Review

15 pages, 907 KiB

Open AccessReview

The Role of the Polymeric Immunoglobulin Receptor and Secretory Immunoglobulins during Mucosal Infection and Immunity

by Holly Turula and Christiane E. Wobus

Viruses 2018, 10(5), 237; https://doi.org/10.3390/v10050237 - 03 May 2018

Cited by 113 | Viewed by 9855

The gastrointestinal tract houses millions of microbes, and thus has evolved several host defense mechanisms to keep them at bay, and prevent their entry into the host. One such mucosal surface defense is the secretion of secretory immunoglobulins (SIg). Secretion of SIg depends [...] Read more.

The gastrointestinal tract houses millions of microbes, and thus has evolved several host defense mechanisms to keep them at bay, and prevent their entry into the host. One such mucosal surface defense is the secretion of secretory immunoglobulins (SIg). Secretion of SIg depends on the polymeric immunoglobulin receptor (pIgR), which transports polymeric Ig (IgA or IgM) from the basolateral surface of the epithelium to the apical side. Upon reaching the luminal side, a portion of pIgR, called secretory component (SC) is cleaved off to release Ig, forming SIg. Through antigen-specific and non-specific binding, SIg can modulate microbial communities and pathogenic microbes via several mechanisms: agglutination and exclusion from the epithelial surface, neutralization, or via host immunity and complement activation. Given the crucial role of SIg as a microbial scavenger, some pathogens also evolved ways to modulate and utilize pIgR and SIg to facilitate infection. This review will cover the regulation of the pIgR/SIg cycle, mechanisms of SIg-mediated mucosal protection as well as pathogen utilization of SIg. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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20 pages, 642 KiB

Open AccessReview

Paneth Cells during Viral Infection and Pathogenesis

by Mayumi K. Holly and Jason G. Smith

Viruses 2018, 10(5), 225; https://doi.org/10.3390/v10050225 - 26 Apr 2018

Cited by 53 | Viewed by 8190

Abstract

Paneth cells are major secretory cells located in the crypts of Lieberkühn in the small intestine. Our understanding of the diverse roles that Paneth cells play in homeostasis and disease has grown substantially since their discovery over a hundred years ago. Classically, Paneth [...] Read more.

Paneth cells are major secretory cells located in the crypts of Lieberkühn in the small intestine. Our understanding of the diverse roles that Paneth cells play in homeostasis and disease has grown substantially since their discovery over a hundred years ago. Classically, Paneth cells have been characterized as a significant source of antimicrobial peptides and proteins important in host defense and shaping the composition of the commensal microbiota. More recently, Paneth cells have been shown to supply key developmental and homeostatic signals to intestinal stem cells in the crypt base. Paneth cell dysfunction leading to dysbiosis and a compromised epithelial barrier have been implicated in the etiology of Crohn’s disease and susceptibility to enteric bacterial infection. Our understanding of the impact of Paneth cells on viral infection is incomplete. Enteric α-defensins, produced by Paneth cells, can directly alter viral infection. In addition, α-defensins and other antimicrobial Paneth cell products may modulate viral infection indirectly by impacting the microbiome. Here, we discuss recent insights into Paneth cell biology, models to study their function, and the impact, both direct and indirect, of Paneth cells on enteric viral infection. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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34 pages, 1790 KiB

Open AccessReview

Enteric Virome Sensing—Its Role in Intestinal Homeostasis and Immunity

by Rebecca N. Metzger, Anne B. Krug and Katharina Eisenächer

Viruses 2018, 10(4), 146; https://doi.org/10.3390/v10040146 - 23 Mar 2018

Cited by 48 | Viewed by 8737

Abstract

Pattern recognition receptors (PRRs) sensing commensal microorganisms in the intestine induce tightly controlled tonic signaling in the intestinal mucosa, which is required to maintain intestinal barrier integrity and immune homeostasis. At the same time, PRR signaling pathways rapidly trigger the innate immune defense [...] Read more.

Pattern recognition receptors (PRRs) sensing commensal microorganisms in the intestine induce tightly controlled tonic signaling in the intestinal mucosa, which is required to maintain intestinal barrier integrity and immune homeostasis. At the same time, PRR signaling pathways rapidly trigger the innate immune defense against invasive pathogens in the intestine. Intestinal epithelial cells and mononuclear phagocytes in the intestine and the gut-associated lymphoid tissues are critically involved in sensing components of the microbiome and regulating immune responses in the intestine to sustain immune tolerance against harmless antigens and to prevent inflammation. These processes have been mostly investigated in the context of the bacterial components of the microbiome so far. The impact of viruses residing in the intestine and the virus sensors, which are activated by these enteric viruses, on intestinal homeostasis and inflammation is just beginning to be unraveled. In this review, we will summarize recent findings indicating an important role of the enteric virome for intestinal homeostasis as well as pathology when the immune system fails to control the enteric virome. We will provide an overview of the virus sensors and signaling pathways, operative in the intestine and the mononuclear phagocyte subsets, which can sense viruses and shape the intestinal immune response. We will discuss how these might interact with resident enteric viruses directly or in context with the bacterial microbiome to affect intestinal homeostasis. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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13 pages, 620 KiB

Open AccessReview

Stem Cell-Derived Models of Viral Infections in the Gastrointestinal Tract

by Wyatt E. Lanik, Madison A. Mara, Belgacem Mihi, Carolyn B. Coyne and Misty Good

Viruses 2018, 10(3), 124; https://doi.org/10.3390/v10030124 - 10 Mar 2018

Cited by 17 | Viewed by 4949

Abstract

Studies on the intestinal epithelial response to viral infection have previously been limited by the absence of in vitro human intestinal models that recapitulate the multicellular complexity of the gastrointestinal tract. Recent technological advances have led to the development of “mini-intestine” models, which [...] Read more.

Studies on the intestinal epithelial response to viral infection have previously been limited by the absence of in vitro human intestinal models that recapitulate the multicellular complexity of the gastrointestinal tract. Recent technological advances have led to the development of “mini-intestine” models, which mimic the diverse cellular nature and physiological activity of the small intestine. Utilizing adult or embryonic intestinal tissue, enteroid and organoid systems, respectively, represent an opportunity to effectively model cellular differentiation, proliferation, and interactions that are specific to the specialized environment of the intestine. Enteroid and organoid systems represent a significant advantage over traditional in vitro methods because they model the structure and function of the small intestine while also maintaining the genetic identity of the host. These more physiologic models also allow for novel approaches to investigate the interaction of enteric viruses with the gastrointestinal tract, making them ideal to study the complexities of host-pathogen interactions in this unique cellular environment. This review aims to provide a summary on the use of human enteroid and organoid systems as models to study virus pathogenesis. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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14 pages, 1389 KiB

Open AccessReview

The Interactions between Host Glycobiology, Bacterial Microbiota, and Viruses in the Gut

by Vicente Monedero, Javier Buesa and Jesús Rodríguez-Díaz

Viruses 2018, 10(2), 96; https://doi.org/10.3390/v10020096 - 24 Feb 2018

Cited by 42 | Viewed by 10573

Abstract

Rotavirus (RV) and norovirus (NoV) are the major etiological agents of viral acute gastroenteritis worldwide. Host genetic factors, the histo-blood group antigens (HBGA), are associated with RV and NoV susceptibility and recent findings additionally point to HBGA as a factor modulating the intestinal [...] Read more.

Rotavirus (RV) and norovirus (NoV) are the major etiological agents of viral acute gastroenteritis worldwide. Host genetic factors, the histo-blood group antigens (HBGA), are associated with RV and NoV susceptibility and recent findings additionally point to HBGA as a factor modulating the intestinal microbial composition. In vitro and in vivo experiments in animal models established that the microbiota enhances RV and NoV infection, uncovering a triangular interplay between RV and NoV, host glycobiology, and the intestinal microbiota that ultimately influences viral infectivity. Studies on the microbiota composition in individuals displaying different RV and NoV susceptibilities allowed the identification of potential bacterial biomarkers, although mechanistic data on the virus–host–microbiota relation are still needed. The identification of the bacterial and HBGA interactions that are exploited by RV and NoV would place the intestinal microbiota as a new target for alternative therapies aimed at preventing and treating viral gastroenteritis. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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12 pages, 792 KiB

Open AccessReview

The Microbial Zoo in the C. elegans Intestine: Bacteria, Fungi and Viruses

by Hongbing Jiang and David Wang

Viruses 2018, 10(2), 85; https://doi.org/10.3390/v10020085 - 14 Feb 2018

Cited by 33 | Viewed by 8632

Abstract

C. elegans is an invaluable model organism that has been a driving force in many fundamental biological discoveries. However, it is only in the past two decades that it has been applied to host–pathogen interaction studies. These studies have been facilitated by the [...] Read more.

C. elegans is an invaluable model organism that has been a driving force in many fundamental biological discoveries. However, it is only in the past two decades that it has been applied to host–pathogen interaction studies. These studies have been facilitated by the discoveries of natural microbes that infect C. elegans, including bacteria, fungi and viruses. Notably, many of these microbes share a common site of infection, the C. elegans intestine. Furthermore, the recent descriptions of a natural gut microbiota in C. elegans raise the possibility that this could be a novel model system for microbiome and trans-kingdom interaction studies. Here we review studies of C. elegans host–microbe interactions with a particular focus on the intestine. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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15 pages, 259 KiB

Open AccessReview

Virus–Bacteria Interactions: Implications and Potential for the Applied and Agricultural Sciences

by Matthew D. Moore and Lee-Ann Jaykus

Viruses 2018, 10(2), 61; https://doi.org/10.3390/v10020061 - 02 Feb 2018

Cited by 29 | Viewed by 4771

Abstract

Eukaryotic virus–bacteria interactions have recently become an emerging topic of study due to multiple significant examples related to human pathogens of clinical interest. However, such omnipresent and likely important interactions for viruses and bacteria relevant to the applied and agricultural sciences have not [...] Read more.

Eukaryotic virus–bacteria interactions have recently become an emerging topic of study due to multiple significant examples related to human pathogens of clinical interest. However, such omnipresent and likely important interactions for viruses and bacteria relevant to the applied and agricultural sciences have not been reviewed or compiled. The fundamental basis of this review is that these interactions have importance and deserve more investigation, as numerous potential consequences and applications arising from their discovery are relevant to the applied sciences. The purpose of this review is to highlight and summarize eukaryotic virus–bacteria findings in the food/water, horticultural, and animal sciences. In many cases in the agricultural sciences, mechanistic understandings of the effects of virus–bacteria interactions remain unstudied, and many studies solely focus on co-infections of bacterial and viral pathogens. Given recent findings relative to human viral pathogens, further research related to virus–bacteria interactions would likely result in numerous discoveries and beneficial applications. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

23 pages, 2072 KiB

Open AccessReview

Distinct Effects of Type I and III Interferons on Enteric Viruses

by Harshad Ingle, Stefan T. Peterson and Megan T. Baldridge

Viruses 2018, 10(1), 46; https://doi.org/10.3390/v10010046 - 20 Jan 2018

Cited by 44 | Viewed by 7375

Abstract

Interferons (IFNs) are key host cytokines in the innate immune response to viral infection, and recent work has identified unique roles for IFN subtypes in regulating different aspects of infection. Currently emerging is a common theme that type III IFNs are critical in [...] Read more.

Interferons (IFNs) are key host cytokines in the innate immune response to viral infection, and recent work has identified unique roles for IFN subtypes in regulating different aspects of infection. Currently emerging is a common theme that type III IFNs are critical in localized control of infection at mucosal barrier sites, while type I IFNs are important for broad systemic control of infections. The intestine is a particular site of interest for exploring these effects, as in addition to being the port of entry for a multitude of pathogens, it is a complex tissue with a variety of cell types as well as the presence of the intestinal microbiota. Here we focus on the roles of type I and III IFNs in control of enteric viruses, discussing what is known about signaling downstream from these cytokines, including induction of specific IFN-stimulated genes. We review viral strategies to evade IFN responses, effects of IFNs on the intestine, interactions between IFNs and the microbiota, and briefly discuss the role of IFNs in controlling viral infections at other barrier sites. Enhanced understanding of the coordinate roles of IFNs in control of viral infections may facilitate development of antiviral therapeutic strategies; here we highlight potential avenues for future exploration. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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10 pages, 775 KiB

Open AccessReview

Interactions between Enteric Bacteria and Eukaryotic Viruses Impact the Outcome of Infection

by Angela K. Berger and Bernardo A. Mainou

Viruses 2018, 10(1), 19; https://doi.org/10.3390/v10010019 - 03 Jan 2018

Cited by 35 | Viewed by 8943

Abstract

Enteric viruses encounter a multitude of environments as they traverse the gastrointestinal tract. The interaction of enteric eukaryotic viruses with members of the host microbiota impacts the outcome of infection. Infection with several enteric viruses is impaired in the absence of the gut [...] Read more.

Enteric viruses encounter a multitude of environments as they traverse the gastrointestinal tract. The interaction of enteric eukaryotic viruses with members of the host microbiota impacts the outcome of infection. Infection with several enteric viruses is impaired in the absence of the gut microbiota, specifically bacteria. The effects of bacteria on virus biology are diverse. Poliovirus capsid stability and receptor engagement are positively impacted by bacteria and bacterial lipopolysaccharides. Norovirus utilizes histo-blood group antigens produced by enteric bacteria to attach and productively infect B cells. Lipopolysaccharides on the envelope of mouse mammary tumor virus promote a tolerogenic environment that allows for the establishment of viral persistence. Reovirus binds Gram negative and Gram-positive bacteria through bacterial envelope components to enhance virion thermostability. Through the direct engagement of bacteria and bacterial components, viruses evolved diverse ways to impact the outcome of infection. Full article

(This article belongs to the Special Issue Viruses–Bacteria Interactions in the Gut)

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