scholarly journals Impact of Influenza A Virus Shutoff Proteins on Host Immune Responses

Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 629
Author(s):  
Megan M. Dunagan ◽  
Kala Hardy ◽  
Toru Takimoto
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Influenza A Virus ◽  
Influenza A ◽  
Human Populations ◽  
Lymphocyte Migration ◽  
Host Immune Responses ◽  
Mhc Molecules ◽  
The Impact

Influenza A virus (IAV) is a significant human pathogen that causes seasonal epidemics. Although various types of vaccines are available, IAVs still circulate among human populations, possibly due to their ability to circumvent host immune responses. IAV expresses two host shutoff proteins, PA-X and NS1, which antagonize the host innate immune response. By transcriptomic analysis, we previously showed that PA-X is a major contributor for general shutoff, while shutoff active NS1 specifically inhibits the expression of host cytokines, MHC molecules, and genes involved in innate immunity in cultured human cells. So far, the impact of these shutoff proteins in the acquired immune response in vivo has not been determined in detail. In this study, we analyzed the effects of PA-X and NS1 shutoff activities on immune response using recombinant influenza A/California/04/2009 viruses containing mutations affecting the expression of shutoff active PA-X and NS1 in a mouse model. Our data indicate that the virus without shutoff activities induced the strongest T and B cell responses. Both PA-X and NS1 reduced host immune responses, but shutoff active NS1 most effectively suppressed lymphocyte migration to the lungs, antibody production, and the generation of IAV specific CD4+ and CD8+ T cells. NS1 also prevented the generation of protective immunity against a heterologous virus challenge. These data indicate that shutoff active NS1 plays a major role in suppressing host immune responses against IAV infection.

scholarly journals Regulation of Early Host Immune Responses Shapes the Pathogenicity of Avian Influenza A Virus

2019 ◽  
Vol 10 ◽  
Author(s):  
Jiya Sun ◽  
Jingfeng Wang ◽  
Xuye Yuan ◽  
Xiangwei Wu ◽  
Tianqi Sui ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Immune Responses ◽  
Influenza A Virus ◽  
Influenza A ◽  
Host Immune Responses ◽  
Avian Influenza A Virus

scholarly journals Established Cotton Stainer Gut Bacterial Mutualists Evade Regulation by Host Antimicrobial Peptides

2019 ◽  
Vol 85 (13) ◽  
Author(s):  
Thomas Ogao Onchuru ◽  
Martin Kaltenpoth
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Target Genes ◽  
Quantitative Composition ◽  
Bacterial Symbionts ◽  
Immune Systems ◽  
Host Fitness ◽  
Host Immune Responses ◽  
Cotton Stainer ◽  
The Impact

ABSTRACT Symbioses with microorganisms are ubiquitous in nature and confer important ecological traits to animal hosts but also require control mechanisms to ensure homeostasis of the symbiotic interactions. In addition to protecting hosts against pathogens, animal immune systems recognize, respond to, and regulate mutualists. The gut bacterial symbionts of the cotton stainer bug, Dysdercus fasciatus, elicit an immune response characterized by the upregulation of c-type lysozyme and the antimicrobial peptide pyrrhocoricin in bugs with their native gut microbiota compared to that in dysbiotic insects. In this study, we investigated the impact of the elicited antimicrobial immune response on the established cotton stainer gut bacterial symbiont populations. To this end, we used RNA interference (RNAi) to knock down immunity-related genes hypothesized to regulate the symbionts, and we subsequently measured the effect of this silencing on host fitness and on the abundance of the major gut bacterial symbionts. Despite successful downregulation of target genes by both ingestion and injection of double-stranded RNA (dsRNA), the silencing of immunity-related genes had no effect on either host fitness or the qualitative and quantitative composition of established gut bacterial symbionts, indicating that the host immune responses are not actively involved in the regulation of the nutritional and defensive gut bacterial mutualists. These results suggest that close associations of bacterial symbionts with their hosts can result in the evolution of mechanisms ensuring that symbionts remain insensitive to host immunological responses, which may be important for the evolutionary stability of animal-microbe symbiotic associations. IMPORTANCE Animal immune systems are central for the protection of hosts against enemies by preventing or eliminating successful infections. However, in the presence of beneficial bacterial mutualists, the immune system must strike a balance of not killing the beneficial symbionts while at the same time preventing enemy attacks. Here, using the cotton stainer bug, we reveal that its long-term associated bacterial symbionts are insensitive to the host’s immune effectors, suggesting adaptation to the host’s defenses, thereby strengthening the stability of the symbiotic relationship. The ability of the symbionts to elicit host immune responses but remain insensitive themselves may be a mechanism by which the symbionts prime hosts to fight future pathogenic infections.

scholarly journals Old Dog, New Tricks: Influenza A Virus NS1 and In Vitro Fibrillogenesis

2020 ◽  
Author(s):  
A.A. Shaldzhyan ◽  
Y.A. Zabrodskaya ◽  
I.L. Baranovskaya ◽  
M.V. Sergeeva ◽  
A.N. Gorshkov ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Immune Response ◽  
Immune Responses ◽  
Protein Aggregation ◽  
Influenza A Virus ◽  
Influenza A ◽  
Structural Changes ◽  
Fibril Formation ◽  
Ns1 Protein

ABSTRACTThe influenza NS1 protein is involved in suppression of the host immune response. Recently, there is growing evidence that prion-like protein aggregation plays an important role in cellular signaling and immune responses. In this work, we obtained a recombinant, influenza A NS1 protein and showed that it is able to form amyloid-like fibrils in vitro. Using proteolysis and subsequent mass spectrometry, we showed that regions resistant to protease hydrolysis highly differ between the native NS1 form (NS1-N) and fibrillar form (NS1-F); this indicates that significant structural changes occur during fibril formation. The discovery of the ability of NS1 to form amyloid-like fibrils may be relevant to uncovering relationships between influenza A infection and modulation of the immune response.

scholarly journals Complement Decay-Accelerating Factor is a modulator of influenza A virus lung immunopathology

2021 ◽  
Vol 17 (7) ◽  
pp. e1009381
Author(s):  
Nuno Brito Santos ◽  
Zoé Enderlin Vaz da Silva ◽  
Catarina Gomes ◽  
Celso A. Reis ◽  
Maria João Amorim
Keyword(s):  
Influenza A Virus ◽  
Complement Activation ◽  
Influenza A ◽  
Viral Infections ◽  
Adaptive Immune System ◽  
Surface Protein ◽  
Decay Accelerating Factor ◽  
Viral Loads ◽  
The Impact

Clearance of viral infections, such as SARS-CoV-2 and influenza A virus (IAV), must be fine-tuned to eliminate the pathogen without causing immunopathology. As such, an aggressive initial innate immune response favors the host in contrast to a detrimental prolonged inflammation. The complement pathway bridges innate and adaptive immune system and contributes to the response by directly clearing pathogens or infected cells, as well as recruiting proinflammatory immune cells and regulating inflammation. However, the impact of modulating complement activation in viral infections is still unclear. In this work, we targeted the complement decay-accelerating factor (DAF/CD55), a surface protein that protects cells from non-specific complement attack, and analyzed its role in IAV infections. We found that DAF modulates IAV infection in vivo, via an interplay with the antigenic viral proteins hemagglutinin (HA) and neuraminidase (NA), in a strain specific manner. Our results reveal that, contrary to what could be expected, DAF potentiates complement activation, increasing the recruitment of neutrophils, monocytes and T cells. We also show that viral NA acts on the heavily sialylated DAF and propose that the NA-dependent DAF removal of sialic acids exacerbates complement activation, leading to lung immunopathology. Remarkably, this mechanism has no impact on viral loads, but rather on the host resilience to infection, and may have direct implications in zoonotic influenza transmissions.

scholarly journals Regulation of Host Immune Responses against Influenza A Virus Infection by Mitogen-Activated Protein Kinases (MAPKs)

2020 ◽  
Vol 8 (7) ◽  
pp. 1067
Author(s):  
Jiabo Yu ◽  
Xiang Sun ◽  
Jian Yi Gerald Goie ◽  
Yongliang Zhang
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Infection ◽  
Influenza Viruses ◽  
Mitogen Activated Protein Kinase ◽  
Viral Diseases ◽  
Cytokine Storm ◽  
Mitogen Activated Protein

Influenza is a major respiratory viral disease caused by infections from the influenza A virus (IAV) that persists across various seasonal outbreaks globally each year. Host immune response is a key factor determining disease severity of influenza infection, presenting an attractive target for the development of novel therapies for treatments. Among the multiple signal transduction pathways regulating the host immune activation and function in response to IAV infections, the mitogen-activated protein kinase (MAPK) pathways are important signalling axes, downstream of various pattern recognition receptors (PRRs), activated by IAVs that regulate various cellular processes in immune cells of both innate and adaptive immunity. Moreover, aberrant MAPK activation underpins overexuberant production of inflammatory mediators, promoting the development of the “cytokine storm”, a characteristic of severe respiratory viral diseases. Therefore, elucidation of the regulatory roles of MAPK in immune responses against IAVs is not only essential for understanding the pathogenesis of severe influenza, but also critical for developing MAPK-dependent therapies for treatment of respiratory viral diseases. In this review, we will summarise the current understanding of MAPK functions in both innate and adaptive immune response against IAVs and discuss their contributions towards the cytokine storm caused by highly pathogenic influenza viruses.

Impact of influenza virus during pregnancy: from disease severity to vaccine efficacy

2020 ◽  
Vol 15 (7) ◽  
pp. 441-453
Author(s):  
Ana Vazquez-Pagan ◽  
Rebekah Honce ◽  
Stacey Schultz-Cherry
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Immune Responses ◽  
Pregnant Women ◽  
Disease Severity ◽  
Influenza A ◽  
Antiviral Treatment ◽  
Influenza Virus Infection ◽  
Severe Influenza ◽  
The Impact

Pregnant women are among the individuals at the highest risk for severe influenza virus infection. Infection of the mother during pregnancy increases the probability of adverse fetal outcomes such as small for gestational age, preterm birth and fetal death. Animal models of syngeneic and allogeneic mating can recapitulate the increased disease severity observed in pregnant women and are used to define the mechanism(s) of that increased severity. This review focuses on influenza A virus pathogenesis, the unique immunological landscape during pregnancy, the impact of maternal influenza virus infection on the fetus and the immune responses at the maternal–fetal interface. Finally, we summarize the importance of immunization and antiviral treatment in this population and highlight issues that warrant further investigation.

scholarly journals Links between fecal microbiota and the response to vaccination against influenza A virus in pigs

npj Vaccines ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Marion Borey ◽  
Fany Blanc ◽  
Gaëtan Lemonnier ◽  
Jean-Jacques Leplat ◽  
Deborah Jardet ◽  
...  
Keyword(s):  
Immune Response ◽  
Influenza A Virus ◽  
Influenza A ◽  
16S Rrna Gene Sequencing ◽  
Serum Levels ◽  
Fecal Microbiota ◽  
Rrna Gene ◽  
Vaccine Response ◽  
Specific Igg ◽  
Rrna Gene Sequencing

AbstractThis study describes the associations between fecal microbiota and vaccine response variability in pigs, using 98 piglets vaccinated against the influenza A virus at 28 days of age (D28) with a booster at D49. Immune response to the vaccine is measured at D49, D56, D63, and D146 by serum levels of IAV-specific IgG and assays of hemagglutination inhibition (HAI). Analysis of the pre-vaccination microbiota characterized by 16S rRNA gene sequencing of fecal DNA reveals a higher vaccine response in piglets with a richer microbiota, and shows that 23 operational taxonomic units (OTUs) are differentially abundant between high and low IAV-specific IgG producers at D63. A stronger immune response is linked with OTUs assigned to the genus Prevotella and family Muribaculaceae, and a weaker response is linked with OTUs assigned to the genera Helicobacter and Escherichia-Shigella. A set of 81 OTUs accurately predicts IAV-specific IgG and HAI titer levels at all time points, highlighting early and late associations between pre-vaccination fecal microbiota composition and immune response to the vaccine.

Ellagitannins, Gallotannins and their Metabolites- The Contribution to the Anti-Inflammatory Effect of Food Products and Medicinal Plants

2019 ◽  
Vol 25 (37) ◽  
pp. 4946-4967 ◽  
Author(s):  
Anna K. Kiss ◽  
Jakub P. Piwowarski
Keyword(s):  
Immune Response ◽  
Gastrointestinal Tract ◽  
Gut Microbiota ◽  
Health Effects ◽  
Biological Effects ◽  
Food Products ◽  
Anti Inflammatory ◽  
The Impact

The popularity of food products and medicinal plant materials containing hydrolysable tannins (HT) is nowadays rapidly increasing. Among various health effects attributable to the products of plant origin rich in gallotannins and/or ellagitannins the most often underlined is the beneficial influence on diseases possessing inflammatory background. Results of clinical, interventional and animal in vivo studies clearly indicate the antiinflammatory potential of HT-containing products, as well as pure ellagitannins and gallotannins. In recent years a great emphasis has been put on the consideration of metabolism and bioavailability of natural products during examination of their biological effects. Conducted in vivo and in vitro studies of polyphenols metabolism put a new light on this issue and indicate the gut microbiota to play a crucial role in the health effects following their oral administration. The aim of the review is to summarize the knowledge about HT-containing products’ phytochemistry and their anti-inflammatory effects together with discussion of the data about observed biological activities with regards to the current concepts on the HTs’ bioavailability and metabolism. Orally administered HT-containing products due to the limited bioavailability of ellagitannins and gallotannins can influence immune response at the level of gastrointestinal tract as well as express modulating effects on the gut microbiota composition. However, due to the chemical changes being a result of their transit through gastrointestinal tract, comprising of hydrolysis and gut microbiota metabolism, the activity of produced metabolites has to be taken into consideration. Studies regarding biological effects of the HTs’ metabolites, in particular urolithins, indicate their strong and structure-dependent anti-inflammatory activities, being observed at the concentrations, which fit the range of their established bioavailability. The impact of HTs on inflammatory processes has been well established on various in vivo and in vitro models, while influence of microbiota metabolites on silencing the immune response gives a new perspective on understanding anti-inflammatory effects attributed to HT containing products, especially their postulated effectiveness in inflammatory bowel diseases (IBD) and cardiovascular diseases.

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