Emergent virus
Other examples include the human immunodeficiency virus which causes HIV/AIDS; the viruses responsible for Ebola; the H5N1 influenza virus responsible for avian flu; and H1N1/09 , which caused the 2009 swine flu pandemic ( an earlier emergent strain of H1N1 caused the 1918 Spanish flu pandemic ) . 
<triplet> human immunodeficiency virus <subj> HIV/AIDS <obj> has effect <triplet> HIV/AIDS <subj> human immunodeficiency virus <obj> has cause <triplet> H1N1/09 <subj> 2009 swine flu <obj> has effect <subj> H1N1 <obj> instance of <triplet> 2009 swine flu <subj> H1N1/09 <obj> has cause