Showing papers by "Jin Zhong published in 2018"

MLL5 suppresses antiviral innate immune response by facilitating STUB1-mediated RIG-I degradation.

Abstract: Trithorax group protein MLL5 is an important epigenetic modifier that controls cell cycle progression, chromatin architecture maintenance, and hematopoiesis. However, whether MLL5 has a role in innate antiviral immunity is largely unknown. Here we show that MLL5 suppresses the RIG-I-mediated anti-viral immune response. Mll5-deficient mice infected with vesicular stomatitis virus show enhanced anti-viral innate immunity, reduced morbidity, and viral load. Mechanistically, a fraction of MLL5 located in the cytoplasm interacts with both RIG-I and its E3 ubiquitin ligase STUB1, which promotes K48-linked polyubiquitination and proteasomal degradation of RIG-I. MLL5 deficiency attenuates the RIG-I and STUB1 association, reducing K48-linked polyubiquitination and accumulation of RIG-I protein in cells. Upon virus infection, nuclear MLL5 protein translocates from the nucleus to the cytoplasm inducing STUB1-mediated degradation of RIG-I. Our study uncovers a previously unrecognized role for MLL5 in antiviral innate immune responses and suggests a new target for controlling viral infection.

Hepatitis C virus NS4B induces the degradation of TRIF to inhibit TLR3-mediated interferon signaling pathway.

Abstract: Toll-like receptor 3 (TLR3) senses dsRNA intermediates produced during RNA virus replication to activate innate immune signaling pathways through adaptor protein TRIF. Many viruses have evolved strategies to block TLR3-mediated interferon signaling via targeting TRIF. Here we studied how hepatitis C virus (HCV) antagonizes the TLR3-mediated interferon signaling. We found that HCV-encoded NS4B protein inhibited TLR3-mediated interferon signaling by down-regulating TRIF protein level. Mechanism studies indicated that the downregulation of TRIF by NS4B was dependent on caspase8. NS4B transfection or HCV infection can activate caspase8 to promote TRIF degradation, leading to suppression of TLR3-mediated interferon signaling. Knockout of caspase8 can prevent TRIF degradation triggered by NS4B, thereby enhancing the TLR3-mediated interferon signaling activation in response to HCV infection. In conclusion, our work revealed a new mechanism for HCV to evade innate immune response by blocking the TLR3-mediated interferon signaling via NS4B-induced TRIF degradation.

Role of Hepatitis C Virus Envelope Glycoprotein E1 in Virus Entry and Assembly.

Abstract: Hepatitis C virus (HCV) glycoproteins E1 and E2 form a heterodimer to constitute viral envelope proteins, which play an essential role in virus entry. E1 does not directly interact with host receptors, and its functions in viral entry are exerted mostly through its interaction with E2 that directly binds the receptors. HCV enters the host cell via receptor-mediated endocytosis during which the fusion of viral and host endosomal membranes occurs to release viral genome to cytoplasm. A putative fusion peptide in E1 has been proposed to participate in membrane fusion, but its exact role and underlying molecular mechanisms remain to be deciphered. Recently solved crystal structures of the E2 ectodomains and N-terminal of E1 fail to reveal a classical fusion-like structure in HCV envelope glycoproteins. In addition, accumulating evidence suggests that E1 also plays an important role in virus assembly. In this mini-review, we summarize current knowledge on HCV E1 including its structure and biological functions in virus entry, fusion, and assembly, which may provide clues for developing HCV vaccines and more effective antivirals.

Antiviral effects of ferric ammonium citrate.

Abstract: Iron is an essential nutrient for cell survival and is crucial for DNA replication, mitochondrial function and erythropoiesis. However, the immunological role of iron in viral infections has not been well defined. Here we found the iron salt ferric ammonium citrate (FAC) inhibited Influenza A virus, HIV virus, Zika virus, and Enterovirus 71 (EV71) infections. Of note, both iron ion and citrate ion were required for the antiviral capability of FAC, as other iron salts and citrates did not exhibit viral inhibition. Mechanistically, FAC inhibited viral infection through inducing viral fusion and blocking endosomal viral release. These were further evidenced by the fact that FAC induced liposome aggregation and intracellular vesicle fusion, which was associated with a unique iron-dependent cell death. Our results demonstrate a novel antiviral function of FAC and suggest a therapeutic potential for iron in the control of viral infections.

Lactobacillus reuteri HCM2 protects mice against Enterotoxigenic Escherichia coli through modulation of gut microbiota.

Abstract: Enterotoxigenic Escherichia coli (ETEC) is a leading cause of infectious diarrhea in children and postweaning piglets. ETEC infection results in induced pro-inflammatory responses in intestinal epithelial cells and dysbiosis of intestinal microbiota. Here, a Lactobacillus reuteri strain, HCM2, isolated from a healthy piglet showed a high survival rate in the harsh gastrointestinal tract environment and inhibited the growth of ETEC and its adherence to intestinal epithelial cells. Pre-supplementation with L. reuteri HCM2 for 14 days reduced the ETEC load in the jejunum of ETEC-infected mice and prevented the disruption of intestinal morphology by ETEC. The colonic microbiota of mice with or without HCM2 pre-supplementation were analyzed, and this analysis revealed that HCM2 could prevent dysbiosis caused by ETEC infection by stabilizing the relative abundance of dominant bacteria. These results indicate that L. reuteri HCM2 has the potential to attenuate the effect of ETEC on the colonic microbiota in infected mice.

Negligible contribution of M2634V substitution to ZIKV pathogenesis in AG6 mice revealed by a bacterial promoter activity reduced infectious clone.

Abstract: ZIKV has emerged as a significant human pathogene for the severe neurological complications, including Guillain-Barre(GBS) syndrome in adults and a variety of fetal abnormalities such as microcephaly A stable and efficient infectious clone of Brazilian ZIKV isolate is required to study pathogenesis of epidemic ZIKV and virus evolution impact on it Here we successfully constructed infectious cDNA clone on an early Brazilian isolate by eliminating the activity of predicted bacterial promoter in 1–3000 nt of ZIKV genome, leading to a stable infectious cDNA clone (pZL1) pZL1 derived virus could infect different cell lines and cause lethal effect to AG6 mice We further investigated the role of a recent emerged substitution in NS5 (M2634V) We found that a reverse mutation (V2634M) caused negligible effect on the ZIKV viral genome replication and infectious progeny production in multiple cell culture systems Additionally, this mutation did not alter the pathogenesis feature and virulence of ZIKV in AG6 mice In summary, our results present another robust infectious ZIKV clone from Brazilian isolate and provide evidences to support that M2634V single mutation did not alter virus life cycle in cell culture and pathogenesis in AG6 mouse model

The concept of “Grass-based Livestock Husbandry” and its practice in Hulun Buir, Inner Mongolia

Abstract: Grassland is the largest area of territorial ecosystems in China, and accounts for more than 30% of the total national land area. Primarily located in the north part and as the homeland of most ethnic minorities, the grassland region is critical for ecological safety and the national security of the country. Furthermore, grassland provides nearly one-third of the country total red meat and dairy products, respectively, and is important for national healthy food supply. Yet, it is believed that a large proportion of China’s grasslands has been degraded or desertified at various degrees because of overgrazing, increased population, mining, farming activities, and climate change. To achieve grassland sustainable development, new concepts and technological advancement are required to tackle the degradation challenges and to balance the relationships between “ecological civilization, sustainable production and better living standard”. For this purpose, we proposed the concept of “Grass-based Livestock Husbandry” (abbreviated as GLiH concept), which defines ecologically-sound management of grass-fed livestock and includes three production systems: forage cultivation, forage processing, and livestock management and processing. This paper documents contents and significance of the GLiH concept, and discusses key scientific and technical issues in the development of grass-based livestock husbandry and their possible solutions. The key of the concept is the coupling and coherent development of an inter-dependent “grass-livestock relationship”. In the GLiH concept, “grasses” (including various perennial and annual grass and shrub species) are considered as the foundation of “livestock” and provides an explanation for the long-standing frustration in China’s livestock farming industry, in which for years forage production has been totally neglected. GLiH also emphasizes the dual (productional and ecological) function of the grassland and proposes to manage the grassland regions according to the “small vs. big” theory, i.e., to allocate a small area of resources-rich land for cultivation of forage crops with high biomass and high quality to protect the vast but fragile grasslands away from over-grazing and over-exploitation, as such to secure the demand of the animal feed supplies as well as to allow the grassland to make its ecological functioning. We also propose eight principles for the development of grass-based livestock husbandry, including grass breeding, artificial grassland farming, conservation and better use of natural grassland, rational allocation between grass production and ecological functioning, efficient harvesting and processing, efficient feeding of livestock, efficient use of natural resources, and systems development. To verify the GLiH concept, a large scale pilot project of “Development of Experimental Zone for Sustainable Management of Grass-based Livestock Systems” has been implemented, in collaboration with Hulun Buir State Farm Conglomerate, and the project has achieved a big success ecologically and economically.

Genetic Analysis of Serum-Derived Defective Hepatitis C Virus Genomes Revealed Novel Viral cis Elements for Virus Replication and Assembly.

Abstract: Defective viral genomes (DVGs) of hepatitis C virus (HCV) exist, but their biological significances have not been thoroughly investigated. Here, we analyzed HCV DVGs circulating in patient sera that possess deletions in the structural protein-encoding region. About 30% of 41 HCV clinical isolates possess DVGs that originated from the full-length genome in the same patients. No correlation between DVGs, viremia, and alanine aminotransferase (ALT) levels was found. Sequencing analysis of DVGs revealed the existence of deletion hot spots, with upstream sites in E1 and downstream sites in E2 and NS2. Interestingly, the coding sequences for the core protein and the C-terminal protease domain of NS2 were always intact in DVGs despite the fact that both proteins are dispensable for HCV genome replication. Mechanistic studies showed that transmembrane segment 3 (TMS3) of NS2, located immediately upstream of its protease domain, was required for the cleavage of NS2-NS3 and the replication of DVGs. Moreover, we identified a highly conserved secondary structure (SL750) within the core domain 2-coding region that is critical for HCV genome packaging. In summary, our analysis of serum-derived HCV DVGs revealed novel viral cis elements that play important roles in virus replication and assembly.IMPORTANCE HCV DVGs have been identified in vivo and in vitro, but their biogenesis and physiological significances remain elusive. In addition, a conventional packaging signal has not yet been identified on the HCV RNA genome, and mechanisms underlying the specificity in the encapsidation of the HCV genome into infectious particles remain to be uncovered. Here, we identified new viral cis elements critical for the HCV life cycle by determining genetic constraints that define the boundary of serum-derived HCV DVGs. We found that transmembrane segment 3 of NS2, located immediately upstream of its protease domain, was required for the cleavage of NS2-NS3 and the replication of DVGs. We identified a highly conserved secondary structure (SL750) within the core-coding region that is critical for HCV genome packaging. In summary, our analysis of serum-derived HCV DVGs revealed previously unexpected novel cis elements critical for HCV replication and morphogenesis.

Celastrol specifically inhibits the activation of NLRP3 inflammasome

Abstract: 1CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China; 2School of Life Sciences, Shanghai University, Shanghai 200444, China; 3Department of Infectious Diseases, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100730, China; 4Clinical Immunology Center, Chinese Academy of Medical Sciences, Beijing 100730, China

Neuralized E3 Ubiquitin Protein Ligase 3 Is an Inducible Antiviral Effector That Inhibits Hepatitis C Virus Assembly by Targeting Viral E1 Glycoprotein.

Abstract: Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. HCV can be sensed by host innate immunity to induce expression of interferons (IFNs) and a number of antiviral effectors. In this study, we found HCV infection induced the expression of neuralized E3 ubiquitin protein ligase 3 (NEURL3), a putative E3 ligase, in a manner that requires the involvement of innate immune sensing but is independent of the IFN action. Furthermore, we showed that NEURL3 inhibited HCV infection while it had little effect on other RNA viruses, including Zika virus (ZIKV), dengue virus (DENV), and vesicular stomatitis virus (VSV). Mechanistic studies demonstrated that NEURL3 inhibited HCV assembly by directly binding HCV envelope glycoprotein E1 to interfere with the E1/E2 heterodimerization, an important prerequisite for virion morphogenesis. Finally, we showed that knockout of NEURL3 significantly enhanced HCV infection. In summary, we identified NEURL3 as a novel inducible antiviral host factor that suppresses HCV assembly. Our results not only shed new insight into how host innate immunity acts against HCV but also revealed a new important biological function for NEURL3.IMPORTANCE The exact biological function of NEURL3, a putative E3 ligase, remains largely unknown. In this study, we found that NEURL3 could be upregulated upon HCV infection in a manner dependent on pattern recognition receptor-mediated innate immune response. NEURL3 inhibits HCV assembly by directly binding viral E1 envelope glycoprotein to disrupt its interaction with E2, an action that requires its Neuralized homology repeat (NHR) domain but not the RING domain. Furthermore, we found that NEURL3 has a pangenotypic anti-HCV activity and interacts with E1 of genotypes 2a, 1b, 3a, and 6a but does not inhibit other closely related RNA viruses, such as ZIKV, DENV, and VSV. To our knowledge, our study is the first report to demonstrate that NEURL3 functions as an antiviral host factor. Our results not only shed new insight into how host innate immunity acts against HCV, but also revealed a new important biological function for NEURL3.

Lactobacillus johnsonii producing feruloyl esterase at high yield and application thereof

Abstract: The invention discloses lactobacillus johnsonii producing feruloyl esterase at high yield and application thereof. The provided lactobacillus is Lactobacillus johnsonii HCOM3 CGMCC No.15447. Experiments prove that the lactobacillus johnsonii HCOM3 CGMCC No.15447 can secrete the feruloyl esterase; the function of degrading the plant cell wall compact reticular structure is realized; the effects ofimproving the digestibility of cellulose in high-fiber silage raw materials, improving the palatability of the silage raw materials, improving the utilization rate of the silage raw materials and improving the growth performance of animal bodies are achieved; meanwhile, the characteristics of fast acid production, fast growth, no poison and harm on human and livestock, no environment pollution andthe like are also realized; very important significance is realized for improving the quality of farm products and pasture products and protecting the environment; the sustainable development of agriculture is favorably promoted.