We propose to isolate and characterize each subunit and structure in the morphogenetic pathway of Bacillus subtilis bacteriophage phi 29, and we will seek to identify the functional role of each nonstructural protein in the morphopoietic process. The known viral-induced proteins account for more than 90 percent of the coding capacity of the phi 29 genome. Transcription of the phi 29 DNA is asymmetric, and both "early" and "late" classes of mRNA have been detected. We have obtained mutation in 23 cistrons and have used three-factor crosses to obtain a genetic map of 18 cistrons. The outline of functional gene clustering is clear. We shall analyze the results of infection of nonpermissive cells by suppressor-sensitive mutants of each cistron by both in situ lysis and thin section techniques of electron microscopy. Particles are fractionated on sucrose gradients, and examined by electron microscopy and SDS polyacrylamide gel electrophoresis. To evaluate the proposed pathway we shall use the following techniques: double mutants to determine precursor structures; rescue of structures in vitro; and temperature-shift, gene dosage, pulse-chase, and serological experiments. We shall also study in vivo and in vitro proteolytic processing of the virion neck appendage precursor protein, and attempt to isolate host defective mutants blocked in morphogenesis.