Neurological manifestations of Zika virus infection

Viruses and the Brain-A Relationship Prone to Trouble

Neurological disorders, some of which are associated with viral infections, are growing due to the aging and expanding population. Despite strong defenses of the central nervous system, some viruses have evolved ways to breach them, which often result in dire consequences. In this review, we recount the various ways by which different viruses can enter the CNS, and we describe the consequences of such invasions. Consequences may manifest as acute disease, such as encephalitis, meningitis, or result in long-term effects, such as neuromuscular dysfunction, as occurs in poliomyelitis. We discuss evidence for viral involvement in the causation of well-known chronic neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, as well as vascular dementia in the elderly. We also describe the approaches currently available to control a few of the neural viral infections. These include antivirals that are effective against human immunodeficiency virus and herpes simplex virus, as well as vaccines valuable for controlling rabies virus, poliomyelitis virus, and some flavivirus infections. There is an urgent need to better understand, at a molecular level, how viruses contribute to acute and, especially, chronic neurological diseases and to develop more precise and effective vaccines and therapies.

Biosensors for the detection of flaviviruses: A review

Flaviviruses affect the lives of millions of people in endemic regions and also have the potential to impact non-endemic areas. Factors such as climate change, global warming, deforestation, and increased travel and trade are linked to the spread of flaviviruses into new habitats and host species. Given the absence of specific treatments and the limited availability of vaccines, it is imperative to understand the biology of flaviviruses and develop rapid and sensitive diagnostic tests. These measures are essential for preventing the transmission of these potentially life-threatening pathogens. Flavivirus infections are mainly diagnosed using conventional methods. However, these techniques present several drawbacks, including high expenses, time-consuming procedures, and the need for skilled professionals. The search for fast, easy-to-use, and affordable alternative techniques as a feasible solution for developing countries is leading to the search for new methods in the diagnosis of flaviviruses, such as biosensors. This review provides a comprehensive overview of different biosensor detection strategies for flaviviruses and describes recent advances in diagnostic technologies. Finally, we explore their future prospects and potential applications in pathogen detection. This review serves as a valuable resource to understand advances in ongoing research into new biosensor-based diagnostic methods for flaviviruses.

Design, synthesis, and molecular modeling studies of novel 2-quinolone-1,2,3-triazole-α-aminophosphonates hybrids as dual antiviral and antibacterial agents

With the aim to identify new antiviral agents with antibacterial properties, a series of 2-quinolone-1,2,3-triazole derivatives bearing α-aminophosphonates was synthesized and characterized by 1H NMR, 13C NMR, 31P NMR, single crystal XRD and HRMS analyses. These compounds were examined against five RNA viruses (YFV, ZIKV, CHIKV, EV71 and HRV) from three distinct families (Picornaviridae, Togaviridae and Flaviviridae) and four bacterial strains (S. aureus, E. feacalis, E. coli and P. aeruginosa). The α-aminophosphonates 4f, 4i, 4j, 4k, 4p and 4q recorded low IC50 values of 6.8-10.91 μM, along with elevated selectivity indices ranging from 2 to more than 3, particularly against YFV, CHIKV and HRV-B14. Besides, the synthesized compounds were generally more sensitive toward Gram-positive bacteria, with the majority of them displaying significant potency against E. feacalis. Specifically, an excellent anti-enterococcus activity was obtained by compound 4q with MIC and MBC values of 0.03 μmol/mL, which were 8.7 and 10 times greater than those of the reference drugs ampicillin and rifampicin, respectively. Also, compounds 4f, 4p and 4q showed potent anti-staphylococcal activity with MIC values varying between 0.11 and 0.13 μmol/mL, compared to 0.27 μmol/mL for ampicillin. The results from DFT and molecular docking simulations were in agreement with the biological assays, proving the binding capability of hybrids 4f, 4i, 4j, 4k, 4p and 4q with viral and bacterial target enzymes through hydrogen bonds and other non-covalent interactions. The in silico ADME/Tox prediction revealed that these molecules possess moderate to good drug-likeness and pharmacokinetic properties, with a minimal chance of causing liver toxicity or carcinogenic effects.

Widespread amyloid aggregates formation by Zika virus proteins and peptides

Viral pathogenesis typically involves numerous molecular mechanisms. Protein aggregation is a relatively unknown characteristic of viruses, despite the fact that viral proteins have been shown to form terminally misfolded forms. Zika virus (ZIKV) is a neurotropic one with the potential to cause neurodegeneration. Its protein amyloid aggregation may link the neurodegenerative component to the pathogenicity associated with the viral infection. Therefore, we investigated protein aggregation in the ZIKV proteome as a putative pathogenic route and one of the alternate pathways. We discovered that it contains numerous anticipated aggregation-prone regions in this investigation. To validate our prediction, we used a combination of supporting experimental techniques routinely used for morphological characterization and study of amyloid aggregates. Several ZIKV proteins and peptides, including the full-length envelope protein, its domain III (EDIII) and fusion peptide, Pr N-terminal peptide, NS1 β-roll peptide, membrane-embedded signal peptide 2K, and cytosolic region of NS4B protein, were shown to be highly aggregating in our study. Because our findings show that viral proteins can form amyloids in vitro, we need to do a thorough functional study of these anticipated APRs to understand better the role of amyloids in the pathophysiology of ZIKV infection.

Incidence of Guillain-Barré syndrome in the world between 1985 and 2020: A systematic review

Introduction

Guillain-Barré syndrome (GBS) is an acute inflammatory demyelinating polyradiculoneuropathy that affects the peripheral nervous system. The study aimed to describe the incidence of GBS in the world up to the year 2020.

Methods

A systematic review was conducted. Searches were done in four databases, PUBMED, EMBASE, EBSCO and Biblioteca virtual em Saude (BVS), and in grey literature and manual search in the reference lists of eligible studies.

Results

A total of 72 studies were included. The incidence of GBS among the cohort studies varied from 0.30 to 6.08 cases per 100.000 habitants and 0.42 to 6.58 cases per 100.000 person-years. Among the self-controlled studies, the risk incidence ranged from 0.072 to 1 case per 100.000 habitants and 1.73 to 4.30 cases per 100.000 person-years.

Conclusions

The reported incidence of GBS in the world among the studies included in the review is slightly higher than that reported in previous studies. The highest incidence rates were associated with public health events of international concern.

How viral infections cause neuronal dysfunction: a focus on the role of microglia and astrocytes

In recent decades, a number of infectious viruses have emerged from wildlife or reemerged that pose a serious threat to global health and economies worldwide. Although many of these viruses have a specific target tissue, neurotropic viruses have evolved mechanisms to exploit weaknesses in immune defenses that eventually allow them to reach and infect cells of the central nervous system (CNS). Once in the CNS, these viruses can cause severe neuronal damage, sometimes with long-lasting, life-threatening consequences. Remarkably, the ability to enter the CNS and cause neuronal infection does not appear to determine whether a viral strain causes neurological complications. The cellular mechanisms underlying the neurological consequences of viral infection are not fully understood, but they involve neuroimmune interactions that have so far focused mainly on microglia. As the major immune cells in the brain, reactive microglia play a central role in neuroinflammation by responding directly or indirectly to viruses. Chronic reactivity of microglia leads to functions that are distinct from their beneficial roles under physiological conditions and may result in neuronal damage that contributes to the pathogenesis of various neurological diseases. However, there is increasing evidence that reactive astrocytes also play an important role in the response to viruses. In this review article, we summarize the recent contributions of microglia and astrocytes to the neurological impairments caused by viral infections. By expanding knowledge in this area, therapeutic approaches targeting immunological pathways may reduce the incidence of neurological and neurodegenerative disorders and increase the therapeutic window for neural protection.

Zika virus infection in pregnant women and their children: A review

Zika virus (ZIKV) is an arthropod-borne virus (arbovirus) transmitted primarily by Aedes mosquitoes. ZIKV can be transmitted to humans by non-vector borne mechanisms such as sexual intercourse, maternal-foetal transmission or blood transfusion. In 2015, ZIKV emerged in the Americas, and spread to 87 countries and territories with autochthonous transmission, distributed across four of the six WHO regions. Most ZIKV infections in pregnancy are asymptomatic, but mother to child transmission of the virus can occur in 20 to 30% of cases and cause severe foetal and child defects. Children exposed to ZIKV while in utero might develop a pattern of structural anomalies and functional disabilities secondary to central nervous system damage, known as congenital Zika syndrome, and whose most common clinical feature is microcephaly. Normocephalic children born to mothers with ZIKV infection in pregnancy, and with no observable Zika-associated birth defects, may also present with later neurodevelopmental delay or post-natal microcephaly. Screening and detection of ZIKV infection in pregnancy is essential, because most women with ZIKV infection are asymptomatic and clinical manifestations are non-specific. However, the diagnosis of ZIKV infection poses multiple challenges due to limited resources and scarce laboratory capabilities in most affected areas, the narrow window of time that the virus persists in the bloodstream, the large proportion of asymptomatic infections, and the cross-reactivity with other flaviviruses such as Dengue virus (DENV). Molecular methods (RT-PCR) are the most reliable tool to confirm ZIKV infection, as serodiagnosis requires confirmation with neutralization tests in case of inconclusive or positive serology results. Prenatal ultrasound assessment is essential for monitoring foetal development and early detection of possible severe anomalies. A mid- and long-term follow-up of children exposed to ZIKV while in utero is necessary to promptly detect clinical manifestations of possible neurological impairment. Tweetable abstract: Zika virus infection during pregnancy is a cause of pregnancy loss and disability in children. Protection against mosquito bites, access to sexual and reproductive health services, prompt screening and detection of ZIKV infection in pregnancy, and prenatal ultrasound monitoring are key control strategies whilst a vaccine is not available.

Selective estrogen receptor modulator, tamoxifen, inhibits Zika virus infection

Zika virus (ZIKV) is an arbovirus belonging to the flaviviridae family with a risk assessment that has been increasing in recent years and was labeled a global health emergency by the World Health Organization in 2016. There are currently no Food and Drug Administration-approved treatment options available for ZIKV, so expeditious development of treatment options is urgent. To expedite this process, an on-market drug, tamoxifen (TAM), was selected as a promising candidate for repurposing due to its wide range of biological activities and because it has already been shown to possess activity against hepatitis C virus, a flavivirus in a separate genus. Anti-ZIKV activity of TAM was assessed by compound screens using an infectious virus and mechanistic details were gleaned from time of addition and virucidal studies. TAM and an active metabolite, 4-hydroxytamoxifen (TAM-OH), both showed promising antiviral activity (EC50 ≈9 and 5 µM, respectively) in initial compound screening and up to 8-h postinfection, though the virucidal assay indicated that they do not possess any direct virucidal activity. Additionally, TAM was assessed for its activity against ZIKV in the human male germ cell line, SEM-1, due to the sexually transmitted nature of ZIKV owing to its extended survival times in germ cells. Virus titers show diminished replication of ZIKV over 7 days compared to controls. These data indicate that TAM has the potential to be repurposed as an anti-ZIKV therapeutic and warrants further investigation.

Enhancement of Zika virus infection by antibodies from West Nile virus seropositive individuals with no history of clinical infection

Background

Recent outbreaks of Zika Virus (ZIKV) infection and associated microcephaly has raised multiple scientific questions. The close antigenic relatedness between flaviviruses makes diagnosis of specific infection difficult. This relatedness also raises the potential of Antibody Dependent Enhancement (ADE) via cross reactive antibodies to flaviviruses like West Nile Virus (WNV) and Dengue Virus (DENV). Asymptomatic WNV infections are endemic throughout the US creating a large proportion of the population that is seropositive for WNV antibodies. Whether these sero-positive individuals potentially carry ZIKV enhancing antibodies remains unknown.

Results

Serum samples obtained from human subjects with symptomatic or asymptomatic WNV infection from a WNV endemic region in Texas were tested for their ability to enhance or neutralize ZIKV infection. Sero-surveillance data demonstrated a ~ 7% prevalence for WNV antibodies in the population. Sera from both symptomatic and asymptomatic WNV seropositive donors effectively neutralized WNV and to some extent DENV infection. Interestingly, WNV+ sera failed to inhibit ZIKV while significantly enhancing infection. Conversely, ZIKV specific sera effectively neutralized ZIKV, with ADE only evident at lower concentrations. The enhancement of ZIKV via WNV antibody positive sera was likely due to non-neutralizing Envelope (E) antibodies as seen with monoclonal ZIKV E antibodies.

Conclusions

Overall, our findings suggest that WNV antibodies in the sera significantly enhance ZIKV infection in Fc receptor positive cells with limited neutralization activity. Further studies in more relevant models of ADE will be needed to confirm the relevance of these findings in vivo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-020-00389-2.

Potential for Protein Kinase Pharmacological Regulation in Flaviviridae Infections

Protein kinases (PKs) are enzymes that catalyze the transfer of the terminal phosphate group from ATP to a protein acceptor, mainly to serine, threonine, and tyrosine residues. PK catalyzed phosphorylation is critical to the regulation of cellular signaling pathways that affect crucial cell processes, such as growth, differentiation, and metabolism. PKs represent attractive targets for drugs against a wide spectrum of diseases, including viral infections. Two different approaches are being applied in the search for antivirals: compounds directed against viral targets (direct-acting antivirals, DAAs), or against cellular components essential for the viral life cycle (host-directed antivirals, HDAs). One of the main drawbacks of DAAs is the rapid emergence of drug-resistant viruses. In contrast, HDAs present a higher barrier to resistance development. This work reviews the use of chemicals that target cellular PKs as HDAs against virus of the Flaviviridae family (Flavivirus and Hepacivirus), thus being potentially valuable therapeutic targets in the control of these pathogens.

Punica granatum Leaf Ethanolic Extract and Ellagic Acid as Inhibitors of Zika Virus Infection

Zika virus, an arthropod-borne flavivirus, is an emerging healthcare threat worldwide. Zika virus is responsible for severe neurological effects, such as paralytic Guillain-Barrè syndrome, in adults, and also congenital malformations, especially microcephaly. No specific antiviral drugs and vaccines are currently available, and treatments are palliative, but medicinal plants show great potential as natural sources of anti-Zika phytochemicals. This study deals with the investigation of the composition, cytotoxicity, and anti-Zika activity of Punica granatum leaf ethanolic extract, fractions, and phytoconstituents. P. granatum leaves were collected from different areas in Italy and Greece in different seasons. Crude extracts were analyzed and fractionated, and the pure compounds were isolated. The phytochemical and biomolecular fingerprint of the pomegranate leaves was determined. The antiviral activities of the leaf extract, fractions, and compounds were investigated against the MR766 and HPF2013 Zika virus strains in vitro. Both the extract and its fractions were found to be active against Zika virus infection. Of the compounds isolated, ellagic acid showed particular anti-Zika activities, with EC₅₀ values of 30.86 µM for MR766 and 46.23 µM for HPF2013. The mechanism of action was investigated using specific antiviral assays, and it was demonstrated that ellagic acid was primarily active as it prevented Zika virus infection and was able to significantly reduce Zika virus progeny production. Our data demonstrate the anti-Zika activity of pomegranate leaf extract and ellagic acid for the first time. These findings identify ellagic acid as a possible anti-Zika candidate compound that can be used for preventive and therapeutic interventions.

Druggability assessment of precursor membrane protein as a target for inhibiting the Zika virus

The Zika virus (ZIKV), a significant zoonotic flavivirus, was neglected as a human pathogen until the recent epidemic. The rapid geographic spread of the virus and association with neurological disorders has created a global public health concern pressing the need for anti-ZIKV drugs. Previous ZIKV drug discovery research has focused on three primary targets, RNA-dependent RNA polymerase, envelope protein, and viral proteases, and none has yet resulted in a commercially viable inhibitor. In the quest for finding effective inhibitors, it is important to expand the number of targets available for drug discovery research. To this end, the ZIKV precursor membrane protein (prM) comes to the forefront as a potential target due to its critical role in virus infectivity and pathogenicity. prM acts as a chaperone for envelope protein folding and prevents premature fusion of virions to the host membrane and has not been attempted as a drug target before. One critical requirement for a protein to be an effective target is the ability of the protein to be druggable, i.e. having active sites that can bind to specific ligands. In this work, the druggability of prM was assessed via molecular docking combined molecular dynamics simulations followed binding affinity kinetics studies. Compounds that had a high affinity to the prM protein were screened in silico and ligand-binding free energies were computed using molecular mechanics with generalized Born and surface area continuum solvation (MM-GBSA) method. In vitro binding kinetics via biolayer interferometry (BLI) and interaction analysis confirmed that prM could be targeted for drug discovery to combat ZIKV infection.Communicated by Ramaswamy H. Sarma.

Evaluation of the frequency of neuroimaging findings in congenital infection by Zika virus and differences between computed tomography and magnetic resonance imaging in the detection of alterations

INTRODUCTION

Congenital infection by the Zika virus (ZIKV) is responsible for severe abnormalities in the development of the central nervous system. The aim of this study was to evaluate and compare the ability of computed tomography (CT) and magnetic resonance (MR) to detect patterns of involvement of the central nervous system in congenital ZIKV syndrome.

METHODS

We retrospectively analyzed CT and MR images from 34 patients with congenital ZIKV syndrome and evaluated the differences between the two methods in detecting alterations.

RESULTS

The predominant radiographic finding was a simplified gyral pattern, present in 97% of cases. The second most common finding was the presence of calcifications (94.1%), followed by ventriculomegaly (85.3%), dysgenesis of the corpus callosum (85.3%), craniofacial disproportion and redundant scalp (79.4%), complete opercular opening (79.4%), occipital prominence (44.1%), cerebellar hypoplasia (14.7%), and pontine hypoplasia (11.8%). The gyral pattern was extensively simplified in most cases, and calcifications were located predominantly at the cortical-subcortical junction. CT was able to better identify calcifications (94.1% × 88.2%), while MRI presented better spatial resolution for the characterization of gyral pattern (97% × 94.1%) and corpus callosum dysgenesis (85.3% × 79.4%).

CONCLUSIONS

Although congenital ZIKV syndrome does not present pathognomonic neuroimaging findings, some aspects, such as calcifications at the cortical-subcortical junction, especially when associated with compatible clinical and laboratory findings, are suggestive of intrauterine ZIKV infection.

Molecular docking and antiviral activities of plant derived compounds against zika virus

Zika virus (ZIKV), a recently emerged pathogen of the genus flavivirus causes Guillain-Barré syndrome and microcephaly in fetus and newborns . Until date, there are no licensed vaccine or approved drug to treat ZIKV infection. Thus, in this study, 5550 phytochemicals retrieved from various databases were subjected for molecular docking in Discovery studio V.4.0 against the ZIKV helicase protein and envelope protein domain III. In addition, in silico ADMET and Density function theory studies were performed to retain the final hit compounds. Further, four of the identified compounds (eleutheroside B, neoandrographolide, apigenin, and madecassic acid) were tested for in vitro cytotoxicity and antiviral activities against ZIKV. Except madecassic acid, the other three compounds reduced ZIKV infection at non-cytotoxic concentrations. Hence, this study encourages the screening of more phytochemicals against druggable targets of ZIKV to identify new promising drug candidates.

What are the implications of Zika Virus for infant feeding? A synthesis of qualitative evidence concerning Congenital Zika Syndrome (CZS) and comparable conditions

If a mother contracts the Zika Virus before or during pregnancy, then there is a risk of the child developing Congenital Zika Syndrome (CZS). An infant can then experience problems feeding due to the specific physical and developmental consequences of Congenital Zika Syndrome (CZS), such as microcephaly, dysphagia and an increased likelihood of choking. This qualitative evidence synthesis accesses direct and indirect evidence to inform WHO infant feeding guidelines. We conducted a qualitative evidence synthesis of the values and preferences of relevant stakeholders (e.g. pregnant women, mothers, family members and health practitioners) concerning infant (0-2 years) feeding in the presence of: 1) CZS (the'direct evidence'); 2) severe disability and nonprogressive, chronic encephalopathies ('indirect evidence'), which present with similar problems. Authors' findings were extracted, synthesised using thematic synthesis techniques, and confidence in the findings were assessed using GRADE-CERQual. Six CZS-specific studies (all from Brazil) were included in the direct evidence, with a further eight indirect studies reporting feeding difficulties in infants with severe disability and nonprogressive, chronic encephalopathies. Included studies highlighted: breast-feeding represented the preference for all mothers in the studies in both reviews, and the inability to do so affected bonding between parents and child, and generated fear and anxiety relating to feeding choices, especially around the risks of choking and swallowing; the perception that health professionals were often unable to offer appropriate advice; the potential value of training; and a strong desire to achieve individual maternal autonomy in infant feeding decisions. Confidence in most findings ranged from low to moderate. The evidence base has limitations, but consistently reported that parents of children with feeding difficulties due to Congenital Zika Syndrome, or similar, need information, advice and counselling, and substantial emotional support. Parents perceive that these needs are often neither recognised nor satisfied; optimal feeding and support strategies for this population have not yet been identified.

Glycosylation of Zika Virus is Important in Host-Virus Interaction and Pathogenic Potential

Zika virus (ZIKV) is a global public health issue due to its association with severe developmental disorders in infants and neurological disorders in adults. ZIKV uses glycosylation of its envelope (E) protein to interact with host cell receptors to facilitate entry; these interactions could also be important for designing therapeutics and vaccines. Due to a lack of proper information about Asn-linked (N-glycans) on ZIKV E, we analyzed ZIKV E of various strains derived from different cells. We found ZIKV E proteins being extensively modified with oligomannose, hybrid and complex N-glycans of a highly heterogeneous nature. Host cell surface glycans correlated strongly with the glycomic features of ZIKV E. Mechanistically, we observed that ZIKV N-glycans might play a role in viral pathogenesis, as mannose-specific C-type lectins DC-SIGN and L-SIGN mediate host cell entry of ZIKV. Our findings represent the first detailed mapping of N-glycans on ZIKV E of various strains and their functional significance.

The potential contribution of impaired brain glucose metabolism to congenital Zika syndrome

The Zika virus (ZIKV) became a major worldwide public concern in 2015 due to the congenital syndrome which presents the highest risk during the first trimester of pregnancy and includes microcephaly and eye malformations. Several cellular, genetic and molecular studies have shown alterations in metabolic pathways, endoplasmic reticulum (ER) stress, immunity and dysregulation of RNA and energy metabolism both in vivo and in vitro. Here we summarise the main metabolic complications, with a particular focus on the possibility that brain energy metabolism is altered following ZIKV infection, contributing to developmental abnormalities. Brain energetic failure has been implicated in neurological conditions such as autism disorder and epilepsy, as well as in metabolic diseases with severe neurodevelopmental complications such as Glut-1 deficiency syndrome. Therefore, these energetic alterations are of wide-ranging interest as they might be directly implicated in congenital ZIKV syndrome. Data showing increased glycolysis during ZIKV infection, presumably required for viral replication, might support the idea that the virus can cause energetic stress in the developing brain cells. Consequences may include neuroinflammation, cell cycle dysregulation and cell death. Ketone bodies are non-glycolytic brain fuels that are produced during neonatal life, starvation or fasting, ingestion of high-fat low-carbohydrate diets, and following supplementation with ketone esters. We propose that dietary ketones might alter the course of the disease and could even provide some degree of prevention of ZIKV-associated abnormalities and potentially related neurological conditions characterised by brain glucose impairment.

Therapeutic Advances Against ZIKV: A Quick Response, a Long Way to Go

Zika virus (ZIKV) is a mosquito-borne flavivirus that spread throughout the American continent in 2015 causing considerable worldwide social and health alarm due to its association with ocular lesions and microcephaly in newborns, and Guillain-Barré syndrome (GBS) cases in adults. Nowadays, no licensed vaccines or antivirals are available against ZIKV, and thus, in this very short time, the scientific community has conducted enormous efforts to develop vaccines and antivirals. So that, different platforms (purified inactivated and live attenuated viruses, DNA and RNA nucleic acid based candidates, virus-like particles, subunit elements, and recombinant viruses) have been evaluated as vaccine candidates. Overall, these vaccines have shown the induction of vigorous humoral and cellular responses, the decrease of viremia and viral RNA levels in natural target organs, the prevention of vertical and sexual transmission, as well as that of ZIKV-associated malformations, and the protection of experimental animal models. Some of these vaccine candidates have already been assayed in clinical trials. Likewise, the search for antivirals have also been the focus of recent investigations, with dozens of compounds tested in cell culture and a few in animal models. Both direct acting antivirals (DAAs), directed to viral structural proteins and enzymes, and host acting antivirals (HAAs), directed to cellular factors affecting all steps of the viral life cycle (binding, entry, fusion, transcription, translation, replication, maturation, and egress), have been evaluated. It is expected that this huge collaborative effort will produce affordable and effective therapeutic and prophylactic tools to combat ZIKV and other related still unknown or nowadays neglected flaviviruses. Here, a comprehensive overview of the advances made in the development of therapeutic measures against ZIKV and the questions that still have to be faced are summarized.

Zika Virus and Other Emerging Arboviral Central Nervous System Infections

PURPOSE OF REVIEW

In recent years, we have observed the emergence and reemergence of a number of arthropod-borne viruses (arboviruses). Zika virus is the most recent addition to this group, first causing sporadic cases of uncomplicated febrile illness followed by sizeable outbreaks in the Pacific. However, the epidemiology and clinical features of Zika virus infection have changed rapidly and dramatically; it is now recognized as causing Guillain-Barré syndrome (GBS) in children and adults and congenital abnormalities in infected fetuses. This article reviews the epidemiology, clinical features, and diagnosis of Zika virus-associated neurologic illness and briefly reviews features of West Nile virus and Japanese encephalitis virus.

RECENT FINDINGS

Zika virus has emerged as a significant human pathogen in recent years. In 2015, it began to cause large outbreaks of febrile rash illness in South America and the Caribbean. During these large Zika virus outbreaks, a significant increase in the incidence of GBS was also observed in multiple countries/territories. Zika virus-associated GBS has several unique features, including a relatively short interval between febrile illness and GBS onset, an unusually high incidence among older people, and prominent cranial nerve abnormalities. Congenital Zika syndrome includes a myriad of abnormalities, including microcephaly, lissencephaly, hydrocephalus, arthrogryposis, and parenchymal calcifications. Currently, no treatment has been identified for Zika virus, although work on vaccines is under way.

SUMMARY

Arboviruses continue to surprise us with unexpected emergence in various locations, the nature of clinical illness, and outcomes. Zika virus presents a classic example of this type of emergence. Ongoing surveillance will be needed to evaluate the long-term pattern of Zika virus and related arboviruses.

Critical Care of Neuromuscular Disorders

PURPOSE OF REVIEW

Weakness is a common reason patients are seen in neurologic consultation. This article reviews the differential diagnosis of neuromuscular disorders in the intensive care unit (ICU), discusses the intensive care needs and evaluation of respiratory failure in patients with neuromuscular disorders, and provides a practical guide for management.

RECENT FINDINGS

Although primary neuromuscular disorders used to be the most common cause for weakness from peripheral nervous system disease in the ICU, a shift toward ICU-acquired weakness is observed in today's clinical practice. Therefore, determining the cause of weakness is important and may have significant prognostic implications. Guillain-Barré syndrome and myasthenia gravis remain the most common primary neuromuscular disorders in the ICU. In patients with myasthenia gravis, it is important to be vigilant with the airway and institute noninvasive ventilation early in the course of the disease to attempt to avoid the need for intubation. On the other hand, patients with Guillain-Barré syndrome should be intubated without delay if the airway is at risk to avoid further complications. In patients with ICU-acquired weakness, failure to wean from the ventilator is usually the challenge. Early mobility, glucose control, minimizing sedation, and avoiding neuromuscular blocking agents remain the only therapeutic regimen available for ICU-acquired weakness.

SUMMARY

Critical care management of neuromuscular disorders requires a multidisciplinary approach engaging members of the ICU and consultative teams. Developing an airway management protocol could have implications on outcome and length of stay for patients with neuromuscular disorders in the ICU. Tending to the appropriate nuances of each patient who is critically ill with a neuromuscular disorder through evidence-based medicine can also have implications on length of stay and outcome.

Secondary Metabolites of Actinomycetes and their Antibacterial, Antifungal and Antiviral Properties

The growing resistance of microorganisms towards antibiotics has become a serious global problem. Therapeutics with novel chemical scaffolds and/or mechanisms of action are urgently needed to combat infections caused by multidrug resistant pathogens, including bacteria, fungi and viruses. Development of novel antimicrobial agents is still highly dependent on the discovery of new natural products. At present, most antimicrobial drugs used in medicine are of natural origin. Among the natural producers of bioactive substances, Actinobacteria continue to be an important source of novel secondary metabolites for drug application. In this review, the authors report on the bioactive antimicrobial secondary metabolites of Actinobacteria that were described between 2011 and April 2018. Special attention is paid to the chemical scaffolds, biological activities and origin of these novel antibacterial, antifungal and antiviral compounds. Arenimycin C, chromopeptide lactone RSP 01, kocurin, macrolactins A1 and B1, chaxamycin D as well as anthracimycin are regarded as the most effective compounds with antibacterial activity. In turn, the highest potency among selected antifungal compounds is exhibited by enduspeptide B, neomaclafungins A-I and kribelloside D, while ahmpatinin i Bu, antimycin A1a, and pentapeptide 4862F are recognized as the strongest antiviral agents.

Cellular Targets and Receptor of Sexual Transmission of Zika Virus

STUDY QUESTION

What is the mechanism of sexual transmission of Zika virus (ZIKV)?

SUMMARY ANSWER

By utilizing exquisite reverse transcriptase-initiated in situ polymerase chain reaction (RT-in situ PCR), which enables an improved visualization of spermatozoa's subcellular compartment, we precisely localized the mid-piece of sperm that carry receptors for ZIKV.

WHAT IS ALREADY KNOWN

ZIKV is transmitted sexually and recent studies have verified ZIKV presence in semen of previously Zika-infected patients for >6-month postinfection when ZIKV had disappeared from blood, saliva, and urine. Strong serial analyses of various body fluids suggest that ZIKV can be transmitted between sexual partners. Currently, there is limited information on the association of the virus with human semen cell types that may carry the virus.

STUDY DESIGN, SIZE, DURATION

Analyses were carried out to localize ZIKV for subcellular localization of ZIKV on cell types. The Tyro3 receptor for ZIKV was colocalized by dual immunocytochemistry with specific monoclonal antibodies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Three semen specimens were purchased from a commercial sperm bank. Motile sperm was separated from nonmotile cells by the "swim-up" technique. Each of the semen fractions was infected with ZIKV at the multiplicity of infection of 0.1.0 and 1.0 and evaluated for the primary targets of ZIKV in the semen cells by RT-in situ PCR and confirmed by real-time RT-PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

ZIKV was present primarily at the mid-piece of mature spermatozoa in about 30% of the sperm. In addition, we determined that Tyro3 receptors, primarily expressed on mid-piece of human spermatozoa, play a role in ZIKV-binding and entry into spermatozoa. Our data strongly suggest a potential sexual/horizontal route of transmission for ZIKV primarily via infected sperms; most likely ZIKV enters the sperm via the Tyro3 receptor found at the mid-piece of the mature spermatozoa.

LIMITATIONS, REASONS FOR CAUTION

We are uncertain as to what phase of spermatogenesis, that in human takes about 120 days, sperms are permissive to ZIKV. If permissiveness was very early during spermatogenesis males could be infectious for ∼120 days after the disappearance of viremia in an infected man.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings bring a new focus on the current affords to develop ZIKV vaccine. Why in the presence of anti-ZIKV antibodies infected men are still able to transmit the virus sexually? We suggest that only certain subclass of immunoglobulin (Ig)G (ie, IgG4) can cross the blood-Sertoli barrier therefore, a successful vaccine must provoke a subclass of IgG can quell ZIKV inside the seminiferous tubules.

A clinical and histopathological study of malformations observed in fetuses infected by the Zika virus

BACKGROUND

The recent outbreak of Zika virus (ZIKV) infection and the associated increased prevalence of microcephaly in Brazil underline the impact of viral infections on embryo fetal development. The aim of the present study is to provide a detailed clinical and histopathological study of the fetal disruption caused by the ZIKV, with a special focus on the associated neuropathological findings.

METHODS

A detailed feto-placental examination, as well as neuropathological and neurobiological studies were performed on three fetuses collected after pregnancy termination between 22 and 25 weeks of gestation (WG), because brain malformations associated with a maternal and fetal ZIKV infection was diagnosed.

RESULTS

In all three cases, the maternal infection occurred during the first trimester of pregnancy. A small head was observed on the ultrasound examination of the second trimester of pregnancy and led to the diagnosis of ZIKV fetopathy and pregnancy termination. The fetal histopathological examination was unremarkable on the viscera but showed on the testis an interstitial lymphocytic infiltrate. The placenta contained a Hofbauer cells hyperplasia with signs of inflammation. Neuropathological findings included a meningoencephalitis and an ex vacuo hydrocephalus. Immunohistochemical studies showed the presence of T lymphocytic and histiocytic meningitis associated with an abundant cerebral astroglial and macrophagic reaction. In situ hybridization demonstrated, abundant ZIKV particles within the cerebral parenchyma mainly in the ventricular/subventricular zone and in the cortical plate. In addition massive cells death and endoplasmic reticulum damage were present.

CONCLUSION

The present study reports on the clinical and histopathological findings observed in three fetuses infected by the ZIKV. It emphasizes the severity of brain damages and the minimal visceral and placental changes observed upon ZIKV infection. This confirms the selective neurotropism of ZIKV. Finally, it allows us to describe the cascade of multifactorial developmental defects leading to microcephaly.

Host-Directed Antivirals: A Realistic Alternative to Fight Zika Virus

Zika virus (ZIKV), a mosquito-borne flavivirus, was an almost neglected pathogen until its introduction in the Americas in 2015, where it has been responsible for a threat to global health, causing a great social and sanitary alarm due to its increased virulence, rapid spread, and an association with severe neurological and ophthalmological complications. Currently, no specific antiviral therapy against ZIKV is available, and treatments are palliative and mainly directed toward the relief of symptoms, such as fever and rash, by administering antipyretics, anti-histamines, and fluids for dehydration. Nevertheless, lately, search for antivirals has been a major aim in ZIKV investigations. To do so, screening of libraries from different sources, testing of natural compounds, and repurposing of drugs with known antiviral activity have allowed the identification of several antiviral candidates directed to both viral (structural proteins and enzymes) and cellular elements. Here, we present an updated review of current knowledge about anti-ZIKV strategies, focusing on host-directed antivirals as a realistic alternative to combat ZIKV infection.

Mobile based surveillance platform for detecting Zika virus among Spanish Delegates attending the Rio de Janeiro Olympic Games

BACKGROUND

Zika virus has created a major epidemic in Central and South America, especially in Brazil, during 2015-16. The infection is strongly associated with fetal malformations, mainly microcephaly, and neurological symptoms in adults. During the preparation of the Rio de Janeiro Olympic Games in 2016, members of Olympic Delegations worldwide expressed their concern about the health consequences of being infected with Zika virus. A major risk highlighted by the scientific community was the impact on the spreading of the virus into new territories immediately after the Games.

OBJECTIVES

To detect real-time incidence of symptoms compatible with arboviral diseases and other tropical imported diseases among the Spanish Olympic Delegation (SOD) attending the Rio Olympic Games in 2016.

METHODS

We developed a surveillance platform based on a mobile application installed in participant's smartphones that monitored the health status of the SOD through a daily interactive check of the user health status including geo-localization data. The results were evaluated by a study physician on-call through a web-based platform monitoring system. Participants presenting severe symptoms or those compatible with Zika infection prompted an alarm in the system triggering specialized medical assistance and allowing early detection and control of the introduction of arboviral diseases in Spain.

SUMMARY OF THE RESULTS

The system was downloaded by 189 participants and used by 143 of them (76%). Median age was 38 years (IQR 16), and 134 (71%) were male. Mean duration of travel was 19 days (+/-9SD). During the Games the highest accumulated incidence observed was for headache: 6.06% cough: 5.30% and conjunctivitis: 3.03%. The incidence rate of cough during the Olympic Games was 1.1% per day per person, followed by headache 0.8% and 0.4% conjunctivitis or diarrhea. In our cohort we observed that non-athletes experienced more incidence of symptoms, except for incidence of cough which was the same in the two groups (1.1%). No participants reported symptoms fulfilling Zika definition case.

CONCLUSION

Our system did not find cases fulfilling Zika definition amongst participants of the SOD during the Games, consistent with limited cases of Zika in Rio during the Games. The app showed good usability and the web based monitoring platform allowed to manage infectious cases in real-time. The overall system has proven to serve as a real-time surveillance platform for detecting symptoms that could be present in tropical imported diseases, especially arboviral diseases, contributing to the preparedness for the introduction of vector borne-diseases in non-endemic countries.

Polymeric Prodrugs Targeting Polyamine Metabolism Inhibit Zika Virus Replication

The Zika virus (ZIKV) is primarily transmitted via an infected mosquito bite, during sexual intercourse, or in utero mother to child transmission. When a fetus is infected, both neurological malformations and deficits in brain development are frequently manifested. As such, there is a need for vaccines or drugs that may be used to cure ZIKV infections. Metabolic pathways play a crucial role in cell differentiation and development. More importantly, polyamines play a key role in replication and translation of several RNA viruses, including ZIKV, Dengue virus, and Chikungunya virus. Here, we present polyamine analogues (BENSpm and PG11047) and their corresponding polymer prodrug derivatives for inhibiting ZIKV infection by intersecting with polyamine catabolism pathways. We tested the compounds against ZIKV African (MR766) and Asian (PRVABC59) strains in human kidney epithelial (Vero) and glioblastoma derived (SNB-19) cell lines. Our results demonstrate potent inhibition of ZIKV viral replication in both cell lines tested. This antiviral effect was mediated by the upregulation of two polyamine catabolic enzymes, spermine oxidase, and spermidine (SMOX)/spermine N1-acetyltransferase (SAT1) as apparent reduction of the ZIKV infection following heterologous expression of SMOX and SAT1. On the basis of these observations, we infer potential use of these polyamine analogues to treat ZIKV infections.

Global Interactomics Uncovers Extensive Organellar Targeting by Zika Virus

Zika virus (ZIKV) is a membrane enveloped Flavivirus with a positive strand RNA genome, transmitted by Aedes mosquitoes. The geographical range of ZIKV has dramatically expanded in recent decades resulting in increasing numbers of infected individuals, and the spike in ZIKV infections has been linked to significant increases in both Guillain-Barré syndrome and microcephaly. Although a large number of host proteins have been physically and/or functionally linked to other Flaviviruses, very little is known about the virus-host protein interactions established by ZIKV. Here we map host cell protein interaction profiles for each of the ten polypeptides encoded in the ZIKV genome, generating a protein topology network comprising 3033 interactions among 1224 unique human polypeptides. The interactome is enriched in proteins with roles in polypeptide processing and quality control, vesicle trafficking, RNA processing and lipid metabolism. >60% of the network components have been previously implicated in other types of viral infections; the remaining interactors comprise hundreds of new putative ZIKV functional partners. Mining this rich data set, we highlight several examples of how ZIKV may usurp or disrupt the function of host cell organelles, and uncover an important role for peroxisomes in ZIKV infection.

Impact of Zika Virus on adult human brain structure and functional organization

Objective

To determine the impact of Zika virus (ZIKV) infection on brain structure and functional organization of severely affected adult patients with neurological complications that extend beyond Guillain–Barré Syndrome (GBS)‐like manifestations and include symptoms of the central nervous system (CNS).

Methods

In this first case–control neuroimaging study, we obtained structural and functional magnetic resonance images in nine rare adult patients in the subacute phase, and healthy age‐ and sex‐matched controls. ZIKV patients showed atypical descending and rapidly progressing peripheral nervous system (PNS) manifestations, and importantly, additional CNS presentations such as perceptual deficits. Voxel‐based morphometry was utilized to evaluate gray matter volume, and resting state functional connectivity and Network Based Statistics were applied to assess the functional organization of the brain.

Results

Gray matter volume was decreased bilaterally in motor areas (supplementary motor cortex, specifically Frontal Eye Fields) and beyond (left inferior frontal sulcus). Additionally, gray matter volume increased in right middle frontal gyrus. Functional connectivity increased in a widespread network within and across temporal lobes.

Interpretation

We provide preliminary evidence for a link between ZIKV neurological complications and changes in adult human brain structure and functional organization, comprising both motor‐related regions potentially secondary to prolonged PNS weakness, and nonsomatomotor regions indicative of PNS‐independent alternations. The latter included the temporal lobes, particularly vulnerable in a range of neurological conditions. While future studies into the ZIKV‐related neuroinflammatory mechanisms in adults are urgently needed, this study indicates that ZIKV infection can lead to an impact on the brain.

Zika virus infection in the Veterans Health Administration (VHA), 2015-2016

BACKGROUND

Zika virus (ZIKV) is an important flavivirus infection. Although ZIKV infection is rarely fatal, risk for severe disease in adults is not well described. Our objective was to describe the spectrum of illness in U.S. Veterans with ZIKV infection.

METHODOLOGY

Case series study including patients with laboratory-confirmed or presumed positive ZIKV infection in all Veterans Health Administration (VHA) medical centers. Adjusted odds ratios of clinical variables associated with hospitalization and neurologic complications was performed.

PRINCIPAL FINDINGS

Of 1,538 patients tested between 12/2015-10/2016 and observed through 3/2017, 736 (48%) were RT-PCR or confirmed IgM positive; 655 (89%) were male, and 683 (93%) from VA Caribbean Healthcare System (VACHCS). Ninety-four (13%) were hospitalized, 91 (12%) in the VACHCS. Nineteen (3%) died after ZIKV infection. Hospitalization was associated with increased Charlson co-morbidity index (adjusted odds ratio [OR] 1.2; 95% confidence interval [CI], 1.1-1.3), underlying connective tissue disease (OR, 29.5; CI, 3.6-244.7), congestive heart failure (OR, 6; CI, 2-18.5), dementia (OR, 3.6; CI, 1.1-11.2), neurologic symptom presentation (OR, 3.9; CI, 1.7-9.2), leukocytosis (OR, 11.8; CI, 4.5-31), thrombocytopenia (OR, 7.8; CI, 3.3-18.6), acute kidney injury (OR, 28.9; CI, 5.8-145.1), or using glucocorticoids within 30 days of testing (OR, 13.3; CI 1.3-133). Patients presenting with rash were less likely to be hospitalized (OR, 0.29; CI, 0.13-0.66). Risk for neurologic complications increased with hospitalization (OR, 5.9; CI 2.9-12.2), cerebrovascular disease (OR 4.9; CI 1.7-14.4), and dementia (OR 2.8; CI 1.2-6.6).

CONCLUSION

Older Veterans with multiple comorbidities or presenting with neurologic symptoms were at increased risk for hospitalization and neurological complications after ZIKV infection.

Prevalence of Guillain-Barré syndrome among Zika virus infected cases: a systematic review and meta-analysis

Zika virus (ZIKV) is an emergent flavivirus transmitted mainly through Aedes spp. mosquitoes that is posing challenge to healthcare services in countries experiencing an outbreak. Usually ZIKV infection is mild, but in some cases it has been reported to progress into neurological diseases such as microcephaly in infants and Guillain-Barré syndrome (GBS) in adults. GBS is a debilitating autoimmune disorder that affects peripheral nerves. Since ZIKV caused massive outbreaks in South America in the past few years, we aimed to systematically review the literature and perform a meta-analysis to estimate the prevalence of GBS among ZIKV-infected individuals. We searched PubMed and Cochrane databases and selected three studies for a meta-analysis. We estimated the prevalence of ZIKV-associated GBS to be 1.23% (95% CI = 1.17–1.29%). Limitations include paucity of data regarding previous flavivirus infections and ZIKV-infection confirmation issues. Our estimate seems to be low, but cannot be ignored, since ZIKV outbreaks affects an overwhelming number of individuals and GBS is a life-threatening debilitating condition, especially in pregnant women. ZIKV infection cases must be closely followed to assure prompt care to reduce the impact of GBS associated-sequelae on the quality of life of those affected.

Kay SI, Mittal J, Bandstra ES, Younis RT, Chapagain P, Jayaweera DT, Liu XZ. Zika Virus: An Emerging Global Health Threat

Zika virus (ZIKV) is an emerging healthcare threat. The presence of the mosquito Aedes species across South and Central America in combination with complementary climates have incited an epidemic of locally transmitted cases of ZIKV infection in Brazil. As one of the most significant current public health concerns in the Americas, ZIKV epidemic has been a cause of alarm due to its known and unknown complications. At this point, there has been a clear association between ZIKV infection and severe clinical manifestations in both adults and neonates, including but not limited to neurological deficits such as Guillain-Barré syndrome (GBS) and microcephaly, respectively. The gravity of the fetal anomalies linked to ZIKV vertical transmission from the mother has prompted a discussion on whether to include ZIKV as a formal member of the TORCH [Toxoplasma gondii, other, rubella virus, cytomegalovirus (CMV), and herpes] family of pathogens known to breach placental barriers and cause congenital disease in the fetus. The mechanisms of these complex phenotypes have yet to be fully described. As such, diagnostic tools are limited and no effective modalities are available to treat ZIKV. This article will review the recent advancements in understanding the pathogenesis of ZIKV infection as well as diagnostic tests available to detect the infection. Due to the increase in incidence of ZIKV infections, there is an immediate need to develop new diagnostic tools and novel preventive as well as therapeutic modalities based on understanding the molecular mechanisms underlying the disease.

Congenital Zika syndrome and neuroimaging findings: what do we know so far?

Although infection with the Zika virus was first recognized in 1942, it received little attention until 2007, when a true pandemic spread throughout Africa, Asia, and the Americas. Since then, numerous forms of central nervous system involvement have been described, mainly malformations related to congenital infection. Although the neuroimaging findings in congenital Zika syndrome are not pathognomonic, many are quite suggestive of the diagnosis, and radiologists should be prepared to interpret such findings accordingly. The objective of this article is to review the computed tomography and magnetic resonance imaging findings in congenital Zika syndrome.

Current status of therapeutic and vaccine approaches against Zika virus

Zika virus (ZIKV) is a global threat because it is spreading at an alarming rate because of its wider range of transmission routes. The neuroteratogenic nature of ZIKV infection is posing serious threats to unborn lives therefore, it is necessary to develop an ideal ZIKV prophylactic or therapeutic agent urgently. Researchers are having tough time finding a treatment for ZIKV in part because of serious consequences of vaccines and drugs to unborn lives and pregnant women. However, in vitro and in vivo evaluation of therapeutic efficacy of DNA vaccine, recombinant subunit vaccine, and ZIKV purified inactivated vaccine offers hope for human protection. Large number of food and drug administration (FDA) approved drugs as wells as compounds with anti-ZIKV activity offer valuable opportunity to control the massive bio-burden of this catastrophic epidemic. Some evidences suggest that immunotherapeutics might prove to be winning strategy in pregnant females. Here, we review the recent advances and current knowledge regarding therapeutic interventions against ZIKV infection. This article will provide baseline data and roadmap to prosecute further research for the development of novel therapeutic strategy to curb the explosive rise in ZIKV.

Zika virus infection confers protection against West Nile virus challenge in mice

Flaviviruses are RNA viruses that constitute a worrisome threat to global human and animal health. Zika virus (ZIKV), which was initially reported to cause a mild disease, recently spread in the Americas, infecting millions of people. During this recent epidemic, ZIKV infection has been linked to serious neurological diseases and birth defects, specifically Guillain-Barrè syndrome (GBS) and microcephaly. Because information about ZIKV immunity remains scarce, we assessed the humoral response of immunocompetent mice to infection with three viral strains of diverse geographical origin (Africa, Asia and America). No infected animals showed any sign of disease or died after infection. However, specific neutralizing antibodies were elicited in all infected mice. Considering the rapid expansion of ZIKV throughout the American continent and its co-circulation with other medically relevant flaviviruses, such as West Nile virus (WNV), the induction of protective immunity between ZIKV and WNV was analyzed. Remarkably, protection after challenge with WNV was observed in mice previously infected with ZIKV, as survival rates were significantly higher than in control mice. Moreover, previous ZIKV infection enhanced the humoral immune response against WNV. These findings may be relevant in geographical areas where both ZIKV and WNV co-circulate, as well as for the future development of broad-spectrum flavivirus vaccines.

Zika Virus: What Have We Learnt Since the Start of the Recent Epidemic?

Zika is a viral disease transmitted mainly by mosquitoes of the genus Aedes. In recent years, it has expanded geographically, changing from an endemic mosquito-borne disease across equatorial Asia and Africa, to an epidemic disease causing large outbreaks in several areas of the world. With the recent Zika virus (ZIKV) outbreaks in the Americas, the disease has become a focus of attention of public health agencies and of the international research community, especially due to an association with neurological disorders in adults and to the severe neurological and ophthalmological abnormalities found in fetuses and newborns of mothers exposed to ZIKV during pregnancy. A large number of studies have been published in the last 3 years, revealing the structure of the virus, how it is transmitted and how it affects human cells. Many different animal models have been developed, which recapitulate several features of ZIKV disease and its neurological consequences. Moreover, several vaccine candidates are now in active preclinical development, and three of them have already entered phase I clinical trials. Likewise, many different compounds targeting viral and cellular components are being tested in in vitro and in experimental animal models. This review aims to discuss the current state of this rapidly growing literature from a multidisciplinary perspective, as well as to present an overview of the public health response to Zika and of the perspectives for the prevention and treatment of this disease.

Antiviral Activity of Nordihydroguaiaretic Acid and Its Derivative Tetra-O-Methyl Nordihydroguaiaretic Acid against West Nile Virus and Zika Virus

Flaviviruses are positive-strand RNA viruses distributed all over the world that infect millions of people every year and for which no specific antiviral agents have been approved. These viruses include the mosquito-borne West Nile virus (WNV), which is responsible for outbreaks of meningitis and encephalitis. Considering that nordihydroguaiaretic acid (NDGA) has been previously shown to inhibit the multiplication of the related dengue virus and hepatitis C virus, we have evaluated the effect of NDGA, and its methylated derivative tetra-O-methyl nordihydroguaiaretic acid (M₄N), on the infection of WNV. Both compounds inhibited the infection of WNV, likely by impairing viral replication. Since flavivirus multiplication is highly dependent on host cell lipid metabolism, the antiviral effect of NDGA has been previously related to its ability to disturb the lipid metabolism, probably by interfering with the sterol regulatory element-binding proteins (SREBP) pathway. Remarkably, we observed that other structurally unrelated inhibitors of the SREBP pathway, such as PF-429242 and fatostatin, also reduced WNV multiplication, supporting that the SREBP pathway may constitute a druggable target suitable for antiviral intervention against flavivirus infection. Moreover, treatment with NDGA, M₄N, PF-429242, and fatostatin also inhibited the multiplication of the mosquito-borne flavivirus Zika virus (ZIKV), which has been recently associated with birth defects (microcephaly) and neurological disorders. Our results point to SREBP inhibitors, such as NDGA and M₄N, as potential candidates for further antiviral development against medically relevant flaviviruses.

Antiviral Properties of the Natural Polyphenols Delphinidin and Epigallocatechin Gallate against the Flaviviruses West Nile Virus, Zika Virus, and Dengue Virus

The Flavivirus genus contains important pathogens, such as West Nile virus (WNV), Zika virus (ZIKV), and Dengue virus (DENV), which are enveloped plus-strand RNA viruses transmitted by mosquitoes and constitute a worrisome threat to global human and animal health. Currently no licensed drugs against them are available, being, thus, still necessary the search for effective antiviral molecules. In this line, a novel antiviral approach (economical, simple to use, and environmental friendly) is the use of natural compounds. Consequently, we have tested the antiviral potential of different polyphenols present in plants and natural products, such as wine and tea, against WNV, ZIKV, and DENV. So that, we assayed the effect of a panel of structurally related polyphenols [delphinidin (D), cyanidin (Cy), catechin (C), epicatechin (EC), epigallocatechin (EGC), and epigallocatechin gallate (EGCG)] on WNV infection, and found that D and EGCG inhibited more effectively the virus production. Further analysis with both compounds indicated that they mainly affected the attachment and entry steps of the virus life cycle. Moreover, D and EGCG showed a direct effect on WNV particles exerting a virucidal effect. We showed a similar inhibition of viral production of these compounds on WNV variants that differed on acidic pH requirements for viral fusion, indicating that their antiviral activity against WNV is produced by a virucidal effect rather than by an inhibition of pH-dependent viral fusion. Both polyphenols also reduced the infectivity of ZIKV and DENV. Therefore, D and EGCG impair the infectivity in cell culture of these three medically relevant flaviviruses.

The Race To Find Antivirals for Zika Virus

Zika virus (ZIKV), a flavivirus transmitted by mosquitoes, was an almost neglected pathogen until its introduction in the Americas in 2015 and its subsequent explosive spread throughout the continent, where it has infected millions of people. The virus has caused social and sanitary alarm, mainly due to its association with severe neurological disorders (Guillain-Barré syndrome and microcephaly in fetuses and newborns). Nowadays, no specific antiviral therapy against ZIKV is available. However, during the past months, a great effort has been made to search for antiviral candidates using different approaches and methodologies, ranging from testing specific compounds with known antiviral activity to the screening of libraries with hundreds of bioactive molecules. The identified antiviral candidates include drugs targeting viral components as well as cellular ones. Here, an updated review of what has been done in this line is presented.

The Race To Find Antivirals for Zika Virus

Zika virus (ZIKV), a flavivirus transmitted by mosquitoes, was an almost neglected pathogen until its introduction in the Americas in 2015 and its subsequent explosive spread throughout the continent, where it has infected millions of people. The virus has caused social and sanitary alarm, mainly due to its association with severe neurological disorders (Guillain-Barré syndrome and microcephaly in fetuses and newborns). Nowadays, no specific antiviral therapy against ZIKV is available. However, during the past months, a great effort has been made to search for antiviral candidates using different approaches and methodologies, ranging from testing specific compounds with known antiviral activity to the screening of libraries with hundreds of bioactive molecules. The identified antiviral candidates include drugs targeting viral components as well as cellular ones. Here, an updated review of what has been done in this line is presented.

An Update on Zika Virus in Asia

Zika virus (ZIKV) was first isolated in Asia from mosquitoes from Malaysia in 1966. However, the incidence of Zika and Zika-related neurological complications in Asia is not well known. The few studies of Zika in Asia have been inconsistent in pointing to likely transmission levels, with some studies suggesting substantial transmission and others not. Interpretation of existing epidemiological and public health data from Asia is constrained by the non-specific symptomatology of Zika, the high proportion of subclinical ZIKV infections, relatively low viremia, and the lack of accurate serological assays. Here, we update the status of Zika cases from countries in Asia, and highlight some key knowledge gaps. In particular, accurate determinations of the incidence of Zika-related congenital Zika syndrome should be a priority for Zika research in Asia. Additional information will be critical to make informed strategies for the prevention and control of this global public health threat.