[Roboprog]

Something that is not explicitly stated in the article, other than "virus kills the host cells, anyway", is that the drug works by finding host cells containing viral (specific) RNA, and then killing the host cells (I assume apoptosis means rupturing lysosomes - digestive enzyme packets).

The article mentions the two active "tags" and what they do, but not the context and effect: kill infected cells to stop further infection.

[andar]

The article does state that, "The drug acts like a homing missile that seeks out and kills cells infected by a virus."

[teyc]

Incidentally my sister just got a paper published in the New England Journal with a similar approach (kill switch) for use in gene therapy http://www.nejm.org/doi/full/10.1056/NEJMoa1106152

This could be pretty important work to make gene therapy much safer.

   A single dose of dimerizing drug, given
   to four patients in whom GVHD developed, 
   eliminated more than 90% of the modified
   T cells within 30 minutes after 
   administration and ended the GVHD
   without recurrence.