(S (S (BASENP (PRP It)) (VP (VP (VP (VBZ is) (RB not)) (VBN known)) (SBAR (SBAR (WHADJP (WRB how) (JJ dangerous)) (S (BASENP (DT the) (JJ new) (NN virus)) (VP (VBZ is)))) (CC and) (SBAR (IN whether) (S (BASENP (PRP it)) (VP (VBZ is) (ADJP (ADJP (JJR stronger) (CC or) (JJR deadlier)) (PP (IN than) (BASENP (DT the) (JJ current) (NN H5N1) (NN virus)))))))))) (PERIOD .))