Pseudolysogeny

Łoś, Marcin; Węgrzyn, Grzegorz

doi:10.1016/b978-0-12-394621-8.00019-4

Cited by 114 publications

(71 citation statements)

References 30 publications

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“…This sort of “hibernation” mode would protect the phage from environmental factors, giving the phage a safe haven for a prolonged period of time, and would also give it a competitive advantage against unbound phage when nutrient conditions abruptly change to allow bacterial growth. Interactions somewhat similar to this have sometimes been referred to as a “pseudolysogenic” state (Łoś et al, 2003; Abedon, 2009; Łoś and Wegrzyn, 2012). However, the term “pseudolysogeny” is used to describe a number of very different phenomena in the literature (Abedon, 2009; Hobbs and Abedon, 2016) so, we choose to avoid using the term here.…”

Section: Discussionmentioning

confidence: 99%

Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective

et al. 2016

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Virtually all studies of phage infections investigate bacteria growing exponentially in rich media. In nature, however, phages largely encounter non-growing cells. Bacteria entering stationary phase often activate well-studied stress defense mechanisms that drastically alter the cell, facilitating its long-term survival. An understanding of phage-host interactions in such conditions is of major importance from both an ecological and therapeutic standpoint. Here, we show that bacteriophage T4 can efficiently bind to, infect and kill E. coli in stationary phase, both in the presence and absence of a functional stationary-phase sigma factor, and explore the response of T4-infected stationary phase cells to the addition of fresh nutrients 5 or 24 h after that infection. An unexpected new mode of response has been identified. “Hibernation” mode is a persistent but reversible dormant state in which the infected cells make at least some phage enzymes, but halt phage development until appropriate nutrients become available before producing phage particles. Our evidence indicates that the block in hibernation mode occurs after the middle-mode stage of phage development; host DNA breakdown and the incorporation of the released nucleotides into phage DNA indicate that the enzymes of the nucleotide synthesizing complex, under middle-mode control, have been made and assembled into a functional state. Once fresh glucose and amino acids become available, the standard lytic infection process rapidly resumes and concentrations of up to 1011 progeny phage (an average of about 40 phage per initially present cell) are produced. All evidence is consistent with the hibernation-mode control point lying between middle mode and late mode T4 gene expression. We have also observed a “scavenger” response, where the infecting phage takes advantage of whatever few nutrients are available to produce small quantities of progeny within 2 to 5 h after infection. The scavenger response seems able to produce no more than an average of one phage per originally available cell, and few if any further progeny are produced by cells in this mode even if fresh nutrients are made available later.

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Section: Discussionmentioning

confidence: 99%

Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective

et al. 2016

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“…Once favorable conditions arise, the phage begins either the lytic or lysogenic cycle. It is thought that this mechanism can lead to persistent infections and might contribute to phage survival during unfavorable growth conditions in natural environments [22,23]. It has been proposed that Bacteroides and Escherichia species can be infected in this manner in the gut [24,25].…”

Section: Outcome Of Phage–bacteria Interactionsmentioning

confidence: 99%

The Human Gut Phage Community and Its Implications for Health and Disease

Manrique

Dills

Young

2017

Viruses

206

177

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In this review, we assess our current understanding of the role of bacteriophages infecting the human gut bacterial community in health and disease. In general, bacteriophages contribute to the structure of their microbial communities by driving host and viral diversification, bacterial evolution, and by expanding the functional diversity of ecosystems. Gut bacteriophages are an ensemble of unique and shared phages in individuals, which encompass temperate phages found predominately as prophage in gut bacteria (prophage reservoir) and lytic phages. In healthy individuals, only a small fraction of the prophage reservoir is activated and found as extracellular phages. Phage community dysbiosis is characterized by a shift in the activated prophage community or an increase of lytic phages, and has been correlated with disease, suggesting that a proper balance between lysis and lysogeny is needed to maintain health. Consequently, the concept of microbial dysbiosis might be extended to the phage component of the microbiome as well. Understanding the dynamics and mechanisms to restore balance after dysbiosis is an active area of research. The use of phage transplants to re-establish health suggests that phages can be used as disease treatment. Such advances represent milestones in our understanding of gut phages in human health and should fuel research on their role in health and disease.

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“…Indeed, the interplay between nutrient demand and availability may influence the lytic-lysogeny decision (Hong et al, 1971;Herskowitz and Hagen, 1980;Jiang and Paul, 1998) that phages make when infecting a cell. This could also result in the establishment of a state that may be perceived as pseudolysogeny (Łoś and Węgrzyn, 2012) where the cell is infected but there are insufficient cellular resources to propagate new virions. Alternatively, infected cells with access to sufficient nutrients may themselves be N enriched and more susceptible to grazing.…”

Section: Ecological Implications and Conclusionmentioning

confidence: 99%

Phage infection of an environmentally relevant marine bacterium alters host metabolism and lysate composition

Ankrah

May²,

Middleton³

et al. 2013

The ISME Journal

129

126

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Viruses contribute to the mortality of marine microbes, consequentially altering biological species composition and system biogeochemistry. Although it is well established that host cells provide metabolic resources for virus replication, the extent to which infection reshapes host metabolism at a global level and the effect of this alteration on the cellular material released following viral lysis is less understood. To address this knowledge gap, the growth dynamics, metabolism and extracellular lysate of roseophage-infected Sulfitobacter sp. 2047 was studied using a variety of techniques, including liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics. Quantitative estimates of the total amount of carbon and nitrogen sequestered into particulate biomass indicate that phage infection redirects B75% of nutrients into virions. Intracellular concentrations for 82 metabolites were measured at seven time points over the infection cycle. By the end of this period, 71% of the detected metabolites were significantly elevated in infected populations, and stable isotope-based flux measurements showed that these cells had elevated metabolic activity. In contrast to simple hypothetical models that assume that extracellular compounds increase because of lysis, a profile of metabolites from infected cultures showed that 470% of the 56 quantified compounds had decreased concentrations in the lysate relative to uninfected controls, suggesting that these small, labile nutrients were being utilized by surviving cells. These results indicate that virus-infected cells are physiologically distinct from their uninfected counterparts, which has implications for microbial community ecology and biogeochemistry.

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Pseudolysogeny

Cited by 114 publications

References 30 publications

Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective

Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective

The Human Gut Phage Community and Its Implications for Health and Disease

Phage infection of an environmentally relevant marine bacterium alters host metabolism and lysate composition

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