Characterization of φ12, a Bacteriophage Related to φ6: Nucleotide Sequence of the Small and Middle Double-Stranded RNA

Abstract

The isolation of additional bacteriophages containing segmented double-stranded RNA genomes has expanded the Cystoviridae family to nine members. Comparing the genomic sequences of these viruses has allowed evaluation of important genetic as well as structural motifs. These comparative studies are resulting in greater understanding of viral evolution and the role played by genetic and structural variation in the assembly mechanisms of the cystoviruses. In this regard, the small and middle double-stranded RNA genomic segments of bacteriophage φ12 were copied as cDNA and their nucleotide sequences determined. This genome's organization is similar to that of the small and middle segments of bacteriophages φ6, φ8, and φ13. Although there is little similarity in the nucleotide sequences, similarity exists in the amino acid sequence of the lysis cassette proteins to those of φ6. The host cell attachment proteins are found to have marked similarity to the φ13 attachment proteins.