( ( These proteins ) ( ( are ( isolated ( to ( ( ( ( inhibit ( the virus ) ) ( from ( replicating ( in ( ( a ( host 's ) ) cells ) ) ) ) ) and ) ( ( stop it ) ( from ( spreading ( to ( other cells ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT These) (NNS proteins)) (VP (VBP are) (ADJP (JJ isolated) (S (VP (TO to) (VP (VP (VB inhibit) (NP (DT the) (NN virus)) (PP (IN from) (S (VP (VBG replicating) (PP (IN in) (NP (NP (DT a) (NN host) (POS 's)) (NNS cells))))))) (CC and) (VP (VB stop) (NP (PRP it)) (PP (IN from) (S (VP (VBG spreading) (PP (TO to) (NP (JJ other) (NNS cells)))))))))))) (. .)))
These proteins are isolated to inhibit the virus from replicating in a host's cells and stop it from spreading to other cells.
(ROOT (S (NP (NNP Tamiflu)) (VP (VBZ inhibits) (NP (NP (NN spread)) (PP (IN of) (NP (NN virus))))) (. .)))