(S (S (BASENP (PRP It)) (VP (VBZ is) (VP (ADVP (RB not) (RB yet)) (VP (VBN known) (SBAR (IN whether) (S (BASENP (DT the) (NN virus)) (VP (VBD escaped) (PP (IN from) (NP (BASENP (DT the) (NNP Merial)) (CC or) (BASENP (DT the) (NNP IAH) (NN lab))))))))))) (PERIOD .))