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At least 19 recordsLinked to original sources
PubMed2026

The Sigma1 ER membrane receptor promotes structural protein folding and genome packaging of dengue virus.

Dengue virus (DENV) exploits the host endoplasmic reticulum (ER) to support viral protein translation and folding, replication, and assembly, although the identity of ER factors that promote these distinct steps during infection remain unclear. Here we demonstrate that the ER-resident Sigma1 ER membrane receptor (S1R) promotes virus structural protein folding and genome packaging of DENV during infection. Under S1R knockdown (KD), DENV infection is impaired without compromising virus translation or replication. Strikingly, EM analysis revealed that DENV particles in and secreted from S1R-depleted cells are smaller, likely because they are empty particles devoid of the vRNA genome. Biochemical experiments demonstrated that S1R binds to the prM structural protein and under S1R KD, the prM, E and C structural proteins became detergent-insoluble. Thus, without S1R, all three virus structural proteins misfold, impairing efficient genome packaging. Together, these findings identify a novel ER chaperone that supports a critical DENV infection step.

Dengue Virus↗
PubMed1979

Electron microscopic observations on Aedes albopictus cells infected with dengue viruses.

In dengue virus infected Aedes albopictus cells, electron-dense particles, larger than single ribosomes, were arranged on the cytoplasmic sides of rough endoplasmic reticulum (RER) membranes. Mature virions 40--45 nm in diameter as well as vesiculotubular structures 50--120 nm in diameter appeared in enlarged cisternae of RER filled with fine granular substance. Many of the mature virions and somewhat degenerated vesiculotubular structures remained to be enclosed in membranous structures presumably derived from RER, even after degeneration of infected cells. The findings suggest that development of dengue viruses in cultured A. albopictus cells takes place in close relationship with the activated membranes of RER. Other morphological changes observed in dengue infected A. albopictus cells were 1. electron-dense "double-track structures" in areas of virion morphogenesis, 2. fine crystalline structures in type-2 dengue infected cells, and 3. aggregates of nucleoid structures, in cells persistently infected with type 2 dengue virus. The implication and nature of these structures in relation to virion morphogenesis remain to be investigated.

Aedes↗
PubMed2025

Dengue Virus Replicative-Form dsRNA Is Recognized by Both RIG-I and MDA5 to Activate Innate Immunity.

RIG-I like receptors (RLRs) are a family of cytosolic RNA sensors that sense RNA virus infection to activate innate immune response. It is generally believed that different RNA viruses are recognized by either RIG-I or MDA5, two important RLR members, depending on the nature of pathogen-associated molecular patterns (PAMPs) that are generated by RNA virus replication. Dengue virus (DENV) is an important RNA virus causing serious human diseases. Despite extensive investigations, the molecular basis of the DENV PAMP recognized by the host RLR has been poorly defined. Here, we demonstrated that the DENV infection-induced interferon response is dependent upon both RIG-I and MDA5, with RIG-I playing a predominant role. Next we purified the DENV PAMP RNA from the DENV-infected cells, and demonstrated that the purified DENV PAMP is viral full-length double-stranded RNA bearing 5'ppp modifications, likely representing the viral replicative-form RNA. Finally, we confirmed the nature of the DENV PAMP by reconstituting the viral replicative-form RNA from in vitro synthesized DENV genomic RNA. In conclusion, our work not only defined the molecular basis of the RLR-PAMP interaction during DENV infection, but also revealed the previously underappreciated recognition of a distinct moiety of the same PAMP by different RLRs in innate immunity against RNA viruses.

Interferon-Induced Helicase, IFIH1↗
PubMed1978

A rapid fluorescent focus-inhibition test for determining dengue neutralizing antibody and for identifying prototype dengue viruses.

Neutralizing antibody to dengue virus in human and animal sera was assayed by the rapid fluorescent focus-inhibition test (RFFIT). Neutralizing-antibody titers could be detected after only 24 h compared to 5--6 days required by the plaque-reduction test. The RFFIT is more definitive than the conventional complement fixation (CF) or hemagglutination-inhibition (HI) test in identifying prototype dengue viruses, is reproducible, and is applicable to the routine detection of neutralizing antibodies to dengue viruses.

Antibodies, Viral↗
PubMed1977

Infections with two dengue viruses in Greece in the 20th century. Did dengue hemorrhagic fever occur in the 1928 epidemic?

From contemporary clinical accounts we hypothesized that the 1928 dengue epidemic in Greece may have been an earlier occurrence of dengue hemorrhagic fiver/dengue shock syndrome (DHF/DSS). To study the possibility that two different dengue viruses may have been involved, serums from 62 Athenians alive during the epidemic were examined for dengue antibodies; 73 per cent showed evidence of prior dengue infection. Monotypic neutralizing antibodies were found to two different dengue viruses, types 1 and 2. A large proportion of the sampled population had evidence of two or more past dengue infections. Since there is no evidence that dengue viruses have been transmitted in Greece since 1928, during the epidemic a very large number of persons immune to one dengue type must have acquired infections with a secon type. The virological criteria for secondary infection DHF/DSS are thus satisfied. Although DHF/DSS is currently restricted to Asia and the Pacific, the Greek oubreak suggests a biological potential for fatal consequences of dengue infections in Caucasians, particularly the elderly.

Adolescent↗
PubMed1977

Effect of immunosuppression on dengue virus infection in mice.

Mean survival time following intracerebral inoculation of dengue virus was reduced and the titre of the virus in the brain of immunosuppressed mice was markedly increased. A single dose of cyclophosphamide given 24 h after dengue virus i.c. or i.p. substantially reduced the number of antibody forming cells in the spleen. Three doses of dengue virus, each followed by cyclophosphamide 24 h later, produced specific hyporesponsiveness to the dengue virus but not to a heterologous virus (Coxsackie B4), with a reduction in antibody forming cells in the spleen of such animals against dengue virus but not against Coxsackie B4 virus. Adoptive immunity by antiserum was abolished along with increased titres of the virus in the brain of immunosuppressed mice but the protection could be restored by a second dose of antiserum. Pre-treatment of mice with immune or normal spleen cells i.v. or reconstitution of immunosuppressed mice by such cells had no effect. Thus, humoral antibodies play a crucially important role in host defence mechanism in recovery of mice from primary dengue virus infection.

Animals↗
PubMed2025

Computational Insights on the Assembly of the Dengue Virus Membrane-Capsid-RNA Complex.

Dengue virus, an arbovirus from the genus Flavivirus in the family Flaviviridae, forms a nucleocapsid structure through interactions between its genome and multiple copies of the capsid protein. Experimental studies have confirmed the interaction between the viral capsid protein and lipid droplets, indicating a protein-lipid interaction. Cryo-EM studies show that in immature viruses, the nucleocapsid is located close to the viral membrane. This study uses multiple MD simulations to explore the orientation of the capsid protein relative to the lipid membrane, focusing on how the protein's hydrophobic pocket interacts with the membrane. We also investigated the interaction between the capsid protein and RNA, considering the effects of sequence length and identity. Finally, we construct a model of the lipid-protein-RNA complex, demonstrating that the capsid protein's hydrophobic pocket interacts with the membrane, while the positively charged H4 helix interacts with the negatively charged RNA. This research may identify crucial interactions for immature virus particle formation and provide insights for future therapeutic interventions.

Dengue Virus↗
PubMed2015

Dengue virus infection elicits highly polarized CX3CR1+ cytotoxic CD4+ T cells associated with protective immunity.

Dengue virus (DENV) is a rapidly spreading pathogen with unusual pathogenesis, and correlates of protection from severe dengue disease and vaccine efficacy have not yet been established. Although DENV-specific CD8(+) T-cell responses have been extensively studied, the breadth and specificity of CD4(+) T-cell responses remains to be defined. Here we define HLA-restricted CD4(+) T-cell epitopes resulting from natural infection with dengue virus in a hyperepidemic setting. Ex vivo flow-cytometric analysis of DENV-specific CD4(+) T cells revealed that the virus-specific cells were highly polarized, with a strong bias toward a CX3CR1(+) Eomesodermin(+) perforin(+) granzyme B(+) CD45RA(+) CD4 CTL phenotype. Importantly, these cells correlated with a protective HLA DR allele, and we demonstrate that these cells have direct ex vivo DENV-specific cytolytic activity. We speculate that cytotoxic dengue-specific CD4(+) T cells may play a role in the control of dengue infection in vivo, and this immune correlate may be a key target for dengue virus vaccine development.

Adult↗
PubMed1979

A method for the isolation and identification of dengue viruses, using mosquito cell cultures.

An improved method for the isolation and identification of dengue viruses is described. Viruses were isolated in mosquito cell cultures (C6/36 or AP-61), identified by indirect fluorescent antibody technique, and typed by complement-fixation test, using the cell culture fluid as antigen. The sensitivity of this method was compared with mosquito inoculation in comparative titrations of 16 low passage dengue virus strains. Although lower virus titers were obtained by the mosquito cell culture technique, its decreased sensitivity was compensated for by the much larger volume (588X) which could be assayed. By incubating the mosquito cells at 32 degrees C, dengue viruses can be identified and typed within 6 days after inoculation.

Animals↗
PubMed2026

Identification and validation of natural dengue virus NS1 inhibitors with promising antiviral potential.

Dengue infection remains a major global public health challenge, with no specific antiviral therapy currently available. The dengue virus non-structural protein 1 (NS1) exists in both intracellular and secreted forms playing a pivotal role in viral replication, immune evasion, and pathogenesis, particularly by contributing to endothelial disruption and vascular leakage during severe disease, thereby making it a promising therapeutic target. In silico screening identified berberine, betulinic acid, and ursolic acid as top candidates, exhibiting high binding affinities and stable interactions within the NS1 binding pocket. These computational predictions were further validated by biophysical assays, which demonstrated strong and specific binding interactions between the purified NS1 protein and the selected compounds. All three compounds significantly reduced viral genome levels, with the highest inhibition observed for berberine (60%), and followed by betulinic acid (40%) and ursolic acid (28%). Consistently, berberine showed the most potent inhibition of both intracellular and extracellular NS1. Overall, these findings highlight the inhibitory potential of natural compounds against DENV NS1 and provide a strong foundation for the development of NS1-targeted antivirals as a novel therapeutic strategy against dengue infection.

Antiviral Agents↗
PubMed2026

Discovery of acridone analogs as novel entry inhibitors targeting e protein of dengue virus.

The envelope (E) protein of the Dengue virus (DENV) is critical for virion attachment and membrane fusion with the host cell, as well as the release of the viral RNA genome into the cytoplasm. In this study, we describe the design, synthesis, and biological evaluation of novel viral entry inhibitors containing an acridone core. Notably, compound 13e demonstrated potent cellular antiviral activity (IC50 = 8.6 μM and selectivity index = 21.4). Compound 13e was evaluated using several methods, including time-of-addition and virus entry/binding assays, which revealed that it selectively blocked DENV2 infection by inhibiting virion attachment. Furthermore, compound 13e exhibited potent antiviral efficacy, as evidenced by viremia quantification and histopathological analysis results, without causing significant body weight loss or other toxicities. Furthermore, target engagement assay supported the role of compound 13e as an E protein binder, consistent with its function as an entry inhibitor.

Dengue Virus↗
PubMed2025

RT-RPA Assisted CRISPR/Cas12a Based One-Pot Rapid and Visual Detection of the Pan-Dengue Virus.

Globally ≤ 4 billion of the population are at potential risk of contracting dengue virus (DENV) infection. Seasonal outbreaks of dengue are frequently reported causing a high healthcare burden. Undiagnosed DENV can lead to severe morbidity and mortality. Early diagnosis of DENV relies on molecular methods, which are impractical in resource-constrained settings (RCSs). Dengue can be caused by any of the four distinct DENV serotypes. Therefore, a simple method for rapid diagnosis of Pan-DENV serotypes is of utmost importance at RCSs. A fluorescence detection platform for Pan-DENV using RT-RPA and CRISPR/Cas12a was developed targeting nonstructural 1 (NS1) gene for DENV-1, 2, and 3, and envelope (E) gene for DENV-2. Further, crRNA specific to DENV serotypes were designed to facilitate CRISPR/Cas12a detection. Analytical sensitivity was determined using synthetic RNA and DENV serotypes genome. Clinical validation of the assay was performed using RNA extracted from AES/AFI clinical samples. The developed CRISPR/Cas12a-based detection platform can detect all four serotypes of DENV viz 1-4 in a single pot using fluorescence detection. This assay showed the limit of detection ≥ 781 zg reaction- 1, ≥ 1.81 ag reaction-1, ≥ 62.5 fg reaction-1, and ≥ 2.5 pg reaction-1 for synthetic DENV-1, DENV-2, DENV-3, and DENV-4 template, respectively. Our assay demonstrated the analytic sensitivity of ≥ 10 ng reaction-1 for DENV-1 and DENV-4, and ≥ 0.5 ng reaction-1 for DENV-3 and DENV-4 genomes. This assay showed no cross-reactivity with other related etiologies tested causing AFI/AES. With 76 clinical samples (DENV PCR positive = 16, DENV PCR negative = 60), the assay demonstrated 93.7% sensitivity and 100% specificity with an overall accuracy of 98.7% for detection of the Pan-DENV serotypes. Our assay displayed comparable results to that of RT-PCR. The ease of interpretation and rapid detection of the Pan-DENV, represents the potential of the developed assay as an ideal point-of-care test. This assay upon field-deployment could help in reducing healthcare burden, provide differential diagnosis and support initiating early and prompt treatment to patients at RCS.

Dengue Virus↗
PubMed1979

Dengue virus isolation in Indonesia, 1975-1978.

Virus isolations from dengue hemorrhagic fever patients in Indonesia are reported from 1975 to 1978. All 4 dengue serotypes were endemic in Jakarta, but dengue 3 was the predominant virus isolated. This type was also the most frequently isolated virus from patients outside Jakarta and had the widest distribution in Indonesia. The sensitivity of the mosquito inoculation technique for isolation of dengue viruses is discussed.

Antigens, Viral↗
PubMed1979

Effects of cell culture and laboratory conditions on type 2 dengue virus infectivity.

The stability of type 2 dengue virus to exposure to a variety of laboratory conditions was determined. Suckling mouse brain passage virus was adapted for growth in BHK-21 cells, and plaque assays were performed using a tragacanth gum overlay. A three- to fourfold increase in plaque size could be obtained if monolayers were subconfluent at time of inoculation. Incubation of virus for 24 h at 37 degrees C, pH 6.5, or in buffer containing 1 mM ethylenediaminetetraacetate considerably reduced virus infectivity as compared with virus incubated for the same period at 4 degrees C, pH 8.0, or in buffer with or without 1 mM CaCl2 and 1 mM MgCl2. Multiple freezing and thawing of virus tissue culture medium containing 10% fetal calf serum did not reduce virus infectivity.

Animals↗
PubMed1975

The effect of dengue virus infection on the clinical sequelae of Japanese encephalitis: a one year follow-up study in Thailand.

In order to determine if prior dengue virus infection reduces the severity of Japanese encephalitis (JE), we examined 127 patients hospitalized during the 1970 JE epidemic in the Chiangmai and Lampang Valleys of northern Thailand. Patients were studied during the first 30 days after onset of JE; 120 of these patients were examined one year later for residual neurologic sequelae. About 21% of patients had serological evidence of a prior dengue virus infection. Morbidity and mortality in patients with and without prior dengue virus experience were compared. These comparisons were made within two age groups to exclude differences due to age alone;

Adolescent↗
PubMed1978

Ultrastructural studies on dengue virus infection of human lymphoblasts.

Ultrastructural studies of dengue-2 virus-infected lymphoblastoid Raji cells showed that the virus induced an increase in the size of the rough endoplasmic reticula (RER) and that the replication of the virus was confined to the cisternae of these RER. The proliferating RER formed cytoplasmic inclusions that could be seen by light microscopy. This observation could be used as evidence of a cytopathogenic effect of dengue virus on infected Rajii cells in routine cultures. Accumulation of virions in the infected cells was minimal in comparison with other cell systems, however. Sporadic clusters of mature virions were often seen on the plasma membrane. These extracellular virions were distributed adjacent to the virus-bearing RER and were presumably released virions. Vertical transmission of the virus was evident in mitotic lymphoblasts. The replication pattern of dengue virus in lymphoblastoid cells suggests that efforts should be made to determine whether blast-transformed lymphocytes, numerous in secondary dengue infections, support dengue virus replication in vivo.

Cell Line↗
PubMed2026

Structural biology of the dengue virus NS2B-NS3 protease as a target for antiviral drug development.

Dengue is the most common global problem in recent times, particularly in tropical and subtropical areas, yet antivirals for therapy or prophylaxis are lacking. Millions of people are affected by this dengue virus, but no proper medication is available yet to cure this disease. One polyprotein that is encoded by the DENV genome is converted into structural and non-structural proteins that are necessary for viral pathogenesis and replication. Among these, the non-structural protein complex NS2B-NS3 is essential for viral polyprotein processing, replication, and host innate immune response control. It acts as a trypsin-like serine protease. The NS2B/NS3 protease is a key enzyme involved in viral replication and serves as a major target for drug development against the dengue virus. The NS3 protease has a conserved catalytic triad (His-Asp-Ser), whereas NS2B serves as an essential cofactor that stabilizes the active conformation of the enzyme and aids in substrate recognition. By disrupting interferon signalling pathways, the NS2B-NS3 protease not only aids in viral replication but also makes immune evasion easier. The compound that inhibits the action of this enzyme could be pioneering in the antiviral drug discovery process. This article provides a comprehensive overview of the detailed structural information of the viral protease (NS2B/NS3) enzyme with the mechanistic role of this enzyme, and highlights various inhibitors related to the NS2B/NS3 protease. A more thorough comprehension of this protease could facilitate the logical development of potent antiviral medications to prevent dengue infection.

Dengue↗