The family Cystoviridae includes enveloped viruses with a tri-segmented dsRNA genome and a double-layered protein capsid. The innermost protein shell is a polymerase complex responsible for genome packaging, replication and transcription. Cystoviruses infect Gram-negative bacteria, primarily plant-pathogenic Pseudomonas syringae strains. This is a summary of the International Committee on Taxon...

The genetic structure of natural bacteriophage populations is poorly understood. Recent metagenomic studies suggest that phage biogeography is characterized by frequent migration. Using virus samples mostly isolated in Southern California, we recently showed that very little population structure exists in segmented RNA phage of the Cystoviridae family due to frequent segment reassortment (sexua...

The family Cystoviridae comprises several bacteriophages with double-stranded RNA (dsRNA) genomes. We have previously purified the catalytic polymerase subunit (Pol) of one of the Cystoviridae members, bacteriophage phi6, and shown that the protein can catalyze RNA synthesis in vitro. In this reaction, both bacteriophage-specific and heterologous RNAs can serve as templates, but those containin...

Bacteriophages are the most numerous entities in the biosphere. Despite this numerical dominance, the genetic structure of bacteriophage populations is poorly understood. Here, we present a biogeography study involving 25 previously undescribed bacteriophages from the Cystoviridae clade, a group characterized by a dsRNA genome divided into three segments. Previous laboratory manipulation has sh...

In most double-stranded RNA (dsRNA) viruses, RNA transcription occurs inside a polymerase (Pol) complex particle, which contains an RNA-dependent RNA Pol subunit as a minor component. Only plus- but not minus-sense copies of genomic segments are produced during this reaction. In the case of phi6, a dsRNA bacteriophage from the Cystoviridae family, isolated Pol synthesizes predominantly plus str...

The packaging of genomic RNA in members of the Cystoviridae is performed by P4, a hexameric protein with NTPase activity. Across family members such as Phi6, Phi8 and Phi13, the P4 proteins show low levels of sequence identity, but presumably have similar atomic structures. Initial structure-determination efforts for P4 from Phi6 and Phi8 were hampered by difficulties in obtaining crystals that...

background in recent decades bacteriophages have been used as treating agents against some pathogens. also, bacteriophages could be considered as alternatives of antimicrobial agents in plant protection. objectives this study aimed to isolate a pathogen from potato (solanum tubersom) tubers (pseudomonas putida), and of its specific bacteriophage from soil and wastewater. materials and methods i...

BACKGROUND Bacteriophage phi12 is a member of the Cystoviridae, a unique group of lipid containing membrane enveloped bacteriophages that infect the bacterial plant pathogen Pseudomonas syringae pv. phaseolicola. The genomes of the virus species contain three double-stranded (dsRNA) segments, and the virus capsid itself is organized in multiple protein shells. The segmented dsRNA genome, the mu...

This study examined whether the practice of incorporating either tetrazolium red or tetrazolium violet dye into plaque assay medium deleteriously influences plaque assay titers. Representative members of six different virus families were studied: Cystoviridae (varphi6), Leviviridae (MS2), Microviridae (varphiX174), Myoviridae (T2), Podoviridae (P22), and Siphoviridae (Denver, T1, and VD13). Eac...

Cryo-electron tomography and subtomogram averaging are utilized to determine that the bacteriophage ϕ12, a member of the Cystoviridae family, contains surface complexes that are toroidal in shape, are composed of six globular domains with six-fold symmetry, and have a discrete density connecting them to the virus membrane-envelope surface. The lack of this kind of spike in a reassortant of ϕ12 ...