It's foreign, it's not part of the host or not a normal part of the host.

所以它成了外源物,外源物不是宿主的一部分,至少不是正常的一部分

耶鲁公开课 - 生物医学工程探索课程节选

This dual life-cycle means that, besides disrupting normal cellular activities in the ways that other viruses do, a retrovirus may also disrupt the normal function of its host's chromosomes.

ECONOMIST: Foulpox

Under normal conditions, this requires the user's computer to send a request to the host computer, which then sends a response back to the user.

ECONOMIST: The faster the internet becomes, the slower it loads pages