( ( ( A ( new class ) ) ( of drugs ) ) ( ( helps ( ( ( ( blunt or ) prevent ) ( flu symptoms ) ) ( by ( ( inhibiting ( ( the spread ) ( of ( influenza virus ) ) ) ) ( within ( cells ( of ( the ( respiratory tract ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (JJ new) (NN class)) (PP (IN of) (NP (NNS drugs)))) (VP (VBZ helps) (VP (VB blunt) (CC or) (VB prevent) (NP (NN flu) (NNS symptoms)) (PP (IN by) (S (VP (VBG inhibiting) (NP (NP (DT the) (NN spread)) (PP (IN of) (NP (NN influenza) (NN virus)))) (PP (IN within) (NP (NP (NNS cells)) (PP (IN of) (NP (DT the) (JJ respiratory) (NN tract)))))))))) (. .)))
A new class of drugs helps blunt or prevent flu  symptoms by inhibiting the spread of influenza virus within cells of the respiratory tract.
(ROOT (S (NP (NNP Tamiflu)) (VP (VBZ inhibits) (NP (NP (NN spread)) (PP (IN of) (NP (NN virus))))) (. .)))