Took it out of the virus completely, cloned it into a plasmid, that plasmid was expressed in a foreign host, in this case it was expressed in yeast cells.

将基因从病毒中完全提取出来,并克隆制成质粒,该质粒在外来宿主中表达,此例中质粒在酵母细胞中表达

耶鲁公开课 - 生物医学工程探索课程节选

Yeast cells were grown in large numbers with this plasmid inside, they expressed the plasmid and so you made Hepatitis B surface antigen not in people but in cell culture where it was not normally formed.

体内携带这种质粒的酵母细胞大量增殖,它们表达质粒,因此,乙型肝炎表面抗原不是在人体内,而是在细胞培养环境下,以非正常方式形成的

耶鲁公开课 - 生物医学工程探索课程节选