( ( This disease ) ( ( ( is not ) ( caused ( ( ( by ( the virus ) ) but ) ( by ( ( the ( immune response ) ) ( against ( the virus ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This) (NN disease)) (VP (VBZ is) (RB not) (VP (VBN caused) (PP (PP (IN by) (NP (DT the) (NN virus))) (CC but) (PP (IN by) (NP (NP (DT the) (JJ immune) (NN response)) (PP (IN against) (NP (DT the) (NN virus)))))))) (. .)))
This disease is not caused by the virus but by the immune response against the virus.
(ROOT (S (NP (NP (NNS Symptoms)) (PP (IN of) (NP (JJ viral) (NNS diseases)))) (VP (VBP result) (PP (IN from) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (JJ immune) (NN response))) (PP (TO to) (NP (DT a) (NN virus)))) (. .)))