Guillain-Barré Syndrome Associated with Zika Virus Infection in Colombia

Preliminary aggregate safety and immunogenicity results from three trials of a purified inactivated Zika virus vaccine candidate: phase 1, randomised, double-blind, placebo-controlled clinical trials

BACKGROUND

A safe, effective, and rapidly scalable vaccine against Zika virus infection is needed. We developed a purified formalin-inactivated Zika virus vaccine (ZPIV) candidate that showed protection in mice and non-human primates against viraemia after Zika virus challenge. Here we present the preliminary results in human beings.

METHODS

We did three phase 1, placebo-controlled, double-blind trials of ZPIV with aluminium hydroxide adjuvant. In all three studies, healthy adults were randomly assigned by a computer-generated list to receive 5 μg ZPIV or saline placebo, in a ratio of 4:1 at Walter Reed Army Institute of Research, Silver Spring, MD, USA, or of 5:1 at Saint Louis University, Saint Louis, MO, USA, and Beth Israel Deaconess Medical Center, Boston, MA, USA. Vaccinations were given intramuscularly on days 1 and 29. The primary objective was safety and immunogenicity of the ZPIV candidate. We recorded adverse events and Zika virus envelope microneutralisation titres up to day 57. These trials are registered at ClinicalTrials.gov, numbers NCT02963909, NCT02952833, and NCT02937233.

FINDINGS

We enrolled 68 participants between Nov 7, 2016, and Jan 25, 2017. One was excluded and 67 participants received two injections of Zika vaccine (n=55) or placebo (n=12). The vaccine caused only mild to moderate adverse events. The most frequent local effects were pain (n=40 [60%]) or tenderness (n=32 [47%]) at the injection site, and the most frequent systemic reactogenic events were fatigue (29 [43%]), headache (26 [39%]), and malaise (15 [22%]). By day 57, 52 (92%) of vaccine recipients had seroconverted (microneutralisation titre ≥1:10), with peak geometric mean titres seen at day 43 and exceeding protective thresholds seen in animal studies.

INTERPRETATION

The ZPIV candidate was well tolerated and elicited robust neutralising antibody titres in healthy adults.

FUNDING

Departments of the Army and Defense and National Institute of Allergy and Infectious Diseases.

Biologic Evidence Required for Zika Disease Enhancement by Dengue Antibodies

The sudden appearance of overt human Zika virus infections that cross the placenta to damage fetal tissues, target sexual organs, and are followed in some instances by Guillain-Barré syndrome raises questions regarding whether these outcomes are caused by genetic mutations or if prior infection by other flaviviruses affects disease outcome. Because dengue and Zika viruses co-circulate in the urban Aedes aegypti mosquito–human cycle, a logical question, as suggested by in vitro data, is whether dengue virus infections result in antibody-dependent enhancement of Zika virus infections. This review emphasizes the critical role for epidemiologic studies (retrospective and prospective) in combination with the studies to identify specific sites of Zika virus infection in humans that are needed to establish antibody-dependent enhancement as a possibility or a reality.

The structural proteins of epidemic and historical strains of Zika virus differ in their ability to initiate viral infection in human host cells

Mosquito-borne Zika virus (ZIKV) recently emerged in South Pacific islands and Americas where large epidemics were documented. In the present study, we investigated the contribution of the structural proteins C, prM and E in the permissiveness of human host cells to epidemic strains of ZIKV. To this end, we evaluated the capacity of the epidemic strain BeH819015 to infect epithelial A549 and neuronal SH-SY5Y cells in comparison to the African historical MR766 strain. For that purpose, we generated a molecular clone of BeH819015 and a chimeric clone of MR766 which contains the BeH819015 structural protein region. We showed that ZIKV containing BeH819015 structural proteins was much less efficient in cell-attachment leading to a reduced susceptibility of A549 and SH-SY5Y cells to viral infection. Our data illustrate a previously underrated role for C, prM, and E in ZIKV epidemic strain ability to initiate viral infection in human host cells.

Clinical, Serological, and Molecular Observations from a Case Series Study during the Asian Lineage Zika Virus Outbreak in Grenada during 2016

This paper describes the spatial and temporal distribution of cases, demographic characteristics of patients, and clinical manifestations of Zika virus (ZIKV) during the 2016 outbreak in Grenada. The first reported case was recorded in St. Andrew Parish in April, and the last reported case was seen in November, with peak transmission occurring in the last week of June, based on test results. Data were collected from a total of 514 patients, of whom 207 (40%) tested positive for ZIKV. No evidence was found that testing positive for ZIKV infection was related to age, gender, or pregnancy status. Clinical presentation with rash (OR = 2.4, 95% CI = 1.5 to 3.7) or with lymphadenopathy (OR = 1.7, 95% CI = 1.0 to 2.9) were the only reported symptoms consistent with testing positive for ZIKV infection. During the Zika outbreak, the infection rate was 20 clinical cases per 10,000 in the population compared to 41 cases per 10,000 during the chikungunya outbreak in Grenada in 2014 and 17 cases per 10,000 during the dengue outbreak in 2001-2002. Even though the country has employed vector control programs, with no apparent decrease in infection rates, it appears that new abatement approaches are needed to minimize morbidity in future arbovirus outbreaks.

Zika clinical updates: implications for pediatrics

PURPOSE OF REVIEW

Zika virus (ZIKV), a mosquito-borne flavivirus, has gained recognition over the past few years as an important new cause of congenital infection. As a result, it is critical that pediatricians understand its epidemiology, clinical presentation, clinical sequelae, and management.

RECENT FINDINGS

The recent ZIKV epidemiology, clinical presentation of acute infection in children and complications, perinatal infection, and congenital infection will be summarized in this ZIKV review. This will be followed by a brief summary on ZIKV diagnosis, management, treatment, and prevention.

SUMMARY

The field of clinical research in ZIKV has rapidly evolved over recent months. It is critical that pediatricians continue to stay up-to-date with the continuously evolving understanding of the clinical aspects of ZIKV to ensure optimal identification and management of affected infants and children. Given the recent changes in Centers for Disease Control and Prevention guidelines to limit screening of asymptomatic pregnant women in the United States with possible ZIKV exposure, comprehensive ZIKV clinical knowledge becomes even more crucial.

The spectrum of neurological disease associated with Zika and chikungunya viruses in adults in Rio de Janeiro, Brazil: A case series

BACKGROUND

During 2015-16 Brazil experienced the largest epidemic of Zika virus ever reported. This arthropod-borne virus (arbovirus) has been linked to Guillain-Barré syndrome (GBS) in adults but other neurological associations are uncertain. Chikungunya virus has caused outbreaks in Brazil since 2014 but associated neurological disease has rarely been reported here. We investigated adults with acute neurological disorders for Zika, chikungunya and dengue, another arbovirus circulating in Brazil.

METHODS

We studied adults who had developed a new neurological condition following suspected Zika virus infection between 1st November 2015 and 1st June 2016. Cerebrospinal fluid (CSF), serum, and urine were tested for evidence of Zika, chikungunya, and dengue viruses.

RESULTS

Of 35 patients studied, 22 had evidence of recent arboviral infection. Twelve had positive PCR or IgM for Zika, five of whom also had evidence for chikungunya, three for dengue, and one for all three viruses. Five of them presented with GBS; seven had presentations other than GBS, including meningoencephalitis, myelitis, radiculitis or combinations of these syndromes. Additionally, ten patients positive for chikungunya virus, two of whom also had evidence for dengue virus, presented with a similar range of neurological conditions.

CONCLUSIONS

Zika virus is associated with a wide range of neurological manifestations, including central nervous system disease. Chikungunya virus appears to have an equally important association with neurological disease in Brazil, and many patients had dual infection. To understand fully the burden of Zika we must look beyond GBS, and also investigate for other co-circulating arboviruses, particularly chikungunya.

AXL promotes Zika virus infection in astrocytes by antagonizing type I interferon signalling

Zika virus (ZIKV) is associated with neonatal microcephaly and Guillain-Barré syndrome^1,2. While progress has been made in understanding the causal link between ZIKV infection and microcephaly^3-9, the life cycle and pathogenesis of ZIKV are less well understood. In particular, there are conflicting reports on the role of AXL, a TAM family kinase receptor that was initially described as the entry receptor for ZIKV^10-22. Here, we show that while genetic ablation of AXL protected primary human astrocytes and astrocytoma cell lines from ZIKV infection, AXL knockout did not block the entry of ZIKV. We found, instead, that the presence of AXL attenuated the ZIKV-induced activation of type I interferon (IFN) signalling genes, including several type I IFNs and IFN-stimulating genes. Knocking out type I IFN receptor α chain (IFNAR1) restored the vulnerability of AXL knockout astrocytes to ZIKV infection. Further experiments suggested that AXL regulates the expression of SOCS1, a known type I IFN signalling suppressor, in a STAT1/STAT2-dependent manner. Collectively, our results demonstrate that AXL is unlikely to function as an entry receptor for ZIKV and may instead promote ZIKV infection in human astrocytes by antagonizing type I IFN signalling.

Immune Response to Dengue and Zika

Flaviviruses such as dengue (DENV), yellow fever (YFV), West Nile (WNV), and Zika (ZIKV) are human pathogens of global significance. In particular, DENV causes the most prevalent mosquito-borne viral diseases in humans, and ZIKV emerged from obscurity into the spotlight in 2016 as the etiologic agent of congenital Zika syndrome. Owing to the recent emergence of ZIKV as a global pandemic threat, the roles of the immune system during ZIKV infections are as yet unclear. In contrast, decades of DENV research implicate a dual role for the immune system in protection against and pathogenesis of DENV infection. As DENV and ZIKV are closely related, knowledge based on DENV studies has been used to prioritize investigation of ZIKV immunity and pathogenesis, and to accelerate ZIKV diagnostic, therapeutic, and vaccine design. This review discusses the following topics related to innate and adaptive immune responses to DENV and ZIKV: the interferon system as the key mechanism of host defense and viral target for immune evasion, antibody-mediated protection versus antibody-dependent enhancement, and T cell-mediated protection versus original T cell antigenic sin. Understanding the mechanisms that regulate the balance between immune-mediated protection and pathogenesis during DENV and ZIKV infections is critical toward development of safe and effective DENV and ZIKV therapeutics and vaccines.

Mosquito-borne arboviruses of African origin: review of key viruses and vectors

Key aspects of 36 mosquito-borne arboviruses indigenous to Africa are summarized, including lesser or poorly-known viruses which, like Zika, may have the potential to escape current sylvatic cycling to achieve greater geographical distribution and medical importance. Major vectors are indicated as well as reservoir hosts, where known. A series of current and future risk factors is addressed. It is apparent that Africa has been the source of most of the major mosquito-borne viruses of medical importance that currently constitute serious global public health threats, but that there are several other viruses with potential for international challenge. The conclusion reached is that increased human population growth in decades ahead coupled with increased international travel and trade is likely to sustain and increase the threat of further geographical spread of current and new arboviral disease.

HOSPITAL- AND COMMUNITY- BASED SURVEILLANCE OF ZIKA AND DENGUE VIRUSES IN INDONESIA

Background:

Zika virus remained silent for few decades after its first recognition in 1947. Recently, Zika drew global attention due to the outbreak in Pacific island and Latin Americas. The concern was escalating given the shared vector of Zika and dengue with possible deleterious complications. Surabaya as one of the largest cities in Indonesia with high mobility of people is endemic to dengue. This study was aimed to detect Zika infection during dengue outbreaks in Surabaya.

Materials and Methods:

This was a surveillance study involving patients visiting 4 public hospitals and 8 primary health care centres (PHCs). Patients were recruited if they were suspected to have dengue infection based on WHO guidelines (1997). The recruitment was based on the attendance of the patients at the healthcare facilities until the maximum quota was fulfilled. Dengue serological diagnostic confirmation was based on non-structural protein 1 (NS1) and/or immunoglobulin M (IgM) detection. Zika virus infection was examined using real time polymerase chain reaction (RT-PCR) test.

Results:

Between February and April 2016, 100 patients consented to participate in this study - 54 females and 46 males. Furthermore, 55 patients were recruited from PHCs and the other 45 patients were from hospitals. Median age was (median (IQR)) 28.6 (14.6) years (range15 to 65 years). Of 100 patients examined, there was no Zika infection detected, but 11 patients were identified to have positive dengue infection with varying clinical and laboratory presentations.

Conclusion:

Serosurveillance of Zika and dengue infection in Surabaya City found no evidence of Zika infection among those presented to healthcare facilities.

Neurological disease caused by flavivirus infections

The Flavivirus genus contains dozens of species with varying geographical distributions. Most flavivirus infections in humans are asymptomatic or manifest as a non-specific febrile illness, sometimes accompanied by rash or arthralgia. Certain species are more commonly associated with neurological disease and may be termed neurotropic flaviviruses. Several flaviviruses endemic to Australia and our near northern neighbours are neurotropic, such as Murray Valley encephalitis virus, West Nile (Kunjin) virus and Japanese encephalitis virus. Flavivirus neurological disease ranges from self-limiting meningitis to fulminant encephalitis causing permanent debilitating neurological sequelae or death. The recent Zika virus outbreak in South America has highlighted the dramatic effects of flavivirus neurotropism on the developing brain. This article focuses on the neurotropic flaviviruses endemic to Australia and those of international significance.

Zika Virus Envelope Protein induces G2/M Cell Cycle Arrest and Apoptosis via an Intrinsic Cell Death Signaling Pathway in Neuroendocrine PC12 Cells

Clinical evidence suggests that there exists a strong correlation between Zika virus (ZIKV) infection and abnormal development of the nervous system. However, the underlying mechanisms remain to be elusive. In this study, recombinant lentiviral vectors coding for ZIKV structural proteins and truncations (prM-Env, M-Env and Env) were transduced into PC12 cells. Envelope (Env) overexpression induced significant inhibition of proliferation and triggered G2/M cell cycle arrest and apoptosis in PC12 cells. Flow cytometry and western blot analysis showed that the apoptosis was associated with up-regulation of both p53 and p21^Cip1/Waf1 and down-regulation of cyclin B1. Presence of aberrant nuclei clusters were confirmed by immunofluorescence staining analysis. The data indicate that overexpression of prM-Env, M-Env or Env led to apoptosis via an intrinsic cell death signaling pathway that is dependent on the activation of caspase-9 and caspase-3 and accompanied by an increased ratio of Bax to Bcl-2 in transduced PC12 cells. In summary, our results suggest that ZIKV Env protein causes apoptosis in PC12 cells via an intrinsic cell death signaling pathway, which may contribute to ZIKV-induced abnormal development of the nervous system.

Ontogeny of the B- and T-cell response in a primary Zika virus infection of a dengue-naïve individual during the 2016 outbreak in Miami, FL

Zika virus (ZIKV) is a mosquito-borne flavivirus of significant public health concern. In the summer of 2016, ZIKV was first detected in the contiguous United States. Here we present one of the first cases of a locally acquired ZIKV infection in a dengue-naïve individual. We collected blood from a female with a maculopapular rash at day (D) 5 and D7 post onset of symptoms (POS) and we continued weekly blood draws out to D148 POS. To establish the ontogeny of the immune response against ZIKV, lymphocytes and plasma were analyzed in a longitudinal fashion. The plasmablast response peaked at D7 POS (19.6% of CD19⁺ B-cells) and was undetectable by D15 POS. ZIKV-specific IgM was present at D5 POS, peaked between D15 and D21 POS, and subsequently decreased. The ZIKV-specific IgG response, however, was not detected until D15 POS and continued to increase after that. Interestingly, even though the patient had never been infected with dengue virus (DENV), cross-reactive IgM and IgG binding against each of the four DENV serotypes could be detected. The highest plasma neutralization activity against ZIKV peaked between D15 and D21 POS, and even though DENV binding antibodies were present in the plasma of the patient, there was neither neutralization nor antibody dependent enhancement (ADE) of DENV. Interestingly, ADE against ZIKV arose at D48 POS and continued until the end of the study. CD4⁺ and CD8⁺ T-cells recognized ZIKV-NS2A and ZIKV-E, respectively. The tetramer positive CD8⁺ T-cell response peaked at D21 POS with elevated levels persisting for months. In summary, this is the first study to establish the timing of the ontogeny of the immune response against ZIKV.

Zika virus (ZIKV) is an emerging viral disease that has the potential to negatively impact future generations by causing birth defects in infected pregnant mothers. While there have been many studies performed in animal models of ZIKV infection, there have only been a limited number of reports studying the immune responses in humans. Ricciardi et. al. analyzed the immune response of a primary ZIKV infection in a dengue virus (DENV) naïve individual during the 2016 outbreak in Miami, Florida. B- and T-cell responses were assessed over multiple time points. Cross-reactive antibodies against DENV, a virus that the patient was never infected with, were generated during the ZIKV infection, but these antibodies failed to neutralize any of the DENV serotypes. Furthermore, while these DENV-cross-reactive antibodies might be expected to cause antibody dependent enhancement (ADE) of DENV infection, they did not. Interestingly, ADE of ZIKV infection was seen at approximately 1 ½ months after infection. Together, these results establish the timing of the ontogeny of the immune response against a primary ZIKV infection in a DENV-naïve individual.

Discovery of a non-nucleoside RNA polymerase inhibitor for blocking Zika virus replication through in silico screening

Zika virus (ZIKV), an emerging arbovirus, has become a major human health concern globally due to its association with congenital abnormalities and neurological diseases. Licensed vaccines or antivirals against ZIKV are currently unavailable. Here, by employing a structure-based approach targeting the ZIKV RNA-dependent RNA polymerase (RdRp), we conducted in silico screening of a library of 100,000 small molecules and tested the top ten lead compounds for their ability to inhibit the virus replication in cell-based in vitro assays. One compound, 3-chloro-N-[({4-[4-(2-thienylcarbonyl)-1-piperazinyl]phenyl}amino)carbonothioyl]-1-benzothiophene-2-carboxamide (TPB), potently inhibited ZIKV replication at sub-micromolar concentrations. Molecular docking analysis suggests that TPB binds to the catalytic active site of the RdRp and therefore likely blocks the viral RNA synthesis by an allosteric effect. The IC₅₀ and the CC₅₀ of TPB in Vero cells were 94 nM and 19.4 μM, respectively, yielding a high selective index of 206. In in vivo studies using immunocompetent mice, TPB reduced ZIKV viremia significantly, indicating TPB as a potential drug candidate for ZIKV infections.

Diagnosis of Zika Virus Infections: Challenges and Opportunities

Accurate diagnosis of Zika virus (ZIKV) infections has become a pressing need for the effective prevention and control of the epidemic. The findings that ZIKV infections are associated with birth defects and neurologic disease, and that the virus can be sexually transmitted, accentuate the need for accurate diagnostic testing for different applications new to the arbovirus field. Antibody response to related flaviviruses has long been known to be cross-reactive, and antibody detection of ZIKV is nonspecific in populations previously exposed to any of the four dengue viruses or West Nile virus, or vaccinated against yellow fever virus. Therefore, the diagnosis of ZIKV infections has increasingly depended on detection by nucleic acid tests. During the recent epidemic, tests authorized for emergency use have been utilized by public health laboratories and the commercial sector, but a more dependable and responsive diagnostic testing has yet to be developed.

ZikaPLAN: Zika Preparedness Latin American Network

The ongoing Zika virus (ZIKV) outbreak in Latin America, the Caribbean, and the Pacific Islands has underlined the need for a coordinated research network across the whole region that can respond rapidly to address the current knowledge gaps in Zika and enhance research preparedness beyond Zika. The European Union under its Horizon 2020 Research and Innovation Programme awarded three research consortia to respond to this need. Here we present the ZikaPLAN (Zika Preparedness Latin American Network) consortium. ZikaPLAN combines the strengths of 25 partners in Latin America, North America, Africa, Asia, and various centers in Europe. We will conduct clinical studies to estimate the risk and further define the full spectrum and risk factors of congenital Zika virus syndrome (including neurodevelopmental milestones in the first 3 years of life), delineate neurological complications associated with ZIKV due to direct neuroinvasion and immune-mediated responses in older children and adults, and strengthen surveillance for birth defects and Guillain-Barré Syndrome. Laboratory-based research to unravel neurotropism and investigate the role of sexual transmission, determinants of severe disease, and viral fitness will underpin the clinical studies. Social messaging and engagement with affected communities, as well as development of wearable repellent technologies against Aedes mosquitoes will enhance the impact. Burden of disease studies, data-driven vector control, and vaccine modeling as well as risk assessments on geographic spread of ZIKV will form the foundation for evidence-informed policies. While addressing the research gaps around ZIKV, we will engage in capacity building in laboratory and clinical research, collaborate with existing and new networks to share knowledge, and work with international organizations to tackle regulatory and other bottlenecks and refine research priorities. In this way, we can leverage the ZIKV response toward building a long-term emerging infectious diseases response capacity in the region to address future challenges.

Zika virus-induced neurological critical illness in Latin America: Severe Guillain-Barre Syndrome and encephalitis

Zika virus (ZIKAV) is classically described as causing minor symptoms in adult patients, however neurologic complications have been recognized. The recent outbreak in Central and South America has resulted in serious illness in some adult patients. We report adult patients in Latin America diagnosed with ZIKAV infection admitted to Intensive Care Units (ICUs).

METHODS

Multicenter, prospective case series of adult patients with laboratory diagnosis of ZIKAV in 16 ICUs in 8 countries.

RESULTS

Between December 1st 2015 and April 2nd 2016, 16 ICUs in 8 countries enrolled 49 critically ill patients with diagnosis of ZIKAV infection. We included 10 critically ill patients with ZIKAV infection, as diagnosed with RT-PCR, admitted to the ICU. Neurologic manifestations concordant with Guillain-Barre Syndrome (GBS) were present in all patients, although 2 evolved into an encephalitis-like picture. 2 cases died, one due to encephalitis, the other septic shock.

CONCLUSIONS

Differing from what was usually reported, ZIKAV infection can result in life-threatening neurologic illness in adults, including GBS and encephalitis. Collaborative reporting to identify severe illness from an emerging pathogen can provide valuable insights into disease epidemiology and clinical presentation, and inform public health authorities about acute care priorities.

Zika Virus-associated Ocular and Neurologic Disorders: The Emergence of New Evidence

BACKGROUND

It has been approximately 70 years since the discovery of the Zika virus (ZIKV). It had been established that the virus causes mild infections and is confined to Africa and Asia; however, major changes in the clinical and epidemiologic patterns of ZIKV infection have occurred in recent years. The virus has attracted intense interest because of the possible association of several autoimmune and neurodevelopmental disorders.

METHODS

We present a summary of the articles that attempt to explain the ZIKV unknowns and strengthen the association with some disorders that are thought to be related to ZIKV, by describing the discovery milestones from the initial identification of the virus to the present day.

RESULTS

New evidence strengthens the association between ZIKV infections and Guillain-Barré syndrome (GBS), microcephaly and various neurodevelopmental and ophthalmologic disorders as a result of numerous new clinical and experimental studies.

CONCLUSIONS

The World Health Organization declared the end of the "Public Health Emergency of International Concern" in December 2016, but ZIKV and associated consequences remain a significant enduring public health challenge.

Guillain-Barré Syndrome, Acute Disseminated Encephalomyelitis and Encephalitis Associated with Zika Virus Infection in Brazil: Detection of Viral RNA and Isolation of Virus during Late Infection

Zika virus (ZIKV) emerged in Brazil in 2015, which was followed by an increase of Guillain-Barre Syndrome (GBS) cases. We report the epidemiological, clinical, and laboratory findings of the first six neurological cases associated with ZIKV in Brazil seen in a reference neurology hospital in Pernambuco, Brazil. In all cases, ZIKV was detected in serum and/or cerebrospinal fluid (CSF) samples. In this case series, four cases were defined as GBS, one as acute disseminated encephalomyelitis (ADEM) and the other as encephalitis. ZIKV was detected in all cases by RT-PCR and virus isolation was successful in two patients. The time between ZIKV acute symptoms and the development of neurological manifestations varied from 3 to 13 days and ZIKV was detected between 15 and 34 days after the initial symptoms. Our results highlight the need to include ZIKV as a differential diagnosis for neurological syndromes in countries with circulation of this arbovirus. Because the viremia in these patients appears to persist longer, direct diagnostic techniques such as RT-PCR and viral isolation should be considered even if it is after the acute phase of viral infection.

Novel pathomechanisms in inflammatory neuropathies

Inflammatory neuropathies are rare autoimmune-mediated disorders affecting the peripheral nervous system. Considerable progress has recently been made in understanding pathomechanisms of these disorders which will be essential for developing novel diagnostic and therapeutic strategies in the future. Here, we summarize our current understanding of antigenic targets and the relevance of new immunological concepts for inflammatory neuropathies. In addition, we provide an overview of available animal models of acute and chronic variants and how new diagnostic tools such as magnetic resonance imaging and novel therapeutic candidates will benefit patients with inflammatory neuropathies in the future. This review thus illustrates the gap between pre-clinical and clinical findings and aims to outline future directions of development.

Zika Virus Escapes NK Cell Detection by Upregulating Major Histocompatibility Complex Class I Molecules

NK cells are innate lymphocytes that participate in many immune processes encompassing cancer, bacterial and fungal infection, autoimmunity, and even pregnancy and that specialize in antiviral defense. NK cells express inhibitory and activating receptors and kill their targets when activating signals overpower inhibitory signals. The NK cell inhibitory receptors include a uniquely diverse array of proteins named killer cell immunoglobulin-like receptors (KIRs), the CD94 family, and the leukocyte immunoglobulin-like receptor (LIR) family. The NK cell inhibitory receptors recognize mostly major histocompatibility complex (MHC) class I (MHC-I) proteins. Zika virus has recently emerged as a major threat due to its association with birth defects and its pandemic potential. How Zika virus interacts with the immune system, and especially with NK cells, is unclear. Here we show that Zika virus infection is barely sensed by NK cells, since little or no increase in the expression of activating NK cell ligands was observed following Zika infection. In contrast, we demonstrate that Zika virus infection leads to the upregulation of MHC class I proteins and consequently to the inhibition of NK cell killing. Mechanistically, we show that MHC class I proteins are upregulated via the RIGI-IRF3 pathway and that this upregulation is mediated via beta interferon (IFN-β). Potentially, countering MHC class I upregulation during Zika virus infection could be used as a prophylactic treatment against Zika virus.IMPORTANCE NK cells are innate lymphocytes that recognize and eliminate various pathogens and are known mostly for their role in controlling viral infections. NK cells express inhibitory and activating receptors, and they kill or spare their targets based on the integration of inhibitory and activating signals. Zika virus has recently emerged as a major threat to humans due to its pandemic potential and its association with birth defects. The role of NK cells in Zika virus infection is largely unknown. Here we demonstrate that Zika virus infection is almost undetected by NK cells, as evidenced by the fact that the expression of activating ligands for NK cells is not induced following Zika infection. We identified a mechanism whereby Zika virus sensing via the RIGI-IRF3 pathway resulted in IFN-β-mediated upregulation of MHC-I molecules and inhibition of NK cell activity. Countering MHC class I upregulation and boosting NK cell activity may be employed as prophylactic measures to combat Zika virus infection.

Zika virus in French Polynesia 2013-14: anatomy of a completed outbreak

The Zika virus crisis exemplified the risk associated with emerging pathogens and was a reminder that preparedness for the worst-case scenario, although challenging, is needed. Herein, we review all data reported during the unexpected emergence of Zika virus in French Polynesia in late 2013. We focus on the new findings reported during this outbreak, especially the first description of severe neurological complications in adults and the retrospective description of CNS malformations in neonates, the isolation of Zika virus in semen, the potential for blood-transfusion transmission, mother-to-child transmission, and the development of new diagnostic assays. We describe the effect of this outbreak on health systems, the implementation of vector-borne control strategies, and the line of communication used to alert the international community of the new risk associated with Zika virus. This outbreak highlighted the need for careful monitoring of all unexpected events that occur during an emergence, to implement surveillance and research programmes in parallel to management of cases, and to be prepared to the worst-case scenario.

Dengue virus-reactive CD8+ T cells mediate cross-protection against subsequent Zika virus challenge

Zika virus (ZIKV) and dengue virus (DENV) are antigenically related flaviviruses that share cross-reactivity in antibody and T cell responses, and co-circulate in increasing numbers of countries. Whether pre-existing DENV immunity can cross-protect or enhance ZIKV infection during sequential infection of the same host is unknown. Here, we show that DENV-immune Ifnar1^−/− or wild-type C57BL/6 mice infected with ZIKV have cross-reactive immunity to subsequent ZIKV infection and pathogenesis. Adoptive transfer and cell depletion studies demonstrate that DENV-immune CD8⁺ T cells predominantly mediate cross-protective responses to ZIKV. In contrast, passive transfer studies suggest that DENV-immune serum does not protect against ZIKV infection. Thus, CD8⁺ T cell immunity generated during primary DENV infection can confer protection against secondary ZIKV infection in mice. Further optimization of current DENV vaccines for T cell responses might confer cross-protection and prevent antibody-mediated enhancement of ZIKV infection.

Dengue virus-specific antibody and CD8⁺ T cells that cross-react with Zika virus have been described. Here, the authors establish a functionally protective role for cross-reactive dengue virus-specific CD8⁺ T cells during challenge with Zika virus.

An update on Zika virus infection

The epidemic history of Zika virus began in 2007, with its emergence in Yap Island in the western Pacific, followed in 2013-14 by a larger epidemic in French Polynesia, south Pacific, where the first severe complications and non-vector-borne transmission of the virus were reported. Zika virus emerged in Brazil in 2015 and was declared a national public health emergency after local researchers and physicians reported an increase in microcephaly cases. In 2016, WHO declared the recent cluster of microcephaly cases and other neurological disorders reported in Brazil a global public health emergency. Similar clusters of microcephaly cases were also observed retrospectively in French Polynesia in 2014. In 2015-16, Zika virus continued its spread to cause outbreaks in the Americas and the Pacific, and the first outbreaks were reported in continental USA, Africa, and southeast Asia. Non-vector-borne transmission was confirmed and Zika virus was established as a cause of severe neurological complications in fetuses, neonates, and adults. This Review focuses on important updates and gaps in the knowledge of Zika virus as of early 2017.

Zika virus disease, microcephaly and Guillain-Barré syndrome in Colombia: epidemiological situation during 21 months of the Zika virus outbreak, 2015-2017

Background

The Zika virus disease (ZVD) has had a huge impact on public health in Colombia for the numbers of people affected and the presentation of Guillain-Barre syndrome (GBS) and microcephaly cases associated to ZVD.

Methods

A retrospective descriptive study was carried out, we analyze the epidemiological situation of ZVD and its association with microcephaly and GBS during a 21-month period, from October 2015 to June 2017. The variables studied were: (i) ZVD cases, (ii) ZVD cases in pregnant women, (iii) laboratory-confirmed ZVD in pregnant women, (iv) ZVD cases associated with microcephaly, (v) laboratory-confirmed ZVD associated with microcephaly, and (vi) ZVD associated to GBS cases. Average number of cases, attack rates (AR) and proportions were also calculated. The studied variables were plotted by epidemiological weeks and months. The distribution of ZVD cases in Colombia was mapped across the time using Kernel density estimator and QGIS software; we adopted Kernel Ridge Regression (KRR) and the Gaussian Kernel to estimate the number of Guillain Barre cases given the number of ZVD cases.

Results

One hundred eight thousand eighty-seven ZVD cases had been reported in Colombia, including 19,963 (18.5%) in pregnant women, 710 (0.66%) associated with microcephaly (AR, 4.87 cases per 10,000 live births) and 453 (0.42%) ZVD associated to GBS cases (AR, 41.9 GBS cases per 10,000 ZVD cases). It appears the cases of GBS increased in parallel with the cases of ZVD, cases of microcephaly appeared 5 months after recognition of the outbreak. The kernel density map shows that throughout the study period, the states most affected by the Zika outbreak in Colombia were mainly San Andrés and Providencia islands, Casanare, Norte de Santander, Arauca and Huila. The KRR shows that there is no proportional relationship between the number of GBS and ZVD cases. During the cross validation, the RMSE achieved for the second order polynomial kernel, the linear kernel, the sigmoid kernel, and the Gaussian kernel are 9.15, 9.2, 10.7, and 7.2 respectively.

Conclusions

This study updates the epidemiological analysis of the ZVD situation in Colombia describes the geographical distribution of ZVD and shows the functional relationship between ZVD cases and GBS.

Human antibodies to the dengue virus E-dimer epitope have therapeutic activity against Zika virus infection

The Zika virus (ZIKV) epidemic has resulted in congenital abnormalities in fetuses and neonates. Although some cross-reactive dengue virus (DENV)-specific antibodies can enhance ZIKV infection in mice, those recognizing the DENV E-dimer epitope (EDE) can neutralize ZIKV infection in cell culture. We evaluated the therapeutic activity of human monoclonal antibodies to DENV EDE for their ability to control ZIKV infection in the brains, testes, placentas, and fetuses of mice. A single dose of the EDE1-B10 antibody given 3 d after ZIKV infection protected against lethality, reduced ZIKV levels in brains and testes, and preserved sperm counts. In pregnant mice, wild-type or engineered LALA variants of EDE1-B10, which cannot engage Fcg receptors, diminished ZIKV burden in maternal and fetal tissues, and protected against fetal demise. Because neutralizing antibodies to EDE have therapeutic potential against ZIKV, in addition to their established inhibitory effects against DENV, it may be possible to develop therapies that control disease caused by both viruses.

Zika Virus Disease in Children in Colombia, August 2015 to May 2016

BACKGROUND

Children are considered a potentially vulnerable population for Zika virus infection. However, data on paediatric Zika virus infection are sparse.

METHODS

We analysed data from Colombia's national surveillance system during the 2015-2016 Zika virus outbreak on patients meeting the clinical case definition of Zika virus disease (ZVD) among children aged 1 month to 18 years to estimate incidence by demographic characteristics and characterize the occurrence of selected complications.

RESULTS

Between August 14, 2015, and May 28, 2016, there were 18 576 reported cases of postnatal ZVD among children aged 1 month to 18 years. Laboratory testing was prioritized for high-risk patients (infants, pregnant women, adults aged ≥65 years, and persons with serious co-morbidities); among 1655 that were tested by real-time reverse transcriptase polymerase chain reaction, 1207 (72.9%) were positive. The cumulative incidence of reported ZVD was 114.4 per 100 000. The incidence differed by sex, depending on age group; the largest difference was observed for 15-18 year olds, with females having a higher incidence than males (cumulative incidence ratio 2.5, 95% confidence interval 2.3, 2.7). At the time of report to the surveillance system, 631 patients (3.4%) were hospitalised and 96 (0.5%) had a report of an accompanying neurological diagnosis, including Guillain-Barré syndrome in 40 patients.

CONCLUSIONS

Only a small proportion of reported paediatric ZVD cases in Colombia were hospitalized or had reported neurological conditions following ZVD. However, the potential for some serious outcomes demonstrates the importance of preventing Zika virus infection in children.

Severity of acute Zika virus infection: A prospective emergency room surveillance study during the 2015-2016 outbreak in Suriname

Acute Zika virus (ZIKV) infection is usually mild and self-limiting. Earlier, we reported three cases of fatal acute ZIKV infection in patients without typical signs of ZIKV, but rather with criteria of systemic inflammation response syndrome (SIRS). To follow up these observations, we prospectively included patients at the emergency room with temperature instability and suspected to have acute ZIKV infection, SIRS, or both. A total of 102 patients were included of whom N = 21 (21%) were suspected of acute ZIKV infection, N = 56 (55%) of acute ZIKV infection with SIRS criteria, and N = 25 (24%) of SIRS alone. ZIKV-PCR was positive in N = 21 (20%) patients. Eight (38%) ZIKV-positive patients needed admission to the hospital of whom four (50%) presented with SIRS alone. One ZIKV-positive patient had vascular co-morbidity and died following shock and severe coagulopathy. We confirm the hypothesis that acute ZIKV infection can present atypical and severely with systemic inflammation and have lethal course particularly amongst patients with significant prior disease.

American Strain of Zika Virus Causes More Severe Microcephaly Than an Old Asian Strain in Neonatal Mice

Zika virus (ZIKV) has evolved from an overlooked mosquito-borne flavivirus into a global health threat due to its astonishing causal link to microcephaly and other disorders. ZIKV has been shown to infect neuronal progenitor cells of the fetal mouse brain, which is comparable to the first-trimester human fetal brain, and result in microcephaly. However, whether there are different effects between the contemporary ZIKV strain and its ancestral strain in the neonatal mouse brain, which is comparable with the second-trimester human fetal brain, is unclear. Here we adopted a mouse model which enables us to study the postnatal effect of ZIKV infection. We show that even 100 pfu of ZIKV can replicate and infect neurons and oligodendrocytes in most parts of the brain. Compared with the ancestral strain from Cambodia (CAM/2010), infection of the ZIKV strain from Venezuela (VEN/2016) leads to much more severe microcephaly, accompanied by more neuronal cell death, abolishment of oligodendrocyte development, and a more dramatic immune response. The serious brain damage caused by VEN/2016 infection would be helpful to elucidate why the American strain resulted in severe neurovirulence in infants and will provide clinical guidance for the diagnosis and treatment of infection by different ZIKV strains.

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The infection of an American strain of ZIKV leads to more severe microcephaly than the ancestral Asian strain.

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American strain infects more cells, and induces more dramatic immune response and cell death than ancestral Asian strain.

World attention has been drawn to a global Zika virus (ZIKV) outbreak due to its unexpected causal link to congenital brain abnormalities, especially microcephaly. Infection of pregnant women with the American Zika strain, but not the ancestral Asian strain, can result in microcephaly in infants. However, the phenotypic difference between the contemporary American strain and ancestral Asian strain of ZIKV is still unclear. We employed the ZIKV infection model of a neonatal mouse brain to compare the difference between these two strains. We find that infection by the American strain leads to more severe microcephaly than the ancestral Asian strain.

Neurologic Complications Associated With the Zika Virus in Brazilian Adults

Importance

There are no prospective cohort studies assessing the incidence and spectrum of neurologic manifestations secondary to Zika virus (ZIKV) infection in adults.

Objective

To evaluate the rates of acute ZIKV infection among patients hospitalized with Guillain-Barré syndrome (GBS), meningoencephalitis, or transverse myelitis.

Design, Setting, and Participants

A prospective, observational cohort study was conducted at a tertiary referral center for neurological diseases in Rio de Janeiro, Brazil, between December 5, 2015, and May 10, 2016, among consecutive hospitalized adults (>18 years of age) with new-onset acute parainfectious or neuroinflammatory disease. All participants were tested for a series of arbovirosis. Three-month functional outcome was assessed.

Interventions

Samples of serum and cerebrospinal fluid were tested for ZIKV using real-time reverse-transcriptase-polymerase chain reaction and an IgM antibody-capture enzyme-linked immunosorbent assay. Clinical, radiographic (magnetic resonance imaging), electrophysiological, and 3-month functional outcome data were collected.

Main Outcomes and Measures

The detection of neurologic complications secondary to ZIKV infection.

Results

Forty patients (15 women and 25 men; median age, 44 years [range, 22-72 years]) were enrolled, including 29 patients (73%) with GBS (90% Brighton level 1 certainty), 7 (18%) with encephalitis, 3 (8%) with transverse myelitis, and 1 (3%) with newly diagnosed chronic inflammatory demyelinating polyneuropathy. Of these, 35 patients (88%) had molecular and/or serologic evidence of recent ZIKV infection in the serum and/or cerebrospinal fluid. Of the patients positive for ZIKV infection, 27 had GBS (18 demyelinating, 8 axonal, and 1 Miller Fisher syndrome), 5 had encephalitis (3 with concomitant acute neuromuscular disease), 2 had transverse myelitis, and 1 had chronic inflammatory demyelinating polyneuropathy. Admission to the intensive care unit was required for 9 patients positive for ZIKV infection (26%), and 5 (14%) required mechanical ventilation. Compared with admission during the period from December 5, 2013, to May 10, 2014 (before the Brazilian outbreak of ZIKV), admissions for GBS increased from a mean of 1.0 per month to 5.6 per month, admissions for encephalitis increased from 0.4 per month to 1.4 per month, and admissions for transverse myelitis remained constant at 0.6 per month. At 3 months, 2 patients positive for ZIKV infection (6%) died (1 with GBS and 1 with encephalitis), 18 (51%) had chronic pain, and the median modified Rankin score among survivors was 2 (range, 0-5).

Conclusions and Relevance

In this single-center Brazilian cohort, ZIKV infection was associated with an increase in the incidence of a diverse spectrum of serious neurologic syndromes. The data also suggest that serologic and molecular testing using blood and cerebrospinal fluid samples can serve as a less expensive, alternative diagnostic strategy in developing countries, where plaque reduction neutralization testing is impractical.

MicroRNA and mRNA Dysregulation in Astrocytes Infected with Zika Virus

The Zika virus (ZIKV) epidemic is an ongoing public health concern. ZIKV is a flavivirus reported to be associated with microcephaly, and recent work in animal models demonstrates the ability of the virus to cross the placenta and affect fetal brain development. Recent findings suggest that the virus preferentially infects neural stem cells and thereby deregulates gene expression, cell cycle progression, and increases cell death. However, neuronal stem cells are not the only brain cells that are susceptible to ZIKV and infection of other brain cells may contribute to disease progression. Herein, we characterized ZIKV replication in astrocytes, and profiled temporal changes in host microRNAs (miRNAs) and transcriptomes during infection. We observed the deregulation of numerous processes known to be involved in flavivirus infection, including genes involved in the unfolded protein response pathway. Moreover, a number of miRNAs were upregulated, including miR-30e-3p, miR-30e-5p, and, miR-17-5p, which have been associated with other flavivirus infections. This study highlights potential miRNAs that may be of importance in ZIKV pathogenesis.

Insights into the molecular roles of Zika virus in human reproductive complications and congenital neuropathologies

The recent upsurge in the association of congenital neurological disorders and infection by the Zika virus (ZIKV) has resulted in increased research focus on the biology of this flavivirus. Studies in animal models indicate that ZIKV can breach the placental barrier and selectively infect and deplete neuroprogenitor cells (NPCs) of the developing fetus, resulting in changes of brain structures, reminiscent of human microcephaly. In vitro and ex vivo studies using human cells and tissues showed that human NPCs and placental cells are targeted by ZIKV. Also of concern is the impact of ZIKV on human reproductive structures, with the potential to cause infertility, as the virus appears to remain in the genital tract for extended periods of time. This review discusses the putative roles of ZIKV on human reproductive complications and congenital neuropathologies.

A single mutation in the prM protein of Zika virus contributes to fetal microcephaly

Zika virus (ZIKV) has evolved into a global health threat because of its unexpected causal link to microcephaly. Phylogenetic analysis reveals that contemporary epidemic strains have accumulated multiple substitutions from their Asian ancestor. Here we show that a single serine-to-asparagine substitution [Ser¹³⁹→Asn¹³⁹ (S139N)] in the viral polyprotein substantially increased ZIKV infectivity in both human and mouse neural progenitor cells (NPCs) and led to more severe microcephaly in the mouse fetus, as well as higher mortality rates in neonatal mice. Evolutionary analysis indicates that the S139N substitution arose before the 2013 outbreak in French Polynesia and has been stably maintained during subsequent spread to the Americas. This functional adaption makes ZIKV more virulent to human NPCs, thus contributing to the increased incidence of microcephaly in recent ZIKV epidemics.

Host genetic background influences diverse neurological responses to viral infection in mice

Infection by Theiler's murine encephalomyelitis virus (TMEV) is a model for neurological outcomes caused by virus infection because it leads to diverse neurological conditions in mice, depending on the strain infected. To extend knowledge on the heterogeneous neurological outcomes caused by TMEV and identify new models of human neurological diseases associated with antecedent infections, we analyzed the phenotypic consequences of TMEV infection in the Collaborative Cross (CC) mouse population. We evaluated 5 different CC strains for outcomes of long-term infection (3 months) and acute vs. early chronic infection (7 vs. 28 days post-infection), using neurological and behavioral phenotyping tests and histology. We correlated phenotypic observations with haplotypes of genomic regions previously linked to TMEV susceptibility to test the hypothesis that genomic diversity within CC mice results in variable disease phenotypes in response to TMEV. None of the 5 strains analyzed had a response identical to that of any other CC strain or inbred strain for which prior data are available, indicating that strains of the CC can produce novel models of neurological disease. Thus, CC strains can be a powerful resource for studying how viral infection can cause different neurological outcomes depending on host genetic background.

Zika virus has oncolytic activity against glioblastoma stem cells

Glioblastoma is a highly lethal brain cancer that frequently recurs in proximity to the original resection cavity. We explored the use of oncolytic virus therapy against glioblastoma with Zika virus (ZIKV), a flavivirus that induces cell death and differentiation of neural precursor cells in the developing fetus. ZIKV preferentially infected and killed glioblastoma stem cells (GSCs) relative to differentiated tumor progeny or normal neuronal cells. The effects against GSCs were not a general property of neurotropic flaviviruses, as West Nile virus indiscriminately killed both tumor and normal neural cells. ZIKV potently depleted patient-derived GSCs grown in culture and in organoids. Moreover, mice with glioblastoma survived substantially longer and at greater rates when the tumor was inoculated with a mouse-adapted strain of ZIKV. Our results suggest that ZIKV is an oncolytic virus that can preferentially target GSCs; thus, genetically modified strains that further optimize safety could have therapeutic efficacy for adult glioblastoma patients.

Zika virus disease-associated Guillain-Barré syndrome-Barranquilla, Colombia 2015-2016

BACKGROUND

An outbreak of Guillain-Barré syndrome (GBS), a disorder characterized by acute, symmetric limb weakness with decreased or absent deep-tendon reflexes, was reported in Barranquilla, Colombia, after the introduction of Zika virus in 2015. We reviewed clinical data for GBS cases in Barranquilla and performed a case-control investigation to assess the association of suspect and probable Zika virus disease with GBS.

METHODS

We used the Brighton Collaboration Criteria to confirm reported GBS patients in Barranquilla during October 2015-April 2016. In April 2016, two neighborhood and age range-matched controls were selected for each confirmed GBS case-patient. We obtained demographics and antecedent symptoms in the 2-month period before GBS onset for case-patients and the same period for controls. Sera were collected for Zika virus antibody testing. Suspected Zika virus disease was defined as a history of rash and ≥2 other Zika-related symptoms (fever, arthralgia, myalgia, or conjunctivitis). Probable Zika virus disease was defined as suspected Zika virus disease with laboratory evidence of a recent Zika virus or flavivirus infection. Conditional logistic regression adjusted for sex and race/ethnicity was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We confirmed 47 GBS cases. Incidence increased with age (10-fold higher in those ≥60years versus those <20years). We interviewed 40 case-patients and 79 controls. There was no significant difference in laboratory evidence of recent Zika virus or flavivirus infection between case-patients and controls (OR: 2.2; 95% CI: 0.9-5.1). GBS was associated with having suspected (OR: 3.0, 95% CI: 1.1-8.6) or probable Zika virus disease (OR: 4.6, CI: 1.1-19.0).

CONCLUSIONS

Older individuals and those with suspected and probable Zika virus disease had higher odds of developing GBS.

KEY POINTS

We confirmed a Guillain-Barré syndrome (GBS) outbreak in Barranquilla, Colombia, during October 2015-April 2016. A case-control investigation using neighborhood controls showed an association of suspected and probable Zika virus disease with GBS.

Increased rates of Guillain-Barré syndrome associated with Zika virus outbreak in the Salvador metropolitan area, Brazil

In mid-2015, Salvador, Brazil, reported an outbreak of Guillain-Barré syndrome (GBS), coinciding with the introduction and spread of Zika virus (ZIKV). We found that GBS incidence during April–July 2015 among those ≥12 years of age was 5.6 cases/100,000 population/year and increased markedly with increasing age to 14.7 among those ≥60 years of age. We conducted interviews with 41 case-patients and 85 neighborhood controls and found no differences in demographics or exposures prior to GBS-symptom onset. A higher proportion of case-patients (83%) compared to controls (21%) reported an antecedent illness (OR 18.1, CI 6.9–47.5), most commonly characterized by rash, headache, fever, and myalgias, within a median of 8 days prior to GBS onset. Our investigation confirmed an outbreak of GBS, particularly in older adults, that was strongly associated with Zika-like illness and geo-temporally associated with ZIKV transmission, suggesting that ZIKV may result in severe neurologic complications.

Shortly following the introduction of Zika virus (ZIKV), a type of flavivirus transmitted by mosquitoes, into Brazil in early 2015, the Brazil Ministry of Health began receiving increased reports of a paralyzing condition known as Guillain-Barré syndrome (GBS). The areas with the greatest number of GBS cases appeared to correlate geographically and temporally with the areas reporting the highest rate of ZIKV infections. This association had been previously observed during a ZIKV outbreak in French Polynesia, however, this had not been systematically examined in a case-control investigation for the ZIKV outbreak in South America. In this investigation, the authors found that the occurrence of GBS in the affected population was nearly four times higher than would be expected, and the risk for GBS was particularly elevated among older adults. GBS was associated with ZIKV-like symptoms and with a combination of ZIKV-like symptoms plus laboratory evidence of a recent flavivirus infection. Taken together, these findings provide strong support for and greater understanding of the link between ZIKV and GBS.

Zika, Chikungunya, and Other Emerging Vector-Borne Viral Diseases

Arthropod-borne viruses (arboviruses) have a long history of emerging to infect humans, but during recent decades, they have been spreading more widely and affecting larger populations. This is due to several factors, including increased air travel and uncontrolled mosquito vector populations. Emergence can involve simple spillover from enzootic (wildlife) cycles, as in the case of West Nile virus accompanying geographic expansion into the Americas; secondary amplification in domesticated animals, as seen with Japanese encephalitis, Venezuelan equine encephalitis, and Rift Valley fever viruses; and urbanization, in which humans become the amplification hosts and peridomestic mosquitoes, mainly Aedes aegypti, mediate human-to-human transmission. Dengue, yellow fever, chikungunya, and Zika viruses have undergone such urban emergence. We focus mainly on the latter two, which are recent arrivals in the Western Hemisphere. We also discuss a few other viruses with the potential to emerge through all of these mechanisms.

Zika virus infects renal proximal tubular epithelial cells with prolonged persistency and cytopathic effects

Zika virus (ZIKV) infection can cause fetal developmental abnormalities and Guillain–Barré syndrome in adults. Although progress has been made in understanding the link between ZIKV infection and microcephaly, the pathology of ZIKV, particularly the viral reservoirs in human, remains poorly understood. Several studies have shown that compared to serum samples, patients’ urine samples often have a longer duration of ZIKV persistency and higher viral load. This finding suggests that an independent viral reservoir may exist in the human urinary system. Despite the clinical observations, the host cells of ZIKV in the human urinary system are poorly characterized. In this study, we demonstrate that ZIKV can infect renal proximal tubular epithelial cells (RPTEpiCs) in immunodeficient mice in vivo and in both immortalized and primary human renal proximal tubular epithelial cells (hRPTEpiCs) in vitro. Importantly, ZIKV infection in mouse kidneys caused caspase-3-mediated apoptosis of renal cells. Similarly, in vitro infection of immortalized and primary hRPTEpiCs resulted in notable cytopathic effects. Consistent with the clinical observations, we found that ZIKV infection can persist with prolonged duration in hRPTEpiCs. RNA-Seq analyses of infected hRPTEpiCs revealed a large number of transcriptional changes in response to ZIKV infection, including type I interferon signaling genes and anti-viral response genes. Our results suggest that hRPTEpiCs are a potential reservoir of ZIKV in the human urinary system, providing a possible explanation for the prolonged persistency of ZIKV in patients’ urine.

Asian Zika virus strains target CD14+ blood monocytes and induce M2-skewed immunosuppression during pregnancy

Blood CD14⁺ monocytes are frontline immunomodulators categorized into classical, intermediate or non-classical subsets, and subsequently differentiated into M1 pro- or M2 anti-inflammatory macrophages on stimulation. Although the Zika virus (ZIKV) rapidly establishes viraemia, the target cells and immune responses, particularly during pregnancy, remain elusive. Furthermore, it is unknown whether African- and Asian-lineage ZIKV have different phenotypic impacts on host immune responses. Using human blood infection, we identified CD14⁺ monocytes as the primary target for African- or Asian-lineage ZIKV infection. When immunoprofiles of human blood infected with ZIKV were compared, a classical/intermediate monocyte-mediated M1-skewed inflammation by the African-lineage ZIKV infection was observed, in contrast to a non-classical monocyte-mediated M2-skewed immunosuppression by the Asian-lineage ZIKV infection. Importantly, infection of the blood of pregnant women revealed an enhanced susceptibility to ZIKV infection. Specifically, Asian-lineage ZIKV infection of pregnant women's blood led to an exacerbated M2-skewed immunosuppression of non-classical monocytes in conjunction with a global suppression of type I interferon-signalling pathway and an aberrant expression of host genes associated with pregnancy complications. Also, 30 ZIKV⁺ sera from symptomatic pregnant patients showed elevated levels of M2-skewed immunosuppressive cytokines and pregnancy-complication-associated fibronectin-1. This study demonstrates the differential immunomodulatory responses of blood monocytes, particularly during pregnancy, on infection with different lineages of ZIKV.

Neurological Presentation of Zika Virus Infection Beyond the Perinatal Period

PURPOSE OF REVIEW

Our purpose was to summarize the current knowledge about the neurological presentation of Zika virus infection after the perinatal period. Other Flaviviruses infections, such as West Nile virus (WNV) or Japanese encephalitis virus (JEV), can result in neuro-invasive disease such as myelitis, encephalitis, or meningitis. We aimed at describing the specificities of ZV neurological infection.

RECENT FINDINGS

The recent outbreaks demonstrated clearly the neurotropism of ZV. However, by contrast with other Flaviviruses, the most frequent neurological presentation of ZV infection beyond the perinatal period was Guillain-Barré syndrome, especially the demyelination form of GBS. Encephalitis and myelitis seem to occur less frequently after ZV infection than after WNV or JEV infection. The pathophysiology of neurological ZV infections is still poorly understood and no specific treatment is available. Moreover, no data is available about long-term persisting symptoms and possible impairment of patients after the acute clinical episode.

Zika Virus: Obstetric and Pediatric Anesthesia Considerations

As of November 2016, the Florida Department of Health (FDH) and the Centers for Disease Control and Prevention have confirmed more than 4000 travel-related Zika virus (ZIKV) infections in the United States with >700 of those in Florida. There have been 139 cases of locally acquired infection, all occurring in Miami, Florida. Within the US territories (eg, Puerto Rico, US Virgin Islands), >30,000 cases of ZIKV infection have been reported. The projected number of individuals at risk for ZIKV infection in the Caribbean and Latin America approximates 5 million. Similar to Dengue and Chikungunya viruses, ZIKV is spread to humans by infected Aedes aegypti mosquitoes, through travel-associated local transmission, via sexual contact, and through blood transfusions. South Florida is an epicenter for ZIKV infection in the United States and the year-round warm climate along with an abundance of mosquito vectors that can harbor the flavivirus raise health care concerns. ZIKV infection is generally mild with clinical manifestations of fever, rash, conjunctivitis, and arthralgia. Of greatest concern, however, is growing evidence for the relationship between ZIKV infection of pregnant women and increased incidence of abnormal pregnancies and congenital abnormalities in the newborn, now medically termed ZIKA Congenital Syndrome. Federal health officials are observing 899 confirmed Zika-positive pregnancies and the FDH is currently monitoring 110 pregnant women with evidence of Zika infection. The University of Miami/Jackson Memorial Hospital is uniquely positioned just north of downtown Miami and within the vicinity of Liberty City, Little Haiti, and Miami Beach, which are currently "hot spots" for Zika virus exposure and transmissions. As the FDH works fervently to prevent a Zika epidemic in the region, health care providers at the University of Miami and Jackson Memorial Hospital prepare for the clinical spectrum of ZIKV effects as well as the safe perioperative care of the parturients and their affected newborns. In an effort to meet anesthetic preparedness for the care of potential Zika-positive patients and perinatal management of babies born with ZIKA Congenital Syndrome, this review highlights the interim guidelines from the Centers for Disease Control and Prevention and also suggest anesthetic implications and recommendations. In addition, this article reviews guidance for the evaluation and anesthetic management of infants with congenital ZIKV infection. To better manage the perioperative care of affected newborns, this article also reviews the comparative anesthetic implications of babies born with related congenital malformations.