<prompt> The only oncogenic virus whose pathogenicity has been proved without doubt is -HTLV - IHTLV - IIHTLV - IIIHTLV - IV  <response>: HTLV1 present world wide.it causes adult T cell leukemia,tropical dpadtic paraparesid.it mainly infect CD4 cells .infected cell express more inter leukin2 REF:pMICROBIOLOGY ANANTHA NARAYANAN NINTH EDITION PAGE.567 