RB43-related bacteriophages have a specific genome type that clearly distinguishes them from other T4-like viruses. Here, we present the complete genome sequence of a new virulent phage, Lw1, isolated as an Escherichia coli BL21(DE3) contaminant. Lw1 shares an RB43-like genome organization, but it does not contain putative AP2-domain endonuclease genes.

Fire blight, caused by plant pathogenic bacterium Erwinia amylovora, is one of the most important diseases of Rosaceae plants. Due to the lack of effective control measures, fire blight infections pose a recurrent threat on agricultural production worldwide. Recently, bacterial viruses, or bacteriophages, have been proposed as environmentally friendly natural antimicrobial agents for fire blight control. Here, we isolated a novel bacteriophage Hena1 with activity against E. amylovora. Further analysis revealed that Hena1 is a narrow-host-range lytic phage belonging to Myoviridae family. Its genome consists of a linear 148,842 bp dsDNA (48.42% GC content) encoding 240 ORFs and 23 tRNA genes. Based on virion structure and genomic composition, Hena1 was classified as a new species of bacteriophage subfamily Vequintavirinae. The comprehensive analysis of Hena1 genome may provide further insights into evolution of bacteriophages infecting plant pathogenic bacteria.

Bacteriophage ZF40 is the only currently available, temperate Myoviridae phage infecting the potato pathogen Pectobacterium carotovorum subsp. carotovorum. Despite its unusual tail morphology, its major tail sheath and tube proteins remained uncharacterized after the initial genome annotation. Using ESI tandem mass-spectrometry, 24 structural proteins of the ZF40 virion were identified, with a sequence coverage ranging between 15.8% and 87.8%. The putative function of 16 proteins could be elucidated based on secondary structure analysis and conservative domain searches. The experimental annotation of 35% of the encoded gene products within the structural region of the genome represents a complete view of the virion structure, which can serve as the basis for future structural analysis as a model phage.

To date, a small number of temperate phages are known to infect members of the genus Erwinia. In this study, the genomes of temperate phages vB_EhrS_49 and vB_EhrS_59 infecting Erwinia horticola, the causative agent of beech black bacteriosis in Ukraine, were sequenced and annotated. Their genomes reveal no significant similarity to that of any previously reported viruses of Enterobacteriaceae. At the same time, phages 49 and 59 share extensive nucleotide sequence identity across the regions encoding head assembly, DNA packaging, and lysis. Despite significant homology between structural modules, the organization of distal tail morphogenesis genes is different. Furthermore, a number of putative morons and DNA methylases have been found in both phage genomes. Due to the revealed synteny as well as the structure of lysogeny module, phages 49 and 59 are suggested to be novel members of the lambdoid phage group. Conservative structural genes together with varying homology across the nonstructural region of the genomes make phages 49 and 59 highly promising objects for studying the genetic recombination and evolution of microbial viruses. The obtained data may as well be helpful for better understanding of relationships among Erwinia species.

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