Surveillance of arthropod-borne viruses in Benin,West Africa 2020–2021:detection of dengue virus 3 in Aedes aegypti(Diptera:Culicidae)

Dear Editor,Dengue virus(DENV,family Flaviviridae,genus Flavivirus)serotypes 1 to 4(DENV-1,-2,-3,and-4)are responsible for more than 100 million infections per year worldwide.Symptoms of DENV infection can be diverse,reaching from an acute febrile illness to the more severe,sometimes fatal dengue haemorrhagic fever/dengue shock syndrome.

Inhibitory activities of extracts of Rumex dentatus, Commelina benghalensis, Ajuga bracteosa, Ziziphus mauritiana as well as their compounds of gallic acid and emodin against dengue virus

Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina benghalensis, Ajuga bracteosa and Ziziphus mauritiana, as well as their constituents(gallic acid, emodin, and isovanillic acid). Methods: All the samples were tested for cytotoxicity on baby hamster kidney cells by MTT assay and for anti-DENV-2 activity by plaque reduction neutralization assay using two DENV-2 doses(45 and 90 plaqueforming units or PFU). Results: All the samples except isovanillic acid exhibited significant prophylactic effects against DENV-2 infectivity(without cytotoxicity) when administered to cells before infection, but were not effective when given 6 h post-infection. The methanol extract of Rumex dentatus demonstrated the highest antiviral efficacy by inhibiting DENV-2 replication, with IC_(50) of 0.154 μg/mL and 0.234 μg/mL, when added before infection with 45 and 90 PFU of virus, respectively. Gallic acid also exhibited significant antiviral effects by prophylactic treatment prior to virus adsorption on cells, with IC_(50) of 0.191 μg/mL and 0.522 μg/mL at 45 and 90 PFU of DENV-2 infection, respectively. Conclusions: The highly potent activities of the extracts and constituent compounds of these plants against DENV-2 infectivity highlight their potential as targets for further research to identify novel antiviral agents against dengue.

A murine model of dengue virus infection in suckling C57BL/6 and BALB/c mice

Dengue is a significant public health concern across tropical and subtropical regions worldwide,principally causing disease in children.Very young children are at increased risk of severe manifestations of dengue infection.The mechanism of dengue disease in this population is not fully understood.In this study,we present a murine model of dengue virus primary infection in suckling C57BL/6 and BALB/c mice in order to investigate disease pathogenesis.Three-day-old C57BL/6 mice intraperitoneally infected with DENV-2 NGC were more susceptible to infection than BALB/c mice,showing increased liver enzymes,extended viremia,dissemination to organs and histological alterations in liver and small intestine.Furthermore,the immune response in DENV-infected C57BL/6 mice exhibited a marked Th1 bias compared to BALB/c mice.These findings highlight the possibility of establishing an immunocompetent mouse model of DENV-2 infection in suckling mice that reproduces certain signs of disease observed in humans and that could be used to further study agerelated mechanisms of dengue pathogenesis.

Contribution of phylogenetics to understanding the evolution and epidemiology of dengue virus

Dengue virus(DENV)is one of the most important arboviral pathogens in the tropics and subtropics,and nearly one-third of the world's population is at risk of infection.The transmission of DENV involves a sylvatic cycle between nonhuman primates(NHP)and Aedes genus mosquitoes,and an endemic cycle between human hosts and predominantly Aedes aegypti.DENV belongs to the genus Flavivirus of the family Flaviviridae and consists of four antigenically distinct serotypes(DENV-1-4).Phylogenetic analyses of DENV have revealed its origin,epidemiology,and the drivers that determine its molecular evolution in nature.This review discusses how phyloge-netic research has improved our understanding of DENV evolution and how it affects viral ecology and improved our ability to analyze and predict future DENV emergence.

Proteomic profile of human monocytic cells infected with dengue virus

Objective: To identify the changes in the proteome of U937 cells infected with dengue virus(DENV).Methods: In this study, differentiated U937 cultures were infected with two DENV-2strains, one of which was associated with dengue(DENV-2/NG) and the other one with severe dengue(DENV-2/16681), with the aim of determining the cellular proteomic profiles under different infection conditions. Cellular proteins were extracted and separated by two-dimensional electrophoresis, and those proteins with differential expression profiles were identified by mass spectrometry. The obtained results were correlated with cellular viability, the number of infectious viral particles, and the viral DNA/protein quantity.Results: In comparison with non-infected cultures, in the cells infected with the DENV-2/NG strain, nine proteins were expressed differentially(five were upregulated and four were downregulated); in those cultures infected with the DENV-2/16681 strain, six proteins were differentially expressed(two were downregulated and four were upregulated). The downregulated proteins included fatty acid-binding protein, heterogeneous nuclear ribonucleoprotein 1, protein disulfide isomerase, enolase 1, heat shock 70 k Da protein 9, phosphotyrosyl phosphatase, and annexin IV. The upregulated proteins included heat shock 90 k Da protein AA1, tubulin beta, enolase 1, pyruvate kinase,transaldolase and phospholipase C-alpha.Conclusions: Because the monocyte/macrophage lineage is critical for disease pathogenicity, additional studies on these proteins could provide a better understanding of the cellular response to DENV infection and could help identify new therapeutic targets against infection.

Intracellular calcium ions facilitate dengue virus entry into endothelial cells and compromise endothelial barrier integrity

Objective:To investigate the involvement of Ca^(2+)in dengue virus(DENV)-infected human umbilical vein endothelial cells(HUVECs)and the disruption of endothelial integrity.Methods:HUVECs were infected with DENV-2 in the presence of intracellular Ca^(2+)or endoplasmic reticulum Ca^(2+)chelators.Virus infectivity was measured by focus-forming assay and quantitative RT-PCR.Intracellular Ca^(2+)was measured using Fluo-4-AM dye.VE-cadherin and focal adhesion kinase(FAK)expressions were investigated by immunofluorescence and immunoblotting assays,respectively.Results:DENV infection increased intracellular cytosolic Ca^(2+)levels and caused disassembly of the adherens junction protein,VEcadherin as evidenced by decreased VE-cadherin expression at the periphery of DENV-2 infected HUVECs.Depletion of intracellular Ca^(2+)stores,particularly those of the endoplasmic reticulum Ca^(2+),significantly decreased DENV yield in HUVECs.Decreased virus yield following the depletion of intracellular Ca^(2+)was caused by the inhibition of viral entry into HUVECs and not the inhibition of viral binding or attachment.DENV-2 infection also resulted in Ca^(2+)-dependent activation of FAK.Conclusions:Intracellular Ca^(2+)is required for the early phases of DENV infection in endothelial cells.Increased cytosolic Ca^(2+)levels in endothelial cells during DENV infection activated FAK,disrupted adherens junctions and compromised barrier integrity.Thus,Ca^(2+)plays an important role in DENV infection in endothelial cells.

Plasmid DNA encoding neutralizing human monoclonal antibody without enhancing activity protects against dengue virus infection in mice

Objective: To evaluate the expression of DNA plasmid-harboring modified antibody gene that produces neutralizing human monoclonal antibodies against four serotypes of dengue virus(DENV) without enhancing activity in BALB/c mice. Methods: We constructed pFUSE-based vectors(pFUSE1 G7 C2hVH and pFUSE1 G7 C2hVL) containing genes encoding the variable domains of the heavy or light chain of the anti-dengue virus antibody 1 G7 C2, a human IgG1 that has been characterized for its neutralizing activity to DENV-1-4. Leucine(L) at positions 234 and 235 on the Fc CH2 domain in pFUSE1 G7 C2hVH was mutated to alanine(A)(LALA mutation) by site direct mutagenesis, and the new plasmid was termed pFUSE1 G7 C2hVHLALA. An equal amount of pFUSE1 G7 C2hVL and 1 G7 C2hG1-LALA plasmids were co-transfected into Chinese hamster ovary cells(CHO-K1) and a single dose of 100 μg 1 G7 C2hG1-LALA plasmid was intramuscularly injected, followed by electroporation in BALB/c mice. The secreted 1 G7 C2hG1-LALA antibodies in cell culture supernatant and mouse serum were examined for their biological functions, neutralization and enhancing activity. Results: The co-transfection of heavy-and light-chain 1 G7 C2hG1-LALA plasmids in CHO-K1 cells produced approximately 3 900 ng/mL human IgG and neutralized 90%-100% all four DENV, with no enhancing activity. Furthermore, the modified human IgG was produced more than 1 000 ng/mL in mouse serum on day 7 post plasmid injection and showed cross-neutralization to four DENV serotypes. Subsequently, antibody production and neutralization decreased rapidly. Nevertheless, the secreted neutralizing 1 G7 C2hG1-LALA in mouse serum demonstrated complete absence of enhancing activities to all DENV serotypes. Conclusions: These findings reveal that a new modified 1 G7 C2h G1-LALA expressing plasmid based on gene transfer is a possible therapeutic antibody candidate against DENV infection.

The Study on The Immune Response Induced by Expressing Recombinant Plasmid of Dengue Virus Type 2 NS3 Protein

The PSV?NS3, an expressing recombinant plasmid of dengue virus type 2 NS3 protein, was injected directly into the quadriceps of Balb/C mice to explore whether it could inducing immune response. The splenic T cell subsets of two groups was analysed by flow cytometry. It was found that the percentage of CD4+ and CD8+ T cells of experimental group were significantly higher than those of the control group. The titer of IgG antibody was as high as 1∶5 120 in experimental group, but it couldn’t be detected in control group by ELISA. The western blot further proved that the IgG antibody was specific for NS3 protein. Those results Suggested that inoculation Balb/C mice with PSV?NS3 could inducing immune response, and the NS3 protein might be used as the candidate protein of DNA vaccine of dengue virus.

Dengue virus infection:A review of advances in the emerging rapid detection methods

Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems are essentially required due to lack of effective vaccine against dengue virus and the progressive spread of the dengue virus infection.The recent progress in developing micro-and nano-fabrication techniques has led to low cost and scale down the biomedical point-of-care devices.Starting from the conventional and modern available methods for the diagnosis of dengue infection,this review examines several emerging rapid and point-of-care diagnostic devices that hold significant potential for the progress in smart diagnosis tools.The given review revealed that an effective vaccine is required urgently against all the dengue virus serotypes.However,the rapid detection methods of dengue virus help in early treatment and significantly reduce the dengue virus outbreak.

Comparison of Four Diagnostic Tests Methods for the Detection of Dengue Virus Non-Structural-1 Antigen and IgM/IgG Antibodies

Objectives: Dengue virus (DENV) infection is a mosquito-borne disease that stands out as one of the major public health issues and has a wide-ranging geographical distribution throughout the tropics and subtropics. The general alarming increase in the number of cases over the last two decades can be attributed to an extent by the change in national practices to keeping records and reporting dengue to the Ministries of Health, and WHO. Dengue diagnosis is routinely carried out by detection of dengue virus (DENV) antigen NS1 (Non-structural Antigen 1) and/or anti-DENV IgM/IgG antibodies using enzyme-linked immunosorbent assays (ELISAs) and rapid diagnostic tests (RDTs). This study compared the performance of three RDTs and one ELISA used for dengue diagnosis in southeastern, Nigeria. Design: This study adopted a cross-sectional design that included prospective hospital-based surveillance of cases among febrile participants attending two major health facilities within the southeastern region of Nigeria. In this study, 338 HIV-infected participants from two teaching hospitals in Nigeria’s southeast were systematically tested for Dengue with four methods: NS1 RDT, IgG RDT, IgM RDT, and NS1 ELISA. Their specificities and sensitivities were compared, as well as their level of concordance. Their respective performances were also evaluated using the Receivers Operational curve (ROC). Results: Out of the 338 patients, the dengue prevalence from the four dengue diagnostic methods Dengue virus NS1 ELISA, NS1 RDT, IgM and IgG seropositivity were 8.9%, 0.6%, 5.6%, and 8.0%, respectively. The Dengue IgM RDT test indicated 36.8% sensitivity, 92.8% specificity, the IgG anti-dengue specific test indicated 29.6% sensitivity, 92.9% specificity and the dengue NS1 RDT test indicated 3.3% sensitivity, 99.4% specificity when compared with the Dengue NSI Elisa test method as a reference method. Conclusion: The use of NSI ELISA for DENV diagnosis showed good performance and the RDTs showed, to an extent, reliable results compared with ELISA. However, diagnostic laboratories should be aware of performance variations across tests and the possibilities of cross-reactivity that may affect results.

Domain Ⅲ of Dengue Virus Serotype 2 Envelope: Expression at High Levels in Escherichia coli and Competitive Inhibition of Virus Entry

Obejective The domainⅢof dengue virus type 2 envelope was cloned and expressed in Escherichia coli and the inhibited effects of recombinant protein on virus was detected. Methods In this study, the domainⅢ(DⅢ) protein of the dengue virus type-2 (DENV-2) envelope (E) antigen was expressed in Escherichia coli by fusion with a carrier protein. The protein was puriifed using enzymatic cleavage and afifnity puriifcation. Rabbit immunization and antibody detection was carried out. Inhibition of DENV-2 infection was observed by DENV-2 EDⅢprotein and its immunity rabbits serum. Results The recombinant expression DENV-2 EDⅢ protein plasmid was constructed successfully. After isopropyl thiogalactoside induction, a speciifc soluble 29 kD protein was obtained, and the expression product accounted for 68.87%of the total protein of the cell lysate. Western blot demonstrated the reactivity of the recombinant protein with his-tag and DENV (Ⅰ-Ⅳ) monoclonal antibodies. The protein was puriifed using enzymatic cleavage and affinity purification. The purified recombinant EDⅢ protein inhibited the entry of DENV-2 into BHK-21 cells. DENV-2 plaque neutralization assays were carried out using serially diluted antibodies against EDⅢprotein. At a 1︰16 dilution, the antibodies produced at least 90%neutralization of the DENV-2 virus. Furthermore, the antibodies continued to exhibit high neutralization effects (approximately 80%) until the anti-EDⅢantibody titer reached 1︰1 024. Conclusions DENV-2 EDⅢwas cloned and expressed successfully. DENV-2 EDⅢprotein could be useful in the development of inexpensive dengue vaccine. The data also suggested that DENV-2 employed an attachment molecule or receptor for its entry into C6/36 mosquito cells.

Critical role of Dengue Virus NS1 protein in viral replication

Dengue virus(DENV) nonstructural protein 1(NS1) is a highly conserved 46-kDa protein that contains 2 glycosylation sites(Asn-130 and Asn-207) and 12 conserved cysteine(Cys) residues. Here, we performed site-directed mutagenesis to generate systematic mutants of viral strain TSV01. The results of the subsequent analysis showed that an alanine substitution at the second N-linked glycan Asn-207 in NS1 delayed viral RNA synthesis, reduced virus plaque size, and weakened the cytopathic effect. Three mutants at Cys sites(Cys-4, Cys-55, Cys-291) and a C-terminal deletion(ΔC) mutant significantly impaired RNA synthesis, and consequently abolished viral growth, whereas alanine mutations at Asn-130 and Glu-173 resulted in phenotypes that were similar to the wild-type(WT) virus. Further analysis showed that the Asn-207 mutation slightly delayed viral replication. These results suggest that the three conserved disulfide bonds and the second N-linked glycan in NS1 are required for DENV-2 replication.

Molecular Characterization of the Four Serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) of Dengue Virus Circulating in Ouagadougou, Burkina Faso

Background and Objectives: Dengue is an arbovirosis caused by the dengue virus with 04 serotypes. The aim of the study was to characterise the four serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) of the dengue virus circulating in Ouagadougou, Burkina Faso. Methods: This was a descriptive analytical study that included 2833 patients and was carried out from January 2021 to December 2022. Rapid diagnosis of dengue was performed using the “Dengue Duo (AgNS1/IgM/IgG)” kit (SD Bioline, Korea). Viral RNA was extracted using the QIAGEN RNA RNeasy Plus Mini Kit (Quiagen, Germany) and virus serotypes were identified using the DENGUE Real-TM Genotype PCR kit (Sacace biotechnologies, Italy). Platelet counts were also performed using the XN-1500 Sysmex. Results: The prevalence of acute infections (NS1Ag positive) by TDR was 5.7% (162/2833), with the peak of dengue virus infection occurring between October and November. On the other hand, the AgNS1+ samples tested by RT-PCR were 53.7% positive for dengue virus;this shows the extent of probable cross-reactions with rapid diagnostic tests and false positives. Serotype 1 accounted for 52.6%, 28.4% had serotype 3, 16.8% had serotype 2 and 2.1% had serotype 4. We found cases of co-infection with DENV-1 and DENV-2 in two patients, co-infection with DENV-1 and DENV-3 in three patients, co-infection with DENV-1 and DENV-4 in one patient, co-infection with DENV-3 and DENV-4 in one patient and co-infection with three serotypes, DENV-1, DENV-2 and DENV-3 in one patient. Conclusion: The study showed that all four serotypes of the dengue virus were circulating in Ouagadougou. Serotype 1 was predominant.

Sublethal exposure to spinetoram impacts life history traits and dengue virus replication in Aedes aegypti

Insecticides are anthropogenic environmental stressors and also a common stressor for mosquito vectors.However,the use of insecticides is often guided by short-term efficacy,and the sublethal effect on their target or nontarget species has long been ignored.Here,we analyzed how sublethal exposure of the promising vector-control bioinsecticide spinetoram to Aedes aegypti larvae alter adult performance and susceptibility to dengue virus(DENV)infection.We found that the surviving adult mosquitoes were significantly smaller and exhibited weaker blood-feeding capacity than control females,apart from the extended immature development period.In terms of reproductive potential,although the F_(0) generation produced a similar number of eggs and offspring during the first gonotrophic cycle,the survival rates of the F_(1) generations were significantly lower as compared to the control group,suggesting transgenerational sublethal effects on the F_(1) generation.Notably,surviving adult females had higher DENV-2 viral loads than the control group after spinetoram sublethal exposure.Mechanistically,transcriptomic analysis showed that inhibition of oxidative phosphorylation may function in stimulating DENV production in adult Ae.aegypti.In Aag2 cells,significant accumulation of apoptosis,mitochondrial reactive oxygen species production,and DENV-2 replication by spinetoram exposure consistently support our conclusion.Our study highlights the threat of sublethal spinetoram exposure on outbreaks of mosquito-borne viruses.

Isolation and characterization of dengue virus serotype 2 from the large dengue outbreak in Guangdong, China in 2014

Dengue has been well recognized as a global public health threat,but only sporadic epidemics and imported cases were reported in recent decades in China.Since July 2014,an unexpected large dengue outbreak has occurred in Guangdong province,China,resulting in more than 40000 patients including six deaths.To clarify and characterize the causative agent of this outbreak,the acute phase serum from a patient diagnosed with severe dengue was subjected to virus isolation and high-throughput sequencing(HTS).Traditional real-time RT-PCR and HTS with Ion Torrent PGM detected the presence of dengue virus serotype 2(DENV-2).A clinical DENV-2 isolate GZ05/2014 was obtained by culturing the patient serum in mosquito C6/36 cells.The complete genome of GZ05/2014 was determined and deposited in Gen Bank under the access number KP012546.Phylogenetic analysis based on the complete envelope gene showed that the newly DENV-2 isolate belonged to Cosmopolitan genotype and clustered closely with other Guangdong strains isolated in the past decade.No amino acid mutations that are obviously known to increase virulence or replication were identified throughout the genome of GZ05/2014.The high homology of Guangdong DENV-2 strains indicated the possibility of establishment of local DENV-2 circulation in Guangdong,China.These results help clarify the origin of this epidemic and predict the future status of dengue in China.

Recent advances in the identification of the host factors involved in dengue virus replication

Dengue virus(DENV) belongs to the genus Flavivirus of the family Flaviviridae and it is primarily transmitted via Aedes aegypti and Aedes albopictus mosquitoes. The life cycle of DENV includes attachment, endocytosis, protein translation, RNA synthesis, assembly, egress, and maturation.Recent researches have indicated that a variety of host factors, including cellular proteins and micro RNAs, positively or negatively regulate the DENV replication process. This review summarizes the latest findings(from 2014 to 2016) in the identification of the host factors involved in the DENV life cycle and Dengue infection.

Suppressed expression of miR-378 targeting gzmb in N cells is required to control dengue virus infection

Dengue virus （DENV） remains a major public health threat because no vaccine or drugs are available for the prevention and treatment of DENV infection, and the immunopathogenesis mechanisms of DENV infection are not fully understood. Cytotoxic molecules, such as granzyme B （GrzB）, may be necessary to control viral infections. However, the exact role of GrzB during DENV infection and the mechanisms regulating GrzB expression during DENV infection are not clear. This study found that miR-27a~, miR-3Oe, and miR-378 were down-regulated in DENV-infected patients, and DENV infection in humans induced a significant up-regulation of GrzB in natural killer （NK） cells and CD8＋ T cells. Further investigation indicated that NK cells, but not CD8＋ T cells, were the major sources of GrzB, and miR-378, but not miR-27a~ or miR-3Oe, suppressed GrzB expression in NK cells. Notably, we found that overexpression of miR-378 using a miR-378 agomir in DENV-infected mice inhibited GrzB expression and promoted DENV replication. These results suggest the critical importance of miR-378 in the regulation of GrzB expression and a protective role for GrzB in controlling DENV replication in vivo. Therefore, this study provides a new insight into the immunopathogenesis mechanism of DENV infection and a biological basis for the development of new therapeutic strategies to control DENV infection.

Induction of virus-neutralizing antibodies and T cell responses by dengue virus type 1 virus-like particles prepared from Pichia pastoris

Background Dengue is currently a significant global health problem but no vaccines are available against the four dengue serotypes virus infections. The development of safe and effective vaccines has been hampered by the requirement of conferring complete protection against all four dengue serotypes and the lack of a convenient animal model. Virus-like particles （VLPs） have emerged as a promising subunit vaccine candidate. One strategy of vaccine development is to produce a tetravalent dengue subunit vaccine by mixing recombinant VLPs, corresponding to all four dengue virus serotypes. Towards this end, this study aimed to establish a Pichia pastoris （P. pastoris） expression system for production of dengue virus type 1 （DENV-1） VLPs and evaluate the humoral and cellular immune response of this particle in mice. Methods A recombinant yeast P. pastoris clone containing prM and E genes of DENV-1 was constructed and DENV-1 VLPs expressed by this clone were analyzed by sucrose density gradient centrifugation, Western blotting, and transmission electron microscope. Groups of mice were immunized by these particles plus adjuvant formulations, then mice were tested by ELISA and neutralization assay for humoral immune response, and by lymphocyte proliferation and cytokine production assays for a cellular immune response. Results Our data demonstrated that recombinant DENV-1 VLPs consisting of prM and E protein were successfully expressed in the yeast P. pastoris. Sera of VLPs immunized mice were shown to contain a high-titer of antibodies and the neutralization assay suggested that those antibodies neutralized virus infection in vitro. Data from the T lymphocyte proliferation assay showed proliferation of T cell, and ELISA found elevated secretion levels of interferon IFN-γ and IL-4. Conclusions P. pastoris-expressed DENV-1 VLPs can induce virus neutralizing antibodies and T cell responses in immunized mice. Using P. pastoris to produce VLPs offers a promising and economic strategy for dengue virus vaccine development.

PTEN Lipid Phosphatase Activity Enhances Dengue Virus Production through Akt/FoxO1/Maf1 Signaling

Dengue virus(DENV) is an arthropod-borne viral pathogen and a global health burden. Knowledge of the DENV-host interactions that mediate virus pathogenicity remains limited. Host lipid metabolism is hijacked by DENV for virus replication in which lipid droplets(LDs) play a key role during the virus lifecycle. In this study, we reveal a novel role for phosphatase and tensin homolog deleted on chromosome 10(PTEN) in LDs-mediated DENV infection. We demonstrate that PTEN expression is downregulated upon DENV infection through post-transcriptional regulation and, in turn, PTEN overexpression enhances DENV replication. PTEN lipid phosphatase activity was found to decrease cellular LDs area and number through Akt/FoxO1/Maf1 signaling, which, together with autophagy, enhanced DENV replication and virus production. We therefore provide mechanistic insight into the interaction between lipid metabolism and the DENV replication cycle.

Proteomics Profiling of Host Cell Response via Protein Expression and Phosphorylation upon Dengue Virus Infection

Dengue virus(DENV)infection is a worldwide public health threat.To date,the knowledge about the pathogenesis and progression of DENV infection is still limited.Combining global profiling based on proteomic analysis together with functional verification analysis is a powerful strategy to investigate the interplay between the virus and host cells.In the present study,quantitative proteomics has been applied to evaluate host responses(as indicated by altered proteins and modifications)in human cells(using K562 cell line)upon DENV-2 infection,as DENV-2 spreads most widely among all DENV serotypes.Comparative analysis was performed to define differentially expressed proteins in the infected cells compared to the mock-control,and it revealed critical pathogen-induced changes covering a broad spectrum of host cellular compartments and processes.We also discovered more dramatic changes(>20%,160 regulated phosphoproteins)in protein phosphorylation compared to protein expression(14%,321 regulated proteins).Most of these proteins/phosphoproteins were involved in transcription regulation,RNA splicing and processing,immune system,cellular response to stimulus,and macromolecule biosynthesis.Western blot analysis was also performed to confirm the proteomic data.Potential roles of these altered proteins were discussed.The present study provides valuable large-scale protein-related information for elucidating the functional emphasis of host cell proteins and their post-translational modifications in virus infection,and also provides insight and protein evidence for understanding the general pathogenesis and pathology of DENV.