Abstract
Serological and chemical properties of the two RNA phages, designated Y and Z, were investigated. Phage Y was serologically distinct from both phage β closely related to MS2 and phage I distinct from β. From this observation, the presence of at least three types of RNA phages was suggested. Phage Z was inactivated by antisera of I, Y, and β, and vice versa. s20, w values of Y and Z were estimated to be 82S and 77S, respectively. The species specificities of these phages were discussed from the aspects of chemical composition of the RNA and the serological relationship.
