Role of neutrophil chemoattractant CXCL5 in SARS-CoV-2 infection-induced lung inflammatory innate immune response in an in vivo hACE2 transfection mouse model.

Understanding the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and clarifying antiviral immunity in hosts are critical aspects for the development of vaccines and antivirals. Mice are frequently used to generate animal models of infectious diseases due to their convenience and ability to undergo genetic manipulation. However, normal adult mice are not susceptible to SARS-CoV-2. Here, we developed a viral receptor (human angiotensin-converting enzyme 2, hACE2) pulmonary transfection mouse model to establish SARS-CoV-2 infection rapidly in the mouse lung. Based on the model, the virus successfully infected the mouse lung 2 days after transfection. Viral RNA/protein, innate immune cell infiltration, inflammatory cytokine expression, and pathological changes in the infected lungs were observed after infection. Further studies indicated that neutrophils were the first and most abundant leukocytes to infiltrate the infected lungs after viral infection. In addition, using infected CXCL5-knockout mice, chemokine CXCL5 was responsible for neutrophil recruitment. CXCL5 knockout decreased lung inflammation without diminishing viral clearance, suggesting a potential target for controlling pneumonia.

Dysbiosis of gut microbiome affecting small intestine morphology and immune balance: a rhesus macaque model.

There is a growing appreciation for the specific health benefits conferred by commensal microbiota on their hosts. Clinical microbiota analysis and animal studies in germ-free or antibiotic-treated mice have been crucial for improving our understanding of the role of the microbiome on the host mucosal surface; however, studies on the mechanisms involved in microbiome-host interactions remain limited to small animal models. Here, we demonstrated that rhesus monkeys under short-term broad-spectrum antibiotic treatment could be used as a model to study the gut mucosal host-microbiome niche and immune balance with steady health status. Results showed that the diversity and community structure of the gut commensal bacteria in rhesus monkeys were both disrupted after antibiotic treatment. Furthermore, the 16S rDNA amplicon sequencing results indicated that Escherichia-Shigella were predominant in stool samples 9 d of treatment, and the abundances of bacterial functional genes and predicted KEGG pathways were significantly changed. In addition to inducing aberrant morphology of small intestinal villi, the depletion of gut commensal bacteria led to increased proportions of CD3 + T, CD4 + T, and CD16 + NK cells in peripheral blood mononuclear cells (PBMCs), but decreased numbers of Treg and CD20 + B cells. The transcriptome of PBMCs from antibiotic-treated monkeys showed that the immune balance was affected by modulation of the expression of many functional genes, including IL-13, VCAM1, and LGR4.

Pulmonary immune cells and inflammatory cytokine dysregulation are associated with mortality of IL-1R1 -/-mice infected with influenza virus (H1N1).

Respirovirus infection can cause viral pneumonia and acute lung injury (ALI). The interleukin-1 (IL-1) family consists of proinflammatory cytokines that play essential roles in regulating immune and inflammatory responses in vivo. IL-1 signaling is associated with protection against respiratory influenza virus infection by mediation of the pulmonary anti-viral immune response and inflammation. We analyzed the infiltration lung immune leukocytes and cytokines that contribute to inflammatory lung pathology and mortality of fatal H1N1 virus-infected IL-1 receptor 1 (IL-1R1) deficient mice. Results showed that early innate immune cells and cytokine/chemokine dysregulation were observed with significantly decreased neutrophil infiltration and IL-6, TNF-α, G-CSF, KC, and MIP-2 cytokine levels in the bronchoalveolar lavage fluid of infected IL-1R1 -/- mice in comparison with that of wild type infected mice. The adaptive immune response against the H1N1 virus in IL-1R1 -/- mice was impaired with downregulated anti-viral Th1 cell, CD8+ cell, and antibody functions, which contributes to attenuated viral clearance. Histological analysis revealed reduced lung inflammation during early infection but severe lung pathology in late infection in IL-1R1 -/- mice compared with that in WT infected mice. Moreover, the infected IL-1R1 -/- mice showed markedly reduced neutrophil generation in bone marrow and neutrophil recruitment to the inflamed lung. Together, these results suggest that IL-1 signaling is associated with pulmonary anti-influenza immune response and inflammatory lung injury, particularly via the influence on neutrophil mobilization and inflammatory cytokine/chemokine production.

Nasal Infection of Enterovirus D68 Leading to Lower Respiratory Tract Pathogenesis in Ferrets (Mustela putorius furo).

Data from EV-D68-infected patients demonstrate that pathological changes in the lower respiratory tract are principally characterized by severe respiratory illness in children and acute flaccid myelitis. However, lack of a suitable animal model for EV-D68 infection has limited the study on the pathogenesis of this critical pathogen, and the development of a vaccine. Ferrets have been widely used to evaluate respiratory virus infections. In the current study, we used EV-D68-infected ferrets as a potential animal to identify impersonal indices, involving clinical features and histopathological changes in the upper and lower respiratory tract (URT and LRT). The research results demonstrate that the EV-D68 virus leads to minimal clinical symptoms in ferrets. According to the viral load detection in the feces, nasal, and respiratory tracts, the infection and shedding of EV-D68 in the ferret model was confirmed, and these results were supported by the EV-D68 VP1 immunofluorescence confocal imaging with α2,6-linked sialic acid (SA) in lung tissues. Furthermore, we detected the inflammatory cytokine/chemokine expression level, which implied high expression levels of interleukin (IL)-1a, IL-8, IL-5, IL-12, IL-13, and IL-17a in the lungs. These data indicate that systemic observation of responses following infection with EV-D68 in ferrets could be used as a model for EV-D68 infection and pathogenesis.

Experimental infection of tree shrews (Tupaia belangeri) with Coxsackie virus A16.

Coxsackie virus A16 (CA16) is commonly recognized as one of the main human pathogens of hand-foot-mouth disease (HFMD). The clinical manifestations of HFMD include vesicles of hand, foot and mouth in young children and severe inflammatory CNS lesions. In this study, experimentally CA16 infected tree shrews (Tupaia belangeri) were used to investigate CA16 pathogenesis. The results showed that both the body temperature and the percentages of blood neutrophilic granulocytes / monocytes of CA16 infected tree shrews increased at 4-7 days post infection. Dynamic distributions of CA16 in different tissues and stools were found at different infection stages. Moreover, the pathological changes in CNS and other organs were also observed. These findings indicate that tree shrews can be used as a viable animal model to study CA16 infection.

Herpes simplex virus 1 ICP22 inhibits the transcription of viral gene promoters by binding to and blocking the recruitment of P-TEFb.

ICP22 is a multifunctional herpes simplex virus 1 (HSV-1) immediate early protein that functions as a general repressor of a subset of cellular and viral promoters in transient expression systems. Although the exact mechanism of repression remains unclear, this protein induces a decrease in RNA polymerase II Serine 2 (RNAPII Ser-2) phosphorylation, which is critical for transcription elongation. To characterize the mechanism of transcriptional repression by ICP22, we established an in vivo transient expression reporter system. We found that ICP22 inhibits transcription of the HSV-1 α, ß and γ gene promoters. The viral tegument protein VP16, which plays vital roles in initiation of viral gene expression and viral proliferation, can overcome the inhibitory effect of ICP22 on α-gene transcription. Further immunoprecipitation studies indicated that both ICP22 and VP16 bind to positive transcription elongation factor b (P-TEFb) and form a complex with it in vivo. We extended this to show that P-TEFb regulates transcription of the viral α-gene promoters and affects transcriptional regulation of ICP22 and VP16 on the α-genes. Additionally, ChIP assays demonstrated that ICP22 blocks the recruitment of P-TEFb to the viral promoters, while VP16 reverses this blocking effect by recruiting P-TEFb to the viral α-gene promoters through recognition of the TAATGARAT motif. Taken together, our results suggest that ICP22 interacts with and blocks the recruitment of P-TEFb to viral promoter regions, which inhibits transcription of the viral gene promoters. The transactivator VP16 binds to and induces the recruitment of P-TEFb to viral α-gene promoters, which counteracts the transcriptional repression of ICP22 on α-genes by recruiting p-TEFb to the promoter region.

[Evaluation of immune responses and related patho-inflammatory reactions of a candidate inactivated EV71 vaccine in neonatal monkeys].

OBJECTIVE: To evaluate the safety of enterovirus type 71 (EV71) inactivated vaccine (human diploid derived) for infection prevention in an animal model by investigating the immune responses and related patho-inflammatory reactions. METHODS: In the neonatal monkey model for EV71 vaccine protection, vaccinated group (n = 4) and unvaccinated group (n = 4) were attacked with live virus at the same time, the parameters of clinical observations, antibodies and inflammatory factors in peripheral blood and cerebrospinal fluid (CSF) were detected. And the pathological changes in major organs were used to determine the patho-inflammatory reactions during the immune responses elicited by vaccination. RESULTS: The neutralizing antibodies of vaccine group reach to 1:32. There was no obvious changes of inflammatory factors in peripheral blood and CSF of monkeys challenged or unchallenged by live virus. In peripheral blood of unvaccinated group, the level of basophilic granulocyte higher 4 - 5 times than normal level and the interferon-γ (IFN-γ) showed obvious increase. Live virus infected after 7 days, the interleukin-6 (IL-6) and IFN-γ in peripheral blood of unvaccinated group (18.5, 12.7 pg/ml) were higher than vaccinated group (10.2, 7.6 pg/ml). Furthermore, the IL-6 in CSF (102.0 pg/ml) had 4 - 5 times increased than vaccinated group (12.4 pg/ml) at 7 days after virus exposure. Meanwhile, the pathological analysis revealed that no obvious changes were detected in CNS and other organs of vaccinated monkeys challenged with live virus. However, the pathological damages induced by virus infection could be determined in the unvaccinated control monkeys, including neuronal damage, massive cellular infiltration associated with pulmonary edema/hemorrhage and pulmonary/bronchial damage due to an infiltration of inflammatory cells. CONCLUSION: Capable of inducing an immune response, the EV71 inactivated vaccine offers protection to neonatal rhesus monkeys against the attacks of live virus. Based on the results of no patho-inflammatory reaction and pathological damage after viral infection in vaccinated animals, the excellent safety of this vaccine may be confirmed in neonatal monkey.

Host cell protein C9orf69 promotes viral proliferation via interaction with HSV-1 UL25 protein.

In light of the scarcity of reports on the interaction between HSV-1 nucleocapsid protein UL25 and its host cell proteins, the purpose of this study is to use yeast two-hybrid screening to search for cellular proteins that can interact with the UL25 protein. C9orf69, a protein of unknown function was identified. The interaction between the two proteins under physiological conditions was also confirmed by biological experiments including co-localization by fluorescence and immunoprecipitation. A preliminary study of the function of C9orf69 showed that it promotes viral proliferation. Further studies showed that C9orf69 did not influence viral multiplication efficiency by transcriptional regulation of viral genes, but indirectly promoted proliferation via interaction with UL25.

Analysis of the cellular localization of herpes simplex virus 1 immediate-early protein ICP22.

Nuclear proteins often form punctiform structures, but the precise mechanism for this process is unknown. As a preliminary study, we investigated the aggregation of an HSV-1 immediate-early protein, infected-cell protein 22 (ICP22), in the nucleus by observing the localization of ICP22-EGFP fusion protein. Results showed that, in high-level expression conditions, ICP22-EGFP gradually concentrates in the nucleus, persists throughout the cell cycle without disaggregation even in the cell division phase, and is finally distributed to daughter cells. We subsequently constructed a mammalian cell expression system, which had tetracycline-dependent transcriptional regulators. Consequently, the location of ICP22-EGFP in the nucleus changed with distinct induction conditions. This suggests that the cellular location of ICP22 is also influenced by promoter regulation, in addition to its own structure. Our findings provide new clues for the investigation of transcriptional regulation of viral genes. In addition, the non-protease reporter system we constructed could be utilized to evaluate the role of internal ribosome entry sites (IRES) on transcriptional regulation.

A comparison of the biological characteristics of EV71 C4 subtypes from different epidemic strains.

The comparative analysis of the biological characterization and the genetic background study of EV71 circulating strains is commonly recognized as basic work necessary for development of an effective EV71 vaccine. In this study, we sequenced five EV71 circulating strains, isolated from Fuyang, Hefei, Kunming and Shenzhen city of China and named them FY-23, FY-22, H44, K9 and S1 respectively. The sequence alignment demonstrated their genotypes be C4. The genetic distance of the VP1 gene from these isolates suggested that they were highly co-related with genetic identity similar to other previously reported EV71 strains in China. Additionally, these strains were identified to display some obvious proliferation dynamics and plaque morphology when propagated in Vero cells. However, a distinctive difference in pathogenic ability in neonatal mice was found. Some differences in cross neutralization test & immunogenic analysis were also found. All these results are related to the biological characterization of circulating EV71 strains in China and aid in the development of an EV71 vaccine in the future.

[Biological characters of a coxsackievirus B3 variant strain isolated from a hand-foot-mouth disease patient with severe clinical symptoms].

OBJECTIVE: To analyze the genetic and biological characters of a new isolate of coxsackievirus B3 (CoxB3), i.e. FY-19 strain, and investigate its mechanistic role in causing different clinical symptoms of hand-foot-mouth disease (HFMD). METHODS: FY-19 strain, isolated from a patient with severe clinical symptoms from Fuyang, China in 2008, was identified by the serological parameters via the Lim Benyesh-Melnick (LBM) antiserum pools. Its genotype was further characterized by sequencing the whole genome. And its biological characters were also examined by proliferation kinetic and pathogenetic analysis. RESULTS: FY-19 strain was identified as CoxB3 showing 23.0%, 16.5% and 32.1% difference with Nancy strain in 3'-, 5'-noncoding and coding regions respectively. FY-19 also showed a high homology with other HFMD-related CoxB3 isolates in China. But its homology with non-HFMD-related CoxB3 isolates was lower (13.5% and 25.0% difference in 3'-NCR and coding region respectively). The viral replication kinetic analysis suggested that the FY-19 proliferation increased rapidly and peaked at 14 hours post-infection. In pathological analysis, FY-19 strain induced mortal pathology in sucking mice. CONCLUSION: Differences in genetic and biological characters exist between FY-19 and Nancy strains. Further analysis on the pathogenesis of this variant may aid in elucidating the mechanisms of HFMD.

Isolation and complete nucleotide sequence of the measles virus IMB-1 strain in China.

The complete nucleotide sequence of the measles virus strain IMB-1, which was isolated in China, was determined. As in other measles viruses, its genome is 15,894 nucleotides in length and encodes six proteins. The full-length nucleotide sequence of the IMB-1 isolate differed from vaccine strains (including wild-type Edmonston strain) by 4%-5% at the nucleotide sequence level. This isolate has amino acid variations over the full genome, including in the hemagglutinin and fusion genes. This report is the first to describe the full-length genome of a genotype H1 strain and provide an overview of the diversity of genetic characteristics of a circulating measles virus.

Transcriptional regulation by HSV-1 induced HTRP via acetylation system.

The protein HTRP (human transcription regulator protein) is encoded by the differential gene htrp and induced by Herpes simplex virus type 1 (HSV-1) infection in KMB-17 cells. HTRP was found to interact with SAP30 (mSin3A Association Protein), one of the components of co-repressor complex mSin3A, which is part of the deacetylation transfer enzyme HDAC. To reveal the biological significance of the interaction between HTRP and SAP30, real- time PCR and a dual-luciferase detecting system was used. The results indicate that HTRP could inhibit the transcription of a viral promoter, whose interaction with SAP30 synergistically affects transcriptional inhibition of the viral genes, and is related to HDAC enzyme activity. ChIP experiments demonstrate that HTRP could promote HDAC activity by increasing the deacetylation level of lysine 14 and lysine 9 in histone H3.

The repairing effect of a recombinant human connective-tissue growth factor in a burn-wounded rhesus-monkey (Macaca mulatta) model.

CTGF (connective-tissue growth factor) has been characterized as an extracellular-matrix-associated protein that modulates basic-fibroblast-growth-factor signalling and angiogenesis. In the present paper, the cloning of the ctgf gene from human umbilical-vein endothelial cells and expression of the protein in Escherichia coli as an N-terminal hexahistidine fusion protein is described. Recombinant human CTGF (rhCTGF) was expressed and purified so that we could investigate its effect on the proliferation of human embryo fibroblast KMB-17 and NIH3T3 cells. The results indicated not only that the protein was properly folded, but also that it had the same specific activity and stability as the native protein. Furthermore, we administered this recombinant protein in a non-human primate [rhesus monkey (Macaca mulatta)] burn-wound model and report the clinical findings and structural effects. Epitheliotrophic effects were conspicuous in wounded tissues at 10-100 ng of CTGF/cm(2), suggesting that administered rhCTGF can play a normal physiological role in wound repairing in a non-human primate model.

Structural and functional characterization of herpes simplex virus 1 immediate-early protein infected-cell protein 22.

Of the five HSV1 immediate-early proteins, infected-cell protein 22 (ICP22), the product of the Us1 gene, is a member whose function is less understood. In order to promote better understanding of the role of ICP22 in viral replication, mutation and fluorescence techniques were used to investigate the biochemical relationship between ICP22's structure and nuclear localization, and the CAT assay was used to analyze the relationship between ICP22's structure and its transcriptional repression. The results of these experiments implied (i) ICP22 is localized to small dense nuclear bodies and is paired with the SC-35 domain in the nucleus, (ii) ICP22 localization in a punctate state requires completion of the main sequence which includes the 1-320th amino acids, (iii) a conservative mutation in the nucleotidylylation site is important for its nuclear localization and transcriptional repression, and (4) despite possessing the same amino acid sequence as the ICP22 carboxyl-terminal, Us1.5 was distinct from ICP22 in location and function.

HTRP--an immediate-early gene product induced by HSV1 infection in human embryo fibroblasts, is involved in cellular co-repressors.

The interaction between virus and receptor is a process that mimics physiological ligand binding receptors and induces signal transduction. In the investigation of the interaction between HSV1 (Herpes Simplex virus 1) and human fibroblasts via virus binding to its receptor complex on cellular membranes, the HTRP (human transcription regulator protein), a protein encoded by an immediate-early gene of cellular response against the specific stimulation of HSV1 binding, was cloned from a cDNA library established from early gene response mRNA. The localization of HTRP expressed as a fusion polypeptide with a fluorescent protein in HeLa cells was confirmed to be the nucleus. The results of a yeast two-hybrid experiment indicated that HTRP is indeed involved in the interaction with the SAP (mSin3-associate polypeptide) complex via SAP30. A pull-down test and Western blotting in vitro, and immunoprecipitation in vivo also provided evidence in support of this result. The interaction of HTRP with SAP30 in its conserved domain implies that this protein family, as the products of immediate-early genes, comprise functional molecules involved in the transcriptional regulation of cells, which might be related to the inhibition of some cell survival genes.

[Structural mechanism studies of hTNF alpha mutants in position 30 and 42 amino acid].

OBJECTIVE: To study the relationship between the structure and functional activity of hTNF alpha. METHODS: Four hTNF alpha mutants were constructed, different binding structures and gene responses related with these mutants were studied by the methods of immunoprecipitation and mRNA differential display. RESULTS: The specific activities and LD50 of the different hTNF alpha mutants indicated their different bioactivities. It was shown that the hTNF alpha mutants had the relative binding affinities to the wild types. The mRNA differential display assay proved that the hTNF alpha mutants stimulated different gene responses. CONCLUSION: These results suggest that the specific anti-tumor activities of hTNF alpha mutants are accomplished by inducing different or same gene response at different quantities after its binding to specific receptor.