( ( ( Persistent Infections ) ( by ( ( Organ System ) ( Some viruses ) ) ) ) ( ( can ( ( establish ( persistent infection ) ) ( at ( ( the ( same time ) ) ( in ( ( different ( cell types ) ) ( of ( ( one or ) ( more ( ( tissues or ) organs ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Persistent) (NNP Infections)) (PP (IN by) (NP (NP (NNP Organ) (NNP System)) (NP (DT Some) (NNS viruses))))) (VP (MD can) (VP (VB establish) (NP (JJ persistent) (NN infection)) (PP (IN at) (NP (NP (DT the) (JJ same) (NN time)) (PP (IN in) (NP (NP (JJ different) (NN cell) (NNS types)) (PP (IN of) (NP (NP (CD one)) (CC or) (NP (JJR more) (NNS tissues) (CC or) (NNS organs)))))))))) (. .)))
Persistent Infections by Organ System Some viruses can establish persistent infection at the same time in different cell types of one or more tissues or organs.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN organ)) (VP (VBZ is) (NP (NP (DT a) (NN structure)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBN composed) (PP (IN of) (NP (NP (QP (CD one) (CC or) (JJR more)) (NNS types)) (PP (IN of) (NP (NNS tissues))))))))))) (. .)))
A(n) organ is a structure that is composed of one or more types of tissues.