The objective of this project is clarification of the nature of bacteriophages and of mechanisms of genetic transfer (lysogenic conversion, transduction, transformation) among streptococci, and determination of their effects on pathogenicity and immunogenicity. In current efforts to transduce type-specific M-proteins, we are evaluating the efficiency of protein A-coated plates to bind cells exposed to specific antibody, for subsequent incubation and scoring of transductant colonies. Continuing studies of erythrogenic toxin failed to incriminate lysogeny in production of ET-B, in contrast to ET-A and ET-C. Other studies showed that extracellular factor of Pseudomonas fluorescens lyses Trypanosoma cruzi in vivo as well as in vitro, causing a drop in parasitemia and decreased tissue damage. All above areas of investigation are continuing.