and very short meq (VS-meq), respectively, were also detected. These genes were also detected in MDV-transformed cell lines, MSB1 and MTB1. In Md5, an oncogenic MDV1, attenuated by prolonged passage in vitro, the 0.6-kb meq was consistently detected, and 0.5-kb S-meq was occasionally detected. This diversity in meq was due to the difference in the copy number of the PRR region: L-meq and meq contained 9 and 6 copies of PRR while 4 and 2 copies of PRR were present in S-meq and VS-meq, respectively. Thus, the meq gene is polymorphic in the attenuated MDV1 and the MDV-transformed cell lines, and gene products from different meq genes may have different functions from each other.
编码339个氨基酸的bZIP反式激活蛋白的meq基因已被鉴定为1型马立克氏病病毒（MDV1）的候选癌基因，该病毒可在鸡体内诱发恶性淋巴瘤。我们之前报道过，除了meq之外，在实验感染MDV的鸡中还检测到了L-meq，即在编码meq反式激活结构域的区域插入了一个180 bp序列的meq。为了进一步分析meq的多样性，使用一组引物进行PCR，该引物组可特异性扩增meq反式激活结构域中富含脯氨酸的重复（PRR）区域。在MDV1疫苗株CVI988/R6和通过体外长时间传代减毒的MDV1株JM中，PCR检测到对应L-meq的0.8 kb主带以及对应meq的0.6 kb次带。此外，还检测到分别对应称为短meq（S-meq）和极短meq（VS-meq）基因的额外0.5 kb和0.3 kb条带。在MDV转化的细胞系MSB1和MTB1中也检测到了这些基因。在通过体外长时间传代减毒的致癌MDV1 Md5中，始终检测到0.6 kb的meq，偶尔检测到0.5 kb的S-meq。meq的这种多样性是由于PRR区域拷贝数的差异：L-meq和meq分别含有9个和6个PRR拷贝，而S-meq和VS-meq中分别存在4个和2个PRR拷贝。因此，meq基因在减毒的MDV1和MDV转化的细胞系中具有多态性，不同meq基因的基因产物可能具有不同的功能。
