The infective test with the pathogenic virus of hemorrhage proved that the cell strain AHZC 88 was not infected with the hemorrhage virus.

经病原病毒的人工侵染等试验表明，AHZC 88细胞不受草鱼出血病病毒感染。

youdao

So maybe you could figure out how to use what we know about molecular biology, to engineer a new virus that's still immunogenic, but not pathogenic any longer.

也许你能指出如何使用,分子生物学的有关知识,来设计一个既能产生免疫性,但又不再有致病性的新病毒

耶鲁公开课 - 生物医学工程探索课程节选

It is circulating in poultry stocks, but is considered a "low pathogenic" virus that is not sickening birds.

NPR: Bird Flu 101: How Bad Is The New H7N9 Strain?

In this research the scientists created a synthetic viral shell, but lacking its pathogenic RNA interior - the genetic material the virus uses to replicate itself.

BBC: Synchrotron yields 'safer' vaccine