Heterologous recombination in the segmented dsRNA genome of bacteriophage Φ6

The genome of bacteriophage Φ6 is composed of three segments of dsRNA. It is the only bacteriophage with a dsRNA genome. Plus strand copies of the genomic segments are packaged in a preformed procapsid, where they then serve as templates for minus strand synthesis. The procapsids, composed of four different proteins, contain all the necessary activities to package and replicate the genome. Under conditions where the minus strand synthesis of one of the segments is inhibited, heterologous recombination is facilitated, leading to the formation of chimeric segments. Although the recombination is heterologous, there is generally a sequence identity of about three nucleotides, but ranging from zero to 12 nucleotides, at the cross over sites. Packaging, replication and recombination of the genome can be studied in vitro using purified procapsids and specifically engineered RNA molecules.