Fatal encephalitis associated with Zika virus infection in an adult

BackgroundZika virus (ZIKV) was first identified in the Americas in 2015, when an outbreak of an exanthematous illness occurred in Brazil. Subsequentely, there was an increase of microcephaly cases, suggesting an association between ZIKV and this neurological complication. Currently, ZIKV has been recognised as causing a wide range of neurological complications including Guillain Barré syndrome, and myelitis.ObjectivesIn this report, we describe the first fatal case of encephalitis in a 47 years old non pregnant woman, infected during the Brazilian zika epidemic of 2016.Study designThe diagnosis of encephalitis was determined by the presence of a disturbed level of consciousness and focal neurological signs during an exanthemous viral infection.ResultsCSF analysis supported the diagnosis of viral encephalitis, revealing lymphocytic pleocytosis, a high protein concentration, and the presence of IgM zika antibodies. RT-PCR analysis for ZIKV was positive in the urine. A brain computed tomography showed massive brain swelling. Our case differs from previous reports, because her neurological picture developed rapidly and in a very aggressive manner leading to brain death after eleven days of admission.ConclusionIn endemic areas, ZIKV should be considered as an aetiological agent in cases of encephalitis, and clinicians should be aware of its potential severity.     

Zika virus: Future reproductive concerns

The pandemic spread of Zika virus (ZIKV), a member of the flavivirus genus of the Flaviviridae family, has become a major public health concern. Reproductive specialists are particularly concerned over the spread of ZIKV as it is now known to have both sexual and transplacental routes of transmission resulting in fetal congenital abnormalities. Other members of the Flaviviridae family, hepatitis C virus (HCV) and bovine viral diarrhea virus (BVDV) (which primarily affects cattle), are well known to reproductive specialists as both sexually transmitted illnesses that are capable of vertical transmission. Congenital infection with BVDV also has a predilection for neuro‐teratogenicity as has been seen with ZIKV. HCV and BVDV are also known to be capable of persistent infection in offspring. Could this be the case with ZIKV? Examining what we know about HCV and BVDV, in addition to what we have already learned about ZIKV, may answer some of the questions that remain about ZIKV. Herein, we review the current literature as it pertains to ZIKV vertical transmission and neuro‐teratogenicity and compare it to what is known about HCV and BVDV.     

Zika virus infection of Hofbauer cells

Recent studies have linked antenatal infection with Zika virus (ZIKV) with major adverse fetal and neonatal outcomes, including microcephaly. There is a growing consensus for the existence of a congenital Zika syndrome (CZS). Previous studies have indicated that non‐placental macrophages play a key role in the replication of dengue virus (DENV), a closely related flavivirus. As the placenta provides the conduit for vertical transmission of certain viruses, and placental Hofbauer cells (HBCs) are fetal—placental macrophages located adjacent to fetal capillaries, it is not surprising that several recent studies have examined infection of HBCs by ZIKV. In this review, we describe congenital abnormalities associated with ZIKV infection, the role of HBCs in the placental response to infection, and evidence for the susceptibility of HBCs to ZIKV infection. We conclude that HBCs may contribute to the spread of ZIKV in placenta and promote vertical transmission of ZIKV, ultimately compromising fetal and neonatal development and function. Current evidence strongly suggests that further studies are warranted to dissect the specific molecular mechanism through which ZIKV infects HBCs and its potential impact on the development of CZS.     

Congenital Zika syndrome: Pitfalls in the placental barrier

Much progress with respect to congenital Zika virus (ZIKV) pathogenesis has been achieved after the 2015 outbreak in Brazil. It is now accepted that ZIKV is vertically transmitted, infects cells of the developing central nervous system and the placenta, yet it is unclear to what extent placental affection contributes to the development of congenital ZIKV. The association between fulminant villitis and severe fetal involvement emerges as a possibility. ZIKV is unique among the Flaviviruses in its ability to be sexually transmitted, possibly responsible for its teratogenicity. Furthermore, there is controversy over the participation of antibody dependent enhancement (ADE) in patients with non‐neutralizing anti‐Flavivirus antibodies, a phenomenon previously recognized in serious DENV infections. Our aim was to analyze information regarding the contribution of the placental barrier as an actual player in neonatal ZIKV. Therefore, we underwent a systematic review with keywords “Zika virus” and “ZIKV”. Articles were screened for relevance concerning the topics of microcephaly, transplacental transmission, sexual transmission, and ADE. We identified variables that affect the severity of congenital Zika syndrome: age of gestation at maternal infection, the extent of placental disruption (villitis), sexual transmission, initial viral replication at the uterine wall, anti‐DENV antibodies, and the possibility of antibody‐mediated transcytosis of ZIKV through the placenta. These questions may not seem relevant when Zika becomes endemic, and we are no longer witness to the extreme clinical sequelae seen when the virus moves through an immunologically naïve population; however, characterizing the pathogenesis of congenital Zika syndrome will continue to further our understanding.     

Zika virus outbreak in Brazil—Lessons learned and perspectives for a safe and effective vaccine

Zika virus (ZIKV) is an emerging pathogen of public health concern, associated with a dramatic burden in places where the virus caused outbreaks between 2015 and 2017. In the Americas, the ZIKV was first reported in Brazil and rapidly spread through the Americas. Since its first report, a number of studies have been published as we continue to learn, not only about modes of transmission, but also clinical manifestations, risk of congenital anomalies, including microcephaly and neurological malformations in fetuses born from mothers infected during pregnancy. Interventions to reduce the burden of ZIKV infection are restricted to mosquito control, and for Aedes spp mosquitoes the strategies implemented to that end proved to be unsuccessful so far. Hence the lessons we can learn following the ZIKV epidemics become of paramount importance in the development of drug treatments and in search for a vaccine.     

Zika virus: A new threat to human reproduction

Zika virus (ZIKV) was first isolated in 1947 in a rhesus monkey from the Zika forest of Uganda. Until 2007, only 14 human cases were reported. The first large human outbreak occurred in 2007 (Yap Island, Federated States of Micronesia, Pacific) followed by French Polynesia in 2013 and Brazil in 2015. The virus is mainly transmitted through Aedes mosquito bites, but sexual and post‐transfusion transmissions have been reported. Symptoms include low‐grade fever, maculopapular rash, conjunctivitis, myalgia, arthralgia, and asthenia. During the recent outbreaks in French Polynesia and Brazil, ZIKV infection has been associated with two major complications: microcephaly and Guillain–Barré syndrome. Since fetal infection includes other birth defects, congenital Zika syndrome has been used to define in utero infection. The majority of sexual transmission occurred from a symptomatic male to a female, but female‐to‐male and male‐to‐male transmission have been reported. Asymptomatic male‐to‐female transmission has also been described. Importantly, ZIKV RNA can persist at least 6 months in semen. The male urogenital tract may therefore act as a reservoir for the virus. ZIKV RNA was detected in a cervical swab of a patient 3 days after presenting the classic symptoms suggesting a potential tropism for the female genital tract. Long‐lasting presence of ZIKV RNA might not indicate that the individual is infectious but makes recommendation for couples potentially exposed to the virus and willing to conceive difficult. It will also be important to determine whether genital ZIKV infection might have a deleterious effect on male and female fertility.     

In utero negativization of Zika virus in a foetus with serious central nervous system abnormalities

We describe a case of a pregnant woman with Zika virus (ZIKV) infection and a foetus with severe brain malformations. ZIKV tested positive in amniotic fluid at 19 weeks but was negative at delivery. The newborn did not meet the case definition of congenital ZIKV syndrome because neither ZIKV RNA nor IgM antibodies were detected; however, prenatal brain lesions were confirmed after birth (Graphical Abstract).     

The phenotypic spectrum of congenital Zika syndrome

In October 2015, Zika virus (ZIKV) outbreak the Brazilian Ministry of Health (MoH). In response, the Brazilian Society of Medical Genetics established a task force (SBGM‐ZETF) to study the phenotype of infants born with microcephaly due to ZIKV congenital infection and delineate the phenotypic spectrum of this newly recognized teratogen. This study was based on the clinical evaluation and neuroimaging of 83 infants born during the period from July, 2015 to March, 2016 and registered by the SBGM‐ZETF. All 83 infants had significant findings on neuroimaging consistent with ZIKV congenital infection and 12 had confirmed ZIKV IgM in CSF. A recognizable phenotype of microcephaly, anomalies of the shape of skull and redundancy of the scalp consistent with the Fetal Brain Disruption Sequence (FBDS) was present in 70% of infants, but was most often subtle. In addition, features consistent with fetal immobility, ranging from dimples (30.1%), distal hand/finger contractures (20.5%), and feet malpositions (15.7%), to generalized arthrogryposis (9.6%), were present in these infants. Some cases had milder microcephaly or even a normal head circumference (HC), and other less distinctive findings. The detailed observation of the dysmorphic and neurologic features in these infants provides insight into the mechanisms and timings of the brain disruption and the sequence of developmental anomalies that may occur after prenatal infection by the ZIKV.

     

Zika virus: Molecular responses and tissue tropism in the mammalian host

Zika virus (ZIKV) outbreaks have raised alarm because of reports of congenital Zika virus syndrome in infants. The virus is also known to cause the debilitating Guillain–Barré syndrome in adults. As a result, extensive research has been carried out on the virus over the past few years. To study the molecular responses of viral infectivity in mammals, in vitro two‐dimensional and three‐dimensional cellular models have been employed. The in vivo models of mouse, pig, chicken, and nonhuman primates are primarily used to investigate the teratogenicity of the virus, to study effects of the virus on specific tissues, and to study the systemic effects of a proposed antiviral agent. The virus exhibits wide tissue tropism in the mammalian host. The major host tissues of viral persistence and propagation are neural tissue, ocular tissue, testicular tissue and placental tissue. An understanding of the function of viral components, viral replication cycle, and the molecular responses elicited in the host tissues is imperative for designing antiviral treatment strategies and for development of vaccines. This review provides an update on ZIKV research models and mammalian host responses with respect to ZIKV tissue infection.     

The expanding arms of Zika virus: An updated review with recent Indian outbreaks

Zika virus (ZIKV) outbreaks and their adverse clinical consequences have raised concerns throughout the world. ZIKV was little known during the initial outbreaks in Yap islands and French Polynesia, but it came to attention after the series of Brazil outbreaks in which severe complications like microcephaly in newborn babies was detected. During 2018, outbreaks of ZIKV occurred in two states of India which, being a tropical country, has congenial climatic conditions, abundance of highly competent mosquito vectors such as Aedes aegypti and Aedes albopictus, and an immunologically naïve population. In this review, we will briefly discuss the history, epidemiology, evolution, transmission (vector‐borne and non‐vector borne), pathogenesis, clinical signs and unusual presentations, laboratory diagnosis, treatment, prevention and control of ZIKV. Finally, we suggest priorities for urgent research required to address unanswered questions about Zika infections and help bring this virus under control.     

Zika virus infection and biological treatment for reproductive medicine

The recent Zika virus (ZIKV) epidemic is particularly challenging in the field of reproductive medicine as various biological tissues and byproducts, such as intravenous immunoglobulin G or cells are utilized during reproductive cycles, and an infected mother has an increased risk of having babies with fetal microcephaly and other congenital brain anomalies. In this review, current guidelines for prevention of sexual transmission of ZIKV, ZIKV testing, and tissue and blood product usages are summarized for physicians caring for those planning pregnancy or going through infertility treatment.     

Zika virus and pregnancy: An overview

In May 2015, the first episodes of Zika virus infection of the Latin America were confirmed in Brazil, where currently 196 976 cases were reported. The main route of transmission occurs by Aedes mosquitoes, and the most common symptoms are maculopapular rash, fever, conjunctivitis, polyarthralgia, and periarticular edema. However, the infection is asymptomatic in 80% of the cases. The congenital infection is characterized when the transmission to the fetus occurs during pregnancy, but the mechanisms of how the virus infects the placenta remain unclear. Anatomopathological findings were described in first‐ and third‐trimester human placentas; however, the major affected tissue of the baby is the neural. Several clinical situations were listed in these fetuses, such as neurological, ophthalmological, auditory, and articular alterations. The World Health Organization proposed a new congenital syndrome caused by Zika virus. The virus has an important neurotropism and the main manifestation observed in the syndrome is microcephaly, which is usually severe and associated with other neurological injuries. The appearance of sudden rash in pregnant women determines immediate investigation through RT‐PCR and serological analysis. Moreover, the prevention consists in using repellents and avoiding endemic areas, considering that the vaccine is still under development.     

Efficiencies and kinetics of infection in different cell types/lines by African and Asian strains of Zika virus

After recent outbreaks, Zika virus (ZIKV) was linked to severe neurological diseases including Guillain-Barré syndrome in adults and microcephaly in newborns. The severities of pathological manifestations have been associated with different ZIKV strains. To better understand the tropism of ZIKV, we infected 10 human and four nonhuman cell lines (types) with two African (IbH30656 and MR766) and two Asian (PRVABC59 and H/FP/2013) ZIKV strains. Cell susceptibility to ZIKV infection was determined by examining viral titers, synthesis of viral proteins, and replication of positive and negative strands of viral genome. Among nonhuman cell lines, only Vero cells were efficiently infected by ZIKV. Among human cell lines, all were permissive to ZIKV infection. However, 293T and HeLa cells showed differential susceptibility towards African strains. In 293T cells, the NS1 protein was expressed at the high level by African strains but was almost not expressed by Asian strains though there was no obvious difference in viral genome replication, suggesting that the differential susceptibility might be controlled at the stage of viral protein translation. This study provides comprehensive results of the permissiveness of different cell types to both African and Asian ZIKV strains, which might help clarify their different pathogenesis.     

Synergistic antiviral activity of Sofosbuvir and type‐I interferons (α and β) against Zika virus

Zika virus (ZIKV) is transmitted by mosquitoes and causes Dengue‐like illness, neurological symptoms such as Guillain‐Barré Syndrome and microcephaly in children born to infected pregnant mothers. Recently, the World Health Organization (WHO) declared ZIKV infection as a Global Health Emergency. However, there are no known prophylactic or therapeutic measures against this virus. As a proof of concept toward combination therapeutic strategy against ZIKV, combinations of host‐targeted (Interferon‐α and Interferon‐β) and direct acting (Sofosbuvir) antivirals were evaluated in a hepatic cell line (Huh7) using a Cytoprotection (CP) assay. The combination of these antivirals resulted in synergistic inhibition of ZIKV infection in the in vitro CP assay. Additional testing in a ZIKV yield assay demonstrated that combination treatment of these antivirals conferred >2‐log reduction in the release of viral RNA. Measurement of ZIKV proteins in the cells infected with multiple ZIKV strains isolated from different geographical regions (Americas, Asia, and Africa) using an immunofluorescence assay confirmed the effective antiviral activity of this combination against ZIKV. These results demonstrate the in vitro proof of concept (POC) for using a combination approach utilizing the strengths of both virus and host‐targeted antivirals. These results suggest the effectiveness of the combination strategy in combating ZIKV, in the in vitro systems. Further evaluation of such combination therapies in vivo might provide an impetus for the development of effective ZIKV therapeutic strategies.     

Neurological manifestations of Zika virus infection

Zika virus (ZIKV) is a flavivirus (Flaviviridae family) transmitted mainly by Aedes mosquitoes. The virus was restricted to the African continent until its spread to south-east Asia in the 1980’s, the Micronesia in 2007, the French Polynesia in 2013 and, more recently in the Americas in 2015, where, up to date, the World Health Organization (WHO) has estimated about 3-4 million total cases of ZIKV infection. During outbreaks in the French Polynesia and Brazil in 2013 and 2015, respectively, national health authorities reported potential neurological complications of ZIKV disease, chiefly an upsurge in Guillain-Barré syndrome, which coincided with ZIKV outbreaks. On the other hand, the emergence of ZIKV in Brazil has been associated with a striking increase in the number of reported cases of microcephaly in fetus and newborns, twenty times higher than in that reported in previous years. While investigations are currently assessing whether there is an actual association between neurological complications and ZIKV infections, the evidence was enough worrisome for WHO to declare a public health emergency of international concern. Here we present an updated review addressing what is currently known about the possible association between ZIKV infection and the development of severe neurological disorders.     

Possible Congenital Zika Syndrome in Older Children Due to Earlier Circulation of Zika Virus

Congenital Zika syndrome (CZS) was identified following a large Zika virus (ZIKV) outbreak in Brazil in 2015. Two children with clinical presentations consistent with CZS, ages 7 and 8 years old, are described. Both mothers lived in Cambodia, a region with known ZIKV, during their pregnancies and reported fever and rash in the second trimester. The infants were born with severe microcephaly. Testing for congenital infection at birth and genetic testing were unremarkable. In 2017, serologic testing for both mothers were consistent with prior ZIKV infection. Review of infant neuroimaging demonstrated ventriculomegaly, severe cerebral atrophy, and subcortical calcifications consistent with CZS. Given the maternal symptoms suggesting ZIKV infection during pregnancy and the combination of clinical and radiological features unique to CZS, CZS is strongly suspected in these children, suggesting that CZS occurred before the 2013–2014 French Polynesia outbreak. As such, CZS should be considered in older children with congenital microcephaly of unknown etiology and a history consistent with possible ZIKV exposure.     

Evidence of increasing diversification of Zika virus strains isolated in the American continent

Zika virus (ZIKV) is a member of the family Flaviviridae . ZIKV emerged in Brazil in 2015, causing an unprecedented epidemic and since then the virus has rapidly spread throughout the Americas. These facts highlight the need of detailed phylogenetic studies to understand the emergence, spread, and evolution of ZIKV populations. For these reasons, a Bayesian coalescent Markov Chain Monte Carlo analysis of complete genome sequences of ZIKV strains recently isolated in the American continent was performed. The results of these studies revealed an increasing diversification of ZIKV strains in different genetic lineages and co‐circulation of distinct genetic lineages in several countries in the region. The time of the most recent common ancestor (tMRCA) was established to be around February 20, 2014 for ZIKV strains circulating in the American region. A mean rate of evolution of 1.55 × 10⁻³ substitutions/site/year was obtained for ZIKV strains included in this study. A Bayesian skyline plot indicate a sharp increase in population size from February 2014 to July 2015 and a decline during 2016. These results are discussed in terms of the emergence and evolution of ZIKV populations in the American continent.

     

Screening and exclusion of Zika virus infection in travellers by an NS1-based ELISA and qRT-PCR

ObjectivesZika virus (ZIKV) infection during pregnancy may cause neurological abnormalities in the foetus, and therefore fast and accurate laboratory assays are critical for rapid diagnosis. ELISA based on ZIKV NS1 protein has been developed and shown to be sensitive and highly specific; however, its negative and positive predictive values have not been tested. In this study we evaluated the ability of the NS1-based ELISA to exclude ZIKV infection and serve as a first-line screening tool for travellers.MethodsWe tested samples obtained during the peak of ZIKV infection from 1188 symptomatic and asymptomatic Israeli travellers using NS1-based IgG and IgM ELISA, real-time RT-PCR analysis and ZIKV neutralization. The Kaplan–Maier method was used to evaluate the duration of ZIKV RNA in whole blood and urine samples.ResultsNS1-based ELISA identified 20 true-positive, five false-positive and four false-negative cases, resulting in sensitivity and specificity of 83.3% (95%CI: 62–94%) and 97.5% (95%CI: 94–99%) respectively, and positive and negative predictive values of 80% (95%CI: 59–92%) and 98% (95%CI: 95–99%) respectively. Based on 14 RT-PCR-positive cases, median time to detect ZIKV RNA in whole blood was 17.5 days (range 5–58 days) and in urine 10 days (range 5–26 days).ConclusionsThe NS1-based ELISA and RT-PCR in whole blood are highly reliable for identification of ZIKV-negative and -positive cases, respectively. Combination of both assays minimizes the risk of false-negative results, and thus allows the exclusion of ZIKV infection in travellers returning from ZIKV-endemic countries, including those who are pregnant or wish for preconception screening.     

The antimalarial drug amodiaquine possesses anti‐ZIKA virus activities

Zika virus (ZIKV) outbreak has emerged as a global health threat, particularly in tropical areas, over the past few years. No antiviral therapy or vaccine is available at present. For these reasons, repurposing clinically approved drugs against ZIKV infection may provide rapid and cost‐effective global health benefits. Here, we explored this strategy and screened eight FDA‐approved drugs for antiviral activity against ZIKV using a cell‐based assay. Our results show that the antimalarial drug amodiaquine has anti‐ZIKV activity with EC₅₀ at low micromolar concentrations in cell culture. We further characterized amodiaquine antiviral activity against ZIKV and found that it targets early events of the viral replication cycle. Altogether, our results suggest that amodiaquine may be efficacious for the treatment of ZIKV infection.