Fucoidan from Ascophyllum nodosum and Undaria pinnatifida attenuate SARS-CoV-2 infection in vitro and in vivo by suppressing ACE2 and alleviating inflammation

The global healthcare challenge posed by COVID-19 necessitates the continuous exploration for novel antiviral agents. Fucoidans have demonstrated antiviral activity. However, the underlying structure-activity mechanism responsible for the inhibitory activity of fucoidans from Ascophyllum nodosum (FUCA) and Undaria pinnatifida (FUCU) against SARS-CoV-2 remains unclear. FUCA was characterized as a homopolymer with a backbone structure of repeating (1 → 3) and (1 → 4) linked α-l-fucopyranose residues, whereas FUCU was a heteropolysaccharide composed of Fuc1-3Gal1-6 repeats. Furthermore, FUCA demonstrated significantly higher anti-SARS-CoV-2 activity than FUCU (EC50: 48.66 vs 69.52 μg/mL), suggesting the degree of branching rather than sulfate content affected the antiviral activity. Additionally, FUCA exhibited a dose-dependent inhibitory effect on ACE2, surpassing the inhibitory activity of FUCU. In vitro, both FUCA and FUCU treatments downregulated the expression of pro-inflammatory cytokines (IL-6, IFN-α, IFN-γ, and TNF-α) and anti-inflammatory cytokines (IL-10 and IFN-β) induced by viral infection. In hamsters, FUCA demonstrated greater effectiveness in attenuating lung and gastrointestinal injury and reducing ACE2 expression, compared to FUCU. Analysis of the 16S rRNA gene sequencing revealed that only FUCU partially alleviated the gut microbiota dysbiosis caused by SARS-CoV-2. Consequently, our study provides a scientific basis for considering fucoidans as poteintial prophylactic food components against SARS-CoV-2.

Cross-species transmission and animal infection model of hepatitis E virus

Zoonotic hepatitis E virus (HEV) infection is an emerging global public health concern, and understanding the dynamics of HEV transmission between animals and humans is crucial for public health. Animal models are critical to advancing the understanding of HEV pathogenesis, drug screening, vaccine development, and other related areas. Here, we provide an overview of recent studies investigating the cross-species transmission of HEV, and also delve into the current research and application of animal HEV infection models including non-human primates, rodents, pigs, and chickens, offering a comprehensive assessment of the advantages and disadvantages of each model. This review highlights the findings related to viral replication, shedding patterns, and immune response in these animal models, and discusses the implications for our understanding of HEV transmission to humans. These advancements in the field enhance our understanding of the biological traits and pathogenic mechanisms of HEV, offering robust support for the development of highly effective and targeted prevention and treatment strategies.

Enteric coronavirus nsp2 is a virulence determinant that recruits NBR1 for autophagic targeting of TBK1 to diminish the innate immune response

Non-structural protein 2 (nsp2) exists in all coronaviruses (CoVs), while its primary function in viral pathogenicity, is largely unclear. One such enteric CoV, porcine epidemic diarrhea virus (PEDV), causes high mortality in neonatal piglets worldwide. To determine the biological role of nsp2, we generated a PEDV mutant containing a complete nsp2 deletion (rPEDV-Δnsp2) from a highly pathogenic strain by reverse genetics, showing that nsp2 was dispensable for PEDV infection, while its deficiency reduced viral replication in vitro. Intriguingly, rPEDV-Δnsp2 was entirely avirulent in vivo, with significantly increased productions of IFNB (interferon beta) and IFN-stimulated genes (ISGs) in various intestinal tissues of challenged newborn piglets. Notably, nsp2 targets and degrades TBK1 (TANK binding kinase 1), the critical kinase in the innate immune response. Mechanistically, nsp2 induced the macroautophagy/autophagy process and recruited a selective autophagic receptor, NBR1 (NBR1 autophagy cargo receptor). NBR1 subsequently facilitated the K48-linked ubiquitination of TBK1 and delivered it for autophagosome-mediated degradation. Accordingly, the replication of rPEDV-Δnsp2 CoV was restrained by reduced autophagy and excess productions of type I IFNs and ISGs. Our data collectively define enteric CoV nsp2 as a novel virulence determinant, propose a crucial role of nsp2 in diminishing innate antiviral immunity by targeting TBK1 for NBR1-mediated selective autophagy, and pave the way to develop a new type of nsp2-based attenuated PEDV vaccine. The study also provides new insights into the prevention and treatment of other pathogenic CoVs.Abbreviations: 3-MA: 3-methyladenine; Baf A1: bafilomycin A1; CoV: coronavirus; CQ: chloroquine; dpi: days post-inoculation; DMVs: double-membrane vesicles; GABARAP: GABA type A receptor-associated protein; GFP: green fluorescent protein; GIGYF2: GRB10 interacting GYF protein 2; hpi: hours post-infection; IFA: immunofluorescence assay; IFIH1: interferon induced with helicase C domain 1; IFIT2: interferon induced protein with tetratricopeptide repeats 2; IFITM1: interferon induced transmembrane protein 1; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISGs: interferon-stimulated genes; mAb: monoclonal antibody; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAVS: mitochondrial antiviral signaling protein; NBR1: NBR1 autophagy cargo receptor; nsp2: non-structural protein 2; OAS1: 2'-5'-oligoadenylate synthetase 1; PEDV: porcine epidemic diarrhea virus; PRRs: pattern recognition receptors; RIGI: RNA sensor RIG-I; RT-qPCR: reverse transcription quantitative polymerase chain reaction; SQSTM1: sequestosome 1; TBK1: TANK binding kinase 1; TCID50: 50% tissue culture infectious doses; VSV: vesicular stomatitis virus.

Heat shock protein 90 facilitates SARS-CoV-2 structural protein-mediated virion assembly and promotes virus-induced pyroptosis

Inhibition of heat shock protein 90 (Hsp90), a prominent molecular chaperone, effectively limits severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but little is known about any interaction between Hsp90 and SARS-CoV-2 proteins. Here, we systematically analyzed the effects of the chaperone isoforms Hsp90α and Hsp90β on individual SARS-CoV-2 viral proteins. Five SARS-CoV-2 proteins, namely nucleocapsid (N), membrane (M), and accessory proteins Orf3, Orf7a, and Orf7b were found to be novel clients of Hsp90β in particular. Pharmacological inhibition of Hsp90 with 17-DMAG results in N protein proteasome-dependent degradation. Hsp90 depletion-induced N protein degradation is independent of CHIP, a ubiquitin E3 ligase previously identified for Hsp90 client proteins, but alleviated by FBXO10, an E3 ligase identified by subsequent siRNA screening. We also provide evidence that Hsp90 depletion may suppress SARS-CoV-2 assembly partially through induced M or N degradation. Additionally, we found that GSDMD-mediated pyroptotic cell death triggered by SARS-CoV-2 was mitigated by inhibition of Hsp90. These findings collectively highlight a beneficial role for targeting of Hsp90 during SARS-CoV-2 infection, directly inhibiting virion production and reducing inflammatory injury by preventing the pyroptosis that contributes to severe SARS-CoV-2 disease.

Targeting proteostasis of the HEV replicase to combat infection in preclinical models

BACKGROUND & AIMS

Appropriate treatment options are lacking for hepatitis E virus (HEV)-infected pregnant women and immunocompromised individuals. Thus, we aimed to identify efficient anti-HEV drugs through high-throughput screening, validate them in vitro and in vivo (in a preclinical animal study), and elucidate their underlying antiviral mechanism of action.

METHODS

Using appropriate cellular and rodent HEV infection models, we studied a critical pathway for host-HEV interactions and performed a preclinical study of the corresponding antivirals, which target proteostasis of the HEV replicase.

RESULTS

We found 17 inhibitors that target HEV-HSP90 interactions by unbiased compound library screening on human hepatocytes harboring an HEV replicon. Inhibitors of HSP90 (iHSP90) markedly suppressed HEV replication with efficacy exceeding that of conventional antivirals (IFNα and ribavirin) in vitro. Mechanistically, iHSP90 treatment released the viral replicase ORF1 protein from the ORF1-HSP90 complex and triggered rapid ubiquitin/proteasome-mediated degradation of ORF1, resulting in abrogated HEV replication. Furthermore, a preclinical trial in a Mongolian gerbil HEV infection model showed this novel anti-HEV strategy to be safe, efficient, and able to prevent HEV-induced liver damage.

CONCLUSIONS

In this study, we uncover a proteostatic pathway that is critical for host-HEV interactions and we provide a foundation from which to translate this new understanding of the HEV life cycle into clinically promising antivirals.

IMPACT AND IMPLICATIONS

Appropriate treatment options for hepatitis E virus (HEV)-infected pregnant women and immunocompromised patients are lacking; hence, there is an urgent need for safe and effective HEV-specific therapies. This study identified new antivirals (inhibitors of HSP90) that significantly limit HEV infection by targeting the viral replicase for degradation. Moreover, these anti-HEV drugs were validated in an HEV rodent model and were found to be safe and efficient for prevention of HEV-induced liver injury in preclinical experiments. Our findings substantially promote the understanding of HEV pathobiology and pave the way for antiviral development.

Role of heat shock protein 90 as an antiviral target for swine enteric coronaviruses

A variety of swine enteric coronaviruses (SECoVs) have emerged and are prevalent in pig populations, including porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and swine acute diarrhea syndrome (SADS)-CoV, a newly identified bat-origin CoV with zoonotic potential. Unfortunately, available traditional, inactivated and attenuated SECoV vaccines are of limited efficacy against the variants currently circulating in most pig populations. In this study, we evaluated the role of host factor heat shock protein 90 (Hsp90) as an antiviral target against SECoVs, exemplified by SADS-CoV. Pharmacological inhibition of Hsp90 diminished SADS-CoV replication significantly in porcine and human cell lines, and also decreased replication of SADS-CoV in a porcine intestinal enteroid model. Further mechanistic experiments revealed that both porcine and human isoforms of Hsp90 interact with the SADS-CoV nucleocapsid (N) protein, and inhibition of Hsp90 resulted in autophagic degradation of N protein. Moreover, we linked Hsp90 to virus-induced cellular pyroptosis, as SADS-CoV was found to trigger caspase-1/gasdermin-D-mediated pyroptotic cell death, which was mitigated by inhibition of Hsp90. Finally, we demonstrated that Hsp90 also associated with N proteins and was involved in propagation of PEDV, PDCoV and TGEV. This study thus extends our understanding of immune responses to SADS-CoV infection and offers a new potential therapeutic option against four SECoVs.

Surface Display of Peptides Corresponding to the Heptad Repeat 2 Domain of the Feline Enteric Coronavirus Spike Protein on Bacillus subtilis Spores Elicits Protective Immune Responses Against Homologous Infection in a Feline Aminopeptidase-N-Transduced Mouse Model

Although feline coronavirus (FCoV) infection is extremely common in cats, there are currently few effective treatments. A peptide derived from the heptad repeat 2 (HR2) domain of the coronavirus (CoV) spike protein has shown effective for inhibition of various human and animal CoVs in vitro, but further use of FCoV-HR2 in vivo has been limited by lack of practical delivery vectors and small animal infection model. To overcome these technical challenges, we first constructed a recombinant Bacillus subtilis (rBS^CotB-HR2P) expressing spore coat protein B (CotB) fused to an HR2-derived peptide (HR2P) from a serotype II feline enteric CoV (FECV). Immunogenic capacity was evaluated in mice after intragastric or intranasal administration, showing that recombinant spores could trigger strong specific cellular and humoral immune responses. Furthermore, we developed a novel mouse model for FECV infection by transduction with its primary receptor (feline aminopeptidase N) using an E1/E3-deleted adenovirus type 5 vector. This model can be used to study the antiviral immune response and evaluate vaccines or drugs, and is an applicable choice to replace cats for the study of FECV. Oral administration of rBS^CotB-HR2P in this mouse model effectively protected against FECV challenge and significantly reduced pathology in the digestive tract. Owing to its safety, low cost, and probiotic features, rBS^CotB-HR2P is a promising oral vaccine candidate for use against FECV/FCoV infection in cats.

Stable Expression of a Hepatitis E Virus (HEV) RNA Replicon in Two Mammalian Cell Lines to Assess Mechanism of Innate Immunity and Antiviral Response

Hepatitis E virus (HEV) is one of the major etiological agents responsible for acute hepatitis. Hepatitis E virus does not replicate efficiently in mammalian cell cultures, thus a useful model that mimics persistent HEV replication is needed to dissect the molecular mechanism of pathogenesis. Here we report a genotype-3 HEV RNA replicon expressing an EGFP-Zeocin (EZ) resistant gene (p6-EZ) that persistently self-replicated in cell lines of human (Huh-7-S10-3) or hamster (BHK-21) origin after transfection with in vitro RNA transcripts and subsequent drug screening. Two cell lines, S10-3-EZ and BHK-21-EZ, stably expressed EGFP in the presence of Zeocin during continuous passages. Both genomic and subgenomic HEV RNAs and viral replicase proteins were stably expressed in persistent HEV replicon cells. The values of the cell models in antiviral testing, innate immune RNA sensing and type I IFN in host defense were further demonstrated. We revealed a role of RIG-I like receptor-interferon regulatory factor 3 in host antiviral innate immune sensing during HEV replication. We further demonstrated that treatment with interferon (IFN-α) or ribavirin significantly reduced expression of replicon RNA in a dose-dependent manner. The availability of the models will greatly facilitate HEV-specific antiviral development, and delineate mechanisms of HEV replication.

[Effective prevention and control of myopia in children and adolescents]

Myopia prevention and control is an important health issue related to children and adolescents, general public physical fitness and national defense security. In 2018, General Secretary Xi Jinping gave instructions on students' myopia. Ministry of Education and other seven ministries and commissions issued the Implementation Plan of the Myopia Prevention and Control for Children and Adolescents. As the myopia prevalence continues to develop into an urgent situation, myopia prevention and control has become a national strategy. In the battle fighting against prevalent myopia, medical and scientific researchers, as professionals, play a key role in guiding the effective implementation of the project and coordinating among five parties including government, schools, medical institutions, families and individual students. It is of great significance to effectively prevent and control myopia for children and adolescents and to achieve the overall goal of prevention and control. This article summarizes the potential effective methods in myopia prevention and control, hoping to provide useful reference and help for the national prevention and control work. (Chin J Ophthalmol, 2019, 55: 81-85).

Porcine Torovirus (PToV)-A Brief Review of Etiology, Diagnostic Assays and Current Epidemiology

Porcine torovirus (PToV) is a potential enteric swine pathogen, found at especially high rates in piglets with diarrhea. It was first reported in the Netherlands in 1998 and has emerged in many countries around the world. Infections are generally asymptomatic and have not directly caused large economic losses, though co-infections with other swine pathogens and intertype recombination may lead to unpredictable outcomes. This review introduces progress in PToV research regarding its discovery, relationship with other Toroviruses, virion morphological characteristics, genetic structure and variation, recent epidemiology, diagnostic methods, and possibilities for future research.

HLA-G polymorphism in a Chinese Han population with recurrent spontaneous abortion

Reproduction is an important biological phenomenon posing an immunological paradox because the semiallogeneic fetus survives by evading maternal immune recognition. The detailed mechanisms behind this maternal-fetal immunotolerance remain elusive. Human leucocyte antigen (HLA)-G, a non-classical HLA class I antigen, initially identified as a molecule selectively expressed on extravillous cytotrophoblasts and first studied in the context of pregnancy, has long been supposed to play a critical role in fetal-maternal immunotolerance. To investigate the role of HLA-G polymorphism in this process and whether the HLA-G genotype is associated with an increased risk for a subsequent miscarriage, 69 women with three or more recurrent spontaneous abortions (RSA) and 146 fertile control women were genotyped for the HLA-G locus in this study. To our knowledge, this is the first report on HLA-G polymorphism in RSA and in normal fertile women from a Chinese Han population. Nine HLA-G alleles were detected in the fertile control group; however, the allele HLA-G*0103 was absent in the RSA group. No statistical significance was observed in the distribution of HLA-G alleles between the two groups. The frequency of the null allele HLA-G*0105 N in the RSA group and in normal fertile women is 0.7% and 1.4%, respectively. Our data suggested that there was no association of HLA-G polymorphism with RSA.

An integrated rule- and case-based approach to AIDS initial assessment

The traditional approach to the development of knowledge-based systems (KBS) has been rule-based, where heuristic knowledge is encoded in a set of production rules. A rule-based reasoning (RBR) system needs a well constructed domain theory as its reasoning basis, and it does not make substantial use of the knowledge embedded in previous cases. An RBR system performs relatively well in a knowledge-rich application environment. Although its capability may be limited when previous experiences are not a good representation of the whole population, a case-based reasoning (CBR) system is capable of using past experiences as problem solving tools, therefore, it is appropriate for an experience-rich domain. In recent years, both RBR and CBR have emerged as important and complementary reasoning methodologies in artificial intelligence. For problem solving in AIDS intervention and prevention, it is useful to integrate RBR and CBR. In this paper, a hybrid KBS which integrates a deductive RBR system and an inductive CBR system is proposed to assess AIDS-risky behaviors.

A decision support system for AIDS intervention and prevention

In recent years, the importance of information systems has been identified as a vital issue to continuing success in AIDS intervention and prevention (AIP). The advances in information technology have resulted in integrative information systems including decision support systems (DSS). The concept of DSS for AIP was created at the intersection of two trends. The first trend was a growing belief that AIP information systems are successful in automating operations in AIP programs. The second was a continuing improvement in modeling and software development in the AIP area. This paper presents an integrated DSS for AIP. The system is integrated with a database and achieves its efficiency by incorporating various algorithms and models to support AIP decision processes. The application examples include screening AIDS-risky behaviors, evaluating educational interventions, and scheduling AIP sessions. The implementation results present evidence of the usefulness of the system in AIP.

Application of information systems to AIDS risk reduction

Acquired immune deficiency syndrome (AIDS) is a specific group of diseases which are indicative of severe immunosuppression related to infection with the human immunodeficiency virus (HIV). In response to the epidemic, a variety of intervention and prevention has been instituted. In such intervention and prevention activities, the role played by information systems becomes more and more important. This paper describes the design and implementation of an information system for AIDS intervention and prevention.

An integrated information system for the intervention and prevention of AIDS

The epidemic of acquired immune deficiency syndrome (AIDS) and its causative agent, the human immunodeficiency virus (HIV), are serious and spreading. In response to the epidemic, a variety of intervention and prevention programs have been instituted. In such AIDS intervention and prevention (AIP) activities, the role played by information systems becomes more and more important. The applications of information systems technology in AIP mostly seem to fall within a spectrum of databases, decision support systems and expert systems. This paper describes the implementation of an information system in a regional AIDS intervention and prevention program. In this integrative information system, the database is integrated with both decision support systems and expert systems, and decision support systems are integrated with expert systems. The implementation results of the system present evidence of the usefulness of the system in AIDS intervention and prevention.

[Nail fold microcirculation in patients with chest malignancy]

Nail fold microcirculation was observed in 90 patients suffering from chest malignancies. 33 were patients with esophageal cancer, 41 cancer of gastric cardia, 4 esophageal and cardiac cancer, 11 lung cancer and 1 malignant neurogenic tumor in the posterior mediastinum. The results indicate that, in cancer patients, marked microcirculatory disturbances are present in the form of marked exudation, cloudy visual field, abnormal and dilated capillary loops, granular and slow blood flow. There is no obvious difference in the various kinds of malignancies. Nor is there any difference between the operable and inoperable cases. Indication of operation is not predicted by this method. The probable cause and clinical significance of microcirculatory disturbances are discussed.