The long-range goal of this project is to study bacteriophages and genetic exchange (mainly lysogenic conversion, transduction and transformation) in streptococci, and to investigate how such mechanisms may affect the pathogencity and immunology of these organisms. Currently we are searching for the nature and site of the genetic coding for a rare, Group A, non-lysogenic, erythrogenic toxin (ET) producing strain. We have attempted: 1) to isolate a defective prophage by phage-genetic recombination, 2) to induce ETB production in ETB strains by lysogenization with phages from ETB ion strains, and 3) to find toxin production in a selected number of Group C and G streptococci. Other studies concern extracellular product of Pseudomonas fluorescens which causes morphological changes and lysis in strains of Trypansoma cruzi. We are trying to identify the factor and assess its significance.