{HEAD ~ A defined regimen} of media changes are used to establish {TAIL ~ a quiescent and nonproductive state} following the withdrawal of the antiviral treatment 
are used to establish
{ HEAD ~ A defined regimen } of media changes are used to establish { TAIL ~ a quiescent and nonproductive state } following the withdrawal of the antiviral treatment
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH