Parker M D, Cox G J, Deregt D, Fitzpatrick D R, Babiuk L A
Veterinary Infectious Disease Organization, University of Saskatchewan, Saskatoon, Canada.
J Gen Virol. 1989 Jan;70 ( Pt 1):155-64. doi: 10.1099/0022-1317-70-1-155.
A cDNA clone representing the gene for the E3 glycoprotein, the haemagglutinin, of bovine coronavirus was isolated from a plasmid cDNA library of the viral genome and sequenced. The gene is located immediately 5' of the E2 glycoprotein gene on the viral genome. Nucleotide sequencing of the E3 gene predicts a polypeptide of 424 amino acids with an Mr of 47K. In vitro translation of mRNA transcribed from the cloned E3 gene yielded a polypeptide of Mr 45K, similar to that predicted from the nucleotide sequence. In the presence of microsomal membranes, the in vitro product was cotranslationally processed to a 62K polypeptide which comigrated on SDS-polyacrylamide gels with the E3 monomer (gp62) obtained from virus-infected cells. Both the 45K and 62K polypeptides were immunoprecipitated with E3-specific monoclonal antibodies, confirming the identity of the gene as that encoding the E3 glycoprotein. Finally, only monoclonal antibodies to the E3 protein inhibited haemagglutination by the virus thus confirming its identity as the haemagglutinin of bovine coronavirus.
从牛冠状病毒病毒基因组的质粒cDNA文库中分离出一个代表E3糖蛋白（血凝素）基因的cDNA克隆并进行测序。该基因位于病毒基因组上E2糖蛋白基因紧邻的5'端。E3基因的核苷酸序列预测出一个由424个氨基酸组成、Mr为47K的多肽。从克隆的E3基因转录的mRNA的体外翻译产生了一个Mr为45K的多肽，与从核苷酸序列预测的多肽相似。在微粒体膜存在的情况下，体外产物共翻译加工成一个62K的多肽，该多肽在SDS-聚丙烯酰胺凝胶上与从病毒感染细胞获得的E3单体（gp62）迁移率相同。45K和62K的多肽都用E3特异性单克隆抗体进行免疫沉淀，证实该基因是编码E3糖蛋白的基因。最后，只有针对E3蛋白的单克隆抗体抑制病毒的血凝作用，从而证实其为牛冠状病毒的血凝素。
