The major goal is the identification of cis-acting regulatory elements in the RNA genome of murine leukemia viruses (MuLV) involved in viral RNA splicing control and in transport of unspliced MuLV RNA from the nucleus to the cytoplasm. By comparison of such elements from different MuLVs in the host lab, correlations between features of RNA metabolism and pathogenesis will be analyzed. These studies may provide new insight into the function of RNA regulatory elements in avian retroviruses that were identified in my laboratory.