Genetic variability of hepatitis C virus in South Egypt and its possible clinical implication

Egypt is one of the countries with very high rates of hepatitis C virus (HCV) related morbidity and mortality. However, little is known about geographical and clinical differences in genetic variability of HCV in Egypt. Using direct sequencing and phylogenetic analysis of partial core/E1 and NS5B regions of the HCV genome, HCV genotype/subtype was determined in 129 HCV‐infected patients residing in three governates in south Egypt: Assuit, Sohag, and Qena. According to clinical stage of infection, patients were categorized into four groups: asymptomatic carriers, n = 16; chronic hepatitis C patients, n = 36; liver cirrhosis, n = 54; and hepatocellular carcinoma (HCC), n = 23. Genotype 4a was detected in 80.6%, whereas 1g, 4l, 4n, 4o, 4f, and 4m were identified in 7.7%, 4.7%, 3.9%, 1.6%, 0.8%, and 0.8% of cases, respectively. The prevalence of 4a differed regionally; from 88.5% (in Sohag) to 64% (in Assuit, P = 0.002). Genotypes 4l and 4n had a higher prevalence in Assuit (12.8%, 10.3%) than Sohag (0%, 0%; P ≤ 0.011). Difference in clinical features of determined genotypes/subtypes was observed; more carriers of non‐4a variants (4l and 4n, 4f, or 4m) had chronic hepatitis compared to carriers of 4a (53.3% vs. 23.1%, P = 0.025), while more patients with 4a had liver cirrhosis (45.2% vs. 13.3%, P = 0.023). Two HCV‐4o strains were isolated in this study, both from patients with HCC. In conclusion, geographical diversity of HCV was revealed in this study in southern Egypt. A further case–control study is required to confirm the trends of differential pathogenicity of HCV subtypes, indicated by this study. J. Med. Virol. 81:1015–1023, 2009. © 2009 Wiley‐Liss, Inc.     

Characterization of sublines of Epstein-Barr virus producing HR-1 cells and its implication in virus propagation in culture

To understand the mechanism regulating the EBV replication cycle, several sublines were obtained from HR-1 cells by the limiting dilution method. Based on their biochemical and molecular characteristics, these sublines can be categorized into two classes: the high EBV-DNA containing (H) subline and low EBV-DNA containing (L) subline. The amount of EBV proteins, such as EBV polymerases, EBV DNase, EAD, ZEBRA, MA, and VCA, was much higher in H sublines than in L sublines. Only 20% of cells in the H subline express those proteins. In addition to regular EBV DNA restriction enzyme fragments, additional DNA restriction enzyme fragments, as detected by different EBV DNA fragment probes, were found to be present in H sublines but not in L sublines. NoBamH1 W-Z DNA fragment rearrangement, which was the primary reason for ZEBRA expression in a high EBV-DNA containing subline, Clone 5, was found in H sublines. When L sublines were treated with 12-0-tetradecanoylphorbol-13-acetate and sodium butyrate, EBV-specific proteins, including ZEBRA protein, could be induced in cells, but no virus could be detected in the medium. Thus, the lack of EBV production by L sublines is more than the simple lack of expression of ZEBRA protein. L sublines are susceptible to EBV infection and are capable of producing EBV after infection. The importance of the presence of L cells in the H subline for the propagation of EBV in culture is suggested.     

Dramatic caspase-dependent apoptosis in antibody-enhanced dengue virus infection of human mast cells

Severe forms of dengue virus disease, known as dengue hemorrhagic fever and dengue shock syndrome, result from an aberrant immune response involving antibody-dependent enhancement of infection, thrombocytopenia, and a loss of vascular integrity, culminating in hemorrhage, shock, and in some cases, death. Several studies have indicated that dengue virus infection results in the induction of apoptosis of certain cells believed to be contributory players in dengue pathogenesis. However, none have specifically examined the role of antibody enhancement in the context of induction of apoptosis. Here, we show that antibody-enhanced dengue virus infection of the FcR-bearing mast cell/basophil KU812 cell line results in a massive induction of apoptosis. Confocal microscopy and flow cytometry indicate two distinct subpopulations consisting of productively infected cells and apoptotic-uninfected bystanders. Apoptosis was found to be caspase-dependent, involving global caspase activation and cleavage of poly-ADP-ribose polymerase (PARP) and D4-guanosine diphosphate dissociation inhibitor (D4-GDI). Additional FcR-bearing cells, including K562, U937, and human mast cell 1 (HMC-1), were analyzed for apoptosis induction following infection. Although all cells displayed high susceptibility to antibody-enhanced dengue virus infection, only cells of a mast cell phenotype (KU812 and HMC-1) were found to undergo apoptosis. Dengue-induced apoptosis of KU812 cells was shown to require antibody-enhanced dengue virus infection by blockade of FcgammaRII. Transfection of KU812 cells with L-SIGN/DC-SIGNR was able to overcome the requirement for antibody enhancement with regard to dengue virus infection and apoptosis.     

A detrimental role for invariant natural killer T cells in the pathogenesis of experimental dengue virus infection

Dengue virus (DENV), a member of the mosquito-borne flaviviruses, is a serious public health problem in many tropical countries. We assessed the in vivo physiologic contribution of invariant natural killer T (iNKT) cells, a population of nonconventional lipid-reactive αβ T lymphocytes, to the host response during experimental DENV infection. We used a mouse-adapted DENV serotype 2 strain that causes a disease that resembles severe dengue in humans. On DENV challenge, splenic and hepatic iNKT cells became activated insofar as CD69 and Fas ligand up-regulation and interferon-γ production. C57BL/6 mice deficient in iNKT cells (Jα18(-/-)) were more resistant to lethal infection than were wild-type animals, and the phenotype was reversed by adoptive transfer of iNKT cells to Jα18(-/-) animals. The absence of iNKT cells in Jα18(-/-) mice was associated with decreased systemic and local inflammatory responses, less liver injury, diminished vascular leak syndrome, and reduced activation of natural killer cells and neutrophils. iNKT cell functions were not necessary for control of primary DENV infection, after either natural endogenous activation or exogenous activation with the canonical iNKT cell agonist α-galactosylceramide. Together, these data reveal a novel and critical role for iNKT cells in the pathogenesis of severe experimental dengue disease.     

Internalization of Jembrana disease virus Tat: possible pathway and implication

Jembrana disease virus (JDV) is a lentivirus highly related to the bovine immunodeficiency virus (BIV). It causes an acute disease with high mortality rate within 1-2 weeks. JDV encodes the most potent Tat (JTat) of any of the lentiviruses. JTat can transactivate all LTRs and functionally substitute for HIV Tat in the viral genome and may function as a pivotal regulator in the acute pathogenesis of JDV. The goal of this paper is to study JTat internalization by cells, the mechanisms involved in internalization, and the effect of JTat on neighbouring cells. By quantification and fluorescence microscopy, we found that the internalization of extracellular EGFP-JTat fusion protein was both time and dose-dependent, but endocytosis and energy independent. We identified that arginines which were responsible for the internalization. Internalized JTat was distributed in both the nucleus and the cytoplasm, could transactivate JDV LTR and modulate cellular gene expression. Based on our findings, we propose that secretion and internalization of JTat may be a way for JDV to influence neighbouring cells and make the cellular environment more amenable to viral infection.     

Expression of apoptosis-related proteins and its clinical implication in surgically resected gastric carcinoma

Apoptosis, via caspase cascade, is involved in tumorigenesis and progression, and thus, altered apoptosis-related protein expressions have clinical and prognostic significance. Moreover, the apoptosis pathway is highlighted due to the recent introduction of apoptosis-targeted therapy for several genes such as the X-linked inhibitor of apoptosis protein (XIAP). XIAP is the most potent direct inhibitor of caspase, and XIAP-associated factor 1 (XAF1) and secondary mitochondrial activator of caspase/direct IAP-binding protein with low PI (Smac/DIABLO) are negative regulators of XIAP. In this study, we evaluated the expression of these proteins and investigated their clinical and prognostic significance in gastric carcinomas. Immunohistochemical analysis by using the tissue array method was performed for XIAP, survivin, Bcl-2, XAF1, Smac/DIABLO, and cleaved caspase-3 proteins in 1,162 surgically resected gastric carcinoma cases. XIAP expression was related to the advanced stage. The expression of XIAP showed negative relationship with XAF1 and Smac/DIABLO expressions. In addition, XIAP expression was associated with a poor prognosis and was also proved to be an independent prognostic factor. Cleaved caspase-3 expression was related to the early stage. In addition, cleaved caspase-3 expression was associated with a favorable prognosis and was also proved to be an independent prognostic factor. The expression of XIAP showed an inverse relationship with cleaved caspase-3. In addition, the expression of XAF1 and Smac/DIABLO had a positive relationship with cleaved caspase-3. These findings are consistent with their known functions, and they may help to identify individuals best suited for apoptosis-targeted therapy as a baseline data in gastric carcinoma.     

Hepatitis C virus core, NS3, NS5A, NS5B proteins induce apoptosis in mature dendritic cells

Although reasons for hepatitis C virus (HCV) persistence are still unknown, specific cellular immune responses appear to influence the pathogenesis and outcome of the infection. Apoptosis of cells infected by viruses may appear suicidal to the viruses that induce programmed cell death of its host. However, apoptosis has been suggested to be a response to virus infection as a mean of facilitating virus dissemination. Annexin V-propidium iodide staining and DNA fragmentation, were used to show that expression of the core, NS3, NS5A, or NS5B protein induces apoptosis in mature dendritic cells. In addition, immunoblotting was used to demonstrate that expression level of p21waf1/cip1 protein decreased in cells expressing one of these HCV proteins. No expression of p53 could be detected and expression of Akt was independent of HCV proteins expression. These results suggest that the effect of these HCV proteins on HCV associated pathogenesis may be linked (at least partially) to its ability to modulate apoptosis pathways in mature dendritic cells.     

Clinical isolates of dengue virus with distinctive susceptibility to nitric oxide radical induce differential gene responses in THP-1 cells

In the present study, 10 clinical isolates of dengue virus were selected according to their susceptibility to the inhibitory effect of nitric oxide radical, NO. Five of them are nitric oxide-susceptible viruses while the other five are nitric oxide-resistant viruses. These isolates were investigated to identify genetic factors that are responsible for the different phenotypes. Due to the evidence showing that NO suppresses DENV RNA polymerase activity, we, therefore, hypothesized that the RdRp domain of NS5 may responsible for NO inhibition. To answer this question, sequences of NS5 gene of NO-susceptible viruses and NO-resistant viruses were compared. We found that these two groups of viruses contain different amino acid sequence at position 621 to 646 in the active site of NS5. These data suggested that response to the inhibitory effect of nitric oxide radical may, at least in part, be regulated by NS5. The effect of these two different phenotypes of viruses on host cells was studied using cDNA array screening. The cDNA array analysis demonstrated that the nitric oxide-resistant group had a stronger influence on host cells since it induced changes in the expression of a greater number of genes than did the nitric oxide-susceptible group, 97 genes versus 71 genes, respectively. The NO-resistant virus also stimulated cytokines known to be virulent factors, such as IL 6, IL 8, RANTES, and the inflammatory factors. In conclusion, our data demonstrated that dengue viruses isolated from patients show genotypic and phenotypic differences which may correlate with virulence.     

Rubella virus does not induce apoptosis in primary human embryo fibroblast cultures: a possible way of viral persistence in congenital infection

Congenital rubella is a persistent infection that contrasts with acute postnatal infection. Basis of the Rubella virus (RV) persistence still remain unknown, though several hypotheses have been postulated. RV induces apoptosis in cell lines, maybe as a way of cell-autonomous defense mechanism against virus. Considering the pattern of c-oncogenes expression during embryogenesis, which promotes proliferation while it inhibits apoptosis in specific cells, at certain times, it can be proposed that when RV infection establishes early in gestation, embryo cells that are proliferating have their apoptotic pathways shut down; then infected proliferating embryo cells cannot execute their apoptotic death program. We here report that RV induces apoptosis in human normal-term placenta chorionic villi explants (CVE) and in monolayers of cytotrophoblasts (CTB), but does not induce apoptosis in primary human embryo fibroblasts (HEF) cultures. These results suggest distinct responses to RV infection when comparing differentiated cells, as CTB, to cells with high proliferating potential, as HEF. RV shoots apoptosis in the former, whereas in fibroblastic dividing cells derived from embryo, RV appears not to be enough stimulus to activate the genetic program of cell death.     

Endometriotic cells are resistant to interferon-gamma-induced cell growth inhibition and apoptosis: a possible mechanism involved in the pathogenesis of endometriosis

In order to evaluate the involvement of cell proliferation and apoptosis in the pathogenesis of endometriosis, we investigated the effects of interferon-gamma (IFN-gamma) on cell growth inhibition and apoptosis of cultured ovarian endometriotic cyst stromal cells (ECSC), eutopic endometrial stromal cells with endometriosis (ESCwE) and normal endometrial stromal cells (NESC) by modified methylthiazoletetrazolium assay, 5-bromo-2'-deoxyuridine incorporation assay and internucleosomal DNA fragmentation assay. The expression of apoptosis-related molecules and IFN-gamma receptor 1 was also examined in ECSC, ESCwE and NESC using western blot analysis. IFN-gamma significantly inhibited cell proliferation and DNA synthesis of ESCwE and NESC, and induced apoptosis of these cells. In contrast, IFN-gamma did not show apparent effects on the viable cell number, DNA synthesis, or apoptosis of ECSC. An up-regulated expression of Bcl-2 and Bcl-X(L) proteins was observed in ECSC in comparison with ESCwE and NESC, whereas the levels of Bax, Bad, Fas and Fas ligand proteins in ECSC were similar to those in ESCwE and NESC. IFN-gamma receptor 1 expression was detected in ECSC, ESCwE and NESC. Enhanced expression of anti-apoptotic molecules in the ectopic endometrial cells may contribute to the development of endometriosis by conferring resistance to cytokine-induced apoptosis and increasing the chance that these cells will survive and implant outside the uterus. Further investigations on the regulation of cell proliferation in both the endometriotic and the normal endometrium may be important for the elucidation of the pathogenesis of endometriosis.     

A plasmid encoding parts of the dengue virus E and NS1 proteins induces an immune response in a mouse model

A DENV-2 plasmid named pEII*EIII/NS1*, containing sequences encoding portions of the envelope protein that are potentially involved in the induction of neutralizing antibodies and a portion of the NS1 sequence that is involved in protection, is reported in this work. The synthesized subunit protein was recognized by human sera from infected patients and had the predicted size. The immunogenicity of this construct was evaluated using a mouse model in a prime-boost vaccination approach. The priming was performed using the plasmid pEII*EIII/NS1*, followed by a boost with recombinant full-length GST–E and GST–NS1 fusion proteins. The mice showed specific antibody responses to the E and NS1 proteins, as detected by ELISA, compared to the response of animals vaccinated with the parental plasmid. Interestingly, some animals had neutralizing antibodies. These results show that EII*, EIII and NS1* sequences could be considered for the design of a recombinant subunit vaccine against dengue disease.     

CXCR4抑制剂AMD3100对2型登革热病毒诱导血管内皮细胞株Eahy926凋亡的影响

目的: 探讨趋化因子受体CXCR4抑制剂AMD3100对2型登革热病毒(DV2)诱导人脐静脉血管内皮细胞株 Eahy926凋亡的影响。方法: 免疫组织化学法检测Eahy926细胞的Ⅷ因子。Eahy926细胞分成未感染组和DV2感染组,流式细胞术检测两组细胞不同时点(24 h、36 h、48 h和60 h)CXCR4的表达水平。流式细胞术分析未感染组、DV2感染组及DV2+AMD3100组不同时点的细胞凋亡率。免疫荧光法检测细胞膜表面磷脂酰丝氨酸(PS)。结果: Eahy926细胞有Ⅷ因子表达。在DV2感染Eahy926后的4个时点中,CXCR4的表达均有上调,其中以48 h感染组最明显(66.13%±10.30%,P<0.05)。DV2感染能诱导Eahy926细胞凋亡,其中36 h感染组凋亡率出现高峰(29.85%±15.78%,P<0.05)。应用AMD3100后在各时点均能上调DV2感染组的凋亡率,免疫荧光观察到DV2感染组及DV2+AMD3100组绿色荧光标记的细胞增多。结论: DV2感染能诱导血管内皮细胞Eahy926凋亡并上调CXCR4的表达,CXCR4抑制剂AMD3100促进DV2诱导Eahy926细胞凋亡的发生。     

Knockdown of WISP1 inhibit proliferation and induce apoptosis in ALL Jurkat cells

WISP1, a Wnt-induced secreted protein, has been found to have anticancer activity. ALL is a leading cause of death. Here we investigate the WISP1 effects on ALL Jurkat cells. Cell viability was assessed by CCK-8. Cell cycle and apoptosis were detected by flow cytometry. Mitochondrial membrane potential (MMP) was monitored using TMRM. Generation of reactive oxygen species (ROS) was quantified using DCFH-DA. Western blot was used to detect the expression of cell proliferation and apoptosis related genes. The results showed that knockdown of WISP1 significantly inhibited proliferation of Jurkat cells. Parallelly, cell cycle distribution was increased at G1 phase and apoptotic rate was induced after WISP1 knockdown. Furthermore, knockdown of WISP1 induced apoptosis of Jurkat cells was also associated with loss of MMP and generation of ROS. Western blot results showed that the protein expression p-AKT, PCNA, CDK1, P-ERK, CDK2, VEGF, VEGFR2 and Bcl2 were decreased, while the expression of Bax was up-regulated. In conclusion, WISP1 plays an important role in proliferation and apoptosis of Jurkat cells in mitochondria dependent pathway, the specific mechanisms need further study.     

Surface proteins of C6/36 cells involved in dengue virus 4 binding and entry

Dengue virus (DENV) is the causative agent of the most important mosquito-borne viral disease, which is endemic to over 100 countries in tropical and subtropical areas of the world. It is transmitted to humans by Aedes mosquitoes. The first step in the viral infection of host cells is virion attachment to the plasma membrane, which is mediated by specific surface molecules. There are several molecules that participate in DENV infection of mosquitoes, but only a few have been identified. In this work, we co-purified 4 proteins from C6/36 cells using a recombinant DENV 4 E protein and identified them as 70 kDa Heat Shock and 70 kDa Heat Shock cognate proteins (HSP70/HSc70), Binding immunoglobulin protein (BiP), Thioredoxin/protein disulphide isomerase (PDI), and 44 kDa Endoplasmic reticulum resident protein (ERp44) via matrix-assisted laser desorption/ionisation time of flight (Maldi-ToF) analysis. Using immunofluorescence and flow cytometry assays, we observed re-localisation of HSP70/HSc70 and, to a lesser extent, BiP to the plasma membrane under stress conditions, such as during DENV infection. By performing binding and infection assays independently, we found that all 4 proteins participate in both processes, but to differing extents: HSP70/HSc70 is the most critical component, while ERp44 is less important. Viral infection was not inhibited when the cells were incubated with antibodies against all of the surface proteins after virus binding, which suggests that DENV entry to C6/36 cells is mediated by these proteins at the same step and not sequentially.     

The dengue virus nonstructural-1 protein (NS1) generatesantibodies to common epitopes on human blood clotting,integrin/adhesin proteins and binds to humanendothelial cells: potential implications in haemorrhagic fever pathogenesis

Summary.  Antibody responses generated by mice to the dengue-2 virus NS1 protein (D-2V NS1) were influenced by MHC class II (I-A) haplotype but each antiserum cross-reacted with human fibrinogen, thrombocytes and endothelial cells. To investigate these findings, a highly avid subclone (MAb 1G5.4-A1-C3) was selected from a parent hybridoma that secreted a monoclonal antibody (MAb) specific for the native dimeric form of D-2V NS1. When MAb reactions were compared using a panel of overlapping synthetic peptides covering the entire protein sequence, dimer specificity was found to be a weak reaction with multiple ELK-type motifs present in either the positive (E/D-hydrophobic-K/R) or negative (K/R-hydrophobic-D/E) orientations. MAb 1G5.4-A1-C3 and highly avid anti-NS1 polyclonal antisera reacted with the NS1 proteins of the four dengue virus serotypes, but only weakly reacted with the NS1 proteins of the other flaviviruses. MAb 1G5.4-A1-C3 and several other anti-NS1 MAbs produced haemorrhage in mice, cross-reacted with human fibrinogen, thrombocytes and endothelial cells, with known epitopes or active sites on human clotting factors and integrin/adhesin proteins present on these cells. D-2V NS1 bound to human endothelial cells via a site within its N-terminal region, which led to significantly increased binding of avid anti-NS1 antibodies. These results identified a potential role of both ‘antigenic’ and ‘biochemical’ mimicry in dengue haemorrhagic fever pathogenesis, consistent with clinical data. Accepted November 29, 1996     

Apoptosis of hepatocytes caused by Punta Toro virus (Bunyaviridae: Phlebovirus) and its implication for Phlebovirus pathogenesis

Experimental infection of hamsters with Punta Toro virus (PTV) produces a disease with clinical and pathological similarities to the severe human hemorrhagic fever caused by Rift Valley fever virus (RVFV), thus providing an animal model for RVFV pathogenesis. In this model, hepatocytic apoptosis is the main pathological component of liver injuries that are responsible for severe hemorrhagic manifestations. To further elucidate whether viral replication in hepatocytes directly causes apoptosis, we studied the morphological and biochemical changes of apoptosis in HepG2 cells at different time points after PTV infection. Cellular viability began to decrease 12 hours after infection compared with controls. Caspases 3/7 were activated significantly at 48 and 72 hours after infection, and phosphatidylserine translocation and DNA fragmentation were also detected at 48 and 72 hours. Cell cycle analysis by flow cytometry showed that infected HepG2 cells were arrested at G(0)/G(1) phase. Furthermore, virus titer increased with apoptosis progression, suggesting that viral replication is necessary for the apoptotic process. These results indicate that PTV infection alone, without a secondary inflammatory cellular reaction, induces hepatocytic apoptosis and suggest that future therapeutics for RVFV hemorrhagic disease might target inhibition of cellular apoptotic pathways during the acute infection.     

Detection of hepatitis A virus proteins in infected BS-C-1 cells.

Hepatitis A virus (HAV) is distinguished from other picornaviruses by its tropism for the liver in infected hosts, a nonlytic infection in hepatocytes, and a slow and nonlytic growth cycle in cultured cells. Although the genome structure and organization of HAV appear to be similar to those of the other picornaviruses, the viral proteins synthesized in infected cells have not been previously characterized. We have utilized specific antisera raised in rabbits to recombinant HAV proteins expressed in Escherichia coli in an effort to identify both structural and nonstructural proteins in BS-C-1 cells throughout the course of a viral replication cycle. Replication was monitored by dot blot hybridization of viral genomes. Structural proteins VP0, VP1, VP2, and VP3 were found to accumulate during the infection cycle as did viral RNA. Nonstructural proteins 2C and 3D were not detected on immunoblots, although a minor amount of 2C could be detected by immunoprecipitation of lysates of radiolabeled, infected cells. The relative sensitivities of the various antisera were determined, and the failure to observe nonstructural proteins was shown not to be due to decreased sensitivity of the detection reagents. Thus, it appears that HAV nonstructural proteins do not accumulate in infected cells to levels comparable to those of capsid proteins.     

FasL/Fas pathway is involved in dengue virus induced apoptosis of the vascular endothelial cells

The hallmark of the dengue hemorrhagic fever/dengue shock syndrome is hematologic abnormality. The pathogenesis of dengue hemorrhagic fever/dengue shock syndrome remains unknown. Our work showed that the dengue virus serotype‐2 induced apoptosis in human umbilical vein endothelial cells. Fas (CD95), Tumor Necrosis Factor receptors, and Tumor Necrosis Factor‐related apoptosis‐inducing ligand receptors are the most common death receptors, which can induce apoptosis. Compared with the untreated human umbilical vein endothelial cells, Fas expression was increased both in the mRNA level and on the surface of infected human umbilical vein endothelial cells. FasL was expressed at similar levels on human umbilical vein endothelial cells over a course of dengue virus serotype‐2 infection, but the expression in mRNA level was increased in infected human umbilical vein endothelial cells. It is possible that there is soluble FasL secreted from human umbilical vein endothelial cells in the supernatant. Tumor Necrosis Factor‐related apoptosis‐inducing ligand receptor 1 and Tumor Necrosis Factor receptors 1–2 were constantly very low, whereas Tumor Necrosis Factor‐related apoptosis‐inducing ligand receptors 2–4 decreased after dengue virus serotype‐2 infection. This result suggested that dengue virus serotype‐2 may inhibit Tumor Necrosis Factor‐related apoptosis‐inducing ligand receptors‐induced apoptosis. The apoptotic rates in human umbilical vein endothelial cells were decreased upon the addition of caspase family inhibitors. In addition, activated caspase 8 and caspase 3 were also observed by Western blot following dengue virus serotype‐2 infection. Thus, it is shown that the Fas/FasL pathway may participate in dengue virus‐induced apoptosis of vascular endothelial cells in vitro. J. Med. Virol. 82:1392–1399, 2010. © 2010 Wiley‐Liss, Inc.