Dengue virus neutralizing antibody: a review of targets, cross-reactivity, and antibody-dependent enhancement

Dengue virus and lipid metabolism: unravelling the interplay for future therapeutic approaches

In recent years, Dengue virus (DENV) has continued to pose significant health risks in tropical and subtropical areas worldwide, raising health alerts worldwide. It can cause hyperviremia in humans and can even lead to fatal clinical diseases. The life cycle of DENV is intricately linked to cellular lipids, and the virus selectively utilizes relevant enzymes involved in lipid metabolism to modulate the existing metabolic system in host cells during entry, replication, assembly, and other stages, thereby creating an environment conducive to its complete replication cycle. At present, there is a lack of effective and specific anti-DENV treatment measures. This review summarizes the recently identified lipid metabolism molecules and metabolic related diseases that affect DENV infection, explores the dependence of DENV on lipid metabolism and provides potential targets for the treatment of dengue fever (DF).

Darunavir inhibits dengue virus replication by targeting the hydrophobic pocket of the envelope protein

Dengue viruses (DENV) pose significant health threats, with no approved antiviral drugs currently available, creating an urgent need for new therapies. This study screened FDA-approved drugs for their antiviral ability against DENV and identified three promising candidates: darunavir (DRV), domperidone, and tetracycline. DRV demonstrated the highest efficacy against three DENV serotypes, with half-maximal effective concentrations (EC50) below 1 µM, surpassing the performance of tetracycline and domperidone. It effectively blocked DENV envelope (E) protein attachment to two type cells with EC50 values less than 0.2 μM. Domperidone reduced DENV-2 attachment to TE671 cells (EC50 = 3.08 μM) but was less effective in BHK-21 cells, while tetracycline inhibited NS3 protease (IC50 = 1.12 μM). Among DRV's structurally related drugs, fosamprenavir (FPV) significantly reduced DENV infectivity and virus yield, with EC50 values below 0.5 µM. In vivo, DRV at 1, 2, and 5 mg/kg achieved 100 % survival in suckling mice, compared to 83.5 % with FPV. Real-time RT-PCR showed DRV more effectively reduced DENV-2 RNA in mouse brains than FPV. Molecular docking showed DRV and FPV bind tightly to the DENV-2 E protein's N-octyl-β-D-glucoside (βOG) hydrophobic pocket, with DRV forming stronger interactions than FPV. Chimeric DENV-2 single-round infectious particle tests confirmed DRV's effective targeting of this pocket, though mutations at K128, L198, Q200, I270, and T280 reduced its efficacy. These findings highlight DRV as a potent antiviral agent against DENV, targeting the E protein's βOG hydrophobic pocket, with the potential for rapid deployment in treating and preventing infections.

Ultrasensitive Peptide-Based Electrochemical Biosensor for Universal Diagnostic of Dengue

Dengue is a neglected disease mainly affecting tropical and subtropical countries. The diagnosis of dengue fever is still a problem since most of it is made from whole or recombinant DENV proteins, which present cross-reactions with other members of the Flavivirus family. Therefore, there is still a huge demand for new diagnostic methods that provide rapid, low-cost, easy-to-use confirmation. Thus, in this study, we developed an affordable electrochemical biosensor for rapidly detecting immunoglobulin G (IgG) serological antibodies in the sera of DENV-infected patients. An identified linear B-cell epitope (DENV/18) specific for DENV 1-4 serotypes recognized by IgG in patient sera was selected as a target molecule after a microarray of peptides using the SPOT-synthesis methodology. After chemical synthesis, the DENV/18-peptide was immobilized on the surface of the working electrode of a commercially available screen-printed gold electrode (SPGE). The capture of DENV-specific IgG allowed for the formation of an immunocomplex that was measured by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) using a potassium ferrocyanide/ferricyanide ([Fe(CN)6]3-/4-) electrochemical probe. An evaluation of the biosensor's performance showed a detection limit of 100 µg mL-1 for the synthetic peptides (DENV/18) and 1.21 ng mL-1 in CV and 0.43 ng mL-1 in DPV for human serum, with a sensitivity of 7.21 µA in CV and 8.79 µA in DPV. The differentiation of infected and uninfected individuals was possible even at a high dilution factor that reduced the required sample volumes to a few microliters. The final device proved suitable for diagnosing DENV by analyzing real serum samples, and the results showed good agreement with molecular biology diagnostics. The flexibility to conjugate other antigenic peptides to SPEs suggests that this technology could be rapidly adapted to diagnose other pathogens.

In vitro and in vivo neutralization of Dengue virus by a single domain antibody

To alleviate the contribution of antibody dependent enhancement in DenV pathogenesis, we obtain a DenV neutralizing single domain antibody (sdAb) from an in-house constructed phage display library of camelid VHH. The anti-DenV sdAb specifically reacts with the envelope (E) protein of DenV with a Kd value of 2x108. Molecular dynamic simulations and docking analysis show that the sdAb interacts with the DenV(E) protein via domain II (EDII) and interferes with the virus internalization process. The anti-DenV(E) sdAb potently inhibits the infectivity of a DenV(E) protein expressing pseudovirus as well as that of a virulent DenV in vitro. A mouse adapted DenV2 induces 100% mortality in the infected IFNRKO mice, but the animals injected with the sdAb neutralized virus remain fully protected. Furthermore, the therapeutically administered anti-DenV(E) sdAb slows down the disease progression and enhances the survival of DenV infected animals. In conclusion, we report an anti-DenV(E) sdAb as a potential therapy to manage DenV pathogenesis.

Structural Virology: The Key Determinants in Development of Antiviral Therapeutics

Structural virology has emerged as the foundation for the development of effective antiviral therapeutics. It is pivotal in providing crucial insights into the three-dimensional frame of viruses and viral proteins at atomic-level or near-atomic-level resolution. Structure-based assessment of viral components, including capsids, envelope proteins, replication machinery, and host interaction interfaces, is instrumental in unraveling the multiplex mechanisms of viral infection, replication, and pathogenesis. The structural elucidation of viral enzymes, including proteases, polymerases, and integrases, has been essential in combating viruses like HIV-1 and HIV-2, SARS-CoV-2, and influenza. Techniques including X-ray crystallography, Nuclear Magnetic Resonance spectroscopy, Cryo-electron Microscopy, and Cryo-electron Tomography have revolutionized the field of virology and significantly aided in the discovery of antiviral therapeutics. The ubiquity of chronic viral infections, along with the emergence and reemergence of new viral threats necessitate the development of novel antiviral strategies and agents, while the extensive structural diversity of viruses and their high mutation rates further underscore the critical need for structural analysis of viral proteins to aid antiviral development. This review highlights the significance of structure-based investigations for bridging the gap between structure and function, thus facilitating the development of effective antiviral therapeutics, vaccines, and antibodies for tackling emerging viral threats.

[Dengue treatments and vaccines]

Dengue fever is a viral disease transmitted by mosquitoes of the Aedes genus, whose incidence and range have been steadily increasing in recent decades. Causing hemorrhagic fever in severe cases, it affects the inter-tropical regions of the world and threatens to spread to new geographical areas. Its complex pathophysiology and the existence of four genetically distant serotypes make vaccine development a challenge. Currently, there is no specific treatment against dengue fever and only a few vaccines are marketed or in development, with some limitations on their use. It is therefore necessary to develop new vaccines and identify new molecules with antiviral properties to reduce the economic and public health burden of this disease in endemic areas.

Simultaneous detection of dengue virus serotypes in a dual-serotype-detection nucleic acid based lateral flow assay

Dengue virus (DENV) is an important arthropod-borne viral disease, with four antigenically and genetically diverse serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). Timely and accurate diagnosis of dengue virus serotypes is crucial for the management of outbreaks. This study focussed on the development of a RT-PCR based lateral flow strip assay to detect DENV serotypes in a dual detection manner without using gel electrophoresis. The assay uses anti-biotin/streptavidin colloidal gold conjugates with fluorescent/enzymatic tagged DENV serotype specific antibodies for the direct detection of DENV infected serum samples on a nitrocellulose membrane using biotin-BSA as control line. The detection limit of the assay was up to 10 copies of cDNA for DENV-1 and 100 copies for DENV-2, DENV-3, and DENV-4. In house evaluation of DENV LFIA demonstrated 100 % sensitivity in all the serotypes compared to conventional RT-PCR, 100 % specificity for DENV-1, DENV-2, DENV-3, and 95 % specificity for DENV-4 detection. DENV serotyping was assessed in a dual detection manner (DENV-1/DENV-3 and DENV-2/DENV-4 at two test lines) on the strip. The limitation of the assay is the requirement of PCR for initial amplification and confirmation of individual serotype in case of DENV-1/DENV-3 and DENV-2/DENV-4 detection, besides the field evaluation of the assay detected DENV-2 and DENV-3 serotypes, and no other serotype was detected in line with RT-PCR findings.

HeterologousPrime-Boost immunizationwithAdenoviral vector and recombinant subunit vaccines strategies against dengue virus type2

Dengue virus (DENV) remains a significant public health threat in tropical and subtropical regions, with effective antiviral treatments and vaccines still not fully established despite extensive research. A critical aspect of vaccine development for DENV involves selecting proteins from both structural and non-structural regions of the virus to activate humoral and cellular immune responses effectively. In this study, we developed a novel vaccine for dengue virus serotype 2 (DENV2) using a heterologous Prime-Boost strategy that combines an adenoviral vector (Ad) with subunit vaccines. The vaccine design included non-structural protein 1 (NS1), envelope protein domain III (EDIII), and the bc-loop of envelope domain II (EDII) as conserved epitopes. These antigens were fused into a single construct P1 and inserted into the pAdTrack-CMV vector to produce a recombinant adenovirus (rAd5-P1) via homologous recombination in E. coli. The examination of the immune response indicated that strong humoral and cellular immunity was generated in various groups of mice. Additionally, the group receiving a heterologous regimen of recombinant adenovirus and protein showed a superior balance of humoral and cellular immunity in terms of IgG2a/IgG1 and INF-γ /IL-4 ratios. These findings validate the vaccine design's ability to utilize both structural and non-structural proteins to generate strong immune responses on two platforms. The promising results from the heterologous regimen highlight its potential as an effective DENV2 vaccine candidate. This research offers significant insights into developing safe and effective DEN vaccines, contributing to efforts to control DENV infections.

Recommendations for dengue vaccine implementation in the elderly population

Dengue is a mosquito-borne flaviviral disease that is endemic to tropical and subtropical regions, affecting hundreds of millions of people worldwide. Although it was once considered a neglected disease, the incidence and mortality rates of dengue have surged over the past decade, in part due to the expanding distribution of the Aedes spp. vector facilitated by changing climatic factors. While most infections are asymptomatic or cause mild flu-like symptoms, some cases can develop into severe forms, leading to serious complications. The burden of the disease is gradually shifting from primarily affecting children, whose immune systems are immature, to increasingly impacting the older population, who typically experience waning immune responsiveness and comorbidities. With no specific treatment available, the development of a prophylactic vaccine is crucial for long-term control and prevention. School-age children are the primary target group for immunization programs of the two recently licensed dengue vaccines. However, there is limited information on the efficacy of either vaccine among the elderly or of two further immunogenic preparations currently undergoing clinical trials. This review gives an update on dengue vaccine implementation and provides recommendations for the vaccination of persons aged 60 years and above.

Standardization, validation, and comparative evaluation of a convenient surrogate recombinant vesicular stomatitis virus plaque reduction test for quantification of Hantaan orthohantavirus (HTNV) neutralizing antibodies

Hantaan orthohantavirus (HTNV) is responsible for severe hemorrhagic fever with renal syndrome (HFRS), which has a case fatality rate of 1% to 10%. Currently, the inactive vaccine licensed in endemic areas elicit low levels of neutralizing antibodies (NAbs). Early NAbs administration is helpful for patients recovery from HFRS. Therefore, measuring NAbs is crucial for evaluating the immune response following infection or vaccination. The golden standard for HTNV NAbs measurement is the focus reduction neutralization test (FRNT), which typically requires skilled technicians and is performed under high biosafety containment facility. Here, we established a surrogate NAbs titration method with replication-competent vesicular stomatitis virus (VSV) bearing HTNV glycoprotein (rVSV-HTNV-GP) based plaque reduction neutralization test (PRNT). Then compared and correlated this method with the authentic HTNV based FRNT, and applied it to measure the NAbs level in 47 serum samples from HFRS patients, healthy donors and inactive vaccine recipients. We observed positive correlations between two neutralization assays among HFRS patients and inactive vaccine recipients (R2 = 0.5994 and 0.3440, respectively) and confirmed the clear specificity with healthy donors without vaccinated and reproducibility with three more assays. Our results suggest that rVSV-HTNV-GP based PRNT is a reliable lower-biosafety level surrogate for HTNV NAbs evaluation, which is easy to perform with higher sensitivity.

Dengue NS1 Antibodies Are Associated With Clearance of Viral Nonstructural Protein-1

BACKGROUND

Dengue vascular permeability syndrome is the primary cause of death in severe dengue infections. The protective versus potentially pathogenic role of dengue nonstructural protein-1 (NS1) antibodies are not well understood. The main goal of this analysis was to characterize the relationship between free NS1 concentration and NS1 antibody titers in primary and secondary dengue infection to better understand the presence and duration of NS1 antibody complexes in clinical dengue infections.

METHODS

Hospitalized participants with acute dengue infection were recruited from Northern Colombia between 2018 and 2020. Symptom assessment, including dengue signs and symptoms, chart review, and blood collection, was performed. Primary versus secondary dengue was assessed serologically. NS1 titers and anti-NS1 antibodies were measured daily.

RESULTS

Patients with secondary infection had higher antibody titers than those in primary infection, and there was a negative correlation between anti-NS1 antibody titer and NS1 protein. We demonstrate that in a subset of secondary infection, there were indeed NS1 antigen-antibody complexes on the admission day during the febrile phase that were not detectable by the recovery phase. Furthermore, dengue infection status was associated with higher circulating sialidases.

DISCUSSION

The negative correlation between antibody and protein suggests that antibodies may play a role in clearing this viral protein.

Clinical and Laboratory Features and Treatment Outcomes of Dengue Fever in Pediatric Cases

Background Globally, dengue fever (DF) is the leading cause of arthropod-borne viral illness, which considerably contributes to an atrocious death rate. The disease is now endemic in some parts of the world, including Bangladesh. The disorder exhibits a wide range of clinical and laboratory features in children. Judicial fluid resuscitation during the critical phase and prompt referral to the appropriate health facility can be lifesaving. Objectives This research appraised clinical and laboratory features and treatment outcomes of DF in pediatric cases. Methods This prospective investigative work was conducted at Islami Bank Hospital, Dhaka, India, from July to October 2023. The study included 135 admitted pediatric cases of DF, either dengue nonstructural protein 1 (NS1) or anti-dengue antibody IgM or IgG positive. Results Among the selected cases, boys were more predominant than girls, and most patients were in the age group of 5 to 10 years (n=46, 34%), most of them belonging to lower-middle-class families (n=56, 41.5%). All of the study participants had raised body temperatures, and most had abdominal pain (n=82, 60.7%), vomiting (n=77, 57%), cough (n=43, 31.9%), headache (n=38, 28.2%), body aches (n=32, 23.7%), and diarrhea (n=23, 17%). Dengue NS1 was positive in 91.1% (n=123) of cases. Raised hematocrit was found in 36.3% (n=49) of cases, leukopenia in 47% (n=63), and thrombocytopenia in 69.6% (n=94) of cases. Most of our patients were categorized as having DF (68.1%, n=92), followed by dengue with warning signs (16.3%, n=22), and severe dengue was present in 15.6% (n=21) of patients. Most were treated with crystalloid, and some with crystalloid and colloid solution. Fortunately, most of them recovered with no death. Conclusion DF may manifest with varied clinical and laboratory features in children. Appropriate treatment of critical phases, depending on clinical and laboratory features, is crucial to reducing dengue-induced miseries and fatal clinical outcomes among the pediatric population.

Genetic and structural characterization of dengue virus involved in the 2023 autochthonous outbreaks in central Italy

Dengue virus (DENV) has been expanding its range to temperate areas that are not usually affected, where the spread of vectors has been facilitated by global trade and climate change. In Europe, there have been many cases of DENV imported from other regions in the past few years, leading to local outbreaks of DENV among people without travel history. Here we describe the epidemiological and molecular investigations of three transmission events locally acquired DENV infections caused by serotypes 1, 2 and 3, respectively, in the Latium Region from August to November 2023. Next-generation or Sanger sequencing was used to obtain the whole genomes, or the complete E-gene of the viruses, respectively. The structure of the DENV-1 and DENV-3 sequences was analysed to identify amino acid changes that were not found in the closest related sequences. The major cluster was supported by DENV-1 (originated in South America), with 42 autochthonous infections almost occurring in the eastern area of Rome, probably due to a single introduction followed by local sustained transmission. Seven DENV-1 subclusters have been identified by mutational and phylogenetic analysis. Structural analysis indicated changes whose meaning can be explained by the adaptation of the virus to human hosts and vectors and their interactions with antibodies and cell receptors.

The Low-Density Lipoprotein Receptor-Related Protein-1 Is Essential for Dengue Virus Infection

Dengue virus (DENV) causes the most prevalent and rapidly spreading arboviral disease of humans. It enters human cells by receptor-mediated endocytosis. Numerous cell-surface proteins were proposed as DENV entry factors. Among these, the phosphatidylserine receptor TIM-1 is the only one known to mediate virus internalization. However, several cellular models lacking TIM-1 are permissive to DENV infection, suggesting that other receptors exist. Here, we show that the low-density lipoprotein receptor-related protein-1 (LRP1) binds DENV virions by interacting with the DIII of the viral envelope glycoprotein. DENV infection is effectively inhibited by the purified receptor at 5 × 10-8 mol/L, and the interaction of the envelope protein with LRP1 is also blocked by a natural ligand of LRP1. The depletion of LRP1 causes 100-fold lower production of infectious virus than controls. Our results indicate that LRP1 is another DENV receptor, thus becoming an attractive target to evaluate for the development of effective antiviral drugs against DENV.

Structure-based identification of small-molecule inhibitors that target the DIII domain of the Dengue virus glycoprotein E pan-serotypically

Dengue viral infection is caused by the Dengue virus, which spreads to humans through the bite of infected mosquitos. Dengue affects over half of the global population, with an estimated 500 million infections per year. Despite this, no effective treatment is currently available, however, several promising candidates are undergoing pre-clinical/clinical testing. The existence of four major serotypes is an important challenge in the development of drugs and vaccines to combat Dengue virus infection. Hence, the drug/vaccine thereby developed should neutralize all the four serotypes equally. However, there is no pan-serotype specific treatment for Dengue virus, thereby emphasizing the need for the identification of novel drug-like compounds that can target all serotypes of the Dengue virus equally. To this end, we employed virtual screening methodologies to find drug-like compounds that target the domain III of glycoprotein E. Most importantly, domain III of E protein is involved in viral fusion with the host membrane and is also targeted by neutralizing antibodies. Our study found two small molecule drug-like compounds (out of the 3 million compounds screened) having similar binding affinity with all four serotypes. The compounds thereby identified exhibit favourable drug like properties and can be developed as a treatment for Dengue virus.

[The dengue vaccine: a major scientific challenge and a public health issue]

Almost half of the world's population is exposed to the risk of transmission of the four dengue virus serotypes (DENV 1-4), by mosquitoes of the genus Aedes. A dengue vaccine is effective if it induces prolonged protective immunity against all circulating viral strains, irrespective of the age and infection history of the vaccinated subject. An effective vaccine strategy against dengue is based on the injection of live attenuated viruses in a tetravalent formulation. In this review, we present the most promising candidate vaccines against dengue, their successes and also the questions raised by the correlates of protection that have been adopted to assess their level of effectiveness against the disease.

Trends and insights in dengue virus research globally: a bibliometric analysis (1995-2023)

BACKGROUND

Dengue virus (DENV) is the most widespread arbovirus. The World Health Organization (WHO) declared dengue one of the top 10 global health threats in 2019. However, it has been underrepresented in bibliometric analyses. This study employs bibliometric analysis to identify research hotspots and trends, offering a comprehensive overview of the current research dynamics in this field.

RESULTS

We present a report spanning from 1995 to 2023 that provides a unique longitudinal analysis of Dengue virus (DENV) research, revealing significant trends and shifts not extensively covered in previous literature. A total of 10,767 DENV-related documents were considered, with a notable increase in publications, peaking at 747 articles in 2021. Plos Neglected Tropical Diseases has become the leading journal in Dengue virus research, publishing 791 articles in this field-the highest number recorded. Our bibliometric analysis provides a comprehensive mapping of DENV research across multiple dimensions, including vector ecology, virology, and emerging therapies. The study delineates a complex network of immune response genes, including IFNA1, DDX58, IFNB1, STAT1, IRF3, and NFKB1, highlighting significant trends and emerging themes, particularly the impacts of climate change and new outbreaks on disease transmission. Our findings detail the progress and current status of key vaccine candidates, including the licensed Dengvaxia, newer vaccines such as Qdenga and TV003, and updated clinical trials. The study underscores significant advancements in antiviral therapies and vector control strategies for dengue, highlighting innovative drug candidates such as AT-752 and JNJ-1802, and the potential of drug repurposing with agents like Ribavirin, Remdesivir, and Lopinavir. Additionally, it discusses biological control methods, including the introduction of Wolbachia-infected mosquitoes and gene-editing technologies.

CONCLUSION

This bibliometric study underscores the critical role of interdisciplinary collaboration in advancing DENV research, identifying key trends and areas needing further exploration, including host-virus dynamics, the development and application of antiviral drugs and vaccines, and the use of artificial intelligence. It advocates for strengthened partnerships across various disciplines to effectively tackle the challenges posed by DENV.

An In Silico Design of a Vaccine against All Serotypes of the Dengue Virus Based on Virtual Screening of B-Cell and T-Cell Epitopes

Dengue virus poses a significant global health challenge, particularly in tropical and subtropical regions. Despite the urgent demand for vaccines in the control of the disease, the two approved vaccines, Dengvaxia and TV003/TV005, there are current questions regarding their effectiveness due to an increased risk of antibody-dependent enhancement (ADE) and reduced protection. These challenges have underscored the need for further development of improved vaccines for Dengue Virus. This study presents a new design using an in silico approach to generate a more effective dengue vaccine. Initially, our design process began with the collection of Dengue polyprotein sequences from 10 representative countries worldwide. And then conserved fragments of viral proteins were retrieved as the bases for epitope screening. The selection of epitopes was then carried out with criteria such as antigenicity, immunogenicity, and binding affinity with MHC molecules, while the exclusion criteria were according to their allergenicity, toxicity, and potential for antibody-dependent enhancement. We then constructed a core antigen with the selected epitopes and linked the outcomes with distinct adjuvant proteins, resulting in three candidate vaccines: PSDV-1, PSDV-2, and PSDV-3. Among these, PSDV-2 was selected for further validation due to its superior physicochemical and structural properties. Extensive simulations demonstrated that PSDV-2 exhibited strong binding to pattern recognition receptors, high stability, and robust immune induction, confirming its potential as a high-quality vaccine candidate. For its recombinant expression, a plasmid was subsequently designed. Our new vaccine design offers a promising additional option for Dengue virus protection. Further experimental validations will be conducted to confirm its protective efficacy and safety.

[Baicalin suppresses type 2 dengue virus-induced autophagy of human umbilical vein endothelial cells by inhibiting the PI3K/AKT pathway]

OBJECTIVE

To investigate the effect of type 2 dengue virus (DENV-2) infection on autophagy in human umbilical vein endothelial cells (HUVECs) and the mechanism mediating the inhibitory effect of baicalin against DENV-2 infection.

METHODS

Cultured HUVECs with DENV-2 infection were treated with different concentrations of baicalin, and the changes in autophagy of the cells were detected using transmission electron microscopy. Lyso Tracker Red staining was used to examine pH changes in the lysosomes of the cells, and the expressions of ATG5, beclin-1, LC3, P62, STX17, SNAP29, VAMP8, and PI3K/AKT signaling pathway-related proteins were detected by Western blotting. DENV-2 replication in the cells were evaluated using RT-qPCR. The differentially expressed proteins in DENV-2-infected HUVECs were identified by proteomics screening.

RESULTS

Treatment with baicalin did not significantly affect the viability of cultured HUVECs. Proteomic studies suggested that the PI3K-AKT pathway played an important role in mediating cell injury induced by DENV-2 infection. The results of RT-qPCR demonstrated that baicalin dose-dependently inhibited DENV-2 replication in HUVECs and produced the strongest inhibitory effect at the concentration of 50 μg/mL. Transmission electron microscopy, Lyso Tracker Red staining, RT-qPCR, and Western blotting all showed significant inhibitory effect of baicalin on DENV-2-induced autophagy in HUVECs. DENV-2 infection of HUVECs caused increased cellular expressions of LC3 and P62 proteins, which were significantly lowered by treatment with LY294002 (a PI3K inhibitor).

CONCLUSION

Baicalin inhibits DENV-2 replication in HUVECs and suppresses DENV-2-induced cell autophagy by inhibiting the PI3K/AKT signaling pathway.

Cross-Neutralizing Anti-Chikungunya and Anti-Dengue 2 IgG Antibodies from Patients and BALB/c Mice against Dengue and Chikungunya Viruses

Dengue (DENV) and Chikungunya (CHIKV) viruses can be transmitted simultaneously by Aedes mosquitoes, and there may be co-infections in humans. However, how the adaptive immune response is modified in the host has yet to be known entirely. In this study, we analyzed the cross-reactivity and neutralizing activity of IgG antibodies against DENV and CHIKV in sera of patients from the Mexican Institute of Social Security in Veracruz, Mexico, collected in 2013 and 2015 and using IgG antibodies of BALB/c mice inoculated with DENV and/or CHIKV. Mice first inoculated with DENV and then with CHIKV produced IgG antibodies that neutralized both viruses. Mice were inoculated with CHIKV, and then with DENV; they had IgG antibodies with more significant anti-CHIKV IgG antibody neutralizing activity. However, the inoculation only with CHIKV resulted in better neutralization of DENV2. In sera obtained from patients in 2013, significant cross-reactivity and low anti-CHIKV IgG antibody neutralizing activity were observed. In CHIKV-positive 2015 sera, the anti-DENV IgG antibody neutralizing activity was high. These results suggest that CHIKV stimulates DENV2-induced memory responses and vice versa. Furthermore, cross-reactivity between the two viruses generated neutralizing antibodies, but exchanging CHIKV for DENV2 generated a better anti-CHIKV neutralizing response.

Serological immune biomarker for disease severity in dengue-infected pediatric hospitalized patients

Clinical manifestation of dengue disease ranges from asymptomatic, febrile fever without warning sign (DOS) to serious outcome dengue with warning sign (DWS) and severe disease (SD) leading to shock syndrome and death. The role of antibody response in natural dengue infection is complex and not completely understood. Here, we aimed to assess serological marker for disease severity. Antibody response of dengue-confirmed pediatric patients with acute secondary infection were evaluated against infecting virus, immature virus, and recombinant envelop protein. Immature virus antibody titers were significantly higher in DWS as compared to DOS (p = 0.0006). However, antibody titers against recombinant envelop protein were higher in DOS as compared to DWS, and antibody avidity was significantly higher against infecting virus in DOS. Serum samples of DOS patients displayed higher in vitro neutralization potential in plaque assay as compared to DWS, whereas DWS serum samples showed higher antibody-dependent enhancement in the in vitro enhancement assays. Thus, antibodies targeting immature virus can predict disease severity and could be used in early forecast of disease outcome using an enzyme-linked immunoassay assay system which is less laborious and cheaper than plaque assay system for correlates of protection and could help optimize medical care and resources.

Binding Evolution of the Dengue Virus Envelope Against DC-SIGN: A Combined Approach of Phylogenetics and Molecular Dynamics Analyses Over 30 Years of Dengue Virus in Brazil

The Red Queen Hypothesis (RQH), derived from Lewis Carroll's "Through the Looking-Glass", postulates that organisms must continually adapt in response to each other to maintain relative fitness. Within the context of host-pathogen interactions, the RQH implies an evolutionary arms race, wherein viruses evolve to exploit hosts and hosts evolve to resist viral invasion. This study delves into the dynamics of the RQH in the context of virus-cell interactions, specifically focusing on virus receptors and cell receptors. We observed multiple virus-host systems and noted patterns of co-evolution. As viruses evolved receptor-binding proteins to effectively engage with cell receptors, cells countered by altering their receptor genes. This ongoing mutual adaptation cycle has influenced the molecular intricacies of receptor-ligand interactions. Our data supports the RQH as a driving force behind the diversification and specialization of both viral and host cell receptors. Understanding this co-evolutionary dance offers insights into the unpredictability of emerging viral diseases and potential therapeutic interventions. Future research is crucial to dissect the nuanced molecular changes and the broader ecological consequences of this ever-evolving battle. Here, we combine phylogenetic inferences, structural modeling, and molecular dynamics analyses to describe the epidemiological characteristics of major Brazilian DENV strains that circulated from 1990 to 2022 from a combined perspective, thus providing us with a more detailed picture on the dynamics of such interactions over time.

Structure-based evaluation of the envelope domain III-nonstructural protein 1 (EDIII-NS1) fusion as a dengue virus vaccine candidate

The lack of effective medicines or vaccines, combined with climate change and other environmental factors, annually subjects a significant proportion of the world's inhabitants to the risk of dengue virus (DENV) infection. These conditions increase the likelihood of exposure to mosquito-borne diseases such as dengue fever. Hence, many research approaches tend to develop efficient vaccine candidates against the dengue virus. Therefore, we used immunoinformatics and bioinformatics to design a construction for developing a candidate vaccine against dengue virus serotypes. In this study, the in silico structure, containing the non-structural protein 1 region (NS1) (consensus and epitope), the envelope domain III protein (EDIII) as the structural part of the virus construction, and the bc-loop of envelope domain II (EDII) as the neutralizing and protected epitope, were employed. We utilized in silico tools to enhance the immunogenicity and effectiveness of dengue virus vaccine candidates. Evaluations included refining and validating physicochemical characteristics, B and T-cell epitopes, homology modeling, and the three-dimensional structure to assess the designed vaccine's quality. In silico results for tertiary structure prediction and validation revealed high-quality modeling for all vaccine constructs. Additionally, the instructed model demonstrated stability throughout molecular dynamics simulation. The results of the immune simulation suggested that the titers of IgG and IgM could be raised to desirable values following injection into in vivo models. It can be concluded that the designed construct effectively induce humoral and cellular immunity and can be proposed as effective vaccine candidate against four dengue serotypes.Communicated by Ramaswamy H. Sarma.

Immunization with different recombinant West Nile virus envelope proteins induces varying levels of serological cross-reactivity and protection from infection

Introduction

West Nile Virus (WNV) is a zoonotic flavivirus transmitted by mosquitoes. Especially in the elderly or in immunocompromised individuals an infection with WNV can lead to severe neurological symptoms. To date, no human vaccine against WNV is available. The Envelope (E) protein, located at the surface of flaviviruses, is involved in the invasion into host cells and is the major target for neutralizing antibodies and therefore central to vaccine development. Due to their close genetic and structural relationship, flaviviruses share highly conserved epitopes, such as the fusion loop domain (FL) in the E protein, that are recognized by cross-reactive antibodies. These antibodies can lead to enhancement of infection with heterologous flaviviruses, which is a major concern for potential vaccines in areas with co-circulation of different flaviviruses, e.g. Dengue or Zika viruses.

Material

To reduce the potential of inducing cross-reactive antibodies, we performed an immunization study in mice using WNV E proteins with either wild type sequence or a mutated FL, and WNV E domain III which does not contain the FL at all.

Results and discussion

Our data show that all antigens induce high levels of WNV-binding antibodies. However, the level of protection against WNV varied, with the wildtype E protein inducing full, the other antigens only partial protection. On the other hand, serological cross-reactivity to heterologous flaviviruses was significantly reduced after immunization with the mutated E protein or domain III as compared to the wild type version. These results have indications for choosing antigens with the optimal specificity and efficacy in WNV vaccine development.

Nanomedicine as a potential novel therapeutic approach against the dengue virus

Dengue is an arbovirus infection which is transmitted by Aedes mosquitoes. Its prompt detection and effective treatment is a global health challenge. Various nanoparticle-based vaccines have been formulated to present immunogen (antigens) to instigate an immune response or prevent virus spread, but no specific treatment has been devised. This review explores the role of nanomedicine-based therapeutic agents against dengue virus, taking into consideration the applicable dengue virus assays that are sensitive, specific, have a short turnaround time and are inexpensive. Various kinds of metallic, polymeric and lipid nanoparticles with safe and effective profiles present an alternative strategy that could provide a better remedy for eradicating the dengue virus.

Antibody-Dependent Enhancement with a Focus on SARS-CoV-2 and Anti-Glycan Antibodies

Antibody-dependent enhancement (ADE) is a phenomenon where virus-specific antibodies paradoxically cause enhanced viral replication and/or excessive immune responses, leading to infection exacerbation, tissue damage, and multiple organ failure. ADE has been observed in many viral infections and is supposed to complicate the course of COVID-19. However, the evidence is insufficient. Since no specific laboratory markers have been described, the prediction and confirmation of ADE are very challenging. The only possible predictor is the presence of already existing (after previous infection) antibodies that can bind to viral epitopes and promote the disease enhancement. At the same time, the virus-specific antibodies are also a part of immune response against a pathogen. These opposite effects of antibodies make ADE research controversial. The assignment of immunoglobulins to ADE-associated or virus neutralizing is based on their affinity, avidity, and content in blood. However, these criteria are not clearly defined. Another debatable issue (rather terminological, but no less important) is that in most publications about ADE, all immunoglobulins produced by the immune system against pathogens are qualified as pre-existing antibodies, thus ignoring the conventional use of this term for natural antibodies produced without any stimulation by pathogens. Anti-glycan antibodies (AGA) make up a significant part of the natural immunoglobulins pool, and there is some evidence of their antiviral effect, particularly in COVID-19. AGA have been shown to be involved in ADE in bacterial infections, but their role in the development of ADE in viral infections has not been studied. This review focuses on pros and cons for AGA as an ADE trigger. We also present the results of our pilot studies, suggesting that AGAs, which bind to complex epitopes (glycan plus something else in tight proximity), may be involved in the development of the ADE phenomenon.

Recent Dengue Infection in Bangladesh: A Seasonal Endemic Progressing to Year-long Serious Health Concern

Dengue represents one of the most dangerous mosquito-borne viral diseases. Although the disease has been prevalent around the globe over the centuries, recent outbreaks of dengue have devasted the healthcare delivery system of many countries. Being a global infection, dengue virus (DENV) is endemically present mainly in Latin America and Caribbean countries as well as countries in South Asia. The recent outbreak of DENV infection has indicated an exceptional outbreak of DENV in some countries in South Asia. There has been a serious endemic of DENV during 2019. After a heterogeneous pause, another severe outbreak of DENV was reported in some Asian countries in 2023. Among the Asian countries, Bangladesh has reported an acute upsurge of DENV infection in 2023 with record numbers of fatalities. However, this pattern of DENV has not been detected in neighbors of Bangladesh, such as India or other countries in Southeast Asia. This provides an emergent task of dissecting the present DENV infection in Bangladesh from different angles to get insights for future containment of the DENV infection, not only in Bangladesh but also in other DENV endemic areas or DENV-native areas.

How to cite this article

Akbar SMF, Khan S, Mahtab M, et al. Recent Dengue Infection in Bangladesh: A Seasonal Endemic Progressing to Year-long Serious Health Concern. Euroasian J Hepato-Gastroenterol 2023;13(2):145-151.