( ( ( ( ( ( ( The ( exact causes ) ) ( of ( ( BSE or ) nvCJD ) ) ) ( ( may not ) ( be known ) ) ) , ) but ) ( ( scientific evidence ) ( indicates ( ( the ( prion theory ) ) ( ( is widely ) ( ( proven and ) accepted ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (JJ exact) (NNS causes)) (PP (IN of) (NP (NN BSE) (CC or) (NN nvCJD)))) (VP (MD may) (RB not) (VP (VB be) (VP (VBN known))))) (, ,) (CC but) (S (NP (JJ scientific) (NN evidence)) (VP (VBZ indicates) (SBAR (S (NP (DT the) (NN prion) (NN theory)) (VP (VBZ is) (ADVP (RB widely)) (VP (VBN proven) (CC and) (VBN accepted))))))) (. .)))
The exact causes of BSE or nvCJD may not be known, but scientific evidence indicates the prion theory is widely proven and accepted.
(ROOT (S (NP (NN Evidence)) (VP (VBZ allows) (S (NP (NNS theories)) (VP (TO to) (VP (VB be) (VP (ADVP (RB widely)) (VBN accepted)))))) (. .)))