[Search for host specificity systems in Shigella using DD-series phages].

A total of 712 Shigella strains were studied with the use of dysentery diagnostic phages DD II, DD VI and DD VII in order to reveal the systems of host DNA specificity. The study comprised 4 tests: mass screening by the intensity of phagolytic reaction of phages in various strains; and the determination of the parameters of adsorption. As a result, an effective modification and restriction systems were revealed in Sh. sonnei 311 with the use of phage DD II. Bacteriophage DD VII was effectively restricted in E. coli CK, BB and BB/T4. Cross titration showed that the modification and restriction systems of E. coli BB and BB/T4 differed from the specificity system of E. coli CK. Phage DD VI had an exceptionally broad spectrum of activity and was not sensitive to any known restriction system.