Filamentous phages: masters of a microbial sharing economy

Abstract

Bacteriophage (“bacteria eaters”) or phage is the collective term for viruses that infect bacteria. While most phages are pathogens that kill their bacterial hosts, the filamentous phages of the sub‐class Inoviridae live in cooperative relationships with their bacterial hosts, akin to the principal behaviours found in the modern‐day sharing economy: peer‐to‐peer support, to offset any burden. Filamentous phages impose very little burden on bacteria and offset this by providing service to help build better biofilms, or provision of toxins and other factors that increase virulence, or modified behaviours that provide novel motile activity to their bacterial hosts. Past, present and future biotechnology applications have been built on this phage–host cooperativity, including DNA sequencing technology, tools for genetic engineering and molecular analysis of gene expression and protein production, and phage‐display technologies for screening protein–ligand and protein–protein interactions. With the explosion of genome and metagenome sequencing surveys around the world, we are coming to realize that our knowledge of filamentous phage diversity remains at a tip‐of‐the‐iceberg stage, promising that new biology and biotechnology are soon to come.

Pf Bacteriophage and Their Impact on Pseudomonas Virulence, Mammalian Immunity, and Chronic Infections

“…Pf virions are ∼6-7 nm in diameter and vary in length from ∼0.8-2 µm, depending on the strain and genome size in question. Like all Inoviruses, Pf virions are composed of thousands of copies of a single major coat protein (p8, CoaB in Pf) with minor coat proteins at either end involved in phage assembly and host recognition (Figure 1) (70)(71)(72). Structurally, Inoviruses can be subdivided into two classes based on helical symmetry.…”

“…Adsorption is mediated by the minor coat protein CoaA (PA0724), which is located on the end of the virion. The adsorbed virion is then drawn into the periplasm as the pili retracts where the phage coat protein CoaA contacts the secondary receptor TolA (72). TolA is part of the highly conserved Tol-Pal system that controls membrane integrity and invagination during cell division and is constitutively expressed and readily available for Pf phages to leverage to infect the host cell.…”

Application of Bacteriophages in Nanotechnology

“…The appearance of stressors, e.g., chemicals, UV radiation, or damage of the host DNA, can cause the conversion of the cycle and change from lysogenic into the lytic [ 19 ]. Only some filamentous phages might cause the continuous generation of progeny virions without causing the death of the host [ 20 ]. Bacteriophages are considered non-toxic to eukaryotes because structural elements of the virion cannot bind to eukaryotic cells [ 21 ].…”

Temperate Bacteriophages (Prophages) in Pseudomonas aeruginosa Isolates Belonging to the International Cystic Fibrosis Clone (CC274)

“…Three of these showed high similarity to the Pseudomonas Pf inovirus, constituted by 9-15 proteins in isolates AUS411, AUS531, and FQSE15-1110. The inoviruses present in isolates AUS531 and FQSE15 were similar to the Pseudomonas Pf4 and Pf5 inoviruses, but the prophage detected in AUS411 was a new phage, designated Pf8_ST274-AUS411 (hereinafter referred to as Pf8) (Hay and Lithgow, 2019;Li et al, 2019). The genome of the Pf8 filamentous phage is of size 10 Kb and has a total of 16 proteins and one tRNA coding region (Genbank:MN710383).…”