Bacteriophage φCb5 is a bacteriophage that infects Caulobacter bacteria and other caulobacteria. The bacteriophage was discovered in 1970, it belongs to the genus Cebevirus of the Steitzviridae family and is the namesake of the genus. The bacteriophage is widely distributed in the soil, freshwater lakes, streams and seawater, places where caulobacteria inhabit and can be sensitive to salinity.