(S (S (BASENP (JJ Resistant) (NNS strains)) (VP (VBP have) (VP (VBN shown) (NP (BASENP (DT no) (NN evidence)) (PP (IN of) (S (VP (VP (VBG causing) (BASENP (ADJP (RBR more) (JJ severe)) (NN disease))) (CC or) (VP (VBG being) (ADJP (ADVP (RBR more) (RB easily)) (ADJP transmissible)))))))))) (PERIOD .))