Bendis I, Shapiro L
J Virol. 1970 Dec;6(6):847-54. doi: 10.1128/JVI.6.6.847-854.1970.
The ribonucleic acid (RNA) bacteriophage phiCb5, which specifically infects only one form of the dimorphic stalked bacterium Caulobacter crescentus, has been obtained in high yield. Since the phage is extremely salt-sensitive, a purification procedure was devised which avoided contact with solutions of high ionic strength. Phage phiCb5 was studied with respect to the physical and chemical properties of both the phage and its RNA. In an electron microscope, the phage particles appear as small polyhedra, 23 nm in diameter. The phage is similar to the Escherichia coli RNA phages in that it (i) sediments at an S(20, w) of 70.6S, (ii) is composed of a single molecule of single-stranded RNA and a protein coat, (iii) contains two structural proteins, and (iv) apparently contains the genetic capacity to code for a coat protein subunit, a maturation-like protein, and an RNA polymerase. Phage phiCb5 differs from the E. coli RNA phages in (i) host specificity, (ii) salt sensitivity, and (iii) the presence of histidine, but not methionine, in the coat protein.
核糖核酸（RNA）噬菌体phiCb5已大量获得，它仅特异性感染双态柄细菌新月柄杆菌的一种形态。由于该噬菌体对盐极为敏感，因此设计了一种纯化程序，避免与高离子强度的溶液接触。对噬菌体phiCb5及其RNA的物理和化学性质进行了研究。在电子显微镜下，噬菌体颗粒呈小多面体，直径为23纳米。该噬菌体与大肠杆菌RNA噬菌体相似之处在于：（i）在S（20，w）为70.6S的条件下沉降；（ii）由单链RNA分子和蛋白质外壳组成；（iii）含有两种结构蛋白；（iv）显然具有编码外壳蛋白亚基、成熟样蛋白和RNA聚合酶的遗传能力。噬菌体phiCb5与大肠杆菌RNA噬菌体的不同之处在于：（i）宿主特异性；（ii）盐敏感性；（iii）外壳蛋白中存在组氨酸而非甲硫氨酸。
