Antigenic similarity of morphologic type CIII1 bacteriophages.

The aim of the study was to demonstrate antigenic differentiation among bacteriophages belonging to the same morphologic type--CIII1 according to Krzywy and Slopek or A2 according to Ackermann. Twenty-six bacteriophages which multiplied on various strains of bacteria of the genera Escherichia, Shigella and Klebsiella, were studied. Serologic tests were done by the quantitative complement fixation test. Immune sera against 5 phi E. coli. D8 Sh. flexneri, G35 Sh. sonnei and Kl7 Klebsiella bacteriophages were obtained from rabbits. It was shown that bacteriophages of CIII1 morphologic type, with morphologically identical virion had different antigenic specificity. On the basis of results obtained the phages could be divided into eight serologic groups. The bacteriophages for which antisera were obtained belonged to four different serologic groups. All bacteriophages had some common antigens with 5 phi E. coli phage. The similarity points to a phylogenetic relationship among phages of CIII1 morphologic type.