Eun H M, Bae Y S, Yoon J W
Department of Microbiology and Infectious Diseases, Julia McFarlane Diabetes Research Centre, University of Calgary, Alberta, Canada.
Virology. 1988 Apr;163(2):369-73. doi: 10.1016/0042-6822(88)90277-2.
The genes for the major capsid protein, VP1(1D), of both diabetogenic D variant (EMC-D) and nondiabetogenic B variant (EMC-B) of encephalomyocarditis virus were cloned by using two synthetic primers which are common to both EMC-D and EMC-B. The cloned genes were mapped for major restriction enzyme sites including AccI, BamHI, EcoRI, HincII, KpnI, PvuII, SstI, TaqI, and XbaI. Among those nine restriction enzyme sites, only the TaqI site distinguished EMC-D genome from the counterpart of EMC-B genome. The complete nucleotide sequences (831 bases) of the VP1 genes revealed five amino acid differences between the two variants. Three of the changes, at positions 41, 58, and 152, were Thr (EMC-B) to Ala (EMC-D). The additional two changes occurred at positions 63 [Gln (EMC-B) to Glu (EMC-D)] and 181 [Thr (EMC-B) to Ser (EMC-D)]. All of these amino acid changes were due to point mutations at the first base of each codon.
利用脑心肌炎病毒致糖尿病性D变异株（EMC-D）和非致糖尿病性B变异株（EMC-B）共有的两条合成引物，克隆了这两种变异株主要衣壳蛋白VP1（1D）的基因。对克隆的基因进行了主要限制酶位点的定位，包括AccI、BamHI、EcoRI、HincII、KpnI、PvuII、SstI、TaqI和XbaI。在这9个限制酶位点中，只有TaqI位点能区分EMC-D基因组和EMC-B基因组的对应部分。VP1基因的完整核苷酸序列（831个碱基）显示，这两种变异株之间有5个氨基酸差异。其中3个变化发生在第41、58和152位，是苏氨酸（EMC-B）变为丙氨酸（EMC-D）。另外两个变化发生在第63位[谷氨酰胺（EMC-B）变为谷氨酸（EMC-D）]和第181位[苏氨酸（EMC-B）变为丝氨酸（EMC-D）]。所有这些氨基酸变化都是由于每个密码子第一个碱基的点突变引起的。
