Cytosolic and nuclear recognition of virus and viral evasion

AbstractThe innate immune system is the first line of host defense, which responds rapidly to viral infection. Innate recognition of viruses is mediated by a set of pattern recognition receptors (PRRs) that sense viral genomic nucleic acids and/or replication intermediates. PRRs are mainly localized either to the endosomes, the plasma membrane or the cytoplasm. Recent evidence suggested that several proteins located in the nucleus could also act as viral sensors. In turn, these important elements are becoming the target for most viruses to evade host immune surveillance. In this review, we focus on the recent progress in the study of viral recognition and evasion.

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The Evasion of Antiviral Innate Immunity by Chicken DNA Viruses

Frontiers in Microbiology ◽

10.3389/fmicb.2021.771292 ◽

2021 ◽

Vol 12 ◽

Author(s):

Li Gao ◽

Shijun Zheng ◽

Yongqiang Wang

Keyword(s):

Innate Immunity ◽

Immune System ◽

Innate Immune System ◽

Immune Surveillance ◽

Innate Immune ◽

Innate Immune Responses ◽

Dna Viruses ◽

Human Dna ◽

Antiviral Innate Immunity ◽

Host Immune Surveillance

The innate immune system constitutes the first line of host defense. Viruses have evolved multiple mechanisms to escape host immune surveillance, which has been explored extensively for human DNA viruses. There is growing evidence showing the interaction between avian DNA viruses and the host innate immune system. In this review, we will survey the present knowledge of chicken DNA viruses, then describe the functions of DNA sensors in avian innate immunity, and finally discuss recent progresses in chicken DNA virus evasion from host innate immune responses.

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Regulation of innate immune responses by autophagy-related proteins

The Journal of Cell Biology ◽

10.1083/jcb.201002021 ◽

2010 ◽

Vol 189 (6) ◽

pp. 925-935 ◽

Cited By ~ 170

Author(s):

Tatsuya Saitoh ◽

Shizuo Akira

Keyword(s):

Immune Response ◽

Pattern Recognition ◽

Immune Responses ◽

Host Defense ◽

Innate Immune ◽

Infectious Agents ◽

Innate Immune Responses ◽

First Line ◽

Cellular Machinery ◽

Related Proteins

Pattern recognition receptors detect microbial components and induce innate immune responses, the first line of host defense against infectious agents. However, aberrant activation of immune responses often causes massive inflammation, leading to the development of autoimmune diseases. Therefore, both activation and inactivation of innate immune responses must be strictly controlled. Recent studies have shown that the cellular machinery associated with protein degradation, such as autophagy, is important for the regulation of innate immunity. These studies reveal that autophagy-related proteins are involved in the innate immune response and may contribute to the development of inflammatory disorders.

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Existence of natural mouse IgG mAbs recognising epitopes shared by malondialdehyde acetaldehyde adducts and Porphyromonas gingivalis

Innate Immunity ◽

10.1177/1753425920981133 ◽

2021 ◽

Vol 27 (2) ◽

pp. 158-169

Author(s):

Mikael Kyrklund ◽

Heidi Kaski ◽

Ramin Akhi ◽

Antti E Nissinen ◽

Outi Kummu ◽

...

Keyword(s):

Porphyromonas Gingivalis ◽

Low Density Lipoprotein ◽

Physiological Role ◽

Density Lipoprotein ◽

Tissue Homeostasis ◽

Innate Immune ◽

Periodontal Pathogen ◽

First Line ◽

Germline Genes ◽

Innate Recognition

Natural Abs are produced by B lymphocytes in the absence of external Ag stimulation. They recognise self, altered self and foreign Ags, comprising an important first-line defence against invading pathogens and serving as innate recognition receptors for tissue homeostasis. Natural IgG Abs have been found in newborns and uninfected individuals. Yet, their physiological role remains unclear. Previously, no natural IgG Abs to oxidation-specific epitopes have been reported. Here, we show the cloning and characterisation of mouse IgG mAbs against malondialdehyde acetaldehyde (MAA)-modified low-density lipoprotein. Sequence analysis reveals high homology with germline genes, suggesting that they are natural. Further investigation shows that the MAA-specific natural IgG Abs cross-react with the major periodontal pathogen Porphyromonas gingivalis and recognise its principle virulence factors gingipain Kgp and long fimbriae. The study provides evidence that natural IgGs may play an important role in innate immune defence and in regulation of tissue homeostasis by recognising and removing invading pathogens and/or modified self-Ags, thus being involved in the development of periodontitis and atherosclerosis.

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Innate immunity and the pneumococcus

Microbiology ◽

10.1099/mic.0.28551-0 ◽

2006 ◽

Vol 152 (2) ◽

pp. 285-293 ◽

Cited By ~ 52

Author(s):

Gavin K. Paterson ◽

Tim J. Mitchell

Keyword(s):

Innate Immunity ◽

Immune System ◽

Streptococcus Pneumoniae ◽

Immune Responses ◽

Innate Immune System ◽

Innate Immune ◽

First Line ◽

Adaptive Immune Responses ◽

Adaptive Immune ◽

Made In

The innate immune system provides a non-specific first line of defence against microbes and is crucial both in the development and effector stages of subsequent adaptive immune responses. Consistent with its importance, study of the innate immune system is a broad and fast-moving field. Here we provide an overview of the recent key advances made in this area with relation to the important pathogen Streptococcus pneumoniae (the pneumococcus).

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Therapeutic Interventions into Innate Immune Diseases by Means of Aptamers

Pharmaceutics ◽

10.3390/pharmaceutics12100955 ◽

2020 ◽

Vol 12 (10) ◽

pp. 955

Author(s):

Farzana Yasmeen ◽

Hana Seo ◽

Nasir Javaid ◽

Moon Suk Kim ◽

Sangdun Choi

Keyword(s):

Pattern Recognition ◽

Immune System ◽

Crucial Role ◽

Innate Immune System ◽

Innate Immune ◽

Therapeutic Interventions ◽

Immune System Diseases ◽

Target Molecules ◽

Molecular Patterns ◽

Recognition Receptor

The immune system plays a crucial role in the body’s defense system against various pathogens, such as bacteria, viruses, and parasites, as well as recognizes non-self- and self-molecules. The innate immune system is composed of special receptors known as pattern recognition receptors, which play a crucial role in the identification of pathogen-associated molecular patterns from diverse microorganisms. Any disequilibrium in the activation of a particular pattern recognition receptor leads to various inflammatory, autoimmune, or immunodeficiency diseases. Aptamers are short single-stranded deoxyribonucleic acid or ribonucleic acid molecules, also termed “chemical antibodies,” which have tremendous specificity and affinity for their target molecules. Their features, such as stability, low immunogenicity, ease of manufacturing, and facile screening against a target, make them preferable as therapeutics. Immune-system–targeting aptamers have a great potential as a targeted therapeutic strategy against immune diseases. This review summarizes components of the innate immune system, aptamer production, pharmacokinetic characteristics of aptamers, and aptamers related to innate-immune-system diseases.

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Peptidoglycan O-Acetylation as a Virulence Factor: Its Effect on Lysozyme in the Innate Immune System

Antibiotics ◽

10.3390/antibiotics8030094 ◽

2019 ◽

Vol 8 (3) ◽

pp. 94 ◽

Cited By ~ 6

Author(s):

Ashley S. Brott ◽

Anthony J. Clarke

Keyword(s):

Immune System ◽

Virulence Factor ◽

Innate Immune System ◽

Innate Immune ◽

Host Immune System ◽

Gram Negative Bacteria ◽

First Line ◽

Structural Support ◽

Important Virulence Factor ◽

Novel Target

The peptidoglycan sacculus of both Gram-positive and Gram-negative bacteria acts as a protective mesh and provides structural support around the entirety of the cell. The integrity of this structure is of utmost importance for cell viability and so naturally is the first target for attack by the host immune system during bacterial infection. Lysozyme, a muramidase and the first line of defense of the innate immune system, targets the peptidoglycan sacculus hydrolyzing the β-(1→4) linkage between repeating glycan units, causing lysis and the death of the invading bacterium. The O-acetylation of N-acetylmuramoyl residues within peptidoglycan precludes the productive binding of lysozyme, and in doing so renders it inactive. This modification has been shown to be an important virulence factor in pathogens such as Staphylococcus aureus and Neisseria gonorrhoeae and is currently being investigated as a novel target for anti-virulence therapies. This article reviews interactions made between peptidoglycan and the host immune system, specifically with respect to lysozyme, and how the O-acetylation of the peptidoglycan interrupts these interactions, leading to increased pathogenicity.

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Diverse Functions of Pulmonary Collectins in Host Defense of the Lung

Journal of Biomedicine and Biotechnology ◽

10.1155/2012/532071 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 22

Author(s):

Shigeru Ariki ◽

Chiaki Nishitani ◽

Yoshio Kuroki

Keyword(s):

Pattern Recognition ◽

Growth Inhibition ◽

Host Defense ◽

Pulmonary Surfactant ◽

Inflammatory Responses ◽

Biological Activities ◽

Innate Immune ◽

The Other ◽

Surfactant Proteins ◽

Specific Proteins

Pulmonary surfactant is a mixture of lipids and proteins that covers alveolar surfaces and keeps alveoli from collapsing. Four specific proteins have been identified in surfactant. Among them, two C-type lectins, surfactant proteins A and D (SP-A and SP-D), are known to be implicated in host defense and regulation of inflammatory responses of the lung. These host defense lectins are structurally characterized by N-terminal collagen-like domains and lectin domains and are called pulmonary collectins. They prevent dissemination of infectious microbes by their biological activities including agglutination and growth inhibition. They also promote clearance of microbes by enhancing phagocytosis in macrophages. In addition, they interact with the other pattern-recognition molecules, including Toll-like receptors (TLRs) and TLR-associated molecules, CD14 and MD-2, and regulate inflammatory responses. Furthermore, recent studies have demonstrated that these collectins modulate functions of neutrophil-derived innate immune molecules by interacting with them. These findings indicate that pulmonary collectins play critical roles in host defense of the lung.

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Ex Vivo Cytokine Release and Pattern Recognition Receptor Expression of Subjects Exposed to Dampness: Pilot Study to Assess the Outcome of Mould Exposure to the Innate Immune System

PLoS ONE ◽

10.1371/journal.pone.0082734 ◽

2013 ◽

Vol 8 (12) ◽

pp. e82734 ◽

Cited By ~ 5

Author(s):

Stefanie Punsmann ◽

Verena Liebers ◽

Anne Lotz ◽

Thomas Brüning ◽

Monika Raulf

Keyword(s):

Pattern Recognition ◽

Immune System ◽

Pilot Study ◽

Innate Immune System ◽

Ex Vivo ◽

Pattern Recognition Receptor ◽

Innate Immune ◽

Receptor Expression ◽

Cytokine Release ◽

Recognition Receptor

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Four Reasons to Consider a Novel Class of Innate Immune Molecules in the Oral Epithelium

Journal of Dental Research ◽

10.1177/154405910308201202 ◽

2003 ◽

Vol 82 (12) ◽

pp. 944-950 ◽

Cited By ~ 29

Author(s):

E.E. LeClair

Keyword(s):

Host Defense ◽

Innate Immune System ◽

Physiological Response ◽

Three Dimensional ◽

Innate Immune ◽

Oral Epithelium ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Defense Protein ◽

Lines Of Evidence

An expanding number of innate immune molecules occupy the “epithelial frontier”. This review introduces a recently recognized class of mammalian proteins with similarity to PLUNC (palate, lung and nasal epithelium clone), which is itself related to the host defense protein BPI (bactericidal/permeability-increasing protein). Four emerging lines of evidence unite the PLUNC-like proteins: conserved genetic structure, epithelial expression, three-dimensional protein similarity, and a physiological response to injury or inflammation. By analogy to known proteins of the innate immune system, an emerging hypothesis for this family is that they act as sensors of Gram-negative bacteria in the oral cavity, among other areas.

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