Influenza B virus is one of the causes for seasonal influenza, which can account for serious illness or even death in some cases. We tested the expression of extracellular domain of hemagglutinin (HA-ecto) of influenza B viruses in mammalian cells, and then determined the immunogenicity of HA-ecto in mice. The gene sequence encoding influenza B virus HA-ecto, foldon sequence, and HIS tag was optimized and inserted into pCAGGS vector. The opening reading frame (ORF) of neuraminidase was also cloned into pCAGGS. The pCAGGS-HA-ecto and pCAGGS-NA were co-transfected into 293T cells using linear polyethylenimine. Cell supernatant after transfection was collected after 96 h, and the secreted trimmeric HA-ecto protein was purified by nickel ion affinity chromatography and size exclusion chromatography. Subsequently, the mice were immunized with HA-ecto protein, and the corresponding antibody titers were detected by ELISA and hemagglutination inhibition (HAI) assays. The results showed that soluble trimeric HA-ecto protein could be obtained using mammalian cell expression system. Moreover, trimeric HA-ecto protein, in combination with the adjuvant, induced high levels of ELISA and HAI antibodies against homogenous and heterologous antigens in mice. Thus, the soluble HA-ecto protein expressed in mammalian cells could be used as a recombinant subunit vaccine candidate for influenza B virus.
Animals ; Hemagglutinin Glycoproteins, Influenza Virus/genetics* ; Hemagglutinins/genetics* ; Influenza B virus/metabolism* ; Influenza Vaccines/genetics* ; Mammals/metabolism* ; Mice ; Mice, Inbred BALB C

This paper aims to explore the effects of chicken interferon-γ (ChIFN-γ) and interleukin-2 (ChIL-2) on type 1 helper (Th1) T lymphocyte differentiation. To be specific, ChIFN-γ and ChIL-2 were first expressed in Escherichia coli competent cells and then purified by Ni-NTA affinity chromatography. Different concentration of ChIFN-γ and ChIL-2 were employed to stimulate the lymphocytes in chicken peripheral blood which had been activated by concanavalin A (Con A), and the mRNA levels of cytokines related to Th1 cell differentiation were detected by real-time quantitative PCR (RT-qPCR). The results showed that both ChIFN-γ and ChIL-2 can significantly up-regulate mRNA levels of cytokines related to Th1 cell differentiation and the optimal concentration was 12.5 μg/mL and 25.0 μg/mL, respectively. In addition, specific-pathogen-free (SPF) chickens were immunized with ChIL-2 or ChIFN-γ together with H9N2 vaccine, or H9N2 vaccine alone by oral administration or intramuscular injection, respectively. The mRNA levels of cytokines related to Th1 cell differentiation were detected after immunization. The results showed that ChIFN-γ and ChIL-2 significantly up-regulated the mRNA levels of cytokines related to Th1 cell differentiation induced by H9N2 vaccine compared with H9N2 vaccine alone, and that the intramuscular injection was better than oral administration. In this study, we verified that ChIFN-γ and ChIL-2 can significantly enhance mRNA levels of cytokines related to Th1 cell differentiation induced by ConA or H9N2 vaccine in vitro and in vivo. The results of this study can lay a theoretical basis for using ChIFN-γ and ChIL-2 as vaccine adjuvants.
Animals ; Cell Differentiation ; Chickens ; Concanavalin A ; Cytokines/genetics* ; Influenza A Virus, H9N2 Subtype/genetics* ; Interferon-gamma/metabolism* ; Interleukin-2/genetics* ; RNA, Messenger

Influenza B virus (IBV) is more likely to cause complications than influenza A virus (IAV) and even causes higher disease burden than IAV in a certain season, but IBV has received less attention. In order to analyze the genetic evolution characteristics of the clinical strain IBV (B/Guangxi-Jiangzhou/1352/2018), we constructed genetic evolution trees and analyzed the homology and different amino acids of hemagglutinin and neuraminidase referring to the vaccine strains recommended by World Health Organization (WHO). We found that strain B/Guangxi-Jiangzhou/1352/2018 was free of interlineage reassortment and poorly matched with the vaccine strain B/Colorado/06/2017 of the same year. We also determined the median lethal dose (LD₅₀) and the pathogenicity of strain B/Guangxi-Jiangzhou/1352/2018 in mice. The results showed that the LD₅₀ was 10^5.9 TCID₅₀ (median tissue culture infective dose), the IBV titer in the lungs reached peak 1 d post infection and the mRNA level of the most of inflammatory cytokines in the lungs reached peak 12 h post infection. The alveoli in the lungs were severely damaged and a large number of inflammatory cells were infiltrated post infection. The study demonstrated that the clinical strain IBV (B/Guangxi-Jiangzhou/1352/2018) could infect mice and induce typical lung inflammation. This will facilitate the research on the pathogenesis and transmission mechanism of IBV, and provide an ideal animal model for evaluation of new vaccines, antiviral and anti-inflammatory drug.
Amino Acids/genetics* ; Animals ; Antiviral Agents/pharmacology* ; China ; Cytokines/metabolism* ; Hemagglutinins/metabolism* ; Humans ; Influenza B virus/pathogenicity* ; Influenza, Human/virology* ; Mice ; Neuraminidase/genetics* ; Orthomyxoviridae Infections/virology* ; Phylogeny ; RNA, Messenger/metabolism* ; Virulence/genetics*

N-glycosylation modification, one of the most common protein post-translational modifications, occurs in heat shock protein gp96. The purpose of this study is to investigate the effect of N-glycosylation modification on immunologic function of the recombinant gp96 using the mutant gp96 in N-glycosylation sites. Firstly, wild-type and mutant gp96 proteins were expressed by insect expression system and their glycosylation levels were detected. To determine the effect of N-glycosylation on gp96 antigen presentation function, the IFN-γ+ CD8+ T cells in gp96-immunized mice and secretion level of IFN-γ were examined by flow cytometry and ELISA. The ATPase activity of gp96 was further detected by the ATPase kit. Finally, the effect of N-glycosylation on adjuvant function of gp96 for influenza vaccine was investigated in immunized mice. It was found that total sugar content of mutant recombinant gp96 was reduced by 27.8%. Compared to the wild type recombinant gp96, mutations in N-glycosylation sites resulted in decreased antigen presentation ability and ATPase activity of gp96. Furthermore, influenza vaccine-specific T cell levels induced by mutant gp96 as adjuvant were dramatically reduced compared to those by wild type recombinant gp96. These results demonstrate that N-glycosylation modification is involved in regulation of ATPase activity and antigen presentation function of gp96, thereby affecting its adjuvant function. The results provide the technical bases for development of gp96- adjuvanted vaccines.
Adjuvants, Immunologic ; Animals ; CD8-Positive T-Lymphocytes/metabolism* ; Glycosylation ; Heat-Shock Proteins ; Influenza Vaccines ; Mice

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of the novel coronavirus SARS-CoV-2. Herein, we identified two potent inhibitors of human DHODH, S312 and S416, with favorable drug-likeness and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus, Zika virus, Ebola virus, and particularly against SARS-CoV-2. Notably, S416 is reported to be the most potent inhibitor so far with an EC of 17 nmol/L and an SI value of 10,505.88 in infected cells. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knock-out cells. This work demonstrates that both S312/S416 and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-regulation may have clinical potentials to cure SARS-CoV-2 or other RNA viruses circulating worldwide, no matter such viruses are mutated or not.
Animals ; Antiviral Agents ; pharmacology ; therapeutic use ; Betacoronavirus ; drug effects ; physiology ; Binding Sites ; drug effects ; Cell Line ; Coronavirus Infections ; drug therapy ; virology ; Crotonates ; pharmacology ; Cytokine Release Syndrome ; drug therapy ; Drug Evaluation, Preclinical ; Gene Knockout Techniques ; Humans ; Influenza A virus ; drug effects ; Leflunomide ; pharmacology ; Mice ; Mice, Inbred BALB C ; Orthomyxoviridae Infections ; drug therapy ; Oseltamivir ; therapeutic use ; Oxidoreductases ; antagonists & inhibitors ; metabolism ; Pandemics ; Pneumonia, Viral ; drug therapy ; virology ; Protein Binding ; drug effects ; Pyrimidines ; biosynthesis ; RNA Viruses ; drug effects ; physiology ; Structure-Activity Relationship ; Toluidines ; pharmacology ; Ubiquinone ; metabolism ; Virus Replication ; drug effects

Objective: Interferon-induced transmembrane protein 3 (IFITM3) is an important member of the IFITM family. However, the molecular mechanisms underlying its antiviral action have not been completely elucidated. Recent studies on IFITM3, particularly those focused on innate antiviral defense mechanisms, have shown that IFITM3 affects the body's adaptive immune response. The aim of this study was to determine the contribution of IFITM3 proteins to immune control of influenza infection . Methods: We performed proteomics, flow cytometry, and immunohistochemistry analysis and used bioinformatics tools to systematically compare and analyze the differences in natural killer (NK) cell numbers, their activation, and their immune function in the lungs of -/- and wild-type mice. Results: -/- mice developed more severe inflammation and apoptotic responses compared to wild-type mice. Moreover, the NK cell activation was higher in the lungs of -/- mice during acute influenza infection. Conclusions Based on our results, we speculate that the NK cells are more readily activated in the absence of IFITM3, increasing mortality in -/- mice.
Acute Disease ; Animals ; Disease Models, Animal ; Female ; Humans ; Influenza, Human ; virology ; Male ; Membrane Proteins ; genetics ; metabolism ; Mice ; Mice, Inbred C57BL ; Orthomyxoviridae Infections ; veterinary ; virology ; Rodent Diseases ; virology

Houttuynia cordata polysaccharide (HCP) is extracted from Houttuynia cordata, a key traditional Chinese medicine. The study was to investigate the effects of HCP on intestinal barrier and microbiota in H1N1 virus infected mice. Mice were infected with H1N1 virus and orally administrated HCP at a dosage of 40 mg(kg(d. H1N1 infection caused pulmonary and intestinal injury and gut microbiota imbalance. HCP significantly suppressed the expression of hypoxia inducible factor-1α and decreased mucosubstances in goblet cells, but restored the level of zonula occludens-1 in intestine. HCP also reversed the composition change of intestinal microbiota caused by H1N1 infection, with significantly reduced relative abundances of Vibrio and Bacillus, the pathogenic bacterial genera. Furthermore, HCP rebalanced the gut microbiota and restored the intestinal homeostasis to some degree. The inhibition of inflammation was associated with the reduced level of Toll-like receptors and interleukin-1β in intestine, as well as the increased production of interleukin-10. Oral administration of HCP alleviated lung injury and intestinal dysfunction caused by H1N1 infection. HCP may gain systemic treatment by local acting on intestine and microbiota. This study proved the high-value application of HCP.
Animals ; Cytokines ; metabolism ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; therapeutic use ; Gastrointestinal Microbiome ; drug effects ; Houttuynia ; chemistry ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Inflammation ; drug therapy ; pathology ; Influenza A Virus, H1N1 Subtype ; pathogenicity ; Intestinal Mucosa ; drug effects ; metabolism ; microbiology ; pathology ; Lung ; drug effects ; metabolism ; pathology ; Male ; Mice, Inbred BALB C ; Orthomyxoviridae Infections ; drug therapy ; pathology ; physiopathology ; Plant Extracts ; chemistry ; Polysaccharides ; chemistry ; pharmacology ; therapeutic use ; Toll-Like Receptors ; metabolism ; Zonula Occludens-1 Protein ; metabolism

We aimed to understand the molecular changes in host cells that accompany infection by the seasonal influenza A H1N1 virus because the initial response rapidly changes owing to the fact that the virus has a robust initial propagation phase. Human epithelial alveolar A549 cells were infected and total RNA was extracted at 30 min, 1 h, 2 h, 4 h, 8 h, 24 h, and 48 h post infection (h.p.i.). The differentially expressed host genes were clustered into two distinct sets of genes as the infection progressed over time. The patterns of expression were significantly different at the early stages of infection. One of the responses showed roles similar to those associated with the enrichment gene sets to known ‘gp120 pathway in HIV.’ This gene set contains genes known to play roles in preventing the progress of apoptosis, which infected cells undergo as a response to viral infection. The other gene set showed enrichment of ‘Drug Metabolism Enzymes (DMEs).’ The identification of two distinct gene sets indicates that the virus regulates the cell's mechanisms to create a favorable environment for its stable replication and protection of gene metabolites within 8 h.
Apoptosis ; Epithelial Cells* ; Gene Expression Regulation ; High-Throughput Nucleotide Sequencing ; Humans* ; Influenza A Virus, H1N1 Subtype ; Influenza, Human* ; Lung* ; Metabolism ; RNA ; Seasons

Adolescent ; Humans ; Influenza A Virus, H7N9 Subtype ; immunology ; pathogenicity ; Lymphopenia ; immunology ; microbiology ; Male ; T-Lymphocytes ; metabolism

To study the effect and underlying mechanism of Mahuang Tang against influenza A virus ， the influenza virus-infected Madin-Darby canine kidney(MDCK) cells were used as the carrier in this study to detect the median tissue culture-infective dose(TCID₅₀) of influenza A virus strains(A/PR8/34) on MDCK cells with cytopathic effect(CPE) assay. Blocking influenza virus invading host cells and anti-influenza virus biosynthesis were used as two different administration methods， and then the methyl thiazolyl tetrazolium(MTT) assay was utilized to determine the antiviral effective rate(ER)， median efficacious concentration(EC₅₀) and therapeutic index(TI) of Mahuang Tang. The quantitative Real-time polymerase chain reaction(RT-PCR) was used to measure virus load and the mRNA expression levels of TLR4， TLR7， MyD88 and TRAF6 in MDCK cells at 24， 48 h after the treatment. The experiment results indicated that TCID₅₀ of A/PR8/34 for MDCK cells was 1×10-4.32/mL. The EC₅₀ values of two different treatment methods were 4.92，1.59 g·L⁻¹ respectively， the TI values were 12.53， 38.78 respectively， and when the concentration of Mahuang Tang was 5.00 g·L⁻¹， ER values were 50.21%， 98.41% respectively， showing that Mahuang Tang can block influenza virus into the host cells and significantly inhibit their biosynthesis. Meanwhile， as compared with the virus group， the virus load was significantly inhibited in Mahuang Tang groups， and Mahuang Tang high and middle doses had the significant effect on decreasing the mRNA expression of TLR4， TLR7，MyD88 and TRAF6 at 24， 48 h after the treatment. It can be demonstrated that the mechanisms of Mahuang Tang against influenza A virus are related to the inhibition of influenza virus replication and the mRNA expression of correlative genes in TLR4 and TLR7 signaling pathways.
Animals ; Antiviral Agents ; pharmacology ; Dogs ; Drugs, Chinese Herbal ; pharmacology ; Influenza A Virus, H1N1 Subtype ; drug effects ; physiology ; Madin Darby Canine Kidney Cells ; Orthomyxoviridae Infections ; Toll-Like Receptor 4 ; metabolism ; Toll-Like Receptor 7 ; metabolism ; Virus Replication ; drug effects