( ( These ( ( newly formed ) viruses ) ) ( ( spread ( by ( infecting ( new cells ) ) ) ) . ) )
(ROOT (S (NP (DT These) (ADJP (RB newly) (VBN formed)) (NNS viruses)) (VP (VBN spread) (PP (IN by) (S (VP (VBG infecting) (NP (JJ new) (NNS cells)))))) (. .)))
These newly formed viruses spread by infecting new cells.
(ROOT (S (NP (NNP Tamiflu)) (VP (VBZ inhibits) (NP (NP (NN spread)) (PP (IN of) (NP (NN virus))))) (. .)))