Survival Of Infected Cells Research Articles

Comprehensive Epstein-Barr Virus Transcriptome by RNA-Sequencing in Angioimmunoblastic T Cell Lymphoma (AITL) and Other Lymphomas.

Simple SummaryAngioimmunoblastic T cell lymphoma (AITL) is probably the most common peripheral T-cell lymphoma. This pathology, although rare, is more common in Europe than in other regions. This lymphoma has a poor prognosis. AITL is very commonly associated with the Epstein-Barr virus (EBV) although the virus is not often found in neoplastic T cells but rather in adjacent B cells. Our objective was to study the transcriptome of EBV in AITLs comparatively to other EBV-associated lymphomas and to compare the results with those obtained for cell lines. We showed in AITLs a strong expression of Bam-HI A rightward transcripts (BARTs) more expressed than in the other lymphomas and especially than in cell lines. BARTs can participate in tumor development. We also showed a latency IIc in AITLs with the expression of BNLF2a and BCRF1 genes which may participate in the survival of infected cells. These results support the involvement of EBV in AITLs.The Epstein–Barr virus (EBV) is associated with angioimmunoblastic T cell lymphoma (AITL) in more than 80% of cases. Few studies have focused on this association and it is not clear now what role the virus plays in this pathology. We used next-generation sequencing (NGS) to study EBV transcriptome in 14 AITLs compared to 21 other lymphoma samples and 11 cell lines including 4 lymphoblastoid cell lines (LCLs). Viral transcripts were recovered using capture probes and sequencing was performed on Illumina. Bam-HI A rightward transcripts (BARTs) were the most latency transcripts expressed in AITLs, suggesting they may play a role in this pathology. Thus, BARTs, already described as highly expressed in carcinoma cells, are also very present in AITLs and other lymphomas. They were poorly expressed in cell lines other than LCLs. AITLs showed a latency IIc, with BNLF2a gene expression. For most AITLs, BCRF1, which encodes a homologous protein of human interleukin 10, vIL-10, was in addition expressed. This co-expression can contribute to immune escape and survival of infected cells. Considering these results, it can be assumed that EBV plays a pathogenic role in AITLs.

Taxonomic, functional and expression analysis of viral communities associated with marine sponges.

Viruses play an essential role in shaping the structure and function of ecological communities. Marine sponges have the capacity to filter large volumes of ‘virus-laden’ seawater through their bodies and host dense communities of microbial symbionts, which are likely accessible to viral infection. However, despite the potential of sponges and their symbionts to act as viral reservoirs, little is known about the sponge-associated virome. Here we address this knowledge gap by analysing metagenomic and (meta-) transcriptomic datasets from several sponge species to determine what viruses are present and elucidate their predicted and expressed functionality. Sponges were found to carry diverse, abundant and active bacteriophages as well as eukaryotic viruses belonging to the Megavirales and Phycodnaviridae. These viruses contain and express auxiliary metabolic genes (AMGs) for photosynthesis and vitamin synthesis as well as for the production of antimicrobials and the defence against toxins. These viral AMGs can therefore contribute to the metabolic capacities of their hosts and also potentially enhance the survival of infected cells. This suggest that viruses may play a key role in regulating the abundance and activities of members of the sponge holobiont.

CRISPR Genome Editing Applied to the Pathogenic Retrovirus HTLV-1.

CRISPR editing of retroviral proviruses has been limited to HIV-1. We propose human T-cell leukemia virus type 1 (HTLV-1) as an excellent model to advance CRISPR/Cas9 genome editing technologies against actively expressing and latent retroviral proviruses. HTLV-1 is a tumorigenic human retrovirus responsible for the development of both leukemia/lymphoma (ATL) and a neurological disease (HAM/TSP). The virus immortalizes and persists in CD4+ T lymphocytes that survive for the lifetime of the host. The most important drivers of HTLV-1-mediated transformation and proliferation are the tax and hbz viral genes. Tax, transcribed from the plus-sense or genome strand, is essential for de novo infection and cellular immortalization. Hbz, transcribed from the minus-strand, supports proliferation and survival of infected cells in both its protein and mRNA forms. Abrogating the function or expression of tax and/or hbz by genome editing and mutagenic double-strand break repair may disable HTLV-1-infected cell growth/survival and prevent immune modulatory effects and ultimately HTLV-1-associated disease. In addition, the HTLV-1 viral genome is highly conserved with remarkable sequence homogeneity, both within the same host and even among different HTLV isolates. This offers more focused guide RNA targeting. In addition, there are several well-established animal models for studying HTLV-1 infection in vivo as well as cell immortalization in vitro. Therefore, studies with HTLV-1 may provide a better basis to assess and advance in vivo genome editing against retroviral infections.

Infusion therapy for cardiovascular diseases: the allowed limits

Background. Analysis of the mortality structure of patients with coronavirus disease (COVID-19) had found that 69.2 % of non-survivors had hypertension. Comorbid diabetes mellitus (31.8 %) and coronary heart disease (28.2 %) were also common. During pandemic, it is necessary to maintain optimal cardiovascular therapy by continuing to administer its main drugs (acetylsalicylic acid, statins, β-blockers, angiotensin-converting enzyme inhibitors – ACEI).
 Objective. To describe infusion therapy (IT) for cerebrovascular and cardiovascular diseases in settings of the COVID-19 pandemic.
 Materials and methods. Analysis of the literature on this topic.
 Results and discussion. Although the spike proteins of the new coronavirus have the tropism to ACE-2, discontinuation of ACEI is unwarranted and may worsen the course of cardiovascular disease (CVD). Particular attention should be paid to the diagnosis of acute coronary syndrome (ACS) in COVID-19. In myocardial infarction, myocarditis or cardiomyopathy on the background of COVID-19, there is a moderate increase in troponin, brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide. An increase in D-dimers is a prognostic marker of the unfavorable prognosis. The algorithm for the ACS diagnosis includes the detection of typical clinical symptoms, ECG analysis, detection of disorders of local contractility of the left ventricle. Determination of troponin in patients without clinical manifestations of ACS with nonspecific manifestations of COVID-19 is not recommended. As for reperfusion therapy strategies, it is indicated in patients with symptoms of ischemia lasting >12 hours and a persistent increase in ST in two adjacent leads. In the absence of prior testing for coronavirus infection, all patients should be managed according to the tactics for COVID-positive patients. In non-STEMI, patients should be stratified according to their risk level (very high, high, moderate, low). In case of high risk, the early (<24 hours) invasive strategy is reasonable, in case of intermediate risk it is reasonable to consider noninvasive treatment. It should be remembered that the use of certain drugs for the treatment of COVID-19 (azithromycin, chloroquine, hydroxychloroquine, lopinavir, ritonavir) is associated with a risk of cardiotoxicity and life-threatening arrhythmias. Cardiotoxicity monitoring (determination of the corrected QT interval) should be performed before the start of therapy and then once in 5 days, primarily in risk groups (men >55 years, women >65 years and people with the CVD history). Lopinavir and ritonavir may also decrease the levels of active metabolites of clopidogrel and increase – of ticagrelor, so prasugrel is the antiplatelet drug of choice for COVID-19. Amiodarone also interacts with a large number of antiviral drugs. In turn, statins have multiple immunomodulatory effects including increase of the innate antiviral immune response. It is recommended to continue taking those statins that were prescribed earlier. If co-administration with lopinavir and ritonavir is required, the minimum dose of rosuvastatin or atorvastatin should be started. These antivirals are able to interact with calcium channel blockers and increase their concentration, so the dose of amlodipine and diltiazem can be reduced by 50 %. Endothelial dysfunction (ED) caused by a viral infection leads to the excessive thrombin formation and inhibition of fibrinolysis, increasing the risk of thrombotic complications. Nitric oxide (NO) plays an important role in counteracting ED. NO also inhibits the replication of the acute severe respiratory syndrome coronavirus and improves the survival of infected cells. L-arginine (Tivortin, “Yuria-Pharm”) is the only substrate for NO synthase that catalyzes the formation of NO in endothelial cells. According to the results of the own study, Tivortin helped to reduce the content of fibrinogen and soluble fibrin-monomer complexes, as well as to increase the thromboplastin time. Endothelium-dependent vasodilation also improved after administration of Tivortin. Tivorel (“Yuria-Pharm”) contains L-arginine and L-carnitine, which allows this drug to increase the survival of cardiomyocytes and endothelial cells, to restore homeostasis in the affected areas of the myocardium, and to counteract the progression of atherogenesis and thrombosis. In case of COVID-19, it is also advisable to prescribe edaravone (Ksavron, “Yuria-Pharm”), which neutralizes the cytokine storm, inhibits lipid peroxidation, protects against endothelial damage and, penetrating the blood-brain barrier, counteracts cerebral edema. In case of the need in IT, it is advisable to choose Reosorbilact (“Yuria-Pharm”), which has anti-shock, rheological, detoxifying, alkalizing and osmodiuretic effects. In hypovolemic shock and intracranial hemorrhage, the use of isotonic low-molecular-weight gelatin preparations (Volutenz, “Yuria-Pharm”) has been shown.
 Conclusions. 1. In the absence of prior testing for coronavirus infection, all patients should be managed following the tactics for COVID-positive patients. 2. The use of azithromycin, chloroquine, hydroxychloroquine, lopinavir, ritonavir is associated with a risk of cardiotoxicity and life-threatening arrhythmias. 3. ED, caused by a viral infection, increases the risk of thrombotic complications. 4. It is reasonable to include the required solutions (Tivortin, Tivorel, Ksavron, Reosorbilact, Volutenz) into the combined IT of COVID-19 patients.

IMMUNOLOGY OF CERVICAL CANCER.

Optimal function of the immune system allows the recognition and elimination of infected and tumor cells. However, these cells can develop mechanisms to evade the cellular immune response. In human papillomavirus (HPV) infection, dysregulation of major histocompatibility complex Class I molecules and other components of the innate immune system promote the survival of infected cells by allowing the infection to persist which, in turn, favors the development of cancer. Further, tumor cells possess inherent mechanisms designed to block the recognition and activation of cytotoxic lymphocytes: particularly, HPV proteins such as E1 and E2 and oncoproteins E5, E6, and E7 that inhibit immune mechanisms and/or stimulate the expression of immunosuppressive cytokines. These mechanisms include a decrease in receptor activation and costimulating molecules on the surface of immune cells, as well as the constitutive expression of molecules that inhibit their function, which allow HPV persistence and tumor progression. Immunotherapy-based therapeutic options are positioned as excellent candidates for the treatment of cervical cancer.

Hantavirus inhibits apoptosis by preventing mitochondrial membrane potential loss through up-regulation of the pro-survival factor BCL-2.

Hantaviruses, zoonotic RNA viruses belonging to the order Bunyavirales, cause two severe acute diseases in humans, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Hantavirus-infected patients show strong cytotoxic lymphocyte responses and hyperinflammation; however, infected cells remain mostly intact. Hantaviruses were recently shown to inhibit apoptosis in infected cells. By inhibiting granzyme B- and TRAIL-mediated apoptosis, hantaviruses specifically and efficiently inhibit cytotoxic lymphocyte-mediated killing of infected cells. Hantaviruses also strongly inhibit apoptosis triggered intrinsically; i.e., initiated through intracellular activation pathways different from those used by cytotoxic lymphocytes. However, insights into the latter mechanisms are currently largely unknown. Here, we dissected the mechanism behind how hantavirus infection, represented by the HFRS-causing Hantaan virus and the HPS-causing Andes virus, results in resistance to staurosporine-induced apoptosis. Less active caspase-8 and caspase-9, and consequently less active caspase-3, was observed in infected compared to uninfected staurosporine-exposed cells. While staurosporine-exposed uninfected cells showed massive release of pro-apoptotic cytochrome C into the cytosol, this was not observed in infected cells. Further, hantaviruses prevented activation of BAX and mitochondrial outer membrane permeabilization (MOMP). In parallel, a significant increase in levels of the pro-survival factor BCL-2 was observed in hantavirus-infected cells. Importantly, direct inhibition of BCL-2 by the inhibitor ABT-737, as well as silencing of BCL-2 by siRNA, resulted in apoptosis in staurosporine-exposed hantavirus-infected cells. Overall, we here provide a tentative mechanism by which hantaviruses protect infected cells from intrinsic apoptosis at the mitochondrial level by inducing an increased expression of the pro-survival factor BCL-2, thereby preventing MOMPs and subsequent activation of caspases. The variety of mechanisms used by hantaviruses to ensure survival of infected cells likely contribute to the persistent infection in natural hosts and may play a role in immunopathogenesis of HFRS and HPS in humans.

Влияние нормальной микрофлоры влагалища на течение папилломавирусной инфекции

Objective. To study the influence of normal vaginal microbiota on papillomavirus (HPV) infection. Patients and methods. We examined 160 women with HPV infection. We assessed the state of normal flora, the presence of sexually transmitted infections (STIs), and the HPV elimination rate. The correlation of living, apoptotic and necrotic epithelial cells depending on the levels of lactobacilli in native and stress-influenced specimens was studied in 140 HPV-positive and 20 HPV-negative patients. Results. We have found a stronger relation between HPV viral load and deficiency of lactobacilli (r = 0.498; р = 0.021) than between the former and the presence of STIs (r = 0.121; р = 0.072). High baseline levels of vaginal lactobacilli increase the likelihood of HPV elimination. Normal levels of lactobacilli enhance the survival of noninfected epithelial cells and reduce the levels of infected ones, which ensures a predominantly apoptotic form of cell death. HPV enhances the survival of infected cells and shifts the cell death structure toward necrosis. Conclusion. Lactobacilli counteract the influence of HPV on the vital conditions of vaginal epithelial cells. This accounts for better outcomes of HPV infection in patients with normal levels of flora. Key words: apoptosis, human papillomavirus, vagina, lactobacilli, cervix, epithelial cells

Glycogen synthase kinase 3ß participates in late stages of Dengue virus-2 infection.

BACKGROUND Viruses can modulate intracellular signalling pathways to complete their infectious cycle. Among these, the PI3K/Akt pathway allows prolonged survival of infected cells that favours viral replication. GSK3β, a protein kinase downstream of PI3K/Akt, gets inactivated upon activation of the PI3K/Akt pathway, and its association with viral infections has been recently established. In this study, the role of GSK3β during Dengue virus-2 (DENV-2) infection was investigated.METHODS GSK3β participation in the DENV-2 replication process was evaluated with pharmacological and genetic inhibition during early [0-12 h post-infection (hpi)], late (12-24 hpi), and 24 hpi in Huh7 and Vero cells. We assessed the viral and cellular processes by calculating the viral titre in the supernatants, In-Cell Western, western blotting and fluorescence microscopy.RESULTS Phosphorylation of GSK3β-Ser9 was observed at the early stages of infection; neither did treatment with small molecule inhibitors nor pre-treatment prior to viral infection of GSK3β reduce viral titres of the supernatant at these time points. However, a decrease in viral titres was observed in cells infected and treated with the inhibitors much later during viral infection. Consistently, the infected cells at this stage displayed plasma membrane damage. Nonetheless, these effects were not elicited with the use of genetic inhibitors of GSK3β.CONCLUSIONS The results suggest that GSK3β participates at the late stages of the DENV replication cycle, where viral activation may promote apoptosis and release of viral particles.

Arachidonic Acid Derived Lipid Mediators Influence Kaposi's Sarcoma-Associated Herpesvirus Infection and Pathogenesis.

Kaposi’s sarcoma-associated herpesvirus (KSHV) infection, particularly latent infection is often associated with inflammation. The arachidonic acid pathway, the home of several inflammation and resolution associated lipid mediators, is widely altered upon viral infections. Several in vitro studies show that these lipid mediators help in the progression of viral pathogenesis. This review summarizes the findings related to human herpesvirus KSHV infection and arachidonic acid pathway metabolites. KSHV infection has been shown to promote inflammation by upregulating cyclooxygenase-2 (COX-2), 5 lipoxygenase (5LO), and their respective metabolites prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) to promote latency and an inflammatory microenvironment. Interestingly, the anti-inflammatory lipid mediator lipoxin is downregulated during KSHV infection to facilitate infected cell survival. These studies aid in understanding the role of arachidonic acid pathway metabolites in the progression of viral infection, the host inflammatory response, and pathogenesis. With limited therapeutic options to treat KSHV infection, use of inhibitors to these inflammatory metabolites and their synthetic pathways or supplementing anti-inflammatory lipid mediators could be an effective alternative therapeutic.

Tryptophan-kynurenine pathway attenuates \u03b2-catenin-dependent pro-parasitic role of STING-TICAM2-IRF3-IDO1 signalosome in Toxoplasma gondii infection

Recent studies have documented the diverse role of host immunity in infection by the protozoan parasite, Toxoplasma gondii. However, the contribution of the β-catenin pathway in this process has not been explored. Here, we show that AKT-mediated phosphorylated β-catenin supports T. gondii multiplication which is arrested in the deficiency of its phosphorylation domain at S552 position. The β-catenin-TCF4 protein complex binds to the promoter region of IRF3 gene and initiates its transcription, which was also abrogated in β-catenin knockout cells. TBK-independent phosphorylation of STING(S366) and its adaptor molecule TICAM2 by phospho-AKT(T308S473) augmented downstream IRF3-dependent IDO1 transcription, which was also dependent on β-catenin. But, proteasomal degradation of IDO1 by its tyrosine phosphorylation (at Y115 and Y253) favoured parasite replication. In absence of IDO1, tryptophan was catabolized into melatonin, which supressed cellular reactive oxygen species (ROS) and boosted parasite growth. Conversely, when tyrosine phosphorylation was abolished by phosphosite mutations, IDO1 escaped its ubiquitin-mediated proteasomal degradation system (UPS) and the stable IDO1 prevented parasite replication by kynurenine synthesis. We propose that T. gondii selectively utilizes tryptophan to produce the antioxidant, melatonin, thus prolonging the survival of infected cells through functional AKT and β-catenin activity for better parasite replication. Stable IDO1 in the presence of IFN-γ catabolized tryptophan into kynurenine, promoting cell death by suppressing phospho-AKT and phospho-β-catenin levels, and circumvented parasite replication. Treatment of infected cells with kynurenine or its analogue, teriflunomide suppressed kinase activity of AKT, and phosphorylation of β-catenin triggering caspase-3 dependent apoptosis of infected cells to inhibit parasite growth. Our results demonstrate that β-catenin regulate phosphorylated STING-TICAM2-IRF3-IDO1 signalosome for a cell-intrinsic pro-parasitic role. We propose that the downstream IRF3-IDO1-reliant tryptophan catabolites and their analogues can act as effective immunotherapeutic molecules to control T. gondii replication by impairing the AKT and β-catenin axis.

Lutzomyia longipalpis Saliva Induces Heme Oxygenase-1 Expression at Bite Sites.

Sand flies bite mammalian hosts to obtain a blood meal, driving changes in the host inflammatory response that support the establishment of Leishmania infection. This effect is partially attributed to components of sand fly saliva, which are able to recruit and activate leukocytes. Our group has shown that heme oxygenase-1 (HO-1) favors Leishmania survival in infected cells by reducing inflammatory responses. Here, we show that exposure to sand fly bites is associated with induction of HO-1 in vivo. Histopathological analyses of skin specimens from human volunteers experimentally exposed to sand fly bites revealed that HO-1 and Nrf2 are produced at bite sites in the skin. These results were recapitulated in mice ears injected with a salivary gland sonicate (SGS) or exposed to sand fly bites, indicating that vector saliva may be a key factor in triggering HO-1 expression. Resident skin macrophages were the main source HO-1 at 24–48 h after bites. Additionally, assays in vivo after bites and in vitro after stimulation with saliva both demonstrated that HO-1 production by macrophages was Nrf2-dependent. Collectively, our data demonstrates that vector saliva induces early HO-1 production at the bite sites, representing a major event associated with establishment of naturally-transmitted Leishmania infections.

Bacterial DNA damage effectors in host cells

The microbiota has a significant, and sometimes decisive, effect on the host's homeostasis. The results of recent metagenomic studies confirm the importance of microbiota in maintaining health or its impact on the development of acute, chronic and neoplastic diseases. One of the important aspects of microbiota exposure is the ability of many bacterial species to induce mutations or modulate a mutation process in the cells of the host organism. This review summarizes the main experimental data revealing various mechanisms of genotoxic action of a bacterial microbiota, including direct damage to the DNA structure, induction of oxidative stress, delay in replication, and a decrease in repair efficiency. It is emphasized that bacteria use different strategies to ensure their own survival and replication, including. by suppressing the repair of host cell DNA, by promoting the survival of infected cells, despite the presence of DNA damage therein.

HCMV Infection and Apoptosis: How Do Monocytes Survive HCMV Infection?

Human cytomegalovirus (HCMV) infection of peripheral blood monocytes plays a key role in the hematogenous dissemination of the virus to multiple organ systems following primary infection or reactivation of latent virus in the bone marrow. Monocytes have a short life span of 1–3 days in circulation; thus, HCMV must alter their survival and differentiation to utilize these cells and their differentiated counterparts—macrophages—for dissemination and long term viral persistence. Because monocytes are not initially permissive for viral gene expression and replication, HCMV must control host-derived factors early during infection to prevent apoptosis or programmed cell death prior to viral induced differentiation into naturally long-lived macrophages. This review provides a short overview of HCMV infection of monocytes and describes how HCMV has evolved to utilize host cell anti-apoptotic pathways to allow infected monocytes to bridge the 48–72 h viability gate so that differentiation into a long term stable mature cell can occur. Because viral gene expression is delayed in monocytes following initial infection and only occurs (begins around two to three weeks post infection in our model) following what appears to be complete differentiation into mature macrophages or dendritic cells, or both; virally-encoded anti-apoptotic gene products cannot initially control long term infected cell survival. Anti-apoptotic viral genes are discussed in the second section of this review and we argue they would play an important role in long term macrophage or dendritic cell survival following infection-induced differentiation.

Influenza virus infection modulates the death receptor pathway during early stages of infection in human bronchial epithelial cells.

Host-viral interaction occurring throughout the infection process between the influenza A virus (IAV) and bronchial cells determines the success of infection. Our previous studies showed that the apoptotic pathway triggered by the host cells was repressed by IAV facilitating prolonged survival of infected cells. A detailed understanding on the role of IAV in altering the cell death pathway during early-stage infection of human bronchial epithelial cells (HBEpCs) is still unclear. We investigated the gene expression profiles of IAV-infected vs. mock-infected cells at the early stage of infection with a PCR array for death receptor (DR) pathway. At early stages infection (2 h) with IAV significantly upregulated DR pathway genes in HBEpCs, whereas 6 h exposure to IAV resulted in downregulation of the same genes. IAV replication in HBEpCs decreased the levels of DR pathway genes including TNF-receptor superfamily 1, Fas-associated death domain, caspase-8, and caspase-3 by 6 h, resulting in increased survival of cells. The apoptotic cell population decreased in 6 h compared with the 2 h exposure to IAV. The PCR array data were imported into Ingenuity Pathway Analysis software, resulting in confirmation of the model showing significant modulation of the DR pathway. Our data indicate that a significant transcriptional regulation of apoptotic, necrotic, and DR genes occur at early and late hours of infection that are vital in modulating the survival of host cells and replication of IAV. These data may have provided a likely roadmap for translational approaches targeting the DR pathway to enhance apoptosis and inhibit replication of the virus.

Salmonella small RNA fragment Sal-1 facilitates bacterial survival in infected cells via suppressing iNOS induction in a microRNA manner

Salmonella can hijack host atypical miRNA processing machinery to cleave its small non-coding RNA into a ~22-nt RNA fragment, Sal-1, which facilitates Salmonella survival in the infected host. The mechanism through which Sal-1 promotes Salmonella survival, however, remains unknown. In the present study, we reported that Sal-1 targets cellular inducible nitric oxide synthase (iNOS) in a miRNA manner, leading to attenuation of host cell iNOS/NO-mediated anti-microbial capacity. First, depletion of Sal-1 in Salmonella-infected epithelial cells significantly increased the iNOS level but not the levels of various inflammatory cytokines. Bioinformatics analysis and mutagenesis strategies were consistent with the identification of mRNA of iNOS as a target of Sal-1 in both human and mice. Second, western blot and immunohistochemical analysis confirmed that Sal-1 suppressed iNOS expression in vitro and in vivo, thus reducing the production of NO. Finally, Sal-1 facilitating Salmonella survival through suppressing iNOS induction was confirmed in mouse model by expressing mutated iNOS that is not targeted by Sal-1 in mice colon. In conclusion, our study provides new insight into the pathogenic mechanism of intracellular bacteria to modulate host innate immune response.

EBNA1-targeted probe for the imaging and growth inhibition of tumours associated with the Epstein–Barr virus

Epstein–Barr nuclear antigen 1 (EBNA1), a dimeric oncoprotein of the Epstein–Barr virus (EBV), is essential for both viral-genome maintenance and the survival of infected cells. Despite EBNA1’s potential as a therapeutic target, tools for the direct monitoring of EBNA1 in vitro and in vivo are lacking. Here, we show that a peptide-based inhibitor that luminesces when bound to EBNA1 inside the nucleus of EBV+ cells can regulate EBNA1 homodimer formation and selectively inhibit the growth of EBV+ tumours of nasopharyngeal carcinoma cells (C666-1 and NPC43) and Burkitt’s lymphoma Raji cells. We also show that the peptide-based probe leads to 93% growth inhibition of EBV+ tumours in mice. Our findings support the hypothesis that selective inhibition of EBNA1 dimerization can be used to afford better EBV-related cancer differentiation, and highlight the potential application of the probe as a new generation of biotracers for investigating the fundamental biological function of EBNA1 and for exploring its application as a therapeutic target. A peptide-based fluorescent inhibitor of the dimerization of an oncoprotein of the Epstein–Barr virus blocks the proliferation of tumours associated with the virus in mice.

Kaposi's Sarcoma-Associated Herpesvirus MicroRNAs Target GADD45B To Protect Infected Cells from Cell Cycle Arrest and Apoptosis.

Kaposi's sarcoma-associated herpesvirus is a leading cause of cancers in individuals with AIDS. Promoting survival of infected cells is essential for maintaining viral infections. A virus needs to combat various cellular defense mechanisms designed to eradicate the viral infection. One such response can include DNA damage response factors, which can promote an arrest in cell growth and trigger cell death. We used a new approach to search for human genes repressed by small nucleic acids (microRNAs) expressed by a gammaherpesvirus (KSHV), which identified a gene called GADD45B as a target of microRNAs. Repression of GADD45B, which is expressed in response to DNA damage, benefited survival of infected cells in response to a DNA damage response. This information could be used to design new treatments for herpesvirus infections.

Antiviral activity of nobiletin against chikungunya virus in vitro.

Chikungunya virus (CHIKV), a highly contagious re-emerging virus, is transmitted by infected mosquitoes. CHIKV is prevalent in tropical countries and is continuing to creep farther north into temperate areas. CHIKV is responsible for induction of chikungunya fever (CF) and severe joint stiffness with the capability of developing into bilateral and systemic arthralgia or even encephalitis. Despite the high morbidity rate, no approved antiviral drug is available. Therefore, an anti-CHIKV therapy is necessary to control this disease. In this study, we screened four flavonoids for anti-CHIKV activities: nobiletin, phlorizin, resveratrol and oxyresveratrol. We performed MTT, Viral ToxGloTM and lactate dehydrogenase (LDH) assays to assess the viability of CHIKV-infected host cells. Plaque assay and immunofluorescent assay were utilized to evaluate the levels of viral production in quantification and qualification, respectively. We first confirmed that nobiletin can maintain the cellular survival of infected cells without inducing significant toxicity to host cells. Nobiletin suppressed virus-induced cell death and viral production. Also, the antiviral efficacy of nobiletin can last for at least 48 h during infection. More importantly, nobiletin inhibited CHIKV infection during the translation/replication stages and viral entry, making nobiletin a potential clinical antiviral agent in prophylaxis and post-exposure treatment. In this study, our results provided a strategy to develop anti-chikungunya agents by utilizing natural compounds. Also, we believe that nobiletin can be a potential antiviral agent against CHIKV infection worthy of being further investigated as a remedial candidate in vivo.

OA2-3 BCL-2 antagonism decreases HIV replication and infected cell survival in acute in vitro infection.

OA2-3 BCL-2 antagonism decreases HIV replication and infected cell survival in acute in vitro infection.

Hepatitis C Virus Infection Induces Autophagy as a Prosurvival Mechanism to Alleviate Hepatic ER-Stress Response.

Hepatitis C virus (HCV) infection frequently leads to chronic liver disease, liver cirrhosis and hepatocellular carcinoma (HCC). The molecular mechanisms by which HCV infection leads to chronic liver disease and HCC are not well understood. The infection cycle of HCV is initiated by the attachment and entry of virus particles into a hepatocyte. Replication of the HCV genome inside hepatocytes leads to accumulation of large amounts of viral proteins and RNA replication intermediates in the endoplasmic reticulum (ER), resulting in production of thousands of new virus particles. HCV-infected hepatocytes mount a substantial stress response. How the infected hepatocyte integrates the viral-induced stress response with chronic infection is unknown. The unfolded protein response (UPR), an ER-associated cellular transcriptional response, is activated in HCV infected hepatocytes. Over the past several years, research performed by a number of laboratories, including ours, has shown that HCV induced UPR robustly activates autophagy to sustain viral replication in the infected hepatocyte. Induction of the cellular autophagy response is required to improve survival of infected cells by inhibition of cellular apoptosis. The autophagy response also inhibits the cellular innate antiviral program that usually inhibits HCV replication. In this review, we discuss the physiological implications of the HCV-induced chronic ER-stress response in the liver disease progression.