LOCALIZATION AND SEQUENCE-ANALYSIS OF MORPHOLOGICAL TRANSFORMING REGION-III WITHIN HUMAN CYTOMEGALOVIRUS STRAIN TOWNE

A 7.6-kbp BamHI/XbaI EJ subfragment of the Towne XbaI-E fragment of hu man cytomegalovirus (HCMV) strain Towne has been previously designated as morphological transforming region III (mtrIII) because it induced focal and tumorigenic transformation of rodent fibroblasts. However, i n two separate cell systems, mtrIII sequences were not retained becaus e they were not detected in either the focal, tumor or tumor-derived c ell lines. In this report, mtrIII was localized to a 2.1-kbp SalI/XbaI DNA fragment. The sequence of the 2,085-bp region was determined and compared to the colinear DNA from HCMV strain AD169. DNA sequence anal ysis revealed the presence of five open reading frames in Towne mtrIII , two of which are conserved in strain AD169. The localization and seq uence analysis of mtrIII will allow further investigation as to the me chanism(s) by which HCMV may play a role in human cancer.