Zhang X M, Kousoulas K G, Storz J
Department of Veterinary Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803.
Virology. 1991 Dec;185(2):847-52. doi: 10.1016/0042-6822(91)90557-r.
The entire nucleotide sequences of the hemagglutinin/esterase (HE) genes specified by the highly virulent strain LY138 and the avirulent strain L9 of bovine coronavirus (BCV) were determined. These sequences were compared with recently published sequences of the HE genes of the Quebec and Mebus strains. A large open reading frame of 1272 nt encoding a protein of 424 amino acid residues was predicted. The putative esterase active site was conserved in the virulent and avirulent BCV strains, indicating that this domain is probably not a determinant for BCV virulence. Four amino acid substitutions occurred between the HE proteins of BCV-L9 and BCV-LY138 (leu to Pro at 5, Leu to Val at 103, Ser to Pro at 367, and Thr to Asn at 379). Monoclonal antibodies specific for the HE glycoprotein inhibited the hemagglutination and acetylesterase activities of BCV-L9, but showed no inhibitory effect on the acetylesterase activity of BCV-LY138. These results suggest that at least one epitope is located proximal to one of the three strain-specific amino acids. Four S-specific monoclonal antibodies inhibited hemagglutination but not acetylesterase activity of BCV-L9, implying that the S glycoprotein can promote hemagglutination of chicken erythrocytes in addition to the HE glycoprotein.
测定了高毒力牛冠状病毒（BCV）毒株LY138和无毒力毒株L9所编码的血凝素/酯酶（HE）基因的完整核苷酸序列。将这些序列与最近发表的魁北克毒株和梅布斯毒株的HE基因序列进行了比较。预测有一个1272个核苷酸的大开放阅读框，编码一个由424个氨基酸残基组成的蛋白质。推定的酯酶活性位点在有毒力和无毒力的BCV毒株中是保守的，这表明该结构域可能不是BCV毒力的决定因素。BCV-L9和BCV-LY138的HE蛋白之间发生了四个氨基酸替换（第5位的亮氨酸替换为脯氨酸、第103位的亮氨酸替换为缬氨酸、第367位的丝氨酸替换为脯氨酸、第379位的苏氨酸替换为天冬酰胺）。针对HE糖蛋白的单克隆抗体抑制了BCV-L9的血凝和乙酰酯酶活性，但对BCV-LY138的乙酰酯酶活性没有抑制作用。这些结果表明，至少有一个表位位于三个毒株特异性氨基酸之一的附近。四种S特异性单克隆抗体抑制了BCV-L9的血凝，但不抑制其乙酰酯酶活性，这意味着除了HE糖蛋白外，S糖蛋白也能促进鸡红细胞的血凝。
