Zika virus (ZIKV) infection, along with the concurrent circulation of other arboviruses, presents a great public health challenge, reminding the utilization of mathematical modelling as a crucial tool for explaining its intricate dynamics and interactions with co-circulating pathogens. Through a scoping review, we aimed to discern current mathematical models investigating ZIKV dynamics, focusing on its interplay with other pathogens, and to identify underlying assumptions and deficiencies supporting attention, particularly regarding the epidemiological attributes characterizing Zika outbreaks. Following the PRISMA-Sc guidelines, a systematic search across PubMed, Web of Science, and MathSciNet provided 137 pertinent studies from an initial pool of 2446 papers, showing a diversity of modelling approaches, predominantly centered on vector-host compartmental models, with a notable concentration on the epidemiological landscapes of Colombia and Brazil during the 2015-2016 Zika epidemic. While modelling studies have been important in explaining Zika transmission dynamics and their intersections with diseases such as Dengue, Chikungunya, and COVID-19 so far, future Zika models should prioritize robust data integration and rigorous validation against diverse datasets to improve the accuracy and reliability of epidemic prediction. In addition, models could benefit from adaptable frameworks incorporating human behavior, environmental factors, and stochastic parameters, with an emphasis on open-access tools to foster transparency and research collaboration.

This study aims to identify and rank the key risk factors associated with the Zika virus by leveraging a novel multi-criteria decision-making (MCDM) framework based on type-2 heptagonal fuzzy sets. By integrating advanced aggregation operators, the framework effectively addresses uncertainties in expert assessments and enhances decision-making reliability.

A robust MCDM approach was developed using type-2 heptagonal fuzzy sets, which provide a more nuanced representation of uncertainty compared to traditional fuzzy models. These sets were selected due to their superior ability to handle vague, imprecise, and subjective expert judgments, common challenges in epidemiological risk assessments. Arithmetic and geometric aggregation operators were employed to process fuzzy data effectively. To ensure comprehensive and reliable rankings, the framework incorporated both outranking methods and distance-based approaches, specifically TOPSIS and WASPAS. A sensitivity analysis was conducted to validate the stability of the rankings under varying conditions.

The proposed framework identified Z 3 (unprotected sexual activity) as the most critical risk factor with a score of 0.6717, followed by Z 8 (blood transfusions) at 0.5783, Z 10 (pregnancy) at 0.5753, Z 9 (mosquito bites) at 0.4917, and Z 7 (travel to endemic areas) at 0.4726. The rankings remained consistent across different MCDM methods (TOPSIS and WASPAS), demonstrating the robustness of the proposed approach. Pearson correlation analysis confirmed a strong agreement between methods, with correlation coefficients, reinforcing the reliability of the model.

This study introduces an advanced decision-support system for healthcare professionals to systematically identify and prioritize Zika virus risk factors. By leveraging type-2 heptagonal fuzzy sets, the framework effectively captures and processes uncertainty stemming from incomplete epidemiological data, imprecise expert assessments, and subjective linguistic evaluations. The consistency of rankings across multiple MCDM methods, along with sensitivity analysis confirming their stability, demonstrates the model's reliability. These findings provide a scientifically grounded tool for improving risk analysis and strategic public health interventions.

Arboviral diseases are viral infections transmitted to humans through the bites of arthropods, such as mosquitoes, often causing a variety of pathologies associated with high levels of morbidity and mortality. Over the past decades, these infections have proven to be a significant challenge to health systems worldwide, particularly following the considerable geographic expansion of the dengue virus (DENV) and its most recent outbreak in Latin America as well as the difficult-to-control outbreaks of yellow fever virus (YFV), chikungunya virus (CHIKV), and Zika virus (ZIKV), leaving behind a substantial portion of the population with complications related to these infections. Currently, the world is experiencing a period of intense globalization, which, combined with global warming, directly contributes to wider dissemination of arbovirus vectors across the globe. Consequently, all continents remain on high alert for potential new outbreaks. Thus, this review aims to provide a comprehensive understanding of the pathogenesis of the four main arboviruses today (DENV, ZIKV, YFV, and CHIKV) discussing their viral characteristics, immune responses, and mechanisms of viral evasion, as well as important clinical aspects for patient management. This includes associated symptoms, laboratory tests, treatments, existing or developing vaccines and the main associated complications, thus integrating a broad historical, scientific and clinical approach.

Infections caused by viruses as the smallest infectious agents, pose a major threat to global public health. Viral infections utilize different host mechanisms to facilitate their own propagation and pathogenesis. MicroRNAs (miRNAs), as small noncoding RNA molecules, play important regulatory roles in different diseases, including viral infections. They can promote or inhibit viral infection and have a pro-viral or antiviral role. Also, viral infections can modulate the expression of host miRNAs. Furthermore, viruses from different families evade the host immune response by producing their own miRNAs called viral miRNAs (v-miRNAs). Understanding the replication cycle of viruses and their relation with host miRNAs and v-miRNAs can help to find new treatments against viral infections. In this review, we aim to outline the structure, genome, and replication cycle of various viruses including hepatitis B, hepatitis C, influenza A virus, coronavirus, human immunodeficiency virus, human papillomavirus, herpes simplex virus, Epstein-Barr virus, Dengue virus, Zika virus, and Ebola virus. We also discuss the role of different host miRNAs and v-miRNAs and their role in the pathogenesis of these viral infections.

Zika virus (ZIKV) is a mosquito-borne flavivirus of the family Flaviviridae. The association between ZIKV and microcephaly was first described in Brazil in 2015. The risk of vertical transmission occurs in pregnant women with or without symptoms, and the risk of malformation appears to be worse when infection occurs in the first and second trimesters of pregnancy. The rate of vertical transmission varies from 26 to 65%, and not all fetuses develop malformations. The incidence of malformations resulting from transmission is uncertain, ranging from 6-8% in the US to 40% in Brazil. Congenital ZIKV syndrome is a set of clinical manifestations that can affect the fetus of a mother infected with ZIKV. The manifestations are broad and nonspecific, including microcephaly, subcortical calcifications, ocular changes, congenital contractures, early hypertension, and pyramidal and extrapyramidal signs. Other findings such as growth restriction and fetal miscarriage/death may also occur. Our aim in this article is to review the literature on mosquito transmission, clinical presentation, serologic diagnosis, intrauterine transmission, pre- and postnatal imaging diagnostic findings, and short- and long-term follow-up.

ZIKA fever (ZIKAF) is an emerging mosquito-borne flavivirus illness in humans. Regarding the etiological agent, ZIKA virus (ZIKAV), though it is known to be distributed in the tropics, causing sporadic cases, its rapid global expansion with pandemic potential has raised global concern. Due to its abrupt emergence in South American countries, the Caribbean, and the Americas, the WHO declared ZIKA a public health emergency of international concern in 2016. ZIKAV usually causes mild infections; however, its recent unusual presentations of Guillen-Barré syndrome in adults and microcephaly in newborn babies of ZIKAV-infected mothers in Brazil has caused concern among global public health authorities. Certain mutations on virus genomes have been found to be correlated with clinical severity, and its unusual transmission routes through sexual and blood transfusions emphasize the necessity for understanding its virological determinants and impact. Its abrupt re-emergence in India (2018-2019), particularly in Gujarat (2016), Tamil Nadu (2017), Uttar Pradesh (2021), Maharashtra, Kerala (2021), and Karnataka (2023), has indicated the need for urgent measures to strengthen surveillance systems and design effective prevention and control measures in this country. Given the global concern around ZIKAV, here, we reviewed current knowledge about global ZIKAV genetic lineages vis à vis the situation in India and discussed future priorities for ZIKAV research in India for effectively designing control strategies.

Zika virus (ZIKV) is unique among orthoflaviviruses in its vertical transmission capacity in humans, yet the underlying mechanisms remain incompletely understood. Here, we show that ZIKV induces tunneling nanotubes (TNTs) in placental trophoblasts which facilitate transfer of viral particles, proteins, mitochondria, and RNA to neighboring uninfected cells. TNT formation is driven exclusively via ZIKV non-structural protein 1 (NS1). Specifically, the N-terminal 1-50 amino acids of membrane-bound ZIKV NS1 are necessary for triggering TNT formation in host cells. Trophoblasts infected with TNT-deficient ZIKVΔTNT mutant virus elicited a robust antiviral IFN-λ 1/2/3 response relative to WT ZIKV, suggesting TNT-mediated trafficking allows ZIKV cell-to-cell transmission camouflaged from host defenses. Using affinity purification-mass spectrometry of cells expressing wild-type NS1 or non-TNT forming NS1, we found mitochondrial proteins are dominant NS1-interacting partners. We demonstrate that ZIKV infection or NS1 expression induces elevated mitochondria levels in trophoblasts and that mitochondria are siphoned via TNTs from healthy to ZIKV-infected cells. Together our findings identify a stealth mechanism that ZIKV employs for intercellular spread among placental trophoblasts, evasion of antiviral interferon response, and the hijacking of mitochondria to augment its propagation and survival and offers a basis for novel therapeutic developments targeting these interactions to limit ZIKV dissemination.

In this review, we summarize some recent findings regarding the likely mechanisms by which HIV-1 uses the testis as a sanctuary site for evading the effects of antiviral drugs from reaching the testis, due to the presence of the blood-testis barrier. This discussion also sheds insights into the possibility of eradicating the small viral pool in the testis behind the blood-testis barrier in future functional studies. These findings also bridge the knowledge gap of eradicating viral particles hiding behind the blood-brain barrier in the brain since it is anticipated that the blood-tissue barriers, namely the blood-testis and the blood-brain barriers, are utilizing similar mechanisms to regulate the dynamic nature of their tight junctions.

Arboviruses currently are regarded as a major worldwide public health concern. The clinical outcomes associated with this group of viruses may vary from asymptomatic infections to severe forms of haemorrhagic fever characterised by bleeding disorders. Similar to other systemic viral infections, arboviruses can either directly or indirectly affect different parts of the body, such as the urogenital system. The human urogenital system anatomically consists of two major subdivisions: (i) the urinary system, including the kidneys, ureters, bladder, and urethra, which plays a significant role in osmoregulation, control of blood volume, pressure, and PH, absorption/excretion of different ions, and toxin metabolism, and (ii) the genital system, composed of the prostate, uterus, testes, ovaries, penis, and vagina, which are responsible for reproductive functions. Arboviruses can impair normal urogenital system functions by direct viral pathogen activity, systemic forms of inflammation, haemorrhagic events and related dysfunctions, and the nephrotoxic side effects of specific medications employed for treatment leading to various urogenital disorders. The present review provides an overview of the potential capacity of two main arboviruses, known as Zika and dengue viruses, to affect the urogenital system. Moreover, it addresses Zika virus as a potential therapeutic oncolytic virus for urogenital cancers.

Fetal immune cell functions during congenital infections are poorly understood. Zika virus (ZIKV) can vertically transmit from mother to fetus, causing nervous system infection and congenital ZIKV syndrome (CZS). We identified differential functional roles for fetal monocyte/macrophage cell types and microglia in ZIKV dissemination versus clearance using mouse models. Trafficking of ZIKV-infected primitive macrophages from the yolk sac allowed initial fetal virus inoculation, while recruited monocytes promoted non-productive neuroinflammation. Conversely, brain-resident differentiated microglia were protective, limiting infection and neuronal death. Single-cell RNA sequencing identified transcriptional profiles linked to the protective versus detrimental contributions of mononuclear phagocyte subsets. In human brain organoids, microglia also promoted neuroprotective transcriptional changes and infection clearance. Thus, microglia are protective before birth, contrasting with the disease-enhancing roles of primitive macrophages and monocytes. Differential modulation of myeloid cell phenotypes by genetically divergent ZIKVs underscores the potential of immune cells to regulate diverse outcomes during fetal infections.

Flaviviruses pose a major public health concern across the globe. Among them, Zika virus (ZIKV) is an emerging and reemerging arthropod-borne flavivirus that has become a major international public health problem following multiple large outbreaks over the past two decades. The majority of infections caused by ZIKV exhibit mild symptoms. However, the virus has been found to be associated with a variety of congenital neural abnormalities, including microcephaly in children and Guillain-Barre syndrome in adults. The exact prediction of the potential of ZIKV transmission is still enigmatic and underlines the significance of routine detection of the virus in suspected areas. ZIKV transmission from mother to fetus (including fetal abnormalities), viral presence in immune-privileged areas, and sexual transmission demonstrate the challenges in understanding the factors governing viral persistence and pathogenesis. This review illustrates the transmission patterns, epidemiology, control strategies (through vaccines, antivirals, and vectors), oncolytic aspects, molecular insights into neuro-immunopathogenesis, and other neuropathies caused by ZIKV. Additionally, we summarize in vivo and in vitro models that could provide an important platform to study ZIKV pathogenesis and the underlying governing cellular and molecular mechanisms.

Zika virus (ZIKV) is a mosquito-borne flavivirus that caused a global pandemic in 2016-2017 with continued ongoing transmission at low levels in several countries. In the absence of an approved ZIKV vaccine, neutralizing monoclonal antibodies (mAbs) provide an option for the prevention and treatment of ZIKV infection. Previous studies identified a potent neutralizing human mAb ZIKV-117 that reduced fetal infection and death in mice following ZIKV challenge. In this study, we report exquisite potency of ZIKV-117-LALA-YTE, which has been engineered to reduce Fc receptor binding and to extend half-life, in a titration study in rhesus macaques to protect against ZIKV challenge. We show complete protection at a dose of 0.016 mg/kg ZIKV-117-LALA-YTE, which resulted in median serum concentrations of 0.13 µg/mL. The high potency of this mAb supports its potential clinical development as a novel biotherapeutic intervention for ZIKV.IMPORTANCEIn this study, we report the potency of the Zika virus (ZIKV)-specific neutralizing antibody ZIKV-117-LALA-YTE against ZIKV challenge in a titration study rhesus macaques. This high potency supports the further development of this monoclonal antibody for ZIKV.

The Zika virus (ZIKV) is classified within the Flavivirus genus of the Flaviviridae family and is categorized as an arbovirus. The virus was initially identified in a rhesus monkey in Uganda in 1947 and later in a human in Nigeria in 1952. Since 2007, the prevalence of the virus has been on the rise, culminating in a major outbreak in the United States (US) in 2015. During this outbreak, the adult population was severely impacted, experiencing a range of symptoms, including organ failure, microcephaly, fetal death, and Guillain-Barré syndrome (GBS). Additionally, skin rash, limb swelling, fever, headache, and heightened sensitivity are found in most adults with Zika syndrome. Although the virus can be transmitted through blood, vertical transmission from mother to child, and sexual contact, the primary way of transmission of the virus is through the Aedes mosquito. Cells such as neurons, macrophages, peripheral dendritic cells, and placental cells are among the target cells that the virus can infect. The TAM AXL receptor plays a crucial role in infection. After the virus enters the body through the bloodstream, it spreads in the body with a latent period of 3 to 12 days. Currently, there is no specific treatment or publicly available vaccine for the ZIKV. Limited laboratory testing has been conducted, and existing drugs originally designed for other pathogens have been repurposed for treatment. Given the Aedes mosquito's role as a vector and the wide geographical impact of the virus, this study aims to comprehensively investigate Zika's pathogenesis and clinical symptoms based on existing knowledge and research. By doing so, we seek to enhance our understanding of the virus and inform future prevention and treatment strategies.

Regulatory T cells (Tregs) are well-known to mediate peripheral tolerance at homeostasis, and there is a growing appreciation for their role in modulating infectious disease immunity. Following acute and chronic infections, Tregs can restrict pathogen-specific T cell responses to limit immunopathology. However, it is unclear if Tregs mediate control of pathology and immunity in distal tissue sites during localized infections. We investigated the role of Tregs in immunity and disease in various tissue compartments in the context of "mild" vaginal Zika virus infection. We found that Tregs are critical to generating robust virus-specific CD8 T cell responses in the initial infection site. Further, Tregs limit inflammatory cytokines and immunopathology during localized infection; a dysregulated immune response in Treg-depleted mice leads to increased T cell infiltrates and immunopathology in both the vagina and the central nervous system (CNS). Importantly, these CNS infiltrates are not present at the same magnitude during infection of Treg-sufficient mice, in which there is no CNS immunopathology. Our data suggest that Tregs are necessary to generate a robust virus-specific response at the mucosal site of infection, while Treg-mediated restriction of bystander inflammation limits immunopathology both at the site of infection as well as distal tissue sites.

This review provides practical recommendations for dental practitioners in dealing with oral lesions associated with sexually transmitted diseases (STDs), offering clinically relevant insights to increase the awareness of these diseases in the mainstream of everyday practice. STDs are acquired through unprotected vaginal, anal or oral sex and are caused by more than 30 different types of bacteria, viruses and protozoa. Saliva, precum, semen, vaginal secretions and menstrual blood could be likely vehicles of infections and defensive barriers to infection by pathogenic microbes could be represented via intact mucosal membrane, the diluent function of saliva, and the antimicrobial action of salivary enzymes that collectively contribute to oral health and protection. STD, can directly and indirectly affect mucous membranes, manifesting with characteristic diagnostic signs and lesions. Given their potential oral manifestations, dental professionals need a comprehensive understanding of STD. The findings of this review lay a foundation for comprehending several STDs, emphasizing the importance of physicians as well dental practitioners being open to discussing sexuality issues with patients and providing appropriate therapeutic interventions.

Zika virus infection, most oft n responsible for a benign arboviral disease or an asymptomatic infection, rarely Guillain-Barré syndrome, can become problematic in pregnant women, due to a risk of fetal malformations, in particular microcephaly linked to its neurotropism. The most recent large-scale epidemic was observed throughout Latin America between 2015 and 2017, causing several hundred thousand cases. Transmission is predominantly vector-borne, but sexual transmission has been described, mainly among travelers, although it undoubtedly accounts for a significant proportion of transmission in epidemic areas. The aim of this review is to describe this sexual transmission, mainly through examples linked to this large-scale epidemic in Latin America, to describe the link with prolonged excretion of infectious viral particles in genital secretions, especially semen but also vaginal secretions, and to highlight possible preventive measures apart from vector transmission, in particular the need for pregnant women or women wishing to become pregnant to avoid visiting countries where circulation of Zika virus is described.

Zika virus (ZIKV) causes human testicular inflammation and alterations in sperm parameters and causes testicular damage in mouse models. The involvement of individual immune cells in testicular damage is not fully understood. We detected virus in the testes of the interferon (IFN) α/β receptor-/- A129 mice three weeks post-infection and found elevated chemokines in the testes, suggesting chronic inflammation and long-term infection play a role in testicular damage. In the testes, myeloid cells and CD4+ T cells were absent at 7 dpi but were present at 23 days post-infection (dpi), and CD8+ T cell infiltration started at 7 dpi. CD8-/- mice with an antibody-depleted IFN response had a significant reduction in spermatogenesis, indicating that CD8+ T cells are essential to prevent testicular damage during long-term ZIKV infections. Our findings on the dynamics of testicular immune cells and the importance of CD8+ T cells function as a framework to understand mechanisms underlying observed inflammation and sperm alterations in humans.

Zika virus (ZIKV), the causative agent of Zika fever, is a flavivirus transmitted by mosquitoes of the Aedes genus. Zika virus infection has become an international concern due to its association with severe neurological complications such as fetal microcephaly. Viral infection can induce the release of ATP in the extracellular environment, activating receptors sensitized by extracellular nucleotides, such as the P2X7 receptor. This receptor is the primary purinergic receptor involved in neuroinflammation, neurodegeneration, and immunity. In this work, we investigated the role of ATP-P2X7 receptor signaling in Zika-related brain abnormalities. Wild-type mice (WT) and P2X7 receptor-deficient (P2X7-/-) C57BL/6 newborn mice were subcutaneously inoculated with 5 × 106plaque-forming units of ZIKV or mock solution. P2X7 receptor expression increased in the brain of Zika virus-infected mice compared to the mock group. Comparative analyses of the hippocampi from WT and P2X7-/-mice revealed that the P2X7 receptor increased hippocampal damage in CA1/CA2 and CA3 regions. Doublecortin expression decreased significantly in the brains of ZIKV-infected mice. WT ZIKV-infected mice showed impaired motor performance compared to P2X7-/- infected mice. WT ZIKV-infected animals showed increased expression of glial markers GFAP (astrocytes) and IBA-1 (microglia) compared to P2X7-/- infected mice. Although the P2X7 receptor contributes to neuronal loss and neuroinflammation, WT mice were more efficient in controlling the viral load in the brain than P2X7 receptor-deficient mice. This result was associated with higher induction of TNF-α, IFN-β, and increased interferon-stimulated gene expression in WT mice than P2X7-/-ZIKV-infected. Finally, we found that the P2X7 receptor contributes to inhibiting the neuroprotective signaling pathway AKT/mTOR while stimulating the caspase-3 activation, possibly two distinct pathways contributing to neurodegeneration. These findings suggest that ATP-P2X7 receptor signaling contributes to the antiviral response in the brain of ZIKV-infected mice while increasing neuronal loss, neuroinflammation, and related brain abnormalities.

In June 2023, a local cluster of 15 Zika cases was reported in a neighbourhood in Northeastern Singapore. The last significant local transmission of Zika virus (ZIKV) with more than 450 cases was in 2016-2017. To monitor the situation and mitigate further transmission, case, entomological and wastewater-based surveillance were carried out.

Primary healthcare practitioners and the community were alerted to encourage timely case identification. Surveillance was enhanced through testing of Aedes mosquitoes collected from the National Gravitrap surveillance system, and wastewater samples were collected from a network of autosamplers deployed at manholes across the country.

ZIKV RNA was detected in mosquito pools (3/43; 7%) and individual mosquitoes (3/82; 3.7%) captured, and in wastewater samples (13/503) collected from the vicinity of the cluster of cases. Respective samples collected from other sites across the country were negative. The peak detection of ZIKV RNA in mosquitoes and wastewater coincided temporally with the peak in the number of cases in the area (15-25 May 2023).

The restriction of ZIKV signals from wastewater and mosquitoes within the neighbourhood suggested limited ZIKV transmission. The subsequent waning of signals suggested effectiveness of control measures. We demonstrate the utility of wastewater-based surveillance of ZIKV, which complements existing case- and entomological-based surveillance. The non-intrusive approach is particularly useful to monitor diseases such as Zika, which generally causes silent or mild infections, but may cause severe outcomes such as congenital Zika syndrome.

This study was funded by Singapore's Ministry of Finance and the National Environment Agency, Singapore.

Zika virus (ZIKV) spread is considered a major public health threat by the World Health Organization (WHO). There are no vaccines or drugs available to control the infection of the Zika virus, therefore a highly effective medicinal molecule is urgently required. In this study, a computationally intensive investigation was performed to identify a potent natural compound that could inhibit the ZIKV NS5 methyltransferase. This research approach is based on target-based drug identification principles where the native inhibitor SAH (S-adenosylhomocysteine) of ZIKV NS5 methyltransferase was selected as a reference. High-throughput virtual screening and tanimoto similarity coefficient were applied to the natural compound library for ranking the potential candidates. The top five compounds were selected for interaction analysis, MD simulation, total binding free energy through MM/GBSA, and steered MD simulation. Among these compounds, Adenosine 5'-monophosphate monohydrate, Tubercidin, and 5-Iodotubercidin showed stable binding to the protein compared to the native compound, SAH. These three compounds also showed less fluctuations in RMSF in contrast to native compound. Additionally, the same interacting residues observed in SAH also made strong interactions with these three compounds. Adenosine 5'-monophosphate monohydrate and 5-Iodotubercidin had greater total binding free energies than the reference ligand. Moreover, the dissociation resistance of all three compounds was equivalent to that of the reference ligand. This study suggested binding properties of three-hit compounds that could be used to develop drugs against Zika virus infections.Communicated by Ramaswamy H. Sarma.

Zika virus (ZIKV) causes human testicular inflammation and alterations in sperm parameters and causes testicular damage in mouse models. The involvement of individual immune cells in testicular damage is not fully understood. We detected virus in the testes of the interferon (IFN) α/β receptor -/- A129 mice three weeks post-infection and found elevated chemokines in the testes, suggesting chronic inflammation and long-term infection play a role in testicular damage. In the testes, myeloid cells and CD4 + T cells were absent at 7 dpi but were present at 23 days post-infection (dpi), and CD8 + T cell infiltration started at 7 dpi. CD8 -/- mice with an antibody-depleted IFN response had a significant reduction in spermatogenesis, indicating that CD8 + T cells are essential to prevent testicular damage during long-term ZIKV infections. Our findings on the dynamics of testicular immune cells and importance of CD8 + T cells functions as a framework to understand mechanisms underlying observed inflammation and sperm alterations in humans.

Flaviviruses such as dengue, Zika, and West Nile viruses are highly concerning pathogens that pose significant risks to public health. The NS1 protein is conserved among flaviviruses and is synthesized as a part of the flavivirus polyprotein. It plays a critical role in viral replication, disease progression, and immune evasion. Post-translational modifications influence NS1's stability, secretion, antigenicity, and interactions with host factors. NS1 protein forms extensive interactions with host cellular proteins allowing it to affect vital processes such as RNA processing, gene expression regulation, and cellular homeostasis, which in turn influence viral replication, disease pathogenesis, and immune responses. NS1 acts as an immune evasion factor by delaying complement-dependent lysis of infected cells and contributes to disease pathogenesis by inducing endothelial cell damage and vascular leakage and triggering autoimmune responses. Anti-NS1 antibodies have been shown to cross-react with host endothelial cells and platelets, causing autoimmune destruction that is hypothesized to contribute to disease pathogenesis. However, in contrast, immunization of animal models with the NS1 protein confers protection against lethal challenges from flaviviruses such as dengue and Zika viruses. Understanding the multifaceted roles of NS1 in flavivirus pathogenesis is crucial for effective disease management and control. Therefore, further research into NS1 biology, including its host protein interactions and additional roles in disease pathology, is imperative for the development of strategies and therapeutics to combat flavivirus infections successfully. This Review provides an in-depth exploration of the current available knowledge on the multifaceted roles of the NS1 protein in the pathogenesis of flaviviruses.

Zika virus (ZIKV) is a mosquito-borne flavivirus of the Flaviviridae family first isolated from a sentinel monkey in the Zika Forest, Uganda, in 1947. Since 2007, the virus has had a vast geographic expansion that extended to the Americas in 2015, leading to a series of large outbreaks. Although mainly transmitted by the bite of Aedes mosquitoes, human infection of ZIKV can also happen through unconventional routes such as sexual intercourse and, more importantly, vertical transmission. The genome of ZIKV is a single-stranded, positive-sense RNA molecule about 11 kb in length. The genome contains a single opening reading frame (ORF) flanked by highly structured 5' and 3' untranslated regions. To understand the mechanisms about ZIKV replication, transmission, and pathogenesis, reverse genetic tools are of great importance. In this chapter, a novel system is described for the generation and manipulation of a ZIKV infectious clone stabilized by a self-splicing group II intron, a mobile element with ribozyme activity. The intron can be spliced in vitro, and thus full-length vRNA can be prepared allowing virus genome manipulation required for further studies.

Flaviviruses are a group of positive-sense, single-stranded RNA viruses predominantly transmitted by arthropods (mainly mosquitoes) that cause severe endemic infections and epidemics on a global scale. They represent a major cause of systemic morbidity and death and are expanding worldwide. Among this group, dengue fever, the West Nile virus, yellow fever, Japanese Encephalitis, and, recently, the Zika virus have been linked to a spectrum of ocular manifestations. These manifestations encompass subconjunctival hemorrhages and conjunctivitis, anterior and posterior uveitis (inclusive of vitritis, chorioretinitis, and retinal vasculitis), maculopathy, retinal hemorrhages, and optic neuritis. Clinical diagnosis of these infectious diseases is primarily based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular involvement. Diagnosis confirmation relies on laboratory testing, including RT-PCR and serological testing. Ocular involvement typically follows a self-limited course but can result in irreversible visual impairment. Effective treatments of flavivirus infections are currently unavailable. Prevention remains the mainstay for arthropod vector and zoonotic disease control. Effective vaccines are available only for the yellow fever virus, dengue virus, and Japanese Encephalitis virus. This review comprehensively summarizes the current knowledge regarding the ophthalmic manifestations of the foremost flavivirus-associated human diseases.

Zika virus (ZIKV) infection continues to pose a significant public health concern due to limited available preventive measures and treatments. ZIKV is unique among flaviviruses in its vertical transmission capacity (i.e., transmission from mother to fetus) yet the underlying mechanisms remain incompletely understood. Here, we show that both African and Asian lineages of ZIKV induce tunneling nanotubes (TNTs) in placental trophoblasts and multiple other mammalian cell types. Amongst investigated flaviviruses, only ZIKV strains trigger TNTs. We show that ZIKV-induced TNTs facilitate transfer of viral particles, proteins, and RNA to neighboring uninfected cells. ZIKV TNT formation is driven exclusively via its non-structural protein 1 (NS1); specifically, the N-terminal region (50 aa) of membrane-bound NS1 is necessary and sufficient for triggering TNT formation in host cells. Using affinity purification-mass spectrometry of cells infected with wild-type NS1 or non-TNT forming NS1 (pNS1ΔTNT) proteins, we found mitochondrial proteins are dominant NS1-interacting partners, consistent with the elevated mitochondrial mass we observed in infected trophoblasts. We demonstrate that mitochondria are siphoned via TNTs from healthy to ZIKV-infected cells, both homotypically and heterotypically, and inhibition of mitochondrial respiration reduced viral replication in trophoblast cells. Finally, ZIKV strains lacking TNT capabilities due to mutant NS1 elicited a robust antiviral IFN-λ 1/2/3 response, indicating ZIKV's TNT-mediated trafficking also allows ZIKV cell-cell transmission that is camouflaged from host defenses. Together, our findings identify a new stealth mechanism that ZIKV employs for intercellular spread among placental trophoblasts, evasion of antiviral interferon response, and the hijacking of mitochondria to augment its propagation and survival. Discerning the mechanisms of ZIKV intercellular strategies offers a basis for novel therapeutic developments targeting these interactions to limit its dissemination.

During viral infections, nucleic acid sensing by intracellular receptors can trigger type I interferon (IFN-I) production, key mediators in antiviral innate immunity. However, many flaviviruses use non-structural proteins to evade immune sensing favoring their survival. These mechanisms remain poorly characterized. Here, we studied the role of Zika virus (ZIKV) NS4B protein in the inhibition of IFN-I induction pathway and its biophysical interaction with host proteins.

Using different cell-based assays, we studied the effect of ZIKV NS4B in the activation of interferon regulatory factors (IRFs), NF-κB, cytokines secretion and the expression of interferon-stimulating genes (ISG). We also analyzed the in vitro interaction between recombinant ZIKV NS4B and TANK-binding kinase 1 (TBK1) using surface plasmon resonance (SPR).

Transfection assays showed that ZIKV NS4B inhibits IRFs activation involved in different nucleic acid sensing cascades. Cells expressing NS4B secreted lower levels of IFN-β and IL-6. Furthermore, early induction of ISGs was also restricted by ZIKV NS4B. For the first time, we demonstrate by SPR assays that TBK1, a critical component in IFN-I production pathway, binds directly to ZIKV NS4B (KD of 3.7 × 10-6 M). In addition, we show that the N-terminal region of NS4B is directly involved in this interaction.

Altogether, our results strongly support that ZIKV NS4B affects nucleic acid sensing cascades and disrupts the TBK1/IRF3 axis, leading to an impairment of IFN-β production.

This study provides the first biophysical data of the interaction between ZIKV NS4B and TBK1, and highlights the role of ZIKV NS4B in evading the early innate immune response.

Zika virus (ZIKV) is a mostly non-lethal disease in humans transmitted by mosquitoes or humans that can produce severe brain defects such as microcephaly in babies and Guillain-Barré syndrome in elderly adults. The use of optimal control strategies involving information campaigns about insect repellents and condoms alongside an available safe and effective vaccine can prevent the number of infected humans with ZIKV. A system of nonlinear ordinary differential equations is formulated for the transmission dynamics of ZIKV in the presence of three control strategies to evaluate the impact of various scenarios during a ZIKV epidemic. In addition, we estimate parameters using weekly incidence data from previous ZIKV outbreaks in Colombia and Puerto Rico to capture the dynamics of an epidemic in each country when control measures are available. The basic reproduction number, R0, of each country is calculated using estimated parameters (without the controls). The vector-borne transmission threshold (Rv) is dominant in both countries , but the sexual transmission threshold (Rd) in Colombia is considerably higher than in Puerto Rico. Numerical simulations for Colombia show that the most effective strategies are to use three controls since the start of the outbreak. However, for Puerto Rico only information campaigns about mosquito repellents and vaccination are the most effective ways to mitigate the epidemic.

Zika virus (ZIKV), a mosquito-borne flavivirus, has been continually emerging and re-emerging since 2010, with sporadic cases reported annually in Thailand, peaking at over 1000 confirmed positive cases in 2016. Leveraging high-throughput sequencing technologies, specifically whole genome sequencing (WGS), has facilitated rapid pathogen genome sequencing. In this study, we used multiplex amplicon sequencing on the Illumina Miseq instrument to describe ZIKV WGS. Six ZIKV WGS were derived from three samples of field-caught Culex quinquefasciatus mosquitoes (two males and one female) and three urine samples collected from patients in three different provinces of Thailand. Additionally, successful isolation of a ZIKV isolate occurred from a female Cx. quinquefasciatus. The WGS analysis revealed a correlation between the 2020 outbreak and the acquisition of five amino acid changes in the Asian lineage ZIKV strains from Thailand (2006), Cambodia (2010 and 2019), and the Philippines (2012). These changes, including C-T106A, prM-V1A, E-V473M, NS1-A188V, and NS5-M872V, were identified in all seven WGS, previously linked to significantly higher mortality rates. Furthermore, phylogenetic analysis indicated that the seven ZIKV sequences belonged to the Asian lineage. Notably, the genomic region of the E gene showed the highest nucleotide diversity (0.7-1.3%). This data holds significance in informing the development of molecular tools that enhance our understanding of virus patterns and evolution. Moreover, it may identify targets for improved methods to prevent and control future ZIKV outbreaks.

Zika virus (ZIKV) infection is associated with severe complications. Recently, reports have raised the possibility of cardiovascular complications. However, the complications that are reported are in case reports and occur immediately after infection. Our aim is to evaluate the cardiovascular complications of ZIKV infection in a younger patient population.

We conducted a prospective cohort and included patients with a one-year history of prior confirmed ZIKV infection. We performed an echocardiogram, a 24-hour automated blood pressure, and a 24-hour Holter. Our primary outcome included a composite of having diastolic dysfunction, left ventricular hypertrophy, arrhythmias, valvular regurgitation, premature beats, or non-dipper status.

We included 47 patients with ZIKV and 16 patients without ZIKV. Patients with ZIKV had a similar age as controls (p>0.05). Having had a prior ZIKV infection was associated with diastolic dysfunction, left ventricular hypertrophy, valvular regurgitation, arrhythmias or premature beats, and non-dipper status (p<0.05). The adjusted OR of having the primary outcome was 2.3; 95% CI 1.3-2.7. After one year, IL-10 and C-reactive protein (CRP) were higher in ZIKV-infected patients compared to controls (p<0.05).

Our study found that young patients with a prior ZIKV infection have more echocardiographic, arrhythmic, and blood pressure changes when compared to similar-aged controls.

Flaviviruses are arthropod-borne RNA viruses found worldwide that, when introduced into the human body, cause diseases, including neuroinfections, that can lead to serious metabolic consequences and even death. Some of the diseases caused by flaviviruses occur continuously in certain regions, while others occur intermittently or sporadically, causing epidemics. Some of the most common flaviviruses are West Nile virus, dengue virus, tick-borne encephalitis virus, Zika virus and Japanese encephalitis virus. Since all the above-mentioned viruses are capable of penetrating the blood-brain barrier through different mechanisms, their actions also affect the central nervous system (CNS). Like other viruses, flaviviruses, after entering the human body, contribute to redox imbalance and, consequently, to oxidative stress, which promotes inflammation in skin cells, in the blood and in CNS. This review focuses on discussing the effects of oxidative stress and inflammation resulting from pathogen invasion on the metabolic antiviral response of the host, and the ability of viruses to evade the consequences of metabolic changes or exploit them for increased replication and further progression of infection, which affects the development of sequelae and difficulties in therapy.

Zika virus (ZIKV) is a flavivirus transmitted by mosquitoes, causing neurological disorders and congenital malformations. RNA-dependent RNA polymerase (RdRp) is one of its essential enzymes and a promising drug target for antiviral therapy due to its involvement in the growth and multiplication of the virus. In this study, we conducted a QSAR-based chemical library screening from the Meliaceae family to identify potential RdRp inhibitors. The QSAR model was built using the known inhibitors of RdRp NS5 of ZIKV and their biological activity (EC50), along with the structural and chemical characteristics of the compounds. The top two hit compounds were selected from QSAR screening for further analysis using molecular docking to evaluate their binding energies and intermolecular interactions with RdRp, including the critical residue Trp485. Furthermore, molecular dynamics (MD) simulations were performed to evaluate their binding stability and flexibility upon binding to RdRp. The MD results showed that the selected compounds formed stable complexes with RdRp, and their binding interactions were similar to those observed for the native ligand. The binding energies of the top two hits (-8.6 and -7.7 kcal/mole) were comparable to those of previously reported ZIKV RdRp inhibitors (-8.9 kcal/mole). The compound IMPHY009135 showed the strongest binding affinity with RdRp, forming multiple hydrogen bonds and hydrophobic interactions with key residues. However, compound IMPHY009276 showed the most stable and consistent RMSD, which was similar to the native ligand. Our findings suggest that IMPHY009135 and IMPHY009276 are potential lead compounds for developing novel antiviral agents against ZIKV.Communicated by Ramaswamy H. Sarma.

The Zika Virus (ZIKV) is an emerging arbovirus of great public health concern, particularly in the Americas after its last outbreak in 2015. There are still major challenges regarding disease control, and there is no ZIKV vaccine currently approved for human use. Among many different vaccine platforms currently under study, the recombinant envelope protein from Zika Virus (rEZIKV) constitutes an alternative option for vaccine development and has great potential for monitoring ZIKV infection and antibody response. This study describes a method to obtain a bioactive and functional rEZIKV using an E. coli expression system, with the aid of a 5-L airlift bioreactor and following an automated fast protein liquid chromatography (FPLC) protocol, capable of obtaining high yields of approximately 20 mg of recombinant protein per liter of bacterium cultures. The purified rEZIKV presented preserved antigenicity and immunogenicity. Our results show that the use of an airlift bioreactor for the production of rEZIKV is ideal for establishing protocols and further research on ZIKV vaccines bioprocess, representing a promising system for the production of a ZIKV envelope recombinant protein-based vaccine candidate.

Zika virus (ZIKV) infection is associated with severe neurological disorders and congenital malformation. Despite efforts to eradicate the disease, there is still neither vaccine nor approved drugs to treat ZIKV infection. The NS2B-NS3 protease is a validated drug target since it is essential to polyprotein virus maturation. In the present study, we describe an experimental screening of 2,320 compounds from the chemical library of the Muséum National d'Histoire Naturelle of Paris on ZIKV NS2B-NS3 protease. A total of 96 hits were identified with 90% or more of inhibitory activity at 10 μM. Amongst the most active compounds, five were analyzed for their inhibitory mechanisms by kinetics assays and computational approaches such as molecular docking. 2-(3-methoxyphenoxy) benzoic acid (compound 945) show characteristics of a competitive inhibition (Ki = 0.49 μM) that was corroborated by its molecular docking at the active site of the NS2B-NS3 protease. Taxifolin (compound 2292) behaves as an allosteric inhibitor whereas 3,8,9-trihydroxy-2-methyl-1H-phenalen-1-one (compound 128), harmol (compound 368) and anthrapurpurin (compound 1499) show uncompetitive inhibitions. These new NS2B-NS3 protease inhibitors are valuable hits to further hit-to-lead optimization.

Zika virus (ZIKV) is an emerging pathogen that causes devastating congenital defects. The overlapping epidemiology and immunologic cross-reactivity between ZIKV and dengue virus (DENV) pose complex challenges to vaccine design, given the potential for antibody-dependent enhancement of disease. Therefore, classification of ZIKV-specific antibody targets is of notable value. From a ZIKV-infected rhesus macaque, we identify ZIKV-reactive B cells and isolate potent neutralizing monoclonal antibodies (mAbs) with no cross-reactivity to DENV. We group these mAbs into four distinct antigenic groups targeting ZIKV-specific cross-protomer epitopes on the envelope glycoprotein. Co-crystal structures of representative mAbs in complex with ZIKV envelope glycoprotein reveal envelope-dimer epitope and unique dimer-dimer epitope targeting. All four specificities are serologically identified in convalescent humans following ZIKV infection, and representative mAbs from all four groups protect against ZIKV replication in mice. These results provide key insights into ZIKV-specific antigenicity and have implications for ZIKV vaccine, diagnostic, and therapeutic development.

Several recent emerging diseases have exhibited both sexual and nonsexual transmission modes (Ebola, Zika, and mpox). In the recent mpox outbreaks, transmission through sexual contacts appears to be the dominant mode of transmission. Motivated by this, we use an SIR-like model to argue that an initially dominant sexual transmission mode can be overtaken by casual transmission at later stages, even if the basic casual reproduction number is less than one. Our results highlight the risk of intervention designs which are informed only by the early dynamics of the disease.

Microcephaly is a neurological condition characterized by anomalies in the growth of the cranial circumference. This study aims to examine the association between sociodemographic and clinical variables and the occurrence of secondary microcephaly in newborns in Brazil. It also aims to investigate the association between this congenital anomaly and teratogenic infections. This research adopts an observational approach with an ecological, descriptive, and analytical design. The sample includes infants aged ≤28 days and registered in the country's Live Births Information System from January 2015 to December 2021. Newborns were categorized into G1, consisting of newborns with one of the three infections (Zika, toxoplasmosis, or syphilis), and G2, consisting of newborns with two of the three infections. A total of 1513 samples were analyzed and divided into two groups: one infection (syphilis n = 423; toxoplasmosis n = 295; or Zika n = 739) and two infections (n = 56). The northeastern region of Brazil has the highest prevalence of microcephaly. Regarding the population profile, the Zika virus infection is more common among white mothers, while the syphilis infection is more common among black mothers. Among newborns with microcephaly, boys have a lower prevalence of toxoplasmosis infection, while girls have a lower prevalence of Zika virus infection. This study provides pertinent information on each infection and contributes to the epidemiologic understanding of the association between teratogenic infections and microcephaly.

β-Escin is a mixture of triterpenoid saponins extracted from horse chestnut seeds that have diverse pharmacological activities, including anti-inflammation, anti-edematous, venotonic, and antiviral effects. In the clinical setting, β-escin is primarily used to treat venous insufficiency and blunt trauma injuries. The anti-Zika virus (ZIKV) activity of β-escin has not been explored. This study investigated the antiviral efficacy of β-escin on ZIKV and dengue virus (DENV) in vitro and then elucidated the underlying mechanism. The inhibitory effects of β-escin on viral RNA synthesis, protein levels, and infection ability were determined using qRT-PCR, Western blotting, and immunofluorescence assays, respectively. To further characterize how β-escin interferes with the viral life cycle, the time-of-addition experiment was performed. An inactivation assay was performed to determine whether β-escin affects ZIKV virion stability. To broaden these findings, the antiviral effects of β-escin on different DENV serotypes were assessed using dose-inhibition and time-of-addition assays. The results showed that β-escin exhibits anti-ZIKV activity by decreasing viral RNA levels, protein expression, progeny yield, and virion stability. β-Escin inhibited ZIKV infection by disrupting viral binding and replication. Furthermore, β-escin demonstrated antiviral activities against four DENV serotypes in a Vero cell model and prophylactic protection against ZIKV and DENV infections.

Zika virus (ZIKV) infection causes neurological disorders and draws great attention. ZIKV infection can elicit a wide range of immune response. Type I interferons (IFNs) as well as its signaling cascade play crucial role in innate immunity against ZIKV infection and in turn ZIKV can antagonize them. ZIKV genome are mainly recognized by Toll-like receptors 3 (TLR3), TLR7/8 and RIG-I-like receptor 1 (RIG-1), which induces the expression of Type I IFNs and interferon-stimulated genes (ISGs). ISGs exert antiviral activity at different stages of the ZIKV life cycle. On the other hand, ZIKV takes multiple strategies to antagonize the Type Ⅰ IFN induction and its signaling pathway to establish a pathogenic infection, especially by using the viral nonstructural (NS) proteins. Most of the NS proteins can directly interact with the factors in the pathways to escape the innate immunity. In addition, structural proteins also participate in the innate immune evasion and activation of antibody-binding of blood dendritic cell antigen 2 (BDCA2) or inflammasome also be used to enhance ZIKV replication. In this review, we summarize the recent findings about the interaction between ZIKV infection and type I IFNs pathways and suggest potential strategies for antiviral drug development.

Asian lineage Zika virus (ZIKV) strains emerged globally, causing outbreaks linked with critical clinical disease outcomes unless the virus is effectively restricted by host immunity. We have previously shown that retinoic acid-inducible gene-I (RIG-I) senses ZIKV to trigger innate immunity to direct interferon (IFN) production and antiviral responses that can control ZIKV infection. However, ZIKV proteins have been demonstrated to antagonize IFN. Here, we conducted in vitro analyses to assess how divergent prototypic ZIKV variants differ in virologic properties, innate immune regulation, and infection outcome. We comparatively assessed African lineage ZIKV/Dakar/1984/ArD41519 (ZIKV/Dakar) and Asian lineage ZIKV/Malaysia/1966/P6740 (ZIKV/Malaysia) in a human epithelial cell infection model. De novo viral sequence determination identified amino acid changes within the ZIKV/Dakar genome compared to ZIKV/Malaysia. Viral growth analyses revealed that ZIKV/Malaysia accumulated viral proteins and genome copies earlier and to higher levels than ZIKV/Dakar. Both ZIKV strains activated RIG-I/IFN regulatory factor (IRF3) and NF-κB pathways to induce inflammatory cytokine expression and types I and III IFNs. However, ZIKV/Malaysia, but not ZIKV/Dakar, potently blocked downstream IFN signaling. Remarkably, ZIKV/Dakar protein accumulation and genome replication were rescued in RIG-I knockout (KO) cells late in acute infection, resulting in ZIKV/Dakar-mediated blockade of IFN signaling. We found that RIG-I signaling specifically restricts viral protein accumulation late in acute infection where early accumulation of viral proteins in infected cells confers enhanced ability to limit IFN signaling, promoting viral replication and spread. Our results demonstrate that RIG-I-mediated innate immune signaling imparts restriction of ZIKV protein accumulation, which permits IFN signaling and antiviral actions controlling ZIKV infection. IMPORTANCE ZIKV isolates are classified under African or Asian lineages. Infection with emerging Asian lineage-derived ZIKV strains is associated with increased incidence of neurological symptoms that were not previously reported during infection with African or preemergent Asian lineage viruses. In this study, we utilized in vitro models to compare the virologic properties of and innate immune responses to two prototypic ZIKV strains from distinct lineages: African lineage ZIKV/Dakar and Asian lineage ZIKV/Malaysia. Compared to ZIKV/Dakar, ZIKV/Malaysia accumulates viral proteins earlier, replicates to higher levels, and robustly blocks IFN signaling during acute infection. Early accumulation of ZIKV/Malaysia NS5 protein confers enhanced ability to antagonize IFN signaling, dampening innate immune responses to promote viral spread. Our data identify the kinetics of viral protein accumulation as a major regulator of host innate immunity, influencing host-mediated control of ZIKV replication and spread. Importantly, these findings provide a novel framework for evaluating the virulence of emerging variants.