Search Results (90)

Dengue virus (DENV) poses a major global health concern, with over 6.5 million cases and 7300 deaths reported in 2023. Accurate serological assays are essential for tracking infection history, evaluating disease severity, and guiding vaccination strategies. However, existing assays are limited in their specificity, sensitivity, and cross-reactivity. Using optical modulation biosensing (OMB) technology and non-structural protein 1 (NS1) antigens from DENV-1–3, we developed highly sensitive and quantitative serotype-specific anti-DENV NS1 IgG serological assays. The OMB-based assays offered a wide dynamic range (~4-log), low detection limits (~400 ng/L), fast turnaround (1.5 h), and a simplified workflow. Using samples from endemic (Vietnam) and non-endemic (Israel) regions, we assessed intra-DENV and inter-Flavivirus cross-reactivity. Each assay detected DENV infection with a 100% sensitivity for the corresponding serotype and 64% to 90% for other serotypes. Cross-reactivity with Zika, Japanese encephalitis, and West Nile viruses ranged from 21% to 65%, reflecting NS1 antigen conservation. Our study provides valuable insights into the cross-reactivity of DENV NS1 antigens widely used in research and highlights the potential of OMB-based assays for quantitative and epidemiological studies. Ongoing efforts should aim to minimize cross-reactivity while maintaining sensitivity and explore integration with complementary platforms for improved diagnostic precision. Full article

Co-infections of dengue serotypes and dengue with other flaviviruses pose substantial hurdles in disease diagnosis, treatment options, and disease management. The overlapping geographic distributions and mosquito vectors significantly enhance the probability of co-infections. Co-infections may result in more severe disease outcomes due to elevated viral loads, modulation of the immune response, and antibody enhancement. Cross-reactivity in serological assays and the likeness of clinical presentations add to the ongoing challenges in disease diagnosis. Molecular diagnostics such as reverse transcription polymerase chain reaction (RT-PCR) and next-generation sequencing (NGS) are, therefore, employed for more specific disease diagnosis although requiring substantial resources. Despite the advancements, specific anti-flaviviral therapy is still limited, hence the urgency for further investigative research into various therapeutic approaches, including peptide inhibitors, host-targeted therapies, and RNA-based interventions. This review discusses the epidemiology, clinical ramifications, and diagnostic obstacles associated with flavivirus co-infections whilst assessing prospective strategies for better disease prevention, treatment, and management. Addressing these critical gaps is essential for disease mitigation whilst improving patient management especially in regions where co-circulation of flaviviruses is common and their diseases are highly endemic. Full article

Flaviviruses are a group of viruses transmitted mainly by mosquitoes and ticks, causing severe diseases in humans. Examples include dengue, Zika, West Nile virus, and yellow fever. They primarily affect individuals in tropical and subtropical regions, causing public health problems such as epidemic outbreaks and significant economic burdens due to hospitalizations and treatments. They share antigens, leading to cross-reactivity where antibodies generated against one flavivirus can react with others, complicating the accurate diagnosis of individual infections and making the development of treatments or vaccines more challenging. The role of T cells in the immune response to flaviviruses is a complex topic debated by scientists. On one hand, T cells help control infection by eliminating infected cells and protecting against disease. However, there is evidence that an excessive or dysregulated T cell response can cause tissue damage and worsen the disease, as seen in severe dengue cases. This duality underscores the complexity of the immune response to flavivirus infections, posing a significant challenge for researchers. Gaining a deeper understanding of the immune response at the cellular level, particularly the role of T follicular helper cells, can reveal new avenues of investigation that could lead to novel strategies for disease management. This review explores the dynamics of T cell responses, focusing on circulatory T follicular helper cells (cT_FH), to enhance our understanding of flavivirus immunity and inform future interventions. Full article

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. Full article

Autochthonous dengue cases have been continuously recorded in Europe in the past two decades. The first autochthonous dengue case in Croatia was reported in 2010 on the Pelješac Peninsula, while imported cases were recorded continuously thereafter. In 2024, dengue re-emerged in Croatia. An epidemiological and entomological study was conducted after receiving information on dengue virus (DENV) infection in a German tourist probably acquired on Dugi Otok Island in Croatia in May 2024. Serum samples were collected from 30 residents of the Veli Rat region where the patient had stayed. In addition, mosquitoes were collected in the same area. Human samples were tested for the presence of DENV antibodies (ELISA and IFA) and DENV RNA (RT-qPCR), while mosquito samples were tested for DENV RNA (RT-qPCR). DENV IgM or IgG antibodies were found in 8 serum samples, while no one sample was RT-qPCR positive. No cross-reactivity with flaviviruses was detected in seropositive samples, supporting DENV infection. One patient was classified as a confirmed dengue case (IgG seroconversion in paired serum samples) and five as probable cases (IgM detection in a single serum sample). One additional patient, sampled only once, was IgG seropositive. Two of the seropositive individuals reported fever and rash three weeks before testing. The re-emergence of dengue in Croatia highlights the need for continuous monitoring of DENV circulation in both humans and vectors. Full article

Tick-borne encephalitis virus (TBEV) is an emerging pathogen that initially causes flu-like symptoms and can progress to central nervous system (CNS) infections. Tick-borne encephalitis (TBE) is an endemic disease in southern coastal counties with regular human cases, while the causative agent, TBEV, is prevalent in ticks in most of the coastal regions of Norway. This study was aimed to understand TBEV infection status across Norway including both TBE endemic and non-endemic areas. For this, we analyzed a total of 1940 residual serum samples from 19 counties of Norway (as of 2016). The samples were initially screened by ELISA, followed by virus neutralization tests for TBEV confirmation. We found a similar TBEV seroprevalence of 1.7% in TBE endemic and 1.6% in non-endemic areas. Since TBE cases are only reported from endemic regions, our findings suggest a potential subclinical or asymptomatic infection and underdiagnosis in non-endemic areas. Notably, only 43% of the ELISA-positive samples were confirmed by virus neutralization tests indicating that not all ELISA positives are true TBEV infections. Additionally, 137 samples of patients presenting with symptoms of CNS infections from a non-endemic area were included. Of these samples, 11 ELISA-positive samples were analyzed for cross-reactivity among flaviviruses. Cross-reactivity was detected with Dengue virus, West Nile Virus, and non-specific reactions. This underscores the importance of using multiple diagnostic tests to confirm TBEV infections. None of the patients with CNS infection was found to be TBE positive, and in the whole cohort, we found a low TBEV seroprevalence of 0.7%. Full article

Annually, the Philippines is burdened by a high number of infections and deaths due to Dengue. This disease is caused by the Dengue virus (DENV) and is transmitted from one human host to another by the female Aedes aegypti mosquito. Being a developing country, most of the high-risk areas in the Philippines are resource-limited and cannot afford equipment for detection and monitoring. Moreover, traditional clinical diagnoses of DENV infection are costly and time-consuming and require expertise. Hence, it is important to establish effective vector control and surveillance measures. In this study, we developed a DNA-based nanobiosensor for the colorimetric detection of Dengue virus serotype 2 (DENV-2) synthetic target DNA (stDNA S2) using gold nanoparticles (AuNPs). We successfully functionalized dextrin-capped gold nanoparticles with the designed DENV-2 oligonucleotide probes. The detection of the complementary stDNA S2, indicated by the pink-colored solution, was successfully performed within 15 min using 0.40 M NaCl solution. We were able to detect up to 36.14 ng/μL of stDNA S2 with some cross-reactivity observed with one non-complementary target. We believe that our study offers a basis for developing nanobiosensors for other DENV serotypes. Full article

Aims: The screening and diagnosis of dengue virus infection play a crucial role in controlling the epidemic of dengue fever, highlighting the urgent need for a highly sensitive, simple, and rapid laboratory testing method. This study aims to assess the clinical performance of MAGLUMI Denv NS1 in detecting dengue virus NS1 antigen. Methods: A retrospective study was conducted to assess the sensitivity and specificity of MAGLUMI Denv NS1 using residual samples. Dengue-confirmed and excluded samples, validated by qPCR, were subjected to testing with MAGLUMI Denv NS1 in accordance with the manufacturer’s instructions. The linear range, endogenous interference, and cross-reactivity of MAGLUMI Denv NS1 were verified, and a consistency analysis with commercial comparator products was carried out. Results: The diagnostic specificity of MAGLUMI Denv NS1 is 98.41% (62/63), and the sensitivity is 98.32% (117/119). It effectively detects various serotypes of dengue virus, with no observed endogenous interference or cross-reactivity. Additionally, the consistency of NS1, IgM, and IgG tests on the MAGLUMI platform compared to commercial comparator reagents reaches 85.71%, 99.25%, and 98.97%, respectively. Conclusions: The MAGLUMI Denv NS1 represents a highly sensitive laboratory testing method capable of enhancing the diagnostic accuracy and efficiency of dengue virus infection detection. Full article

Despite successful vaccination efforts, the emergence of new SARS-CoV-2 variants poses ongoing challenges to control COVID-19. Understanding humoral responses regarding SARS-CoV-2 infections and their impact is crucial for developing future vaccines that are effective worldwide. Here, we identified 41 immunodominant linear B-cell epitopes in its spike glycoprotein with an SPOT synthesis peptide array probed with a pool of serum from hospitalized COVID-19 patients. The bioinformatics showed a restricted set of epitopes unique to SARS-CoV-2 compared to other coronavirus family members. Potential crosstalk was also detected with Dengue virus (DENV), which was confirmed by screening individuals infected with DENV before the COVID-19 pandemic in a commercial ELISA for anti-SARS-CoV-2 antibodies. A high-resolution evaluation of antibody reactivity against peptides representing epitopes in the spike protein identified ten sequences in the NTD, RBD, and S2 domains. Functionally, antibody-dependent enhancement (ADE) in SARS-CoV-2 infections of monocytes was observed in vitro with pre-pandemic Dengue-positive sera. A significant increase in viral load was measured compared to that of the controls, with no detectable neutralization or considerable cell death, suggesting its role in viral entry. Cross-reactivity against peptides from spike proteins was observed for the pre-pandemic sera. This study highlights the importance of identifying specific epitopes generated during the humoral response to a pathogenic infection to understand the potential interplay of previous and future infections on diseases and their impact on vaccinations and immunodiagnostics. Full article

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. Full article

In response to the 2015 Zika virus (ZIKV) epidemic that occurred in Brazil, numerous commercial serological assays have been developed for clinical and research applications. Diagnosis of recent infection in pregnant women remains challenging. Having standardized, comparative studies of ZIKV tests is important for implementing optimal diagnostic testing and disease surveillance. This is especially important for serology tests used to detect ZIKV infection given that antibodies against ZIKV can cross-react with other arboviruses in the same virus family, such as dengue virus (DENV), yellow fever virus (YFV) and West Nile virus (WNV). We looked at the sensitivity and specificity of tests detecting ZIKV antibodies (IgM, IgG) from multiple manufacturers using panels of samples previously collected with known exposure to ZIKV and other arboviruses. We found that performance of the IgM tests was highly variable, with only one test (Inbios 2.0 IgM capture ELISA) having both high sensitivity and specificity. All IgG tests showed good sensitivity; however, specificity was highly variable, with some assays giving false-positive results on samples infected by another flavivirus. Overall, the results confirmed that accurate ZIKV antibody testing is challenging, especially in specimens from regions endemic for multiple other flaviviruses, and highlight the importance of available and suitable reference samples to evaluate ZIKV diagnostics. Full article

The dengue virus, the primary cause of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is the most widespread mosquito-borne virus worldwide. In recent decades, the prevalence of dengue fever has increased markedly, presenting substantial public health challenges. Consequently, the development of an efficacious vaccine against dengue remains a critical goal for mitigating its spread. Our research utilized Celcradle™, an innovative tidal bioreactor optimized for high-density cell cultures, to grow Vero cells for dengue virus production. By maintaining optimal pH levels (7.0 to 7.4) and glucose concentrations (1.5 g/L to 3.5 g/L) during the proliferation of cells and viruses, we achieved a peak Vero cell count of approximately 2.46 × 10⁹, nearly ten times the initial count. The use of Celcradle™ substantially decreased the time required for cell yield and virus production compared to conventional Petri dish methods. Moreover, our evaluation of the immunogenicity of the Celcradle™-produced inactivated DENV4 through immunization of mice revealed that sera from these mice demonstrated cross-reactivity with DENV4 cultured in Petri dishes and showed elevated antibody titers compared to those from mice immunized with virus from Petri dishes. These results indicate that the dengue virus cultivated using the Celcradle™ system exhibited enhanced immunogenicity relative to that produced in traditional methods. In conclusion, our study highlights the potential of the Celcradle™ bioreactor for large-scale production of inactivated dengue virus vaccines, offering significant promise for reducing the global impact of dengue virus infections and accelerating the development of effective vaccination strategies. Full article

The West Nile Virus (WNV), a member of the family Flaviviridae, is an emerging mosquito-borne flavivirus causing potentially severe infections in humans and animals involving the central nervous system (CNS). Due to its emerging tendency, WNV now occurs in many areas where other flaviviruses are co-occurring. Cross-reactive antibodies with flavivirus infections or vaccination (e.g., tick-borne encephalitis virus (TBEV), Usutu virus (USUV), yellow fever virus (YFV), dengue virus (DENV), Japanese encephalitis virus (JEV)) therefore remain a major challenge in diagnosing flavivirus infections. Virus neutralization tests are considered as reference tests for the detection of specific flavivirus antibodies, but are elaborate, time-consuming and need biosafety level 3 facilities. A simple and straightforward assay for the differentiation and detection of specific WNV IgG antibodies for the routine laboratory is urgently needed. In this study, we compared two commercially available enzyme-linked immunosorbent assays (anti-IgG WNV ELISA and anti-NS1-IgG WNV), a commercially available indirect immunofluorescence assay, and a newly developed in-house ELISA for the detection of WNV-NS1-IgG antibodies. All four tests were compared to an in-house NT to determine both the sensitivity and specificity of the four test systems. None of the assays could match the specificity of the NT, although the two NS1-IgG based ELISAs were very close to the specificity of the NT at 97.3% and 94.6%. The in-house WNV-NS1-IgG ELISA had the best performance regarding sensitivity and specificity. The specificities of the ELISA assays and the indirect immunofluorescence assays could not meet the necessary specificity and/or sensitivity. Full article

Zika virus (ZIKV) is a reemerging flavivirus that is primarily spread through bites from infected mosquitos. It was first discovered in 1947 in sentinel monkeys in Uganda and has since been the cause of several outbreaks, primarily in tropical and subtropical areas. Unlike earlier outbreaks, the 2015–2016 epidemic in Brazil was characterized by the emergence of neurovirulent strains of ZIKV strains that could be sexually and perinatally transmitted, leading to the Congenital Zika Syndrome (CZS) in newborns, and Guillain-Barre Syndrome (GBS) along with encephalitis and meningitis in adults. The immune response elicited by ZIKV infection is highly effective and characterized by the induction of both ZIKV-specific neutralizing antibodies and robust effector CD8⁺ T cell responses. However, the structural similarities between ZIKV and Dengue virus (DENV) lead to the induction of cross-reactive immune responses that could potentially enhance subsequent DENV infection, which imposes a constraint on the development of a highly efficacious ZIKV vaccine. The isolation and characterization of antibodies capable of cross-neutralizing both ZIKV and DENV along with cross-reactive CD8⁺ T cell responses suggest that vaccine immunogens can be designed to overcome these constraints. Here we review the structural characteristics of ZIKV along with the evidence of neuropathogenesis associated with ZIKV infection and the complex nature of the immune response that is elicited by ZIKV infection. Full article

There is currently a lot of interest in the construction of point-of-care devices stemming from paper-based origami biosensors. These devices demonstrate how paper’s foldability permits the construction of sensitive, selective, user-friendly, intelligent, and maintainable analytical devices for the detection of several ailments. Herein, the first example of the electrochemical aptasensor-based polyvalent dengue viral antigen detection using the origami paper-folding method is presented. Coupling it with an aptamer leads to the development of a new notation known as OBAs, or origami-based aptasensor, that presents a multitude of advantages to the developed platform, such as assisting in safeguarding the sample from air-dust particles, providing confidentiality, and providing a closed chamber to the electrodes. In this paper, gold-decorated nanocomposites of zinc and graphene oxide (Au/ZnO/GO) were synthesized via the chemical method, and characterization was conducted by Scanning Electron Microscope, Transmission Electron Microscope, UV-Vis, and XRD which reveals the successful formation of nanocomposites, mainly helping to enhance the signal and specificity of the sensor by employing aptamers, since isolation and purification procedures are not required. The biosensor that is being demonstrated here is affordable, simple, and efficient. The reported biosensor is an OBA detection of polyvalent antigens of the dengue virus in human serum, presenting a good range from 0.0001 to 0.1 mg/mL with a limit of detection of 0.0001 mg/mL. The reported single-folding ori-aptasensor demonstrates exceptional sensitivity, specificity, and performance in human serum assays, and can also be used for the POC testing of various viral infections in remote areas and underdeveloped countries, as well as being potentially effective during outbreaks. Highlights: (1) First report on origami-based aptasensors for the detection of polyvalent antigens of DENV; (2) In-house construction of low-cost origami-based setup; (3) Gold-decorated zinc/graphene nanocomposite characterization was confirmed via FESEM/UV-Vis/FTIR; (4) Cross-reactivity of dengue-aptamer has been deduced; (5) Electrochemical validation was conducted through CV. Full article