Search Results (229)

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

Orthoflaviviruses (formerly flaviviruses) are known for their role in numerous diseases affecting both humans and animals. Despite the worldwide distribution of orthoflaviviruses, individual species are only found in endemic or epidemic regions. However, in recent decades, certain orthoflaviviruses have spread beyond their traditional geographic boundaries, even crossing continents. Given the long-distance movements of birds, the knowledge of zoonotic orthoflaviviruses associated with birds is essential because of their possible introduction into new regions, as was the case with West Nile virus and Usutu virus. A thorough literature review was conducted on zoonotic orthoflaviviruses related to birds, including lesser-known (re-)emerging and neglected orthoflaviviruses that are limited to specific regions and/or avian hosts but have the potential to spread to a wider geographical area and pose a higher risk of transmission to humans. Several of these viruses possess significant zoonotic potential and can cause a wide spectrum of diseases in humans, ranging from mild febrile illnesses (Zika virus) to severe neuroinvasive diseases (tick-borne encephalitis, West Nile, Japanese encephalitis virus) and hemorrhagic fevers (yellow fever, dengue virus). Geographic distribution, hosts, vectors, incidence of human infections, and impact on human and animal health of zoonotic flaviviruses related to birds are critically reviewed. The viruses have been categorized based on the role of birds as an orthoflavivirus host and the clinical presentation in human infections. Full article

Japanese encephalitis virus (JEV) is a mosquito-borne orthoflavivirus and a major cause of human encephalitis throughout Asia, although it is currently not reported in Europe. To assess the potential impact of climate change, such as increased temperatures, and the potential for native Cx. pipiens to transmit JEV genotype I in the United Kingdom (UK), we have investigated vector competence at two different temperatures. Culex pipiens f. pipiens were provided a bloodmeal containing JEV genotype I at 7.8 × 10⁸ PFU/mL. Mosquitoes were maintained for 14 days at 21 °C or 25 °C, and rates of infection, dissemination, and transmission potential were assessed. There was no evidence for virus infection, dissemination, or potential for transmission at 21 °C. However, at 25 °C, virus infection was detected in 5 of 36 mosquitoes (13.9%). Of these, JEV disseminated to legs and wings in three specimens (3/5) and viral RNA was detected in saliva from one specimen (1/3). These data indicate that at elevated temperatures of 25 °C, UK Cx. pipiens f. pipiens could transmit JEV genotype 1. Full article

Japanese encephalitis (JE), a mosquito-borne viral disease caused by the Japanese encephalitis virus (JEV), remains a significant public health threat in Asia. Although vaccination programs have successfully reduced the incidence of JE, challenges persist in the adult population, and the emergence of rare JEV genotypes poses additional risks. In this study, a phylogenetic analysis of the whole JEV genome sequence, along with a temporal–spatial analysis of isolates and a host–vector analysis, was used to examine the changes in JEV transmission dynamics before and after 2012. The results revealed persistent differences between the dominant G1 and G3 genotypes, as well as the re-emergence of G4 and G5 genotypes. Although JEV has been detected in non-traditional vectors and atypical mammalian hosts, Culex tritaeniorhynchus and pigs remain the primary vector and amplifying host, respectively. These findings underscore the need to enhance existing JEV genotype surveillance while addressing emerging threats from genotype diversity, host expansion, and geographic spread. Full article

Arboviruses, transmitted by blood-sucking arthropods, are responsible for significant human and animal diseases, including fever, hemorrhagic fever, and encephalitis, posing a serious threat to global public health. Nevertheless, research on the mechanisms of arbovirus infection and the development of therapeutic interventions has been impeded. This delay is primarily due to the limitations inherent in current in vitro research models, including cell cultures and animal models. The simplicity of cell types and interspecies differences present significant obstacles to advancing our understanding of arbovirus infection mechanisms and the development of effective drugs. Human brain organoids, derived from human pluripotent stem cells or human embryonic stem cells and cultured in three-dimensional systems, more accurately replicate the extensive neuronal cellular diversity and key characteristics of human neurodevelopment. These organoids serve as an ideal model for investigating the intricate interactions between viruses and human hosts, and providing a novel platform for the development of antiviral drugs. In this review, we summarize how brain organoid models complement classical approaches to accelerate research into the infection mechanisms of arboviruses, with a particular focus on the types of neural cells, key factors, and cellular signaling pathways involved in the arbovirus infection of brain organoids that have been reported. Furthermore, we examine the development of brain organoids, address their current limitations, and propose future directions to enhance the application of brain organoids in the study of arboviral infectious diseases. Full article

The Japanese encephalitis virus is an arbovirus that causes severe damage to the central nervous system. At present, there are still 67,900 cases of Japanese encephalitis worldwide every year, which poses a global public health concern and causes great economic losses to animal husbandry. In this study, we analyzed the epidemiology, transmission, and evolution of JEV based on the NCBI database. E and NS1 were emphatically analyzed for amino acid variation and predicted protein structure. Gene recombination and the evolutionary rate of JEV were analyzed using RDP 4 and BEAST. The maximum clade credibility tree of E was reconstructed to estimate the time of the most recent common ancestor. Chinese genotype Ⅰ (GI) strain recombination events occurred in the C, M/PrM, E, NS2A, NS4B, and NS5 proteins, and genotype III (GIII) strains occurred in the E, NS1, NS3, NS4A, and NS5 proteins. The average evolutionary rates of JEV were comparable (3.3830 × 10⁻⁴, 2.0481 × 10⁻⁴, 3.5650 × 10⁻⁴, 2.2423 × 10⁻⁴, 3.0844 × 10⁻⁴, and 1.9757 × 10⁻⁴ substitutions/site/year for the JEV-I whole genome, JEV-III whole genome, JEV-I E gene, JEV-III E gene, JEV-I NS1 gene, and JEV-III NS1 gene, respectively). The MCC tree revealed the evolutionary order was GⅢ, GⅠ, GⅤ, GⅡ, and GⅣ. This study was expected to provide theoretical support for vaccine development and comprehensive prevention and treatment of JEV. Full article

Viral replicons are efficient tools to understand the mechanisms of viral replication and screen antiviral drugs. In this study, a viral-cDNA-based replicon of Japanese encephalitis virus (JEV), which is the causative agent of Japanese encephalitis, was constructed by replacing the viral structural proteins with a green fluorescent protein (JEV-GFP replicon). The resulting JEV-GFP replicon was used as a tool to screen antiviral drugs targeting JEV nonstructural proteins, and the five compounds JNJ-A07, HZ-1157, NITD-2, quinine, and NITD008 were obtained, which significantly inhibited the replication of the JEV-GFP replicon and JEV in vitro, and the properties of these five compounds were also analyzed. The CC₅₀, EC₅₀, and SI indices of these five compounds were analyzed. In addition, the JEV-GFP replicon was used as a tool to identify the residues of viral nonstructural proteins involved in RNA replication, and the cysteine residue at position 4 of nonstructural protein 1 was found to be essential for JEV RNA replication. These data suggested that the noninfectious JEV-GFP replicon could be used as tool for different purposes, such as antiviral drug screening and gene function studies. Full article

Nipah virus (NiV) is an emerging zoonotic pathogen whose surface glycoprotein (G)-mediated host cell invasion mechanism leads to fatal encephalitis in infected patients (case fatality rate 40–75%). Given the limitations of existing diagnostic technologies, such as low sensitivity and prolonged processing times, we prepared an anti-NiV-G monoclonal antibody to establish a novel Amplified Luminescent Proximity Homogeneous Assay (AlphaLISA) detection system. Firstly, five high-affinity anti-NiV-G monoclonal antibodies were screened from the spleens of immunized mice by flow cytometry-single-cell cloning technology. The reaction system was further optimized, and the optimal dilution ratio of antibody-conjugated receptor microspheres, biotinylated antibodies, and donor microspheres was screened, and the AlphaLISA detection platform was successfully constructed. The detection sensitivity of NiV-G protein was 0.024 ng/mL (41.7 times higher than that of conventional ELISA), the coefficient of variation was <9.5%, and the repetition was good. It showed good specificity in the detection of 5 zoonotic viruses, including Japanese encephalitis virus and Zika virus. At the same time, this method is less disturbed by human serum, and the detection time is less than 30 min, showing a good clinical application prospect. Full article

Flaviviruses are arthropod-borne RNA viruses that can cause a wide range of human diseases, from mild symptoms to severe illness with multiorgan failure and death. Effective prevention of these diseases relies on identifying reliable vaccine targets, typically measured by correlates of protection (CoPs), which help indicate host immunity after vaccination. Current vaccines primarily focus on neutralizing antibodies (nAbs) against the viral envelope E protein, though emerging evidence suggests other potential targets may also be effective in disease prevention. Additionally, there is growing evidence of cross-protection between different flaviviruses when immunity to one virus is achieved, although this can be limited by antibody-dependent enhancement. This review examines the current understanding of flavivirus immunity, CoPs, and the potential for cross-protection in the context of existing vaccine strategies. Full article

Pigs serve as critical reservoirs and amplifiers for numerous zoonotic viral diseases, presenting substantial public health challenges in India. This study highlights the epidemiology and emerging trends of key zoonotic viruses associated with pigs, emphasizing their role in endemic and emerging disease dynamics. Japanese encephalitis virus (JEV) persists as a major concern, with pigs acting as amplifying host, while hepatitis E virus (HEV) remains a prominent cause of viral hepatitis, transmitted via contaminated water and pork products. Emerging high-fatality viral zoonoses caused by Nipah virus (NiV) and recurrent threats from swine influenza virus (SIV) demonstrate that the zoonotic landscape is evolving. Furthermore, zoonotic viruses like rotavirus, pseudorabies (ADV or SuHV-1), porcine astrovirus (PAstV), and Torque teno sus virus (TTSuV) reflect the expanding diversity of pig-associated pathogens in India. Emerging evidence also implicates viruses such as Chandipura virus (CHPV) in localized outbreaks, indicating broader zoonotic potential. Novel risks such as swine acute diarrhea syndrome coronavirus (SADS-CoV) and SARS-CoV-2 emphasize the role of pigs as potential intermediaries for pandemic-prone viruses. This comprehensive study evaluates the prevalence, outbreak dynamics, and public health implications of zoonotic viral diseases of pigs in India, providing valuable direction for developing effective control measures. Full article

Chimeric orthoflaviviruses derived from the insect-specific Binjari virus (BinJV) offer a promising basis for safe orthoflavivirus vaccines. However, these vaccines have so far only been produced using adherent C6/36 Aedes albopictus mosquito cell cultures grown in serum-supplemented media, limiting their scalable manufacture. To address this, we adapted C6/36 cells for serum-free suspension culture using Sf900-III medium, achieving high peak cell densities (up to 2.5 × 10⁷ cells/mL). Higher agitation rates reduced cell aggregation, and cryopreservation and direct-to-suspension revival were successful, confirming the adapted line’s stability for research and industrial applications. Despite this, BinJV-based chimeric orthoflaviviruses, including BinJV/WNV_KUN, a candidate vaccine for West Nile virus, and similar vaccines (BinJV/DENV2 and BinJV/JEV_NSW22) for dengue 2 virus and Japanese encephalitis virus, respectively, exhibited substantially reduced titres in C6/36 cultures infected in Sf900-III, a phenomenon attributed to the medium’s acidic pH. Switching to the more alkaline, serum-free CD-FortiCHO medium enhanced the replication of these chimeric viruses to peak titres between 1.7 × 10⁷ and 7.6 × 10⁹ infectious units per mL whilst preserving viral integrity. These findings suggest that suspension-adapted C6/36 cultures in CD-FortiCHO medium can support high-yield vaccine production for various orthoflaviviruses and highlight the important role of cell culture media pH for orthoflavivirus bioprocessing. This scalable mosquito cell-based system could reduce production costs and improve vaccine accessibility, supporting efforts to combat arbovirus-related public health challenges. Full article

Arboviruses pose significant public health challenges globally, particularly in Pakistan, where deforestation, climate change, urbanization, inadequate sanitation, and natural disasters have all contributed to the spread of mosquito-borne flavivirus diseases like dengue fever. The lack of a thorough national surveillance system has made it difficult to determine the extent and distribution of these diseases. Concern has been raised by recent outbreaks of West Nile virus (WNV) and chikungunya (CHIKV) epidemics, which may lead to Zika virus (ZIKV) outbreaks in the future. Additionally, hospital-based surveillance has detected the Japanese encephalitis virus (JEV) in the region. Evidence also points to the presence of additional arboviruses in healthy populations, such as the Karshi virus (KSV), Tamdy virus (TAMV), Crimean–Congo hemorrhagic fever virus (CCHFV), and severe fever with thrombocytopenia syndrome virus (SFTSV). This review aims to address the risk factors linked to these diseases, provide specific policy recommendations for efficient disease prevention and control, and describe the epidemiological trends of these diseases in Pakistan while emphasizing the critical need for improved surveillance and thorough epidemiological investigations. Full article

The Bagaza virus (BAGV) belongs to the genus Orthoflavivirus (Ntaya serocomplex) and emerged in Europe, Spain, in 2010. The natural transmission cycle of this virus is perpetuated by Culex spp. mosquitoes and viraemic birds. The ability of BAGV to cause infection in several game birds from the family Phasianidae has been well-studied. BAGV is antigenically similar to other orthoflaviviruses from the Japanese encephalitis serocomplex, such as the West Nile and Usutu viruses, a circumstance which can lead to cross-reactivity in less specific serological techniques (e.g., ELISA). Severe implications in animal health has already been described, but some aspects of the dynamics of transmission and the limits of zoonotic potential of BAGV still need to be clarified. Further investigation focused on epidemiological surveillance in high-risk areas would be beneficial for prevention and control of new outbreaks. The present study is a systematic review of the BAGV reports in Europe. Full article

Japanese encephalitis (JE) is a zoonotic disease caused by the Japanese encephalitis virus (JEV), belonging to the Flaviviridae family. Diagnosis of Japanese encephalitis (JE) based on clinical signs alone is challenging due to the high proportion of subclinical cases. The Plaque Reduction Neutralization Test (PRNT) is considered the gold standard for detecting JE-specific antibodies because of its high specificity. However, PRNT is complex, time-consuming, and requires live viruses, limiting its applicability in routine diagnostics. In this study, we compared the sensitivity and correlation of the Hemagglutination Inhibition (HI) assay and PRNT for detecting JE antibodies in avian serum samples. We conducted a comparative analysis of the outcomes obtained from the PRNT and HI using 240 serum samples collected from 30 JEV-immunized avian subjects at various time points. Comparative analysis revealed a significant correlation between the HI and PRNT (R² = 0.9321, p ≤ 0.0001). The Bland–Altman analysis also exhibited favorable concordance between the two assays. Consequently, HI may function as a viable substitute for PRNT in the screening of a substantial number of serum samples. Full article

Flaviviruses are a diverse group of viruses primarily transmitted through hematophagous insects like mosquitoes and ticks. Significant expansion in the geographic range, prevalence, and vectors of flavivirus over the last 50 years has led to a dramatic increase in infections that can manifest as hemorrhagic fever or encephalitis, leading to prolonged morbidity and mortality. Millions of infections every year pose a serious threat to worldwide public health, encouraging scientists to develop a better understanding of the pathophysiology and immune evasion mechanisms of these viruses for vaccine development and antiviral therapy. Extensive research has been conducted in developing effective antivirals for flavivirus. Various approaches have been extensively utilized in clinical trials for antiviral development, targeting virus entry, replication, polyprotein synthesis and processing, and egress pathways exploiting virus as well as host proteins. However, to date, no licensed antiviral drug exists to treat the diseases caused by these viruses. Understanding the mechanisms of host–pathogen interaction, host immunity, viral immune evasion, and disease pathogenesis is highly warranted to foster the development of antivirals. This review provides an extensively detailed summary of the most recent advances in the development of antiviral drugs to combat diseases. Full article