Corticovirus

The virus family Corticoviridae (Latin cortex: bark, crust ) comprises only a monotypic genus Corticovirus of bacteriophages. The only species Pseudoalteromonas PM2 phage (also PM2 phage Alteromonas PM2 phage called ) has a circular, double-stranded DNA genome, and approximately 56 nm in diameter, large, non-enveloped icosahedral capsid.

The capsomeres are composed of trimers of the capsid protein P2; at the corners of the icosahedral structure are projections ( spikes ) that are formed by the viral protein P1. Within (!) Of the capsid is a lipid membrane vesicle which consists of viral proteins and the lipid membrane of the host bacterium. This inner membrane vesicles, the PM2 phage in common with the Tectiviridae, but it serves the PM2 phage not to inject the DNA into the host bacterium.

The annular genome is packaged in a highly twisted form ( supercoiled ) within the membrane vesicle. The double stranded DNA is 10,079 bp and encodes nine structural proteins (P1 -9) five non-structural proteins (P12 -16) and seven gene products of unknown function.

So far, two marine bacterial species, Pseudoalteromonas BAL -31 and ER72M2 identified as host for the PM2 phage.