Rotavirus NSP4 Triggers Secretion of Proinflammatory Cytokines from Macrophages via Toll-Like Receptor 2

The synergy of recombinant NSP4 and VP4 from porcine rotavirus elicited a strong mucosal response

Porcine rotavirus (PoRV) is one of the main pathogens causing diarrhea in piglets, and multiple genotypes coexist. However, an effective vaccine is currently lacking. Here, the potential adjuvant of nonstructural protein 4 (NSP4) and highly immunogenic structural protein VP4 prompted us to construct recombinant NSP486-175aa (NSP4*) and VP426-476aa (VP4*) proteins, combine them as immunogens to evaluate their efficacy. Results indicated that NSP4* enhanced systemic and local mucosal responses induced by VP4*. The VP4*-IgG, VP4*-IgA in feces and IgA-secreting cells in intestines induced by the co-immunization were significantly higher than those induced by VP4* alone. Co-immunization of NSP4* and VP4* also induced strong cellular immunity with significantly increased IFN-λ than the single VP4*. Summarily, the NSP4* as a synergistical antigen exerted limited effects on the PoRV NAbs elevation, but conferred strong VP4*-specific mucosal and cellular efficacy, which lays the foundation for the development of a more effective porcine rotavirus subunit vaccine.

Rotavirus non-structural protein 4 usurps host cellular RIPK1-RIPK3 complex to induce MLKL-dependent necroptotic cell death

The dynamic interface between invading viral pathogens and programmed cell death (PCD) of the host is a finely regulated process. Host cellular demise at the end of the viral life cycle ensures the release of progeny virions to initiate new infection cycles. Rotavirus (RV), a diarrheagenic virus with double-stranded RNA genome, has been reported to trigger different types of PCD such as apoptosis and pyroptosis in a highly regulated way to successfully disseminate progeny virions. Recently our lab also showed that induction of MLKL-driven programmed necroptosis by RV. However, the host cellular machinery involved in RV-induced necroptosis and the upstream viral trigger responsible for it remained unaddressed. In the present study, the signalling upstream of MLKL-driven necroptosis has been delineated where the involvement of Receptor interacting serine/threonine kinase 3 (RIPK3) and 1 (RIPK1) from the host side and RV non-structural protein 4 (NSP4) as the viral trigger for necroptosis has been shown. Interestingly, RV-NSP4 was found to be an integral component of the necrosome complex by interacting with RIPK1, thereby bypassing the requirement of RIPK1 kinase activity. Subsequently, NSP4-driven elevated cytosolic Ca2+ concentration and Ca2+-binding to NSP4 lead further to RHIM domain-dependent RIPK1-RIPK3 interaction, RIPK3-dependent MLKL phosphorylation, and eventual necroptosis. Overall, this study presents the interplay between RV-NSP4 and the host cellular necrosome complex to induce necroptotic death of host cells.

Identification and functional analysis of Toll-like receptor 2 from razor clam Sinonovacula constricta

Toll-like receptor 2 (TLR2) is a member of TLR family that plays important roles in the innate immune system, such as pathogen recognition and inflammation regulation. In this study, the TLR2 homologue was cloned from razor clam Sinonovacula constricta (denoted as ScTLR2) and its immune function was explored. The full-length cDNA of ScTLR2 comprised 2890 nucleotides with a 5'-UTR of 218 bp, an open reading frame of 2169 bp encoding 722 amino acids and a 3'-UTR of 503 bp. The deduced amino acid of ScTLR2 showed similar structure to TLR2 homologue with a conserved signal peptide, four LRR domains, one LRR-TYP domain, one LRR-CT domain, one transmembrane domain and a conserved TIR domain. ScTLR2 mRNA was detected in all examined tissues with the highest expression in the gill. After Vibrio parahaemolyticus challenge, the mRNA expression of ScTLR2 was significantly induced both in gill and haemocytes. The recombinant ScTLR2-LRR protein could bind all tested PAMPs including LPS, PGN and MAN. Bacterial agglutination assay showed that rScTLR2 could agglutinate the six tested bacteria with a calcium dependent manner. More importantly, ScTLR2 silencing by siRNA transfection could significantly depress the mRNA expression of Myd88, NF-κB, Tollip, IRF1, and IRF8. The survival rate of S. constricta was markedly decreased after V. parahaemolyticus challenge under this condition. Our current study demonstrated that ScTLR2 served as a pattern recognition receptor to induce immune response against invasive pathogen.

Network pharmacology, computational biology integrated surface plasmon resonance technology reveals the mechanism of ellagic acid against rotavirus

The target and mechanism of ellagic acid (EA) against rotavirus (RV) were investigated by network pharmacology, computational biology, and surface plasmon resonance verification. The target of EA was obtained from 11 databases such as HIT and TCMSP, and RV-related targets were obtained from the Gene Cards database. The relevant targets were imported into the Venny platform to draw a Venn diagram, and their intersections were visualized. The protein-protein interaction networks (PPI) were constructed using STRING, DAVID database, and Cytoscape software, and key targets were screened. The target was enriched by Gene Ontology (GO) and KEGG pathway, and the 'EA anti-RV target-pathway network' was constructed. Schrodinger Maestro 13.5 software was used for molecular docking to determine the binding free energy and binding mode of ellagic acid and target protein. The Desmond program was used for molecular dynamics simulation. Saturation mutagenesis analysis was performed using Schrodinger's Maestro 13.5 software. Finally, the affinity between ellagic acid and TLR4 protein was investigated by surface plasmon resonance (SPR) experiments. The results of network pharmacological analysis showed that there were 35 intersection proteins, among which Interleukin-1β (IL-1β), Albumin (ALB), Nuclear factor kappa-B1 (NF-κB1), Toll-Like Receptor 4 (TLR4), Tumor necrosis factor alpha (TNF-α), Tumor protein p53 (TP53), Recombinant SMAD family member 3 (SAMD3), Epidermal growth factor (EGF) and Interleukin-4 (IL-4) were potential core targets of EA anti-RV. The GO analysis consists of biological processes (BP), cellular components (CC), and molecular functions (MF). The KEGG pathways with the highest gene count were mainly related to enteritis, cancer, IL-17 signaling pathway, and MAPK signaling pathway. Based on the crystal structure of key targets, the complex structure models of TP53-EA, TLR4-EA, TNF-EA, IL-1β-EA, ALB-EA, NF-κB1-EA, SAMD3-EA, EGF-EA, and IL-4-EA were constructed by molecular docking (XP mode of flexible docking). The MMGBS analysis and molecular dynamics simulation were also studied. The Δaffinity of TP53 was highest in 220 (CYS → TRP), 220 (CYS → TYR), and 220 (CYS → PHE), respectively. The Δaffinity of TLR4 was highest in 136 (THR → TYR), 136 (THR → PHE), and 136 (THR → TRP). The Δaffinity of TNF-α was highest in 150 (VAL → TRP), 18 (ALA → GLU), and 144 (PHE → GLY). SPR results showed that ellagic acid could bind TLR4 protein specifically. TP53, TLR4, and TNF-α are potential targets for EA to exert anti-RV effects, which may ultimately provide theoretical basis and clues for EA to be used as anti-RV drugs by regulating TLR4/NF-κB related pathways.

Immunogenicity of bacteriophages

Hundreds of trillions of diverse bacteriophages (phages) peacefully thrive within and on the human body. However, whether and how phages influence their mammalian hosts is poorly understood. In this review, we explore current knowledge and present growing evidence that direct interactions between phages and mammalian cells often induce host inflammatory and antiviral immune responses. We show evidence that, like viruses of the eukaryotic host, phages are actively internalized by host cells and activate conserved viral detection receptors. This interaction often generates proinflammatory cytokine secretion and recruitment of adaptive immune programs. However, significant variability exists in phage-immune interactions, suggesting an important role for structural phage characteristics. The factors leading to the differential immunogenicity of phages remain largely unknown but are highly influenced by their human and bacterial hosts.

Cell membrane-bound toll-like receptor-1/2/4/6 monomers and -2 heterodimer inhibit enterovirus 71 replication by activating the antiviral innate response

Host immune activation is critical for enterovirus 71 (EV71) clearance and immunopathogenesis. However, the mechanism of innate immune activation, especially of cell membrane-bound toll-like receptors (TLRs), against EV71 remains unknown. We previously demonstrated that TLR2 and its heterodimer inhibit EV71 replication. In this study, we systematically investigated the effects of TLR1/2/4/6 monomers and TLR2 heterodimer (TLR2/TLR1, TLR2/TLR6, and TLR2/TLR4) on EV71 replication and innate immune activation. We found that the overexpression of human- or mouse-derived TLR1/2/4/6 monomers and TLR2 heterodimer significantly inhibited EV71 replication and induced the production of interleukin (IL)-8 via activation of the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) and mitogen-activated protein kinase (MAPK) pathways. Furthermore,human-mouse chimeric TLR2 heterodimer inhibited EV71 replication and activated innate immunity. Dominant-negative TIR-less (DN)-TLR1/2/4/6 did not exert any inhibitory effects, whereas DN-TLR2 heterodimer inhibited EV71 replication. Prokaryotic expression of purified recombinant EV71 capsid proteins (VP1, VP2, VP3, and VP4) or overexpression of EV71 capsid proteins induced the production of IL-6 and IL-8 via activation of the PI3K/AKT and MAPK pathways. Notably, two types of EV71 capsid proteins served as pathogen-associated molecular patterns for TLR monomers (TLR2 and TLR4) and TLR2 heterodimer (TLR2/TLR1, TLR2/TLR6, and TLR2/TLR4) and activated innate immunity. Collectively, our results revealed that membrane TLRs inhibited EV71 replication via activation of the antiviral innate response, providing insights into the EV71 innate immune activation mechanism.

Scratching the Surface Takes a Toll: Immune Recognition of Viral Proteins by Surface Toll-like Receptors

Early innate viral recognition by the host is critical for the rapid response and subsequent clearance of an infection. Innate immune cells patrol sites of infection to detect and respond to invading microorganisms including viruses. Surface Toll-like receptors (TLRs) are a group of pattern recognition receptors (PRRs) that can be activated by viruses even before the host cell becomes infected. However, the early activation of surface TLRs by viruses can lead to viral clearance by the host or promote pathogenesis. Thus, a plethora of research has attempted to identify specific viral ligands that bind to surface TLRs and mediate progression of viral infection. Herein, we will discuss the past two decades of research that have identified specific viral proteins recognized by cell surface-associated TLRs, how these viral proteins and host surface TLR interactions affect the host inflammatory response and outcome of infection, and address why controversy remains regarding host surface TLR recognition of viral proteins.

Co-infection of porcine deltacoronavirus and porcine epidemic diarrhea virus induces early TRAF6-mediated NF-κB and IRF7 signaling pathways through TLRs

Porcine deltacoronavirus (PDCoV) and porcine epidemic diarrhea virus (PEDV) infect the small intestine and cause swine enteric coronavirus disease. The mucosal innate immune system is the first line of defense against viral infection. The modulatory effect of PDCoV and PEDV coinfection on antiviral signaling cascades of the intestinal mucosa has not been reported. Here, we investigate the gene expression levels of pattern recognition receptors, downstream inflammatory signaling pathway molecules, and associated cytokines on the intestinal mucosa of neonatal piglets either infected with a single- or co-infected with PDCoV and PEDV using real-time PCR. The results demonstrate that single-PEDV regulates the noncanonical NF-κB signaling pathway through RIG-I regulation. In contrast, single-PDCoV and PDCoV/PEDV coinfection regulate proinflammatory and regulatory cytokines through TRAF6-mediated canonical NF-κB and IRF7 signaling pathways through TLRs. Although PDCoV/PEDV coinfection demonstrated an earlier modulatory effect in these signaling pathways, the regulation of proinflammatory and regulatory cytokines was observed simultaneously during single viral infection. These results suggested that PDCoV/PEDV coinfection may have synergistic effects that lead to enhanced viral evasion of the mucosal innate immune response.

Rotavirus infection-associated central nervous system complications: clinicoradiological features and potential mechanisms

Despite the introduction of vaccines in 2006, rotavirus remains one of the most common causes of pediatric gastroenteritis worldwide. While many studies have conclusively shown that rotavirus infection causes gastroenteritis and is associated with various extraintestinal manifestations including central nervous system (CNS) complications, extraintestinal manifestations due to rotavirus infection have been relatively overlooked. Rotavirus infection-associated CNS complications are common in children and present with diverse clinicoradiological features. Rotavirus infection-associated CNS complications can be classified based on clinical features and brain magnetic resonance imaging findings, particularly lesion location on diffusion-weighted imaging. Common clinicoradiological features of rotavirus infection-associated CNS complications include: (1) benign convulsions with mild gastroenteritis; (2) acute encephalopathies/encephalitis, such as mild encephalopathy with a reversible splenial lesion, acute encephalopathy with biphasic seizures and late reduced diffusion, and acute necrotizing encephalopathy; (3) acute cerebellitis; and (4) neonatal rotavirus-associated leukoencephalopathy. The precise mechanism underlying the development of these complications remains unknown despite a number of clinical and laboratory studies. Here we review the diverse clinicoradiological features of rotavirus infection-associated CNS complications and propose a hypothesis of their pathophysiology.

Toll-like Receptor Mediation in SARS-CoV-2: A Therapeutic Approach

The innate immune system facilitates defense mechanisms against pathogen invasion and cell damage. Toll-like receptors (TLRs) assist in the activation of the innate immune system by binding to pathogenic ligands. This leads to the generation of intracellular signaling cascades including the biosynthesis of molecular mediators. TLRs on cell membranes are adept at recognizing viral components. Viruses can modulate the innate immune response with the help of proteins and RNAs that downregulate or upregulate the expression of various TLRs. In the case of COVID-19, molecular modulators such as type 1 interferons interfere with signaling pathways in the host cells, leading to an inflammatory response. Coronaviruses are responsible for an enhanced immune signature of inflammatory chemokines and cytokines. TLRs have been employed as therapeutic agents in viral infections as numerous antiviral Food and Drug Administration-approved drugs are TLR agonists. This review highlights the therapeutic approaches associated with SARS-CoV-2 and the TLRs involved in COVID-19 infection.

Evaluation of a bivalent recombinant vaccine candidate targeting norovirus and rotavirus: Antibodies to rotavirus NSP4 exert antidiarrheal effects without virus neutralization

We previously found that when tandemly expressed with S_R69A -VP8*, nonstructural protein 4 (NSP4) of the rotavirus Wa strain exerts a minor effect on elevating the antibody responses targeting the rotavirus antigen VP8* of the 60-valent nanoparticle S_R69A -VP8* but could fully protect mice from diarrhea induced by the rotavirus strain Wa. In this study, we chose comparably less immunogenic norovirus 24-valent P particles with homogenous (i.e., VP8* from rotavirus) and heterogeneous (i.e., protruding domain of norovirus) antigens and in more challenging rotavirus SA11 strain-induced diarrhea mouse models to evaluate its main role in recombinant gastroenteritis virus-specific vaccines. The results showed that although as an adjuvant NSP4 exerted limited effects on the elevation of norovirus-specific or VP8*-specific neutralizing antibody production, as an antigen it could confer potent protection, particularly when synergized with VP8*, in rotavirus SA11 strain-induced diarrhea mouse models, possibly blocking the invasion of the intestinal wall by enterotoxin. NSP4 may be unnecessary for other recombinant vaccines as adjuvants, and its display mode should be evaluated specifically to avoid blocking coexpressed antigens in the norovirus P particles. This article is protected by copyright. All rights reserved.

p38 activation and viral infection

Viruses completely rely on the energy and metabolic systems of host cells for life activities. Viral infections usually lead to cytopathic effects and host diseases. To date, there are still no specific clinical vaccines or drugs against most viral infections. Therefore, understanding the molecular and cellular mechanisms of viral infections is of great significance to prevent and treat viral diseases. A variety of viral infections are related to the p38 MAPK signalling pathway, and p38 is an important host factor in virus-infected cells. Here, we introduce the different signalling pathways of p38 activation and then summarise how different viruses induce p38 phosphorylation. Finally, we provide a general summary of the effect of p38 activation on virus replication. Our review provides integrated data on p38 activation and viral infections and describes the potential application of targeting p38 as an antiviral strategy.

Co-administration of rotavirus nanospheres VP6 and NSP4 proteins enhanced the anti-NSP4 humoral responses in immunized mice

Inconveniences associated with the efficacy and safety of the World Health Organization (WHO) approved/prequalified live attenuated rotavirus (RV) vaccines, sounded for finding alternative non-replicating modals and proper RV antigens (Ags). Herein, we report the development of a RV candidate vaccine based on the combination of RV VP6 nanospheres (S) and NSP4_112-175 proteins (VP6S + NSP4). Self-assembled VP6S protein was produced in insect cells. Analyses by western blotting and transmission electron microscopy (TEM) indicated expression of VP6 trimer structures with sizes of ≥140 kDa and presence of VP6S. Four group of mice were immunized (2-dose formulation) intra-peritoneally (IP) by either¨VP6S + NSP4¨ or each protein alone (VP6S or NSP4_112-175) emulsified in aluminium hydroxide or control. Results indicated that VP6S + NSP4 formulation induced significant anti-VP6 IgG (P < 0.001) and IgA (P < 0.05) as well as anti-NSP4 IgG (P < 0.001) and enhancement of protective immunity. Analyses of anti-VP6S and anti-NSP4 IgG subclass (IgG1 and IgG2a) showed IgG1/IgG2a ≥6 and IgG1/IgG2a ≥3 ratios, respectively indicating Th2 polarization of immune responses. The combination of VP6S + NSP4 proteins emulsified in aluminum hydroxide adjuvant might present a dual universal, efficient and cost-effective candidate vaccine against RV infection.

Immune Response to Viruses

Viruses are essentially, obligate intracellular parasites. They require a host to replicate their genetic material, spread to other cells, and eventually to other hosts. For humans, most viral infections are not considered lethal, regardless if at the cellular level, the virus can obliterate individual cells. Constant genomic mutations, (which can alter the antigenic content of viruses such as influenza or coronaviruses), zoonosis or immunosuppression/immunocompromisation, is when viruses achieve higher host mortality. Frequent examples of the severe consequenses of viral infection can be seen in children and the elderly. In most instances, the immune system will take a multifaceted approach in defending the host against viruses. Depending on the virus, the individual, and the point of entry, the immune system will initiate a robust response which involves multiple components. In this chapter, we expand on the total immune system, breaking it down to the two principal types: Innate and Adaptive Immunity, their different roles in viral recognition and clearance. Finally, how different viruses activate and evade different arms of the immune system.

Lactobacillus delbrueckii CRL 581 Differentially Modulates TLR3-Triggered Antiviral Innate Immune Response in Intestinal Epithelial Cells and Macrophages

Lactobacillus delbrueckii subsp. lactis CRL 581 beneficially modulates the intestinal antiviral innate immune response triggered by the Toll-like receptor 3 (TLR3) agonist poly(I:C) in vivo. This study aimed to characterize further the immunomodulatory properties of the technologically relevant starter culture L. delbrueckii subsp. lactis CRL 581 by evaluating its interaction with intestinal epithelial cells and macrophages in the context of innate immune responses triggered by TLR3. Our results showed that the CRL 581 strain was able to adhere to porcine intestinal epithelial (PIE) cells and mucins. The CRL 581 strain also augmented the expression of antiviral factors (IFN-α, IFN-β, Mx1, OAS1, and OAS2) and reduced inflammatory cytokines in PIE cells triggered by TLR3 stimulation. In addition, the influence of L. delbrueckii subsp. lactis CRL 581 on the response of murine RAW macrophages to the activation of TLR3 was evaluated. The CRL 581 strain was capable of enhancing the expression of IFN-α, IFN-β, IFN-γ, Mx1, OAS1, TNF-α, and IL-1β. Of note, the CRL 581 strain also augmented the expression of IL-10 in macrophages. The results of this study show that the high proteolytic strain L. delbrueckii spp. lactis CRL 581 was able to beneficially modulate the intestinal innate antiviral immune response by regulating the response of both epithelial cells and macrophages relative to TLR3 activation.

Transcriptome Analysis for Genes Associated with Small Ruminant Lentiviruses Infection in Goats of Carpathian Breed

Small ruminant lentiviruses (SRLV) are economically important viral pathogens of sheep and goats. SRLV infection may interfere in the innate and adaptive immunity of the host, and genes associated with resistance or susceptibility to infection with SRLV have not been fully recognized. The presence of animals with relatively high and low proviral load suggests that some host factors are involved in the control of virus replication. To better understand the role of the genes involved in the host response to SRLV infection, RNA sequencing (RNA-seq) method was used to compare whole gene expression profiles in goats carrying both a high (HPL) and low (LPL) proviral load of SRLV and uninfected animals. Data enabled the identification of 1130 significant differentially expressed genes (DEGs) between control and LPL groups: 411 between control and HPL groups and 1434 DEGs between HPL and LPL groups. DEGs detected between the control group and groups with a proviral load were found to be significantly enriched in several gene ontology (GO) terms, including an integral component of membrane, extracellular region, response to growth factor, inflammatory and innate immune response, transmembrane signaling receptor activity, myeloid differentiation primary response gene 88 (MyD88)-dependent toll-like receptor signaling pathway as well as regulation of cytokine secretion. Our results also demonstrated significant deregulation of selected pathways in response to viral infection. The presence of SRLV proviral load in blood resulted in the modification of gene expression belonging to the toll-like receptor signaling pathway, the tumor necrosis factor (TNF) signaling pathway, the cytokine-cytokine receptor interaction, the phagosome, the Ras signaling pathway, the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) (PI3K-Akt) signaling pathway and rheumatoid arthritis. It is worth mentioning that the most predominant in all pathways were genes represented by toll-like receptors, tubulins, growth factors as well as interferon gamma receptors. DEGs detected between LPL and HPL groups were found to have significantly enriched regulation of signaling receptor activity, the response to toxic substances, nicotinamide adenine dinucleotide (NADH) dehydrogenase complex assembly, cytokine production, vesicle, and vacuole organization. In turn, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway tool classified DEGs that enrich molecular processes such as B and T-cell receptor signaling pathways, natural killer cell-mediated cytotoxicity, Fc gamma R-mediated phagocytosis, toll-like receptor signaling pathways, TNF, mammalian target of rapamycin (mTOR) signaling and forkhead box O (Foxo) signaling pathways, etc. Our data indicate that changes in SRLV proviral load induced altered expression of genes related to different biological processes such as immune response, inflammation, cell locomotion, and cytokine production. These findings provide significant insights into defense mechanisms against SRLV infection. Furthermore, these data can be useful to develop strategies against SRLV infection by selection of animals with reduced SRLV proviral concentration that may lead to a reduction in the spread of the virus.

Ultraviolet radiation, vitamin D, and COVID-19

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has become pandemic on March 11^th, 2020. COVID-19 has a range of symptoms that includes fever, fatigue, dry cough, aches, and labored breathing to acute respiratory distress and possibly death. Health systems and hospitals have been completely rearranged since March 2020 in order to limit the high rate of virus spreading. Hence, a great debate on deferrable visits and treatments including phototherapy for skin diseases is developing. In particular, as regards phototherapy very few data are currently available regarding the chance to continue it, even if it may be a useful resource for treating numerous dermatological patients. However, phototherapy has an immunosuppressive action possibly facilitating virus infection. In the context of COVID-19 infection risk it is important to pointed out whether sunlight, phototherapy and in particular ultraviolet radiation (UV-R) constitute or not a risk for patients. In this review we aimed to focus on the relationship between UV-R, sunlight, phototherapy, and viral infections particularly focusing on COVID-19.

Rotavirus in Calves and Its Zoonotic Importance

Rotavirus is a major pathogen responsible for diarrheal disease in calves, resulting in loss of productivity and economy of farmers. However, various facets of diarrheal disease caused by rotavirus in calves in the world are inadequately understood, considering that diarrheal disease caused by rotavirus is a vital health problem in calves that interrupts production benefits with reduced weight gain and increased mortality, and its potential for zoonotic spread. The pathological changes made by rotavirus are almost exclusively limited to the small intestine that leads to diarrhea. It is environmentally distributed worldwide and was extensively studied. Reassortment is one of the important mechanisms for generating genetic diversity of rotaviruses and eventually for viral evolution. So, the primary strategy is to reduce the burden of rotavirus infections by practicing early colostrum's feeding in newborn calves, using vaccine, and improving livestock management. Rotaviruses have a wide host range, infecting many animal species as well as humans. As it was found that certain animal rotavirus strains had antigenic similarities to some human strains, this may be an indication for an animal to play a role as a source of rotavirus infection in humans. Groups A to C have been shown to infect both humans and animals. The most commonly detected strains in both human and animals are G2, G3, G4, and G9, P [6]. Therefore, this review was made to get overview epidemiology status and zoonotic importance of bovine rotavirus.

Neurosteroid allopregnanolone (3α,5α-THP) inhibits inflammatory signals induced by activated MyD88-dependent toll-like receptors

We have shown that endogenous neurosteroids, including pregnenolone and 3α,5α-THP inhibit toll-like receptor 4 (TLR4) signal activation in mouse macrophages and the brain of alcohol-preferring (P) rat, which exhibits innate TLR4 signal activation. The current studies were designed to examine whether other activated TLR signals are similarly inhibited by 3α,5α-THP. We report that 3α,5α-THP inhibits selective agonist-mediated activation of TLR2 and TLR7, but not TLR3 signaling in the RAW246.7 macrophage cell line. The TLR4 and TLR7 signals are innately activated in the amygdala and NAc from P rat brains and inhibited by 3α,5α-THP. The TLR2 and TLR3 signals are not activated in P rat brain and they are not affected by 3α,5α-THP. Co-immunoprecipitation studies indicate that 3α,5α-THP inhibits the binding of MyD88 with TLR4 or TLR7 in P rat brain, but the levels of TLR4 co-precipitating with TRIF are not altered by 3α,5α-THP treatment. Collectively, the data indicate that 3α,5α-THP inhibits MyD88- but not TRIF-dependent TLR signal activation and the production of pro-inflammatory mediators through its ability to block TLR-MyD88 binding. These results have applicability to many conditions involving pro-inflammatory TLR activation of cytokines, chemokines, and interferons and support the use of 3α,5α-THP as a therapeutic for inflammatory disease.

Hemagglutinin protein of Peste des Petits Ruminants virus (PPRV) activates the innate immune response via Toll-like receptor 2 signaling

The toll-like receptor (TLR) family comprises both cell-surface and intracellular receptors that recognize different types of pathogen-associated molecular patterns (PAMPs) leading to the production of pro-inflammatory cytokines and subsequent development of adaptive immunity. TLR2 is a cell-surface receptor initially thought to act as a bacterial sentinel but also shown to recognize a number of viral glycoproteins. In this study, we sought to characterize the role of TLR2 in the activation of the immune response by peste des petits ruminants virus (PPRV), a morbillivirus of the Paramixoviridae family that causes an acute, highly contagious disease in goats and sheep. Using human embryonic kidney (HEK) 293 cells stably expressing human (h)TLR2 but lacking any other TLR, we found that PPRV induces IL-8 production in a dose-dependent manner. That activation is only observed in cells expressing hTLR2 and is greatly reduced when the receptor is blocked by pretreatment with specific antibody. We identified hemagglutinin (H) as the viral protein responsible of TLR2 activation by performing the same assays with purified recombinant mammalian-expressed H protein. Exogenous addition of recombinant H protein to cell culture induces high levels of interleukin (IL)-8 only in TLR2-expressing cells. Moreover, H engagement on TLR2 in the monocytic cell line THP-1 activates extracellular-signal-regulated kinase (ERK) signaling. Stimulation of primary ovine dendritic cells with either inactivated PPRV or purified recombinant H protein results in transcription of pro-inflammatory cytokines and the secretion of the Th1-polarizing cytokine IL-12. The role of these host immune mechanisms in the control of PPR is discussed.

Effects of rotavirus NSP4 protein on the immune response and protection of the SR69A-VP8* nanoparticle rotavirus vaccine

Rotavirus causes severe diarrhea and dehydration in young children. Even with the implementation of the current live vaccines, rotavirus infections still cause significant mortality and morbidity, indicating a need for new rotavirus vaccines with improved efficacy. To this end, we have developed an SR69A-VP8*/S60-VP8* nanoparticle rotavirus vaccine candidate that will be delivered parenterally with Alum adjuvant. In this study, as parts of our further development of this nanoparticle vaccine, we evaluated 1) roles of rotavirus nonstructural protein 4 (NSP4) that is the rotavirus enterotoxin, a possible vaccine target, and an immune stimulator, and 2) effects of CpG adjuvant that is a toll-like receptor 9 (TLR9) ligand and agonist on the immune response and protection of our SR69A-VP8*/S60-VP8* nanoparticle vaccine. The resulted vaccine candidates were examined for their IgG responses in mice. In addition, the resulted mouse sera were assessed for i) blocking titers against interactions of rotavirus VP8* proteins with their glycan ligands, ii) neutralization titers against rotavirus replication in cell culture, and iii) passive protection against rotavirus challenge with diarrhea in suckling mice. Our data showed that the Alum adjuvant appeared to work better with the SR69A-VP8*/S60-VP8* nanoparticles than the CpG adjuvant, while an addition of the NSP4 antigen to the SR69A-VP8*/S60-VP8* vaccine may not help to further increase the immune response and protection of the resulted vaccine.

Immunological Aspects of Age-Related Macular Degeneration

Increasing evidence over the past two decades points to a pivotal role for immune mechanisms in age-related macular degeneration (AMD) pathobiology. In this chapter, we will explore immunological aspects of AMD, with a specific focus on how immune mechanisms modulate clinical phenotypes of disease and severity and how components of the immune system may serve as triggers for disease progression in both dry and neovascular AMD. We will briefly review the biology of the immune system, defining the role of immune mechanisms in chronic degenerative disease and differentiating from immune responses to acute injury or infection. We will explore current understanding of the roles of innate immunity (especially macrophages), antigen-specific immunity (T cells, B cells, and autoimmunity), immune amplifications systems, especially complement activity and the NLRP3 inflammasome, in the pathogenesis of both dry and neovascular AMD, reviewing data from pathology, experimental animal models, and clinical studies of AMD patients. We will also assess how interactions between the immune system and infectious pathogens could potentially modulate AMD pathobiology via alterations in in immune effector mechanisms. We will conclude by reviewing the paradigm of "response to injury," which provides a means to integrate various immunologic mechanisms along with nonimmune mechanisms of tissue injury and repair as a model to understand the pathobiology of AMD.

The Role of Toll-Like Receptors in Retroviral Infection

Toll-like receptors (TLRs) are key pathogen sensing receptors that respond to diverse microbial ligands, and trigger both innate and adaptive immune responses to infection. Since their discovery, a growing body of evidence has pointed to an important role for TLRs in retroviral infection and pathogenesis. These data suggest that multiple TLRs contribute to the anti-retroviral response, and that TLR engagement by retroviruses can have complex and divergent outcomes for infection. Despite this progress, numerous questions remain about the role of TLRs in retroviral infection. In this review, I summarize existing evidence for TLR-retrovirus interactions and the functional roles these receptors play in immunity and pathogenesis, with particular focus on human immunodeficiency virus (HIV).

Targeting Macrophages as a Therapeutic Option in Coronavirus Disease 2019

Immune cells of the monocyte/macrophage lineage are characterized by their diversity, plasticity, and variety of functions. Among them, macrophages play a central role in antiviral responses, tissue repair, and fibrosis. Macrophages can be reprogrammed by environmental cues, thus changing their phenotype during an antiviral immune response as the viral infection progresses. While M1-like macrophages are essential for the initial inflammatory responses, M2-like macrophages are critical for tissue repair after pathogen clearance. Numerous reports have evaluated the detrimental effects that coronaviruses, e.g., HCoV-229E, SARS-CoV, MERS-CoV, and SARS-CoV-2, have on the antiviral immune response and macrophage functions. In this review, we have addressed the breadth of macrophage phenotypes during the antiviral response and provided an overview of macrophage-coronavirus interactions. We also discussed therapeutic approaches to target macrophage-induced complications, currently under evaluation in clinical trials for coronavirus disease 2019 patients. Additionally, we have proposed alternative approaches that target macrophage recruitment, interferon signaling, cytokine storm, pulmonary fibrosis, and hypercoagulability.

Incomplete response to Anti-VEGF therapy in neovascular AMD: Exploring disease mechanisms and therapeutic opportunities

Intravitreal anti-vascular endothelial growth factor (VEGF) drugs have revolutionized the treatment of neovascular age-related macular degeneration (NVAMD). However, many patients suffer from incomplete response to anti-VEGF therapy (IRT), which is defined as (1) persistent (plasma) fluid exudation; (2) unresolved or new hemorrhage; (3) progressive lesion fibrosis; and/or (4) suboptimal vision recovery. The first three of these collectively comprise the problem of persistent disease activity (PDA) in spite of anti-VEGF therapy. Meanwhile, the problem of suboptimal vision recovery (SVR) is defined as a failure to achieve excellent functional visual acuity of 20/40 or better in spite of sufficient anti-VEGF treatment. Thus, incomplete response to anti-VEGF therapy, and specifically PDA and SVR, represent significant clinical unmet needs. In this review, we will explore PDA and SVR in NVAMD, characterizing the clinical manifestations and exploring the pathobiology of each. We will demonstrate that PDA occurs most frequently in NVAMD patients who develop high-flow CNV lesions with arteriolarization, in contrast to patients with capillary CNV who are highly responsive to anti-VEGF therapy. We will review investigations of experimental CNV and demonstrate that both types of CNV can be modeled in mice. We will present and consider a provocative hypothesis: formation of arteriolar CNV occurs via a distinct pathobiology, termed neovascular remodeling (NVR), wherein blood-derived macrophages infiltrate the incipient CNV lesion, recruit bone marrow-derived mesenchymal precursor cells (MPCs) from the circulation, and activate MPCs to become vascular smooth muscle cells (VSMCs) and myofibroblasts, driving the development of high-flow CNV with arteriolarization and perivascular fibrosis. In considering SVR, we will discuss the concept that limited or poor vision in spite of anti-VEGF may not be caused simply by photoreceptor degeneration but instead may be associated with photoreceptor synaptic dysfunction in the neurosensory retina overlying CNV, triggered by infiltrating blood-derived macrophages and mediated by Müller cell activation Finally, for each of PDA and SVR, we will discuss current approaches to disease management and treatment and consider novel avenues for potential future therapies.

Plant Viruses and Bacteriophage-Based Reagents for Diagnosis and Therapy

Viral nanotechnology exploits the prefabricated nanostructures of viruses, which are already abundant in nature. With well-defined molecular architectures, viral nanocarriers offer unprecedented opportunities for precise structural and functional manipulation using genetic engineering and/or bio-orthogonal chemistries. In this manner, they can be loaded with diverse molecular payloads for targeted delivery. Mammalian viruses are already established in the clinic for gene therapy and immunotherapy, and inactivated viruses or virus-like particles have long been used as vaccines. More recently, plant viruses and bacteriophages have been developed as nanocarriers for diagnostic imaging, vaccine and drug delivery, and combined diagnosis/therapy (theranostics). The first wave of these novel virus-based tools has completed clinical development and is poised to make an impact on clinical practice.

Khademul Islam AB. Perversely expressed long noncoding RNAs can alter host response and viral proliferation in SARS-CoV-2 infection

BACKGROUND

Regulatory roles of long noncoding RNAs (lncRNAs) during viral infection has become more evident in last decade, but are yet to be explored for SARS-CoV-2.

MATERIALS & METHODS

We analyzed RNA-seq dataset of SARS-CoV-2 infected lung epithelial cells to identify differentially expressed genes.

RESULTS

Our analyses uncover 21 differentially expressed lncRNAs broadly involved in cell survival and regulation of gene expression. These lncRNAs can directly interact with six differentially expressed protein-coding genes, and ten host genes that interact with SARS-CoV-2 proteins. Also, they can block the suppressive effect of nine microRNAs induced in viral infections.

CONCLUSION

Our investigation determines that deregulated lncRNAs in SARS-CoV-2 infection are involved in viral proliferation, cellular survival, and immune response, ultimately determining disease outcome.

BCG as a game-changer to prevent the infection and severity of COVID-19 pandemic?

The impact of COVID-19 is changing with country wise and depend on universal immunization policies. COVID-19 badly affects countries that did not have universal immunization policies or having them only for the selective population of countries (highly prominent population) like Italy, USA, UK, Netherland, etc. Universal immunization of BCG can provide great protection against the COVID-19 infection because the BCG vaccine gives broad protection against respiratory infections. BCG vaccine induces expressions of the gene that are involved in the antiviral innate immune response against viral infections with long-term maintenance of BCG vaccine-induced cellular immunity. COVID-19 cases are reported very much less in the countries with universal BCG vaccination policies such as India, Afghanistan, Nepal, Bhutan, Bangladesh, Israel, Japan, etc. as compared to without BCG implemented countries such as the USA, Italy, Spain, Canada, UK, etc. BCG vaccine provides protection for 50–60 years of immunization, so the elderly population needs to be revaccinated with BCG. Several countries started clinical trials of the BCG vaccine for health care workers and elderly people. BCG can be uses as a prophylactic treatment until the availability of the COVID-19 vaccine.

An alternative model for type I interferon induction downstream of human TLR2

Surface-exposed Toll-like receptors (TLRs) such as TLR2 and TLR4 survey the extracellular environment for pathogens. TLR activation initiates the production of various cytokines and chemokines, including type I interferons (IFN-I). Downstream of TLR4, IFNβ secretion is only vigorously triggered in macrophages when the receptor undergoes endocytosis and switches signaling adaptor; surface TLR4 engagement predominantly induces proinflammatory cytokines via the signaling adaptor MyD88. It is unclear whether this dichotomy is generally applicable to other TLRs, cell types, or differentiation states. Here, we report that diverse TLR2 ligands induce an IFN-I response in human monocyte-like cells, but not in differentiated macrophages. This TLR2-dependent IFN-I signaling originates from the cell surface and depends on MyD88; it involves combined activation of the transcription factors IRF3 and NF-κB, driven by the kinases TBK1 and TAK1-IKKβ, respectively. TLR2-stimulated monocytes produced modest IFNβ levels that caused productive downstream signaling, reflected by STAT1 phosphorylation and expression of numerous interferon-stimulated genes. Our findings reveal that the outcome of TLR2 signaling includes an IFN-I response in human monocytes, which is lost upon macrophage differentiation, and differs mechanistically from IFN-I-induction through TLR4. These findings point to molecular mechanisms tailored to the differentiation state of a cell and the nature of receptors activated to control and limit TLR-triggered IFN-I responses.

Bio-evaluation of the role of chitosan and curcumin nanoparticles in ameliorating genotoxicity and inflammatory responses in rats' gastric tissue followed hydroxyapatite nanoparticles' oral uptake

Hydroxyapatite has been extensively used in tissue engineering due to its osteogenic potency, but its present toxicological facts are relatively insufficient. Here, the possible gastric toxicity of hydroxyapatite nanoparticles was evaluated biochemically to determine oxidant and antioxidant parameters in rats' stomach tissues. At results, hydroxyapatite nanoparticles have declined stomach antioxidant enzymes and reduced glutathione level, while an induction in lipid peroxidation and nitric oxide has been observed. Furthermore, DNA oxidation was analyzed by the suppression of toll-like receptors 2, nuclear factor-kappa B and Forkhead box P3 gene expression and also 8-Oxo-2'-deoxyguanosine level as a genotoxicity indicator. Various pro-inflammatory gene products have been identified that intercede a vital role in proliferation and apoptosis suppression, among these products: tumor suppressor p53, tumor necrosis factor-α and interliukin-6. Moreover, the hydroxyapatite-treated group revealed wide histological alterations and significant elevation in the number of proliferating cell nuclear antigen-positive cells, which has been observed in the mucosal layer of the small intestine, and these alterations are an indication of small intestine injury, while the appearance of chitosan and curcumin nanoparticles in the combination group showed improvement in all the above parameters with inhibition of toxic-oxidant parameters and activation of antioxidant parameters.

Vero Cells as a Mammalian Cell Substrate for Human Norovirus

Human norovirus (HuNoV) is a principal cause of acute gastroenteritis worldwide, particularly in developing countries. Its global prevalence is underscored by more serious morbidity and some mortality in the young (<5 years) and the elderly. To date, there are no licensed vaccines or approved therapeutics for HuNoV, mostly because there are limited cell culture systems and small animal models available. Recently described cell culture systems are not ideal substrates for HuNoV vaccine development because they are not clonal or only support a single strain. In this study, we show Vero cell-based replication of two pandemic GII.4 HuNoV strains and one GII.3 strain and confirm exosome-mediated HuNoV infection in Vero cells. Lastly, we show that trypsin addition to virus cultures or disruption of Vero cell host genes can modestly increase HuNoV replication. These data provide support for Vero cells as a cell culture model for HuNoV.

The Role of Innate Immunity in Regulating Rotavirus Replication, Pathogenesis, and Host Range Restriction and the Implications for Live Rotaviral Vaccine Development

Rotaviruses (RVs) are important causative agents of viral gastroenteritis in the young of most mammalian species studied, including humans, in which they are the most important cause of severe gastroenteritis worldwide despite the availability of several safe and effective vaccines. Replication of RVs is restricted in a host species-specific manner, and this barrier is determined predominantly by the host interferon (IFN) signaling and the ability of different RV strains to successfully negate IFN activation and amplification pathways. In addition, viral attachment to the target intestinal epithelial cells also regulates host range restriction. Several studies have focused on the role of the innate immune response in regulating RV replication and pathogenesis. The knowledge accrued from these efforts is likely to result in rational attenuation of RV vaccines to closely match circulating (and host species-matched) virus strains. In this chapter, we review prevalent models of RV interactions with innate immune factors, viral strategies employed to regulate their function, and the implications of these findings for improved RV vaccine development.

Pathology of Rotavirus-driven Multiple Organ Failure in a 16-month-old Boy

Autopsy investigation of a fatal case of rotavirus severe acute gastroenteritis and multiple organ failure in a 16-month boy with previous intrauterine growth retardation showed colocalization of nonstructural and structural rotavirus proteins within viroplasms in nephrons. This case brings new insights into extraintestinal rotavirus infection and new clues to its abilities to bind to human histo-blood group antigens.

Viral Infections and the Neonatal Brain

This review includes the congenital infections best known by the acronym TORCH (Toxoplasma gondii, rubella virus, cytomegalovirus, and herpes virus), as well as Zika virus infection and perinatally acquired infections (enterovirus, parechovirus, rotavirus, parvovirus). Congenital infections are due to pathogens that can cross the placenta and are more likely to injure the brain when the infection occurs early in pregnancy. There are many similarities, with regards to brain lesions, for congenital Zika syndrome and congenital cytomegalovirus infection. Perinatally acquired viral infections tend to injure the white matter, with cystic evolution being more likely in the (late) preterm infant compared to the full-term infant. Congenital and perinatally acquired viral infections can be associated with adverse neurological outcomes. Prevention is important, especially as therapeutic options are limited. In this review both congenital as well as perinatally acquired viral infections will be discussed with a focus on neuro-imaging findings.

Oligosaccharides Modulate Rotavirus-Associated Dysbiosis and TLR Gene Expression in Neonatal Rats

Colonization of the gut in early life can be altered through multiple environmental factors. The present study aimed to investigate the effects of 2'-fucosyllactose (2'-FL), a mixture of short-chain galactooligosaccharides/long-chain fructooligosaccharides (scGOS/lcFOS) 9:1 and their combination (scGOS/lcFOS/2'-FL) on dysbiosis induced during rotavirus (RV) diarrhea in neonatal rats, elucidating crosstalk between bacteria and the immune system. The dietary interventions were administered daily by oral gavage at days 2-8 of life in neonatal Lewis rats. On day 5, RV SA11 was intragastrically delivered to induce infection and diarrhea assessment, microbiota composition, and gene expression of Toll-like receptors (TLRs) in the small intestine were studied. All dietary interventions showed reduction in clinical variables of RV-induced diarrhea. RV infection increased TLR2 expression, whereas 2'-FL boosted TLR5 and TLR7 expressions and scGOS/lcFOS increased that of TLR9. RV-infected rats displayed an intestinal dysbiosis that was effectively prevented by the dietary interventions, and consequently, their microbiota was more similar to microbiota of the noninfected groups. The preventive effect of 2'-FL, scGOS/lcFOS, and their combination on dysbiosis associated to RV diarrhea in rats could be due to changes in the crosstalk between gut microbiota and the innate immune system.

Immunobiotic Strains Modulate Toll-Like Receptor 3 Agonist Induced Innate Antiviral Immune Response in Human Intestinal Epithelial Cells by Modulating IFN Regulatory Factor 3 and NF-κB Signaling

Many studies have demonstrated that immunobiotics with immunoregulatory functions improve the outcomes of several bacterial and viral infections by modulating the mucosal immune system. However, the precise mechanisms underlying the immunoregulatory and antiviral activities of immunobiotics have not yet been elucidated in detail. The present study was conducted to determine whether selected lactic acid bacteria (LAB) modulate toll-like receptor 3 (TLR3) agonist polyinosinic:polycytidylic acid (PolyI:C) induced viral response in human intestinal epithelial cells (IECs). PolyI:C increased the expression of interferon-β (IFN-β), interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein (MCP-1), and interleukin-1β (IL-1β) in HCT116 cells, and these up-regulations were significantly altered when cells were pre-stimulated with LAB isolated from Korean fermented foods. LAB strains were capable to up-regulate IFN-β but down-regulated IL-6, IL-8, MCP-1, and IL-1β mRNA levels as compared with PolyI: C. HCT-116 cell treatment with LABs beneficially modulated the mRNA levels of C-X-C motif chemokine 10 (CXCL-10), 2-5A oligoadenylate synthetase 1 (OSA1), myxovirus resistance protein (MxA), TLR3, and retinoic acid inducible gene-I (RIG-I), and TLR negative regulators. In addition, LABs increased IFN-β, IFN-α, and interleukin-10 (IL-10) and decreased tumor necrosis factor-α (TNF-α) and IL-1β protein/mRNA levels in THP-1 cells. LABs also protected the cells by maintaining tight-junction proteins (zonula occludens-1 and occludin). The beneficial effects of these LABs were mediated via modulation of the interferon regulatory factor 3 (IRF3) and nuclear factor-kappa B (NF-κB) pathways. Overall, the results of this study indicate that immunobiotics have potent antiviral and anti-inflammatory activities that may use as antiviral substitutes for human and animal applications.

Physiology of Electrolyte Transport in the Gut: Implications for Disease

We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na⁺ /K⁺ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl^- channels and the basolateral Na⁺ -K⁺ -2Cl^- cotransporter, NKCC1 and K⁺ channels. Absorption chiefly involves apical membrane Na⁺ /H⁺ exchangers and Cl^- /HCO₃ ^- exchangers in the small intestine and proximal colon and Na⁺ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.

The Good, the Bad, and the Shocking: The Multiple Roles of Dengue Virus Nonstructural Protein 1 in Protection and Pathogenesis

Dengue virus (DENV) is the most prevalent medically important mosquito-borne virus in the world. Upon DENV infection of a host cell, DENV nonstructural protein 1 (NS1) can be found intracellularly as a monomer, associated with the cell surface as a dimer, and secreted as a hexamer into the bloodstream. NS1 plays a variety of roles in the viral life cycle, particularly in RNA replication and immune evasion of the complement pathway. Over the past several years, key roles for NS1 in the pathogenesis of severe dengue disease have emerged, including direct action of the protein on the vascular endothelium and triggering release of vasoactive cytokines from immune cells, both of which result in endothelial hyperpermeability and vascular leak. Importantly, the adaptive immune response generates a robust response against NS1, and its potential contribution to dengue vaccines is also discussed.

Tripartite motif-containing proteins precisely and positively affect host antiviral immune response

The tripartite motif-containing proteins (TRIMs) comprise a large family of proteins with over 70 members in humans. Recent studies have shown that TRIMs play unexpected roles in the antiviral immune responses to infections by HIV, MLV, EMCV, AIV and other viruses. There are two mechanisms used by TRIMs in the inhibition of virus infections: (1) TRIMs target the produced viruses for ubiquitination, which induces proteasome-dependent degradation, or they interact with host proteins to inhibit viral infection in various periods of the viral life cycle. (2) TRIMs activate innate immune signalling pathways, such as RLR and TLR, which induce IFN production. In this study, we will review recent studies regarding the means by which TRIMs function as inhibitors in viral infection through the mechanisms described above.

Clinical Findings and Neurologic Outcome in Neonatal Encephalopathy With White Matter Injury Accompanied by Rotavirus

Our objective was to elucidate the clinical characteristics and neurodevelopmental outcomes in neonatal encephalopathy with characteristic white matter injury as compared with other injury patterns on magnetic resonance diffusion-weighted imaging. We conducted a retrospective study comparing clinical and laboratory findings, and neurologic outcomes between 17 newborns with diffuse lesions in the periventricular white matter and white matter tract (group I) and 22 newborns with other patterns (group II). Stool samples indicated that 16 neonates (94.1%) in group I were rotavirus-positive, whereas none in group II had rotavirus infection. Significantly lower calcium levels were found in group I than in group II ( P < .001). Moreover, a more favorable neurodevelopmental outcome was observed in group I than in group II. This study suggests that characteristic white matter injury in neonatal encephalopathy may be related to decreased calcium levels induced by rotavirus, and may have a better neurodevelopmental prognosis than other causes.

Immunization of Mice by Rotavirus NSP4-VP6 Fusion Protein Elicited Stronger Responses Compared to VP6 Alone

Due to the limitations and safety issues of the two currently approved live attenuated rotavirus (RV) vaccines "RotaTeq and Rotarix," studies on nonreplicating sources of RV vaccines and search for proper RV antigens are actively carried out. The adjuvant activity of NSP4 and highly immunogenic properties of RV VP6 protein prompted us to consider the construction of a NSP4_112-175-VP6 fusion protein and to assess the anti-VP6 IgG, IgA, and IgG subclass responses induced by Escherichia coli-derived NSP4-VP6 fusion protein compared to that of VP6 protein with/without formulation in Montanide ISA 50V2 (M50) in BALB/c mice. Results indicated to the proper expression of the fused NSP4-VP6 and VP6 proteins in E. coli. Intraperitoneal immunization by M50 formulated NSP4-VP6 fusion protein (M5+NSP4-VP6) induced the highest titration of VP6-specific IgG and IgA responses compared to the other groups. Indeed, the presence of NSP4 resulted to the induction of stronger humoral immune responses against the fused protein compared to that elicited by administration of VP6 protein alone (with/without M50 formulation), implying the adjuvant properties of NSP4 for the fused protein. Moreover, the "M50+NSP4-VP6" formulation induced higher serum IgG2a titers than IgG1 and increased Interferon-γ levels, despite unchanged interleukin-4 amounts compared to other groups, indicating Th1-oriented responses with a possible role of NSP4. In conclusion, this study further highlights the potentiality of NSP4-VP6 fusion protein as an efficient and cost-effective immunogen in the field of RV vaccine development.

TLR2/MyD88 pathway-dependent regulation of dendritic cells by dengue virus promotes antibody-dependent enhancement via Th2-biased immunity

Possible risk mediators in primary dengue virus (DenV) infection that favor secondary DenV infection to life-threatening dengue hemorrhagic fever (DHF) and shock syndrome (DSS) via antibody-dependent enhancement (ADE) have not yet been described. Here, DenV infection enhanced the expression of inflammatory mediators and activation molecules in dendritic cells (DCs) through TLR2/MyD88 pathway. TLR2 appeared to facilitate DenV infection in DCs that were less permissive than macrophages for viral replication. In experiments using separate evaluations of DenV-infected and uninfected bystander DCs, infected DCs showed impaired maturation accompanied with TLR2-dependent production of inflammatory cytokines, by which uninfected bystander DCs showed increased expression of co-stimulatory molecules. Differential phosphorylation of MAPK and STAT3 was also detected between DenV-infected and uninfected DCs. Furthermore, DenV infection stimulated Th2-polarized humoral and cellular immunity against foreign and DenV Ag via TLR2/MyD88 pathway, and DenV-infected DCs were revealed to facilitate Th2-biased immune responses in TLR2-dependent manner. TLR2/MyD88-mediated Th2-biased Ab responses to primary DenV infection increased the infectivity of secondary homotypic or heterotypic DenV via ADE. Collectively, these results indicate that TLR2/MyD88 pathway in DC-priming receptors can drive Th2-biased immune responses during primary DenV infection, which could favor secondary DenV infection to DHF/DSS via ADE.

Cellular RNA Helicase DDX1 Is Involved in Transmissible Gastroenteritis Virus nsp14-Induced Interferon-Beta Production

Transmissible gastroenteritis virus (TGEV), an enteropathogenic coronavirus (CoV) of porcine, causes lethal watery diarrhea and severe dehydration in piglets and leads to severe economic losses in the swine industry. Unlike most CoVs that antagonize type I interferon (IFN) production, previous studies showed that TGEV infection induces IFN-I production both in vivo and in vitro. However, the underlying mechanism(s) remain largely unknown. In this study, we found that TGEV infection significantly facilitated IFN-β production as well as activation of the transcription factors IFN regulatory factor 3 (IRF3) and nuclear factor-kappaB (NF-κB) in porcine kidney (PK-15) cells. Screening of TGEV-encoded proteins demonstrated that non-structural protein 14 (nsp14) was the most potent IFN-β inducer and induced IFN-β production mainly by activating NF-κB but not IRF3. Further analysis showed that nsp14 interacted with DDX1, a member of the DExD/H helicase family. Knockdown of DDX1 by specific small interfering RNA (siRNA) significantly decreased nsp14-induced IFN-β production and NF-κB activation. Furthermore, TGEV-induced IFN-β production and IFN-stimulated gene (ISG) expression were decreased in cells transfected with DDX1-specific siRNA, indicating the vital role of DDX1 to TGEV-induced IFN-β responses. In summary, our data revealed a potential coactivator role of host RNA helicase DDX1 to the induction of IFN-β response initiated by TGEV and demonstrated that nsp14 is an important IFN inducer among the TGEV-encoded proteins.

Exopolysaccharides from Lactobacillus delbrueckii OLL1073R-1 modulate innate antiviral immune response in porcine intestinal epithelial cells

Previous studies demonstrated that the extracellular polysaccharides (EPSs) produced by Lactobacillus delbrueckii OLL1073R-1 (LDR-1) improve antiviral immunity, especially in the systemic and respiratory compartments. However, it was not studied before whether those EPSs are able to beneficially modulate intestinal antiviral immunity. In addition, LDR-1-host interaction has been evaluated mainly with immune cells while its interaction with intestinal epithelial cells (IECs) was not addressed before. In this work, we investigated the capacity of EPSs from LDR-1 to modulate the response of porcine IECs (PIE cells) to the stimulation with the Toll-like receptor (TLR)-3 agonist poly(I:C) and the role of TLR2, TLR4, and TLR negative regulators in the immunoregulatory effect. We showed that innate immune response triggered by TLR3 activation in porcine IECs was differentially modulated by EPS from LDR-1. EPSs treatment induced an increment in the expression of interferon (IFN)-α and IFN-β in PIE cells after the stimulation with poly(I:C) as well as the expression of the antiviral factors MxA and RNase L. Those effects were related to the reduced expression of A20 in EPS-treated PIE cells. EPS from LDR-1 was also able to reduce the expression of IL-6 and proinflammatory chemokines. Although further in vivo studies are needed, our results suggest that these EPSs or a yogurt fermented with LDR-1 have potential to improve intestinal innate antiviral response and protect against intestinal viruses.

Immunomodulatory potential of β-glucan as supportive treatment in porcine rotavirus enteritis

A non-blinded randomized clinical trial was conducted to assess the immunomodulatory potential of β-glucan (BG) in piglet diarrhoea associated with type A rotavirus infection. A total of 12 rotavirus-infected diarrheic piglets were randomly divided into two groups: wherein six rotavirus-infected piglets were treated with supportive treatment (ST) and other six rotavirus-infected piglets were treated with BG along with ST (ST-BG). Simultaneously, six healthy piglets were also included in the study which served as control. In rotavirus-infected piglets, marked increase of Intestinal Fatty Acid Binding Protein-2 (I-FABP2), nitric oxide (NOx), Interferon-γ (IFN-γ) concentrations and decrease of immunoglobulin G (IgG) were noticed compared to healthy piglets. The faecal consistency and dehydration scores were significantly higher in rotavirus-infected piglets than healthy piglets. The ST-BG treatment progressively reduced the I-FABP2 and increased the IgG concentrations over the time in rotavirus-infected piglets compared to piglets received only ST. A pronounced enhancement of NOx and IFN-γ concentrations was observed initially on day 3 and thereafter the values reduced on day 5 in ST-BG treated piglets in comparison to piglets which received only ST. Additionally, ST-BG treatment significantly reduced faecal consistency and dehydration scores on day 3 compared to ST in rotavirus-infected piglets. These findings point that BG represents a potential additional therapeutic option to improve the health condition and reduce the piglet mortality from rotavirus associated diarrhoea where porcine rotavirus vaccine is not available.

Activation of COX-2/PGE2 Promotes Sapovirus Replication via the Inhibition of Nitric Oxide Production

Enteric caliciviruses in the genera Norovirus and Sapovirus are important pathogens that cause severe acute gastroenteritis in both humans and animals. Cyclooxygenases (COXs) and their final product, prostaglandin E₂ (PGE₂), are known to play important roles in the modulation of both the host response to infection and the replicative cycles of several viruses. However, the precise mechanism(s) by which the COX/PGE₂ pathway regulates sapovirus replication remains largely unknown. In this study, infection with porcine sapovirus (PSaV) strain Cowden, the only cultivable virus within the genus Sapovirus, markedly increased COX-2 mRNA and protein levels at 24 and 36 h postinfection (hpi), with only a transient increase in COX-1 levels seen at 24 hpi. The treatment of cells with pharmacological inhibitors, such as nonsteroidal anti-inflammatory drugs or small interfering RNAs (siRNAs) against COX-1 and COX-2, significantly reduced PGE₂ production, as well as PSaV replication. Expression of the viral proteins VPg and ProPol was associated with activation of the COX/PGE₂ pathway. We observed that pharmacological inhibition of COX-2 dramatically increased NO production, causing a reduction in PSaV replication that could be restored by inhibition of nitric oxide synthase via the inhibitor N-nitro-l-methyl-arginine ester. This study identified a pivotal role for the COX/PGE₂ pathway in the regulation of NO production during the sapovirus life cycle, providing new insights into the life cycle of this poorly characterized family of viruses. Our findings also reveal potential new targets for treatment of sapovirus infection.

IMPORTANCE

Sapoviruses are among the major etiological agents of acute gastroenteritis in both humans and animals, but little is known about sapovirus host factor requirements. Here, using only cultivable porcine sapovirus (PSaV) strain Cowden, we demonstrate that PSaV induced the vitalization of the cyclooxygenase (COX) and prostaglandin E₂ (PGE₂) pathway. Targeting of COX-1/2 using nonsteroidal anti-inflammatory drugs (NSAIDs) such as the COX-1/2 inhibitor indomethacin and the COX-2-specific inhibitors NS-398 and celecoxib or siRNAs targeting COXs, inhibited PSaV replication. Expression of the viral proteins VPg and ProPol was associated with activation of the COX/PGE₂ pathway. We further demonstrate that the production of PGE₂ provides a protective effect against the antiviral effector mechanism of nitric oxide. Our findings uncover a new mechanism by which PSaV manipulates the host cell to provide an environment suitable for efficient viral growth, which in turn can be a new target for treatment of sapovirus infection.

Benign convulsions in children with mild gastroenteritis

BACKGROUND

Benign convulsions with mild gastroenteritis (CwG) is a clinical condition characterized by convulsions occurring in otherwise healthy children, usually in the absence of fever and in the presence of mild acute gastroenteritis. Until now, CwG had not been fully recognized as an epileptic syndrome, and several aspects of this condition are not clearly defined, especially its pathogenesis.

METHODS

The main aim of this paper is to discuss after the review of the literature what is known about CwG to facilitate its recognition and treatment.

RESULTS

CwG is a benign condition that has several clinical and prognostic similarities with febrile seizures. The disease occurs in infants and in children who are 1 month to 3 years old, during the winter and early spring when rotavirus and norovirus are circulating. In most cases, seizures follow gastrointestinal symptoms. In a minority of patients, the seizures and gastrointestinal symptoms occur before or simultaneously with the development of diarrhoea. Even if convulsions are mostly described as generalized tonic-clonic, the ictal recordings have always demonstrated a focal origin. Electroencephalography, lumbar punctures, and radiological examinations are not useful because they are normal in these patients; and when alterations are present, they disappear in a relatively short time. Only prolonged seizures, which are usually not common, require antiepileptic treatments in the acute phase.

CONCLUSION

Knowledge of CwG characteristics is essential for paediatricians to avoid useless hospitalization, examinations and, above all, drug administration, as the drugs have potential side effects.