We are using paramyxoviruses as our primary models to answer three questions about virus replication: 1. How is the transcriptional regulation of Sendai virus gene expression mediated by intercistronic or contiguous signals in the viral genome? We are using recombinant DNA technology and rapid nucleic acid sequencing procedures to determine these nucleotide sequences. 2. How are the enzymatic functions required for messenger RNA synthesis apportioned among a small number of gene products in viral nucleocapsids? This question is investigated by affinity labeling and ultraviolet photo-crosslinking techniques. 3. Do post-translational modifications of viral nucleocapsid proteins regulate nucleocapsid functions? We are characterizing the modified proteins chemically, tracing the kinetics of their formation in subcellular compartments, and testing the functional effects of reversing the modifications.