Zika Virus: An Emerging Global Health Threat

Neurological manifestations of Flaviviridae, Togaviridae, and Peribunyaviridae as vector-borne viruses

Vector-borne viruses pose a significant health problem worldwide, as they are transmitted to humans through the bite of infected arthropods such as mosquitoes and ticks. In recent years, emerging and re-emerging vector-borne diseases have gained attention as they can cause a wide spectrum of neurological manifestations. The neurological manifestations of vector-borne viruses encompass a board spectrum of clinical manifestations, ranging from mild and self-limiting symptoms to severe and life-threatening conditions. Common neurological complications include viral encephalitis, acute flaccid paralysis, aseptic meningitis, and various neuromuscular disorders. The specific viruses responsible for these neurological sequelae vary by geographic region and include Orthoflavivirus nilense, Zika virus, dengue virus, chikungunya virus, Japanese encephalitis virus, and tick-borne encephalitis virus. This review focuses on the pathogenesis of these neurologic complications and highlights the mechanisms by which vector-borne viruses invade the central nervous system and trigger neuroinflammatory responses. Diagnostic challenges and strategies for early detection of neurological manifestations are discussed, emphasising the importance of clinical suspicion and advanced laboratory testing.

Human otic progenitor cell models of congenital hearing loss reveal potential pathophysiologic mechanisms of Zika virus and cytomegalovirus infections

Congenital hearing loss is a common chronic condition affecting children in both developed and developing nations. Viruses correlated with congenital hearing loss include human cytomegalovirus (HCMV) and Zika virus (ZIKV), which causes congenital Zika syndrome. The mechanisms by which HCMV and ZIKV infections cause hearing loss are poorly understood. It is challenging to study human inner ear cells because they are encased in bone and also scarce as autopsy samples. Recent advances in culturing human stem cell-derived otic progenitor cells (OPCs) have allowed us herein to describe successful in vitro infection of OPCs with HCMV and ZIKV, and also to propose potential mechanisms by which each viral infection could affect hearing. We find that ZIKV infection rapidly and significantly induces the expression of type I interferon and interferon-stimulated genes, while OPC viability declines, at least in part, from apoptosis. In contrast, HCMV infection did not appear to upregulate interferons or cause a reduction in cell viability, and instead disrupted expression of key genes and pathways associated with inner ear development and function, including Cochlin, nerve growth factor receptor, SRY-box transcription factor 11, and transforming growth factor-beta signaling. These findings suggest that ZIKV and HCMV infections cause congenital hearing loss through distinct pathways, that is, by inducing progenitor cell death in the case of ZIKV infection, and by disruption of critical developmental pathways in the case of HCMV infection.

IMPORTANCE

Congenital virus infections inflict substantial morbidity and devastating disease in neonates worldwide, and hearing loss is a common outcome. It has been difficult to study viral infections of the human hearing apparatus because it is embedded in the temporal bone of the skull. Recent technological advances permit the differentiation of otic progenitor cells (OPCs) from human-induced pluripotent stem cells. This paper is important for demonstrating that inner ear virus infections can be modeled in vitro using OPCs. We infected OPCs with two viruses associated with congenital hearing loss: human cytomegalovirus (HCMV), a DNA virus, or Zika virus (ZIKV), an RNA virus. An important result is that the gene expression and cytokine production profiles of HCMV/ZIKV-infected OPCs are markedly dissimilar, suggesting that mechanisms of hearing loss are also distinct. The specific molecular regulatory pathways identified in this work could suggest important targets for therapeutics.

Zika Virus: A Neurotropic Warrior against High-Grade Gliomas-Unveiling Its Potential for Oncolytic Virotherapy

Gliomas account for approximately 75-80% of all malignant primary tumors in the central nervous system (CNS), with glioblastoma multiforme (GBM) considered the deadliest. Despite aggressive treatment involving a combination of chemotherapy, radiotherapy, and surgical intervention, patients with GBM have limited survival rates of 2 to 5 years, accompanied by a significant decline in their quality of life. In recent years, novel management strategies have emerged, such as immunotherapy, which includes the development of vaccines or T cells with chimeric antigen receptors, and oncolytic virotherapy (OVT), wherein wild type (WT) or genetically modified viruses are utilized to selectively lyse tumor cells. In vitro and in vivo studies have shown that the Zika virus (ZIKV) can infect glioma cells and induce a robust oncolytic activity. Consequently, interest in exploring this virus as a potential oncolytic virus (OV) for high-grade gliomas has surged. Given that ZIKV actively circulates in Colombia, evaluating its neurotropic and oncolytic capabilities holds considerable national and international importance, as it may emerge as an alternative for treating highly complex gliomas. Therefore, this literature review outlines the generalities of GBM, the factors determining ZIKV's specific tropism for nervous tissue, and its oncolytic capacity. Additionally, we briefly present the progress in preclinical studies supporting the use of ZIKV as an OVT for gliomas.

Re-mining serum proteomics data reveals extensive post-translational modifications upon Zika and dengue infection

Zika virus (ZIKV) and dengue virus (DENV) are two closely related flaviviruses with similar symptoms. However, due to the implications of ZIKV infections for pregnancy outcomes, understanding differences in their molecular impact on the host is of high interest. Viral infections change the host proteome, including post-translational modifications. As modifications are diverse and of low abundance, they typically require additional sample processing which is not feasible for large cohort studies. Therefore, we tested the potential of next-generation proteomics data in its ability to prioritize specific modifications for later analysis. We re-mined published mass spectra from 122 serum samples from ZIKV and DENV patients for the presence of phosphorylated, methylated, oxidized, glycosylated/glycated, sulfated, and carboxylated peptides. We identified 246 modified peptides with significantly differential abundance in ZIKV and DENV patients. Amongst these, methionine-oxidized peptides from apolipoproteins and glycosylated peptides from immunoglobulin proteins were more abundant in ZIKV patient serum and generate hypotheses on the potential roles of the modification in the infection. The results demonstrate how data-independent acquisition techniques can help prioritize future analyses of peptide modifications.

Seroprevalence of high incidence congenital infections among pregnant women in Coatepeque, Guatemala and surrounding areas, 2017-2018

Maternal infections during pregnancy can potentially cause birth defects and severe adverse effects in infants. From 2017 to 2018, we investigated the seroprevalence of five antibodies among 436 mother-infant pairs enrolled in a pregnancy cohort study in Coatepeque, Guatemala. Upon enrollment (< 20 weeks gestational age) and shortly after delivery, we measured the prevalence of IgG and IgM antibodies against Toxoplasma gondii (T. gondii), rubella, and cytomegalovirus (CMV) in mothers and newborns and used rapid tests to detect HIV and syphilis (Treponema pallidum) in mothers. The mean cohort age was 24.5 years. Maternal T. gondii IgM and IgG seropositivity was 1.9% and 69.7%, respectively. No women were positive for HIV, syphilis, or rubella IgM. Maternal rubella IgG seropositivity was 80.8% and significantly increased with age. Maternal CMV IgM and IgG seropositivity were 2.3% and 99.5%, respectively. Of the 323 women tested at both timepoints, IgM reactivation occurred in one woman for T. gondii infection and in eight for CMV. No newborn was seropositive for CMV IgM or rubella IgM. One newborn was seropositive for T. gondii IgM. Congenital T. gondii and CMV infections are important public health issues for pregnant women, newborns, and healthcare providers in Coatepeque and Guatemala.

MEK/ERK activation plays a decisive role in Zika virus morphogenesis and release

Brazil has experienced an increase in outbreaks caused by flaviviruses. The high incidence of dengue fever, the morbidity of Zika in children, and the high mortality of yellow fever have affected millions in recent years. Deciphering host-virus interactions is important for treating viral infections, and the mitogen-activated protein kinases (MAPK) are an interesting target because of their role in flavivirus replication. In particular, mitogen-activated protein kinase kinase (MEK), which targets extracellular-signal-regulated kinase (ERK), is necessary for dengue and yellow fever infections. In this study, we evaluated the role of the MEK/ERK pathway and the effect of the MEK inhibitor trametinib on the Asian ZIKV strain PE243 and the prototype African ZIKV strain MR766, addressing genome replication, morphogenesis, and viral release. ZIKV infection stimulated ERK phosphorylation in Vero cells at 12 and 18 hours postinfection (hpi). Trametinib showed sustained antiviral activity, inhibiting both ZIKV strains for at least four days, and electron microscopy showed probable inhibition of ZIKV morphogenesis. ZIKV PE243 can complete one cycle in Vero cells in 14 hours; genome replication was detected around 8 hpi, intracellular viral particles at 12 hpi, and extracellular progeny at 14 hpi. Treatments at 6-hour intervals showed that trametinib inhibited late stages of viral replication, and the titration of intra- or extracellular virions showed that the treatment especially affected viral morphogenesis and release. Thus, ZIKV stimulated ERK phosphorylation during viral morphogenesis and release, which correlated with trametinib inhibiting both the signaling pathway and viral replication.

The Zika virus: an opportunity to revisit reproductive health needs and disparities

First isolated in 1947, the Zika virus was initially connected only to limited or sporadic human infections. In late 2015, the temporal clustering of a Zika outbreak and microcephaly in newborn babies from northeastern Brazil, and the identification of a causal link between the two, led to the characterization of the congenital Zika syndrome. In the wake of the epidemic, several countries from Latin America advised women to postpone pregnancies for periods ranging from six months to two years. These recommendations initiated critical conversations about the challenges of implementing them in societies with limited access to contraception, widespread socioeconomic inequalities, and high rates of unplanned and adolescent pregnancies. The messaging targeted exclusively women, despite a high prevalence of imbalances in the relationship power, and addressed all women as a group, failing to recognize that the decision to postpone pregnancies will impact different women in different ways, depending on their age at the time. Finally, in several countries affected by the Zika epidemic, due to restrictive reproductive policies, legally terminating a pregnancy is no longer an option even at the earliest time when brain malformations as part of the congenital Zika syndrome can be detected by ultrasonography. The virus continued to circulate after 2016 in several countries. Climate change models predict an expansion of the geographical area where local Zika transmission may occur, indicating that the interface between the virus, teratogenesis, and reproductive rights is a topic of considerable interest for medicine, social sciences, and public health for years to come.

Modeling infectious diseases of the central nervous system with human brain organoids

Bacteria, fungi, viruses, and protozoa are known to infect and induce diseases in the human central nervous system (CNS). Modeling the mechanisms of interaction between pathogens and the CNS microenvironment is essential to understand their pathophysiology and develop new treatments. Recent advancements in stem cell technologies have allowed for the creation of human brain organoids, which more closely resembles the human CNS microenvironment when compared to classical 2-dimensional (2D) cultures. Now researchers can utilize these systems to investigate and reinvestigate questions related to CNS infection in a human-derived brain organoid system. Here in this review, we highlight several infectious diseases which have been tested in human brain organoids and compare similarities in response to these pathogens across different investigations. We also provide a brief overview of some recent advancements which can further enrich this model to develop new and better therapies to treat brain infections.

Human Testicular Germ Cells, a Reservoir for Zika Virus, Lack Antiviral Response Upon Zika or Poly(I:C) Exposure

Zika virus (ZIKV) is an emerging teratogenic arbovirus that persists in semen and is sexually transmitted. We previously demonstrated that ZIKV infects the human testis and persists in testicular germ cells (TGCs) for several months after patients’ recovery. To decipher the mechanisms underlying prolonged ZIKV replication in TGCs, we compared the innate immune response of human testis explants and isolated TGCs to ZIKV and to Poly(I:C), a viral RNA analog. Our results demonstrate the weak innate responses of human testis to both ZIKV and Poly(I:C) as compared with other tissues or species. TGCs failed to up-regulate antiviral effectors and type I IFN upon ZIKV or Poly(I:C) stimulation, which might be due to a tight control of PRR signaling, as evidenced by the absence of activation of the downstream effector IRF3 and elevated expression of repressors. Importantly, exogenous IFNβ boosted the innate immunity of TGCs and inhibited ZIKV replication in the testis ex vivo, raising hopes for the prevention of ZIKV infection and persistence in this organ.

Cranberry Pomace Extract Exerts Antiviral Activity against Zika and Dengue Virus at Safe Doses for Adult Zebrafish

Mosquito-borne dengue virus (DENV) and zika virus (ZIKV) infections constitute a global health emergency. Antivirals directly targeting the virus infectious cycle are still needed to prevent dengue hemorrhagic fever and congenital zika syndrome. In the present study, we demonstrated that Cranberry Pomace (CP) extract, a polyphenol-rich agrifood byproduct recovered following cranberry juice extraction, blocks DENV and ZIKV infection in human Huh7.5 and A549 cell lines, respectively, in non-cytotoxic concentrations. Our virological assays identified CP extract as a potential inhibitor of virus entry into the host-cell by acting directly on viral particles, thus preventing their attachment to the cell surface. At effective antiviral doses, CP extract proved safe and tolerable in a zebrafish model. In conclusion, polyphenol-rich agrifood byproducts such as berry extracts are a promising source of safe and naturally derived nutraceutical antivirals that target medically important pathogens.

ML-SA1 and SN-2 inhibit endocytosed viruses through regulating TRPML channel expression and activity

Transient receptor potential mucolipin 2 and 3 (TRPML2 and TRPML3), as key channels in the endosomal-lysosomal system, are associated with many different cellular processes, including ion release, membrane trafficking and autophagy. In particular, they can also facilitate viral entry into host cells and enhance viral infection. We previously identified that two selective TRPML agonists, ML-SA1 and SN-2, that showed antiviral activities against dengue virus type 2 (DENV2) and Zika virus (ZIKV) in vitro, but their antiviral mechanisms are still elusive. Here, we reported that ML-SA1 could inhibit DENV2 replication by downregulating the expression of both TRPML2 and TRPML3, while the other TRPML activator, SN-2, suppressed DENV2 infection by reducing only TRPML3 expression. Consistently, the channel activities of both TRPML2 and TRPML3 were also found to be associated with the antiviral activity of ML-SA1 on DENV2 and ZIKV, but SN-2 relied only on TRPML3 channel activity. Further mechanistic experiments revealed that ML-SA1 and SN-2 decreased the expression of the late endosomal marker Rab7, dependent on TRPML2 and TRPML3, indicating that these two compounds likely inhibit viral infection by promoting vesicular trafficking from late endosomes to lysosomes and then accelerating lysosomal degradation of the virus. As expected, neither ML-SA1 nor SN-2 inhibited herpes simplex virus type I (HSV-1), whose entry is independent of the endolysosomal network. Together, our work reveals the antiviral mechanisms of ML-SA1 and SN-2 in targeting TRPML channels, possibly leading to the discovery of new drug candidates to inhibit endocytosed viruses.

Cell membrane skeletal protein 4.1R participates in entry of Zika virus into cells

Zika virus (ZIKV) is a typical mosquito-borne flavivirus known to cause severe fetal microcephaly and adult Guillain-Barré syndrome. Currently, there are no specific drugs or licensed vaccines available for ZIKV infection, and further research is required to identify host cell proteins involved in the virus's life cycle. Viruses are known to use host cell membrane skeletal proteins, such as actin and spectrin, to complete cell entry, transportation, and release. Here, based on immunoprecipitation, the Axl and ZIKV envelope (E) protein were shown to interact with the cell membrane skeleton protein 4.1R. Furthermore, deletion of 4.1R significantly reduced virus titer and viral protein synthesis. Our study showed that 4.1R is an important host cell protein during ZIKV infection and may be involved in the process of viral entry into host cells.

A methanol extract and N,N-dimethyltryptamine from Psychotria viridis Ruiz & Pav. inhibit Zika virus infection in vitro

Zika virus (ZIKV) is a public health problem due to its association with serious fetal and neurological complications and the lack of antiviral agents and licensed vaccines against this virus. Surveillance studies have alerted about the potential occurrence of a new South American epidemic episode due to the recent circulation of an African ZIKV strain detected in Brazil. Therefore, it is essential to discover antiviral agents, including natural substances, that are capable of neutralizing the action of ZIKV. Several Psychotria species have antimicrobial and anti-inflammatory properties. Thus, a methanol extract and dimethyltryptamine from Psychotria viridis were evaluated for their ability to inhibit ZIKV infection in vitro by measuring the effective concentration that protects 50% of cells and investigating their possible mechanisms of action. The tested samples showed antiviral activity against ZIKV. The extract showed virucidal activity, affecting viral and non-cellular elements, inactivating the virus before infection or when it becomes extracellular after the second cycle of infection. It was also observed that both extract and dimethyltryptamine could inhibit the virus at intracellular stages of the viral cycle. In addition to dimethyltryptamine, it is believed that other compounds also contribute to the promising virucidal effect observed for the methanol extract. To our knowledge, this is the first report of the activity of a methanolic extract and dimethyltryptamine from Psychotria viridis against cellular ZIKV infection. These two samples, extracted from natural sources, are potential candidates for use as antiviral drugs to inhibit ZIKV infections.

Identification and Characterization of Zika Virus NS5 Methyltransferase Inhibitors

The recurring outbreak of Zika virus (ZIKV) worldwide makes an emergent demand for novel, safe and efficacious anti-ZIKV agents. ZIKV non-structural protein 5 (NS5) methyltransferase (MTase), which is essential for viral replication, is regarded as a potential drug target. In our study, a luminescence-based methyltransferase assay was used to establish the ZIKV NS5 MTase inhibitor screening model. Through screening a natural product library, we found theaflavin, a polyphenol derived from tea, could inhibit ZIKV NS5 MTase activity with a 50% inhibitory concentration (IC₅₀) of 10.10 μM. Molecular docking and site-directed mutagenesis analyses identified D146 as the key amino acid in the interaction between ZIKV NS5 MTase and theaflavin. The SPR assay indicated that theaflavin had a stronger binding activity with ZIKV NS5 wild-type (WT)-MTase than it with D146A-MTase. Moreover, theaflavin exhibited a dose dependent inhibitory effect on ZIKV replication with a 50% effective concentration (EC₅₀) of 8.19 μM. All these results indicate that theaflavin is likely to be a promising lead compound against ZIKV.

The impact of SARS-CoV-2 and COVID-19 on male reproduction and men's health

Many couples initially deferred attempts at pregnancy or delayed fertility care due to concerns about coronavirus disease 2019 (COVID-19). One significant fear during the COVID-19 pandemic was the possibility of sexual transmission. Many couples have since resumed fertility care while accepting the various uncertainties associated with severe acute respiratory syndrome coronavirus 2, including the evolving knowledge related to male reproductive health. Significant research has been conducted exploring viral shedding, tropism, sexual transmission, the impact of male reproductive hormones, and possible implications to semen quality. However, to date, limited definitive evidence exists regarding many of these aspects, creating a challenging landscape for both patients and physicians to obtain and provide the best clinical care. This review provides a comprehensive assessment of the evolving literature concerning COVID-19 and male sexual and reproductive health, and guidance for patient counseling.

Evaluation of kinase inhibitors as potential therapeutics for flavivirus infections

The recent introduction of Zika virus (ZIKV), the recurrence of dengue virus (DENV), and the lethality of yellow fever virus (YFV) have had a significant impact on Brazilian society and public health. Here, we targeted two cellular kinases implicated in cell proliferation and cancer that are also important for viral replication: mitogen-activated protein kinase kinase (MEK) and Src. We used two MEK inhibitors - trametinib and selumetinib - and two Src inhibitors - saracatinib and bosutinib - to inhibit ZIKV, DENV, and YFV replication in cell culture. The cytotoxicity of the four inhibitors was determined by the observation of abnormal morphology and quantification of adherent cells by crystal violet staining. The antiviral activity of these drugs was assessed based on the reduction of plaque-forming units in cell culture as evidence of the inhibition of the replication of the selected flaviviruses. All four inhibitors showed antiviral activity, but among them, trametinib was the safest and most efficacious against all of the viruses, inhibiting the replication of ZIKV and YFV by 1000-fold, and DENV2/3 by nearly 100-fold. This pan-antiviral effect shows that trametinib could be repurposed for the treatment of flaviviral infections.

Zika virus infection induces endoplasmic reticulum stress and apoptosis in placental trophoblasts

Zika virus (ZIKV) infection to a pregnant woman can be vertically transmitted to the fetus via the placenta leading to Congenital Zika syndrome. This is characterized by microcephaly, retinal defects, and intrauterine growth retardation. ZIKV induces placental trophoblast apoptosis leading to severe abnormalities in the growth and development of the fetus. However, the molecular mechanism behind ZIKV-induced apoptosis in placental trophoblasts remains unclear. We hypothesize that ZIKV infection induces endoplasmic reticulum (ER) stress in the trophoblasts, and sustained ER stress results in apoptosis. HTR-8 (HTR-8/SVneo), a human normal immortalized trophoblast cell and human choriocarcinoma-derived cell lines (JEG-3 and JAR) were infected with ZIKV. Biochemical and structural markers of apoptosis like caspase 3/7 activity and percent apoptotic nuclear morphological changes, respectively were assessed. ZIKV infection in placental trophoblasts showed an increase in the levels of CHOP mRNA and protein expression, which is an inducer of apoptosis. Next, we also observed increased levels of ER stress markers such as phosphorylated forms of inositol-requiring transmembrane kinase/endoribonuclease 1α (P-IRE1α), and its downstream target, the spliced form of XBP1 mRNA, phosphorylated eukaryotic initiation factor 2α (P-eIF2α), and activation of cJun N-terminal Kinase (JNK) and p38 mitogen activated protein kinase (MAPK) after 16-24 h of ZIKV infection in trophoblasts. Inhibition of JNK or pan-caspases using small molecule inhibitors significantly prevented ZIKV-induced apoptosis in trophoblasts. Further, JNK inhibition also reduced XBP1 mRNA splicing and viral E protein staining in ZIKV infected cells. In conclusion, the mechanism of ZIKV-induced placental trophoblast apoptosis involves the activation of ER stress and JNK activation, and the inhibition of JNK dramatically prevents ZIKV-induced trophoblast apoptosis.

In Silico Analysis of Possible Interaction between Host Genomic Transcription Factors (TFs) and Zika Virus (ZikaSPH2015) Strain with Combinatorial Gene Regulation; Virus Versus Host-The Game Reloaded

In silico analysis is a promising approach for understanding biological events in complex diseases. Herein we report on the innovative computational workflow allowed to highlight new direct interactions between human transcription factors (TFs) and an entire genome of virus ZikaSPH2015 strain in order to identify the occurrence of specific motifs on a genomic Zika Virus sequence that is able to bind and, therefore, sequester host’s TFs. The analysis pipeline was performed using different bioinformatics tools available online (free of charge). According to obtained results of this in silico analysis, it is possible to hypothesize that these TFs binding motifs might be able to explain the complex and heterogeneous phenotype presentation in Zika-virus-affected fetuses/newborns, as well as the less severe condition in adults. Moreover, the proposed in silico protocol identified thirty-three different TFs identical to the distribution of TFBSs (Transcription Factor Binding Sites) on ZikaSPH2015 strain, potentially able to influence genes and pathways with biological functions confirming that this approach could find potential answers on disease pathogenesis.

The Antimalarial Compound Atovaquone Inhibits Zika and Dengue Virus Infection by Blocking E Protein-Mediated Membrane Fusion

Flaviviruses bear class II fusion proteins as their envelope (E) proteins. Here, we describe the development of an in vitro quantitative mosquito-cell-based membrane-fusion assay for the E protein using dual split proteins (DSPs). The assay does not involve the use of live viruses and allows the analysis of a membrane-fusion step independent of other events in the viral lifecycle, such as endocytosis. The progress of membrane fusion can be monitored continuously by measuring the activities of Renilla luciferase derived from the reassociation of DSPs during cell fusion. We optimized the assay to screen an FDA-approved drug library for a potential membrane fusion inhibitor using the E protein of Zika virus. Screening results identified atovaquone, which was previously described as an antimalarial agent. Atovaquone potently blocked the in vitro Zika virus infection of mammalian cells with an IC₉₀ of 2.1 µM. Furthermore, four distinct serotypes of dengue virus were also inhibited by atovaquone with IC₉₀ values of 1.6–2.5 µM, which is a range below the average blood concentration of atovaquone after its oral administration in humans. These findings make atovaquone a likely candidate drug to treat illnesses caused by Zika as well as dengue viruses. Additionally, the DSP assay is useful to study the mechanism of membrane fusion in Flaviviruses.

Burn injury induces elevated inflammatory traffic: the role of NF-κB

A burn insult generally sustains a hypovolemic shock due to a significant loss of plasma from the vessels. The burn injury triggers the release of various mediators, such as reactive oxygen species (ROS), cytokines, and inflammatory mediators. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), stemming from foreign microbial discharge and damaged tissue or necrotic cells from the burn-injured site, enter the systemic circulation, activate toll-like receptors (TLRs), and trigger the excessive secretion of cytokines and inflammatory mediators. Inflammation plays a vital role in remodeling an injured tissue, detoxifying toxins, and helps in the healing process. A transcription factor, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), contributes to a variety of physiological and pathological conditions, including immune response, cell death, cell survival, and inflammatory processes. During the pathogenesis of a burn wound, upregulation of various cytokines and growth factors lead to undesirable tissue inflammation. Thus, NF-κB, a dominant moderator of inflammation, needs to be altered to prove beneficial to the treatment of burns or other inflammation-associated diseases. This review addresses the relationship between NF-κB and elevated inflammation in a burn condition that could potentially be altered to induce an early wound-healing mechanism of burn wounds.

Dengue and Zika Viruses: Epidemiological History, Potential Therapies, and Promising Vaccines

Dengue virus (DENV), which can lead to fatal hemorrhagic fever, affects 390 million people worldwide. The closely related Zika virus (ZIKV) causes microcephaly in newborns and Guillain-Barré syndrome in adults. Both viruses are mostly transmitted by Aedes albopictus and Aedes aegypti mosquitoes, which, due to globalization of trade and travel alongside climate change, are spreading worldwide, paving the way to DENV and ZIKV transmission and the occurrence of new epidemics. Local outbreaks have already occurred in temperate climates, even in Europe. As there are no specific treatments, these viruses are an international public health concern. Here, we analyze and discuss DENV and ZIKV outbreaks history, clinical and pathogenesis features, and modes of transmission, supplementing with information on advances on potential therapies and restraining measures. Taking advantage of the knowledge of the structure and biological function of the capsid (C) protein, a relatively conserved protein among flaviviruses, within a genus that includes DENV and ZIKV, we designed and patented a new drug lead, pep14-23 (WO2008/028939A1). It was demonstrated that it inhibits the interaction of DENV C protein with the host lipid system, a process essential for viral replication. Such an approach can be used to develop new therapies for related viruses, such as ZIKV.

Papaya Fruit Pulp and Resulting Lactic Fermented Pulp Exert Antiviral Activity against Zika Virus

There are a several emerging and re-emerging RNA viruses that are prevalent around the world for which there are no licensed vaccines or antiviral drugs. Zika virus (ZIKV) is an example of an emerging virus that has become a significant concern worldwide because of its association with severe congenital malformations and neurological disorders in adults. Several polyphenol-rich extracts from plants were used as nutraceuticals which exhibit potent in vitro antiviral effects. Here, we demonstrated that the papaya pulp extracted from Carica papaya fruit inhibits the infection of ZIKV in human cells without loss of cell viability. At the non-cytotoxic concentrations, papaya pulp extract has the ability to reduce the virus progeny production in ZIKV-infected human cells by at least 4-log, regardless of viral strains tested. Time-of-drug-addition assays revealed that papaya pulp extract interfered with the attachment of viral particles to the host cells. With a view of preserving the properties of papaya pulp over time, lactic fermentation based on the use of bacterial strains Weissella cibaria 64, Lactobacillus plantarum 75 and Leuconostoc pseudomesenteroides 56 was performed and the resulting fermented papaya pulp samples were tested on ZIKV. We found that lactic fermentation of papaya pulp causes a moderate loss of antiviral activity against ZIKV in a bacterial strain-dependent manner. Whereas IC₅₀ of the papaya pulp extract was 0.3 mg/mL, we found that fermentation resulted in IC₅₀ up to 4 mg/mL. We can conclude that papaya pulp possesses antiviral activity against ZIKV and the fermentation process has a moderate effect on the antiviral effect.

Investigating the utility of Google trends for Zika and Chikungunya surveillance in Venezuela

INTRODUCTION

Chikungunya and Zika Virus are vector-borne diseases responsible for a substantial disease burden in the Americas. Between 2013 and 2016, no cases of Chikungunya or Zika Virus were reported by the Venezuelan Ministry of Health. However, peaks of undiagnosed fever cases have been observed during the same period. In the context of scarce data, alternative surveillance methods are needed. Assuming that unusual peaks of acute fever cases correspond to the incidences of both diseases, this study aims to evaluate the use of Google Trends as an indicator of the epidemic behavior of Chikungunya and Zika.

METHODS

Time-series cross-correlations of acute fever cases reported by the Venezuelan Ministry of Health and data on Google search queries related to Chikungunya and Zika were calculated.

RESULTS

A temporal distinction has been made so that acute febrile cases occurring between 25th of June 2014 and 23rd of April 2015 were attributed to the Chikungunya virus, while cases occurring between 30th of April 2015 and 29th of April 2016 were ascribed to the Zika virus. The highest cross-correlations for each disease were shown at a lag of 0 (r = 0.784) for Chikungunya and at + 1 (r = 0.754) for Zika.

CONCLUSION

The strong positive correlation between Google search queries and official data on acute febrile cases suggests that this resource can be used as an indicator of endemic urban arboviruses activity. In the Venezuelan context, Internet search queries might help to overcome some of the gaps that exist in the national surveillance system.

Glucose-Regulated Protein 78 Interacts with Zika Virus Envelope Protein and Contributes to a Productive Infection

Zika virus (ZIKV; Flaviviridae) is a mosquito-borne flavivirus shown to cause fetal abnormalities collectively known as congenital Zika syndrome and Guillain-Barré syndrome in recent outbreaks. Currently, there is no specific treatment or vaccine available, and more effort is needed to identify cellular factors in the viral life cycle. Here, we investigated interactors of ZIKV envelope (E) protein by combining protein pull-down with mass spectrometry. We found that E interacts with the endoplasmic reticulum (ER) resident chaperone, glucose regulated protein 78 (GRP78). Although other flaviviruses are known to co-opt ER resident proteins, including GRP78, to enhance viral infectivity, the role ER proteins play during the ZIKV life cycle is yet to be elucidated. We showed that GRP78 levels increased during ZIKV infection and localised to sites coincident with ZIKV E staining. Depletion of GRP78 using specific siRNAs significantly reduced reporter-virus luciferase readings, viral protein synthesis, and viral titres. Additionally, GRP78 depletion reduced the ability of ZIKV to disrupt host cell translation and altered the localisation of viral replication factories, though there was no effect on viral RNA synthesis. In summary, we showed GRP78 is a vital host-factor during ZIKV infection, which may be involved in the coordination of viral replication factories.

The Mechanism of the Zika Virus Crossing the Placental Barrier and the Blood-Brain Barrier

Zika virus (ZIKV) infection causes severe neurological symptoms in adults and fetal microcephaly and the virus is detected in the brain of microcephaly and meningoencephalitis patient. However, the mechanism of ZIKV crossing the physiological barrier to the central nervous systems (CNS) remains elusive. The placental barrier and the blood brain barrier (BBB) protect the fetus from pathogens and ensure healthy brain development during pregnancy. In this study, we used human placenta trophoblasts cells (JEG-3) and human brain-derived endothelial cells (hCMEC/D3) as in vitro models of the physiological barriers. Results showed that ZIKV could infect JEG-3 cells effectively and reduce the amounts of ZO-1 and occludin between adjacent cells by the proteasomal degradation pathway, suggesting that the permeability of the barrier differentially changed in response to ZIKV infection, allowing the virus particle to cross the host barrier. In contrast, ZIKV could infect hCMEC/D3 cells without disrupting the BBB barrier permeability and tight junction protein expression. Although no disruption to the BBB was observed during ZIKV infection, ZIKV particles were released on the basal side of the BBB model and infected underlying cells. In addition, we observed that fluorescence-labeled ZIKV particles could cross the in vitro placenta barrier and BBB model by transcytosis and the action of transcytosis could be blocked by either low temperature or pharmacological inhibitors of endocytosis. In summary, the ZIKV uses a cell-type specific paracellular pathway to cross the placenta monolayer barrier by disrupting cellular tight junction. In addition, the ZIKV can also cross both the placenta barrier and the BBB by transcytosis. Our study provided new insights into on the mechanism of the cellular barrier penetration of ZIKV particles.

Can in utero Zika virus exposure be a risk factor for schizophrenia in the offspring?

Objectives: Schizophrenia is a severe psychiatric illness that has been purported to be causally related to in utero infection of neurotropic organisms. For obvious ethical reasons, this hypothesis has never been tested prospectively in humans. However, with the recent introduction of Zika virus into the New World offers the opportunity to test the hypothesis of infection in schizophrenia.Methods: This is a directed review examining the hypothesis. The literature relevant to Zika virus transmission in the New World, its biology and neurotropy is reviewed.Results: Zika virus has been associated with a wide variety of neural tube and neuroanatomical abnormalities. In its original range, Zika is only infrequently associated with congenital anomalies, but in the New World, where the majority of the population has not developed immunity, infections are associated with a wide range of neurologic abnormalities.Conclusions: The current outbreak of Zika virus in the Western Hemisphere, offers the opportunity to prospectively examine the congenital infection hypothesis of the pathogenesis of schizophrenia.

Zika virus: A possible emerging threat for Bangladesh!

Zika virus, a member of Flaviviridae is the etiology of Zika or Zika fever or Zika virus (ZIKV) disease characterized by mild symptoms similar to very mild form of Dengue or Chikungunya. The virus transmits through Aedes mosquitoes, particularly by Aedes aegypti. The most dangerous effect of ZIKV infection is the ability of the virus to cause microcephaly and congenital malformation to the newborn baby if the mother is infected. The neurological disorders including Guillain-Barré syndrome might be associated with adults and children due to ZIKV infections. Zika has emerged as a serious global public health problem as it has been found in 87 countries, particularly in Africa, America, and Asia and has no vaccine and treatment so far. Bangladesh is at a high risk of ZIKV infection and we consider ZIKV as a possible emerging threat for Bangladesh. This short review summarizes the insights of ZIKV infection, present status of the disease in Bangladesh and its neighboring countries, and recommendations for necessary preparations and strategies to be taken for effective controlling of the ZIKV infection in Bangladesh before getting any havoc.

Human Antimicrobial Peptides as Therapeutics for Viral Infections

Successful in vivo infection following pathogen entry requires the evasion and subversion of multiple immunological barriers. Antimicrobial peptides (AMPs) are one of the first immune pathways upregulated during infection by multiple pathogens, in multiple organs in vivo. In humans, there are many classes of AMPs exhibiting broad antimicrobial activities, with defensins and the human cathelicidin LL-37 being the best studied examples. Whereas historically the efficacy and therapeutic potential of AMPs against bacterial infection has been the primary focus of research, recent studies have begun to elucidate the antiviral properties of AMPs as well as their role in regulation of inflammation and chemoattraction. AMPs as therapeutic tools seem especially promising against emerging infectious viral pathogens for which no approved vaccines or treatments are currently available, such as dengue virus (DENV) and Zika virus (ZIKV). In this review, we summarize recent studies elucidating the efficacy and diverse mechanisms of action of various classes of AMPs against multiple viral pathogens, as well as the potential use of human AMPs in novel antiviral therapeutic strategies.

In Vitro Antiviral Activity Against Zika Virus From a Natural Product of the Brazilian Brown Seaweed Dictyota menstrualis

Natural products isolated from seaweeds have shown great antiviral potential against numerous viruses such as human type 1 herpes, human immunodeficiency virus, and dengue. Diterpenes produced by the brown seaweeds Dictyota and Canistrocarpus, in particular, have shown antiviral or virucidal activity. Recently, the Zika virus (ZIKV) has become a major public health concern due to its widespread dissemination throughout the Americas. Since no vaccines are available, and no drugs have effectively treated recent cases of infection, our group evaluated products from Dictyota menstrualis for their antiviral potential, alone and in combination with Ribavirin. We first evaluated the compounds’ cytotoxicity at high concentrations, and then evaluated the inhibition of ZIKV replication by crude extracts and acetylated crude extracts and their fractions at 20 μg/mL. The F-6 and FAc-2 fractions, rich in cyclic diterpenes with aldehyde groupings, inhibited ZIKV replication by >74%, with inhibition behaving in a dose-dependent manner and the 50% effective concentration (EC50) values of 2.80 (F-6) and 0.81 (FAc-2) μg/mL. Regarding the mechanism of action, FAc-2 had strong virucidal potential, and F-6 inhibited viral adsorption. Associating FAc-2 with Ribavirin at suboptimal dosages produced a strong synergistic effect that completely inhibited viral replication. Our results indicate that these natural products have excellent inhibitory potential against ZIKV replication and may be promising for developing affective therapies.

Viral threat to male fertility

The detrimental effects of Zika virus (ZIKV) infection on mouse testicular functions have reminded a viral threat to male fertility. A broad range of virus families has tropism for male reproductive system, particularly the testes. Certain virus types of these viruses, such as mumps virus and human immunodeficiency virus (HIV), may severely damage the testes and consequently lead to male infertility. ZIKV has been recently found to damage testicular functions and lead to male infertility in mice. Many other viruses also have detrimental effects on host reproduction. Public attention has been paid to sexually transmitted viruses, such as HIV and hepatitis B and C viruses in humans and likewise in economically important farm animals. This article provides an overview on main viruses affecting the male reproductive system and their detrimental effects on fertility, and outlines some important issues for future study.

Doratoxylon apetalum, an Indigenous Medicinal Plant from Mascarene Islands, Is a Potent Inhibitor of Zika and Dengue Virus Infection in Human Cells

Zika virus (ZIKV) and Dengue virus (DENV) are mosquito-borne viruses of the Flavivirus genus that could cause congenital microcephaly and hemorrhage, respectively, in humans, and thus present a risk to global public health. A preventive vaccine against ZIKV remains unavailable, and no specific antiviral drugs against ZIKV and DENV are licensed. Medicinal plants may be a source of natural antiviral drugs which mostly target viral entry. In this study, we evaluate the antiviral activity of Doratoxylum apetalum, an indigenous medicinal plant from the Mascarene Islands, against ZIKV and DENV infection. Our data indicated that D. apetalum exhibited potent antiviral activity against a contemporary epidemic strain of ZIKV and clinical isolates of four DENV serotypes at non-cytotoxic concentrations in human cells. Time-of-drug-addition assays revealed that D. apetalum extract acts on ZIKV entry by preventing the internalisation of virus particles into the host cells. Our data suggest that D. apetalum-mediated ZIKV inhibition relates to virus particle inactivation. We suggest that D. apetalum could be a promising natural source for the development of potential antivirals against medically important flaviviruses.

The Polyphenol-Rich Extract from Psiloxylon mauritianum, an Endemic Medicinal Plant from Reunion Island, Inhibits the Early Stages of Dengue and Zika Virus Infection

The recent emergence and re-emergence of viral infections transmitted by vectors, such as the Zika virus (ZIKV) and Dengue virus (DENV), is a cause for international concern. These highly pathogenic arboviruses represent a serious health burden in tropical and subtropical areas of the world. Despite the high morbidity and mortality associated with these viral infections, antiviral therapies are missing. Medicinal plants have been widely used to treat various infectious diseases since millenaries. Several compounds extracted from plants exhibit potent effects against viruses in vitro, calling for further investigations regarding their efficacy as antiviral drugs. Here, we demonstrate that an extract from Psiloxylon mauritianum, an endemic medicinal plant from Reunion Island, inhibits the infection of ZIKV in vitro without exhibiting cytotoxic effects. The extract was active against different ZIKV African and Asian strains, including an epidemic one. Time-of-drug-addition assays revealed that the P. mauritianum extract interfered with the attachment of the viral particles to the host cells. Importantly, the P. mauritianum extract was also able to prevent the infection of human cells by four dengue virus serotypes. Due to its potency and ability to target ZIKV and DENV particles, P. mauritianum may be of value for identifying and characterizing antiviral compounds to fight medically-important flaviviruses.

Time-scaled phylogeography of complete Zika virus genomes using discrete and continuous space diffusion models

Zika virus (ZIKV), a vector-borne infectious agent that has recently been associated with neurological diseases and congenital microcephaly, was first reported in the Western hemisphere in early 2015. A number of authors have reconstructed its epidemiological history using advanced phylogenetic approaches, and the majority of Zika phylogeography studies have used discrete diffusion models. Continuous space diffusion models make it possible to infer the possible origin of the virus in real space by reconstructing its ancestral location on the basis of geographical coordinates deduced from the latitude and longitude of the sampling locations. We analysed all the ZIKV complete genome isolates whose sampling times and localities were available in public databases at the time the study began, using a Bayesian approach for discrete and continuous phylogeographic reconstruction. The discrete phylogeographic analysis suggested that ZIKV emerged to become endemic/epidemic in the first decade of the 1900s in the Ugandan rainforests, and then reached Western Africa and Asia between the 1930s and 1950s. After a long period of about 40 years, it spread to the Pacific islands and reached Brazil from French Polynesia. Continuous phylogeography of the American epidemic showed that the virus entered in north-eastern Brazil in late 2012 and started to spread in early 2013 from two high probability regions: one corresponding to the entire north-east Brazil and the second surrounding the city of Rio de Janeiro, in a mainly northwesterly direction to Central America, the north-western countries of south America and the Caribbean islands. Our data suggest its cryptic circulation in both French Polynesia and Brazil, thus raising questions about the mechanisms underlying its undetected persistence in the absence of a known animal reservoir, and underline the importance of continuous diffusion models in making more reliable phylogeographic reconstructions of emerging viruses.

Determinants of Zika virus host tropism uncovered by deep mutational scanning

Arboviruses cycle between, and replicate in, both invertebrate and vertebrate hosts, which for Zika virus (ZIKV) involves Aedes mosquitoes and primates¹. The viral determinants required for replication in such obligate hosts are under strong purifying selection during natural virus evolution, making it challenging to resolve which determinants are optimal for viral fitness in each host. Herein we describe a deep mutational scanning (DMS) strategy^2-5 whereby a viral cDNA library was constructed containing all codon substitutions in the C-terminal 204 amino acids of ZIKV envelope protein (E). The cDNA library was transfected into C6/36 (Aedes) and Vero (primate) cells, with subsequent deep sequencing and computational analyses of recovered viruses showing that substitutions K316Q and S461G, or Q350L and T397S, conferred substantial replicative advantages in mosquito and primate cells, respectively. A 316Q/461G virus was constructed and shown to be replication-defective in mammalian cells due to severely compromised virus particle formation and secretion. The 316Q/461G virus was also highly attenuated in human brain organoids, and illustrated utility as a vaccine in mice. This approach can thus imitate evolutionary selection in a matter of days and identify amino acids key to the regulation of virus replication in specific host environments.

Emerging and threatening vector-borne zoonoses in the world and in Europe: a brief update

Climatic changes, landscape management, massive human, animal and commodity transportation represent important factors which are contributing to the spread of zoonotic diseases. The environmental and socioeconomic factors affecting the incidence of vector-borne zoonoses and possibilities for the reduction of disease impacts are discussed in the article. The most important zoonoses with expanding area of incidence and/or increasing occurrence are summarized, with special emphasis on the European region. While some diseases and their respective pathogens are indigenous to Europe (e.g. Lyme disease), others have been introduced to Europe from tropical areas (e.g. chikungunya or dengue fever). These emerging diseases may represent a serious threat in near future and better understanding of their spreading mechanisms, pathogenesis and consequent treatment is very important.

ZIKV Demonstrates Minimal Pathologic Effects and Mosquito Infectivity in Viremic Cynomolgus Macaques

To evaluate the effects of ZIKV infection on non-human primates (NHPs), as well as to investigate whether these NHPs develop sufficient viremia to infect the major urban vector mosquito, Aedes aegypti, four cynomolgus macaques (Macaca fascicularis) were subcutaneously infected with 5.0 log₁₀ focus-forming units (FFU) of DNA clone-derived ZIKV strain FSS13025 (Asian lineage, Cambodia, 2010). Following infection, the animals were sampled (blood, urine, tears, and saliva), underwent daily health monitoring, and were exposed to Ae. aegypti at specified time points. All four animals developed viremia, which peaked 3⁻4 days post-infection at a maximum value of 6.9 log₁₀ genome copies/mL. No virus was detected in urine, tears, or saliva. Infection by ZIKV caused minimal overt disease: serum biochemistry and CBC values largely fell within the normal ranges, and cytokine elevations were minimal. Strikingly, the minimally colonized population of Ae. aegypti exposed to viremic animals demonstrated a maximum infection rate of 26% during peak viremia, with two of the four macaques failing to infect a single mosquito at any time point. These data indicate that cynomolgus macaques may be an effective model for ZIKV infection of humans and highlights the relative refractoriness of Ae. aegypti for ZIKV infection at the levels of viremia observed.

A Comprehensive Review of the Manifestations and Pathogenesis of Zika Virus in Neonates and Adults

The Zika Virus (ZIKV) has been slowly becoming an epidemic in different parts of the world. Since its discovery in 1947, there have been numerous outbreaks affecting many different populations. Currently, there is an ongoing threat of ZIKV in Latin America and the United States of America. ZIKV is mainly spread by the Aedes aegypti mosquito and causes non-specific symptoms such as fever, myalgia, and generalized weakness. In addition to these symptoms, it has been noted the ZIKV is capable of causing associated conditions in adults, particularly in pregnant women as well as in newborns via vertical transmission. These manifestations include microcephaly, lissencephaly, ventriculomegaly, optic neuropathy, and congenital glaucoma, arthralgia, maculopapular rash, and cardiovascular anomalies such as atrial fibrillation. It is important to understand the reason for this specific set of associated conditions that emerge with ZIKV. This paper aims to identify the manifestations of ZIKV in adults and neonates in detail and attempts to understand the pathophysiology behind each one.

Zika virus: epidemiology, clinical aspects, diagnosis, and control of infection

Zika virus (ZIKV) is an emerging pathogen of huge public health significance to human beings. Although majority of infections are benign with self-limiting symptoms, the recent outbreak has established an association with the increased incidence of some congenital anomalies such as microcephaly. In other words, due to the large extent of the virus and mosquito vectors, the infection has become a thoughtful health problem for human societies, though now, there are no antiviral therapies or vaccines against this virus. In spite of extensive research carried out by scientists, not so much information has been gathered about this viral infection. In the current review, we prepared an overview of the remarkable progress made in understanding about the epidemiology, immunology, clinical presentation, and diagnosis methods of ZIKV infection.

Probing Zika Virus Neutralization Determinants with Glycoprotein Mutants Bearing Linear Epitope Insertions

Zika virus (ZIKV) glycoproteins are the primary target of the humoral immune response. In this study, we explored the capacity of these glycoproteins to tolerate insertion of linear epitope sequences and the potential of antibodies that bind these epitopes to inhibit infection. We first created a panel of ZIKV mutants with the FLAG epitope inserted in the premembrane (prM) and envelope (E) glycoprotein regions. The insertion locations were based on the results of our recent transposon insertional mutagenesis screen. Although FLAG insertions in prM greatly impaired viral fitness, this sequence was tolerated in numerous surface-exposed E protein sites. We observed that mutants bearing FLAG epitopes in E domains I and II and the E domain I-II hinge region were all neutralized by FLAG antibody; however, the neutralization sensitivity varied highly. We measured the antibody binding efficiency and found that this closely matched the pattern of neutralization sensitivity. We determined that E glycosylation did not affect antibody binding to a nearby epitope or its capacity to serve as a neutralization target. Although we could not generate infectious viruses with FLAG epitope insertions in a buried region of E protein domain III, we found that the V5 epitope could be inserted at this site without greatly impacting fitness. Furthermore, this virus was efficiently neutralized by V5 antibodies, highlighting that even buried epitopes can function as neutralization targets. Finally, we analyzed the timing of antibody neutralization activity during cell entry and found that all antibodies blocked a step after cell attachment.IMPORTANCE Zika virus (ZIKV) infections are associated with severe birth defects and neurological disease. The structure of the mature ZIKV particle reveals a virion surface covered by the envelope glycoprotein, which is the dominant target of the humoral immune response. It is unclear if all regions of the envelope protein surface or even buried epitopes can function as neutralization targets. To test this, we created a panel of ZIKV mutants with epitope insertions in different regions of the envelope protein. In characterizing these viruses, we found that the strength of antibody binding to an epitope is the major determinant of the neutralization potential of an antibody, that even a buried region of the envelope protein can be efficiently targeted, and that the sole potential envelope glycan does not impact nearby epitope antibody binding and neutralization. Furthermore, this work provides important insights into our understanding of how antibodies neutralize ZIKV.

Creation of a new hospital service for iron therapy

Iron deficiency anemia is one of the widespread forms of anemia worldwide with important consequences on public health in general and in the management of the hospital blood supply in particular. In this context we decided to "de novo"organize a new hospital service specifically dedicated to iron therapy to correctly diagnose iron deficiency anemia and support patients with the latest generation of i.v. iron formulation. We describe the organizational and educational solutions we adopted to start the new service. The initial results in terms of safety, increase in Hb value, and RBC units saved were encouraging and it has led us to expand the categories of patients to be supported.

Viral and Antibody Kinetics, and Mosquito Infectivity of an Imported Case of Zika Fever Due to Asian Genotype (American Strain) in Singapore

We report a case of a Singaporean who acquired Zika virus (ZIKV) during a visit to Cuba. The infection was confirmed using molecular and serological methods. This report highlights potential drawbacks of using IgG serology for diagnosis of flavivirus infections in endemic regions. The low viremia detected during the early phase of this case resulted in low mosquito infectivity rates, suggesting the possibility of ZIKV transmission prior to clinical onset. The report also emphasizes the challenges of public health interventions for Zika fever and the importance of sustaining a low vector population to reduce the risk of arbovirus transmission in vulnerable regions.