Detailed Instructions: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
Problem:The flu virus has receptors, which are like viral Velcro, on the surface of the virus particle. The receptors will lock onto a target cell using these chemical receptors on the surface, which docks onto the cell surface. The receptors  then go into the cell. The receptors use it like a factory. The receptors take it over and make it produce thousands or in some cases millions of copies of new viruses. The copies come streaming out of the cell. The copies infect other cells to make more viruses, or they escape from the body and infect a new victim. 
Solution:
receptors ,copies 