Serological relatedness of the ribonucleic acid-containing coliphages.

The serological relationship of the ribonucleic acid (RNA)-containing coliphages MS-2, M-12, R-17, f(2), beta, fr, f(4), and Qbeta was determined. Antisera against MS-2, R-17, f(2), fr, and Qbeta neutralized the infectivity of all of these RNA phages to varying degrees. Although each phage was serologically distinct, the antisera cross-reacted with certain phages to approximately the same degree, indicating the antigenic relationship of the coat proteins of these phages. Adsorption of anti-MS-2 sera with varying concentrations of all of the phages demonstrated that these viruses contain similar yet unique antigenic determinants. It is suggested that these RNA phages are mutants of two related phages rather than of the same phage.