Transcriptomic analysis of cells in response to EV71 infection and 2Apro as a trigger for apoptosis via TXNIP gene

Research of recombinant influenza A virus as a vector for Mycoplasma pneumoniae P1a and P30a

BACKGROUND

Mycoplasma pneumoniae (MP) is a common respiratory pathogen affecting the longevity of the elderly and the health of children. However, the human vaccine against MP has not been successfully developed till now due to the poor immunogenicity and side effects of MP inactivated or attenuated vaccine. Therefore, it is necessary to develop a MP genetic engineering vaccine with influenza virus strain as vector.

METHODS

In this study, the major antigen genes P1a of MP adhesion factor P1(3862-4554 bases) and P30a of P30(49-822 bases) were inserted into the nonstructural protein (NS) gene of Influenza A virus strain A/Puerto Rio/8/34(H1N1), PR8 for short, to construct the recombinant vectors NS-P1a or NS-P30a. The recombinant pHW2000 plasmids containing NS-P1a or NS-P30a were cotransfected with the rest 7 fragments of PR8 into HEK293T cells. After inoculating chicken embryos, the recombinant influenza viruses rFLU-P1a and rFLU-P30a were rescued. RT-PCR and sequencing were used to identify the recombinant viruses. The hemagglutination titers of rFLU-P1a and rFLU-P30a were determined after five successive generations in chicken embryos so as to indicate the genetic stability of the recombinant viruses. The morphology of recombinant influenza viruses was observed under electron microscopy.

RESULTS

P1a or P30a was designed to be inserted into the modified NS gene sequence separately and synthesized successfully. RT-PCR identification of the recombinant viruses rFLU-P1a and rFLU-P30a showed that P1a (693 bp), P30a (774 bp), NS-P1a (1992bp) and NS-P30a (2073 bp) bands were found, and the sequencing results were correct. After five successive generations, each virus generation has a certain hemagglutination titer (from 1:32 to 1:64), and the band of P1a or P30a can be seen in the corresponding positions. The virus particles under the electron microscope appeared as spheres or long strips connected by several particles, revealing a complete viral membrane structure composed of virus lipid bilayer, hemagglutinin, neuraminidase, and matrix proteins.

CONCLUSION

The recombinant viruses rFLU-P1a and rFLU-P30a which carried the advantaged immune regions of the P1 and P30 genes in MP were successfully constructed and identified. And the genetic stability of rFLU-P1a or rFLU-P30a was relatively high. The typical and complete morphology of influenza virus was observed under the electron microscope. Our research provided a foundation for the further development of MP vaccines for human.

Ubiquitin E3 ligase SPOP is a host negative regulator of enterovirus 71-encoded 2A protease

IMPORTANCE

EV71 poses a significant health threat to children aged 5 and below. The process of EV71 infection and replication is predominantly influenced by ubiquitination modifications. Our previous findings indicate that EV71 prompts the activation of host deubiquitinating enzymes, thereby impeding the host interferon signaling pathway as a means of evading the immune response. Nevertheless, the precise mechanisms by which the host employs ubiquitination modifications to hinder EV71 infection remain unclear. The present study demonstrated that the nonstructural protein 2Apro, which is encoded by EV71, exhibits ubiquitination and degradation mediated by the host E3 ubiquitin ligase SPOP. In addition, it is the first report, to our knowledge, that SPOP is involved in the host antiviral response.

Cyr61 Mediates Angiotensin II-Induced Podocyte Apoptosis via the Upregulation of TXNIP

Purpose. It is well documented that angiotensin II (Ang II) elevation promotes apoptosis of podocytes in vivo and vitro, but the potential mechanism is still oscular. The current study is aimed at probing into the assignment of cysteine-rich protein 61 (Cyr61) in Ang II-induced podocyte apoptosis. Methods. Podocytes were treated with Ang II (10-6 mol/L) for 48 hours to establish an injury model in vitro. Western blot assays were detected the expression of Cyr61, Cyt-c, Bax, and Bcl-2. Gene microarray was used to analyze the expression of mRNAs after treatment with Ang II. CRISPR/Cas9 technology was used to knock down Cyr61 and overexpress TXNIP gene, respectively. Results. The expression of Cyr61, TXNIP, Cyt-c, and Bax in podocytes treated with Ang II were upregulated, but the expression and apoptotic rates of Bcl-2 in podocytes were inhibited. The level of the above factors was not significantly different after the knockdown of Cyr61 with Ang II in podocytes. In Ang II group, when knocked down Cyr61, the expressed level of TXNIP, Cyt-c, and Bax was diminished after Ang II treatment; interestingly Bcl-2 expression and podocyte apoptotic rate were reduced. Under the stimulation of Ang II, the expression of Cyt-c and Bax were growing, whereas Bcl-2 was reduced, and the apoptotic rates were higher in the TXNIP overexpression group. Cyt-c and Bax were put on, whereas that of Bcl-2 was to be cut down when the Cyr61 was knockdown, and the apoptotic rates were gained in the TXNIP overexpression+Cyr61 knockdown group. Conclusions. The results of the study extrapolate that Cyr61 plays a dominant role in Ang II-induced podocyte apoptosis. Additionally, Cyr61 may mediate the Ang II-induced podocyte apoptosis by promoting the expression of TNXIP.

Inhibitory effects and mechanisms of proanthocyanidins against enterovirus 71 infection

Proanthocyanidins (PC), a natural flavonoid compound, was reported to possess a variety of pharmacological activities such as anti-tumor and anti-viral effects. In this study, the anti-Enterovirus 71 (EV71) activities and mechanisms of PC were investigated both in vitro and in vivo. The results showed that PC possessed anti-EV71 activities in different cell lines with low toxicity. PC can block both the adsorption and entry processes of EV71 via directly binding to virus VP1 protein. PC may competitively interfere with the binding of VP1 to its receptor SCARB2. PC can also regulate three different MAPK signaling pathways to reduce EV71 infection and attenuate virus induced inflammatory responses. Importantly, intramuscular therapy of EV71-infected mice with PC markedly improved their survival and attenuated the severe clinical symptoms. Therefore, the natural compound PC has potential to be developed into a novel anti-EV71 agent targeting viral VP1 protein and MAPK pathways.

Long non-coding RNA ENST00000469812 promotes Enterovirus type 71 replication via targeting the miR-4443/NUPR1 axis in rhabdomyosarcoma cells

Hand, foot, and mouth disease (HFMD) caused by Enterovirus type 71 (EV71) is a serious threat to children's health. However, the pathogenic mechanism of EV71 is still unclear. Long non-coding RNAs (lncRNAs), some of which bind to miRNA as competitive endogenous RNAs (ceRNA) and weaken the silencing effect on the mRNA of downstream target genes, play a key role in regulating the viral infection process. In this study, through experimental verification, we found miR-4443 to be downregulated in cells infected with EV71. Next, by predicting lncRNAs that potentially regulate miR-4443, we found that EV71 infection induced upregulation of lncRNA ENST00000469812 and then further downregulated miR-4443 expression by direct interaction. We also demonstrated that nuclear protein 1 (NUPR1) is one of the target genes of miR-4443 and is involved in the ENST00000469812/miR-4443/NUPR1 regulatory axis. Finally, the ENST00000469812/miR-4443/NUPR1 regulatory axis exhibited a positive effect on EV71 replication. Here, we lay a foundation for exploring the pathogenic mechanism of EV71 and identify potential targets for HFMD treatment.

Transcriptome analysis following enterovirus 71 and coxsackievirus A16 infection in respiratory epithelial cells

Enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) are the major pathogens responsible for hand, foot and mouth disease (HFMD), but the mechanism by which these viruses cause disease remains unclear. In this study, we used transcriptome sequencing technology to investigate changes in the transcriptome profiles after infection with EV-A71 and CV-A16 in human bronchial epithelial (16HBE) cells. Using systematic bioinformatics analysis, we then searched for useful clues regarding the pathogenesis of HFMD. As a result, a total of 111 common differentially expressed genes were present in both EV-A71- and CV-A16-infected cells. A trend analysis of these 111 genes showed that 91 of them displayed the same trend in EV-A71 and CV-A16 infection, including 49 upregulated genes and 42 downregulated genes. These 91 genes were further used to conduct GO, pathway, and coexpression network analysis. It was discovered that enriched GO terms (such as histone acetylation and positive regulation of phosphorylation) and pathways (such as glycosylphosphatidylinositol (GPI)-anchor biosynthesis and DNA replication) might be closely associated with the pathogenic mechanism of these two viruses, and key genes (such as TBCK and GPC) might be involved in the progression of HFMD. Finally, we randomly selected 10 differentially expressed genes for qRT-PCR to validate the transcriptome sequencing data. The experimental qRT-PCR results were roughly in agreement with the results of transcriptome sequencing. Collectively, our results provide clues to the mechanism of pathogenesis of HFMD induced by EV-A71 and CV-A16.

Global profiling of the alternative splicing landscape reveals transcriptomic diversity during the early phase of enterovirus 71 infection

The alteration of host cell splicing is a major strategy favouring viral replication; however, the interaction between human tonsillar epithelial cells (HTECs) and enterovirus 71 (EV71) has not been fully elucidated. Here, a total of 201 differentially expressed genes (DEGs) and 3266 novel genes with coding potential were identified. A total of 3479 skipped exons (SEs), 515 alternative 3' splice sites (A3SSs), 391 alternative 5' splice sites (A5SSs), 531 mutually exclusive exons (MXEs) and 825 retained introns (RIs) were identified as significantly altered alternative splicing (AS) events. The enriched DEGs were mainly related to the cell cycle, spliceosome, and Toll-like receptor (TLR) signalling pathways. Finally, the replication of EV71 was significantly inhibited by TLR2 heterodimers. Our findings suggest that AS events induced by EV71 increase the transcriptomic diversity of HTECs in response to EV71 infection. Additionally, TLR2 heterodimers have the potential to protect HTECs against EV71.

Regulation of Apoptosis by Enteroviruses

Enterovirus infection can cause a variety of diseases and severely impair the health of humans, animals, poultry, and other organisms. To resist viral infection, host organisms clear infected cells and viruses via apoptosis. However, throughout their long-term competition with host cells, enteroviruses have evolved a series of mechanisms to regulate the balance of apoptosis in order to replicate and proliferate. In the early stage of infection, enteroviruses mainly inhibit apoptosis by regulating the PI3K/Akt pathway and the autophagy pathway and by impairing cell sensors, thereby delaying viral replication. In the late stage of infection, enteroviruses mainly regulate apoptotic pathways and the host translation process via various viral proteins, ultimately inducing apoptosis. This paper discusses the means by which these two phenomena are balanced in enteroviruses to produce virus-favoring conditions – in a temporal sequence or through competition with each other. This information is important for further elucidation of the relevant mechanisms of acute infection by enteroviruses and other members of the picornavirus family.

Virucidal activity and the antiviral mechanism of acidic polysaccharides against Enterovirus 71 infection in vitro

Enterovirus 71 (EV71) is the predominant pathogen for severe hand, foot, and mouth disease (HFMD) in children younger than 5 years, and currently no effective drugs are available for EV71. Thus, there is an urgent need to develop new drugs for the control of EV71 infection. In this study, LJ04 was extracted from Laminaria japonica using diethylaminoethyl cellulose-52 with 0.4 mol/l NaCl as the eluent, and its virucidal activity was evaluated based on its cytopathic effects on a microplate. LJ04 is composed of fucose, galactose, and mannose and mainly showed good virucidal activity against EV71. The antiviral mechanisms of LJ04 were the direct inactivation of the virus, the blockage of virus binding, disruptions to viral entry, and weak inhibitory activity against the nonstructural protein 3C. The two most important findings from this study were that LJ04 inhibited EV71 proliferation in HM1900 cells, which are a human microglia cell line, and that LJ04 can directly inactivate EV71 within 2 hr at 37°C. This study demonstrates for the first time the ability of a polysaccharide from L. japonica to inhibit viral and 3C activity; importantly, the inhibition of 3C might have a minor effect on the antiviral effect of LJ04. Consequently, our results identify LJ04 as a potential drug candidate for the control of severe EV71 infection in clinical settings.

Host relieves lnc-IRAK3-3-sequestered miR-891b to attenuate apoptosis in Enterovirus 71 infection

Enterovirus 71 (EV71) is an emerging life-threatening pathogen particularly in the Asia-Pacific region. Apoptosis is a major pathogenic feature in EV71 infection. However, which molecular mechanism participating in EV71-induced apoptosis is not completely understood. Long noncoding RNAs (lncRNAs), a newly discovered class of regulatory RNA molecules, govern a wide range of biological functions through multiple regulatory mechanisms. Whether lncRNAs involved in EV71-induced apoptosis was investigated in this study. We conducted an apoptosis-oriented approach by integrating lncRNA and mRNA profilings. lnc-IRAK3-3 is down-regulated in EV71 infection and plays an important role in EV71 infection-induced apoptosis. Compensation of lnc-IRAK3-3 in EV71 infection promoted cell apoptosis wherein GADD45β expression was increased and further triggered caspase3 and PARP cleavage. Using bioinformatics analysis and functional assays, lnc-IRAK3-3 could functionally sequester miR-891b and GADD45β 3'UTR whereas miR-891b showed the inhibitory activity on GADD45β expression. Taken together, lnc-IRAK3-3 has the ability capturing miR-891b to enforce GADD45β expression and eventually promotes apoptosis. On the contrary, host cells suppress lnc-IRAK3-3 to relieve lnc-IRAK3-3-sequestered miR-891b, restrain GADD45β, and attenuate apoptosis in EV71 infection that prevent host cells from severe damages. We discover a new molecular mechanism by which host cells counteract EV71-induced apoptosis through the lnc-IRAK3-3/miR-891b/GADD45β axis partially.