Zika Virus Infection as a Cause of Congenital Brain Abnormalities and Guillain-Barré Syndrome: Systematic Review

Spatiotemporal Heterogeneity in the Distribution of Chikungunya and Zika Virus Case Incidences during their 2014 to 2016 Epidemics in Barranquilla, Colombia

Chikungunya virus (CHIKV) and Zika virus (ZIKV) have recently emerged as globally important infections. This study aimed to explore the spatiotemporal heterogeneity in the occurrence of CHIKV and ZIKV outbreaks throughout the major international seaport city of Barranquilla, Colombia in 2014 and 2016 and the potential for clustering. Incidence data were fitted using multiple Bayesian Poisson models based on multiple explanatory variables as potential risk factors identified from other studies and options for random effects. A best fit model was used to analyse their case incidence risks and identify any risk factors during their epidemics. Neighbourhoods in the northern region were hotspots for both CHIKV and ZIKV outbreaks. Additional hotspots occurred in the southwestern and some eastern/southeastern areas during their outbreaks containing part of, or immediately adjacent to, the major circular city road with its import/export cargo warehouses and harbour area. Multivariate conditional autoregressive models strongly identified higher socioeconomic strata and living in a neighbourhood near a major road as risk factors for ZIKV case incidences. These findings will help to appropriately focus vector control efforts but also challenge the belief that these infections are driven by social vulnerability and merit further study both in Barranquilla and throughout the world's tropical and subtropical regions.

[Reporting of birth defects from the Zika outbreak in Colombia, 2015-2017Notificação de defeitos congênitos associados ao surto de vírus zika na Colômbia, 2015-2017]

Objetivo.

El brote por virus del Zika afectó a varios países tropicales durante 2015 y 2016. Esto obligó a crear estrategias de vigilancia intensificada de microcefalia y otros síndromes neurológicos. Se evaluó el efecto del brote por virus del Zika en la notificación de defectos congénitos en Colombia desde la perspectiva del sistema nacional de vigilancia.

Métodos.

Se analizó la notificación nacional de recién nacidos con diferentes defectos congénitos y se determinaron las variaciones en la notificación atribuidas a la epidemia mediante un modelo semiparamétrico denominado “diferencia en diferencias” (DID).

Resultados.

Un total de 18 234 casos por defectos congénitos fueron notificados en Colombia durante el período de estudio. La mayoría eran malformaciones congénitas (91,9%). El 82,3% se confirmó por diagnóstico clínico o nexo epidemiológico. En el caso de la microcefalia, se notificaron ocho casos nuevos por semana epidemiológica (coeficiente de notificación de casos [D] = 8,8; P = 0,000) y 32 casos por otras malformaciones congénitas anatómicas (D = 32,0; P = 0,000). El valor absoluto del estimador de diferencia en diferencias atribuido al brote por virus del Zika incrementó la notificación semanal de casos de microcefalia (DID = |-5,0|; P = 0,008) y malformaciones congénitas (DID = |-12,0|; P = 0,111).

Conclusiones.

El brote por virus del Zika incrementó la notificación de recién nacidos con microcefalia, pero sin ninguna variación significativa en la notificación de otras malformaciones y defectos congénitos funcionales de origen sensorial o metabólico en el sistema de vigilancia.

Human cytomegaloviral multifunctional protein kinase pUL97 impairs zebrafish embryonic development and increases mortality

Cytomegalovirus is a worldwide-distributed human pathogen, which is the leading cause of congenital virus infection, affecting 0.5 to 2% of live births. To date, it is largely unclear which molecular mechanisms underlie the symptomatic outcomes. This is mainly due to species specificity and limited homology among cytomegalovirus genomes. As it is not possible to infect model organisms with human cytomegalovirus, the aim of this study was to develop a heterologous system allowing in the future the elucidation of the pathological role of individual viral proteins. As a model organism the zebrafish has been chosen due to its ease of manipulation and characterization as well as its large offspring. As cytomegalovirus model protein, pUL97 was characterized because it is multiply involved in virus-host interaction. Here, we show in zebrafish embryos, that (i) pUL97 can be expressed in zebrafish, (ii) increasing pUL97 expression levels quantitatively correlate with both minor and major pathological defects, (iii) pUL97 expression impairs cell cycle progression and induces cell death, (iv) active pUL97, but not an inactive mutant, induces excess mortality, and (v) co-administration of a pUL97 inhibitor reduces embryonic pathology. Collectively, these data indicate the suitability of zebrafish to elucidate the pathological role of human cytomegaloviral proteins.

The challenge of the laboratory diagnosis in a confirmed congenital Zika virus syndrome in utero: A case report

INTRODUCTION

Zika virus (ZIKV) has caused one of the most challenging global infectious epidemics in recent years because of its causal association with severe microcephaly and other congenital malformations. The diagnosis of viral infections usually relies on the detection of virus proteins or genetic material in clinical samples as well as on the infected host immune responses. Serial serologic testing is required for the diagnosis of congenital infection when diagnostic molecular biology is not possible.

PATIENT CONCERNS

A 2-year-old girl, born to a mother with confirmed ZIKV infection during pregnancy, with a confirmed ZIKV infection in utero, showed at birth a severe microcephaly and clinical characteristics of fetal brain disruption sequence compatible with a congenital ZIKV syndrome (CZS).

DIAGNOSIS

ZIKV-RNA and ZIKV-IgM serological response performed at birth and during the follow-up time tested always negative. Serial serologic ZIKV-IgG tests were performed to assess the laboratory ZIKV diagnosis, ZIKV-IgG seroreversion was observed at 21 months of age. ZIKV diagnosis of this baby had to be relied on her clinical and radiological characteristics that were compatible with a CZS.

INTERVENTIONS

The patient was followed-up as per protocol at approximately 1, 4, 9, 12, 18-21, and 24 months of age. Neurological, radiological, audiological, and ophthalmological assessment were performed during this period of time. Prompt rehabilitation was initiated to prevent potential adverse long-term neurological outcomes.

OUTCOMES

The growth of this girl showed a great restriction at 24 months of age with a weight of 8.5 kg (-2.5 z-score) and a head circumference of 40.5 cm (-4.8 z-score). She also had a great neurodevelopmental delay at the time of this report.

CONCLUSION

We presume that as a consequence of prenatal ZIKV infection, the fetal brain and other organs are damaged before birth through direct injury. Following this, active infection ends during intrauterine life, and as a consequence the immune system of the infant is unable to build up a consistent immune response thereafter. Further understanding of the mechanisms taking part in the pathogenesis of ZIKV congenital infection is needed. This finding might change our paradigm regarding serological response in the ZIKV congenital infection.

A Viral Polymerase Inhibitor Reduces Zika Virus Replication in the Reproductive Organs of Male Mice

In humans, Zika virus and viral RNA have been detected in semen up to 2.2 months and 6 months post infection (pi), respectively. Although the contribution of sexual transmission to the spread of ZIKV is too low to sustain an outbreak, it can increase the risk of infection and the epidemic size as well as prolong the duration of an outbreak. In this study, we explored the potential of antivirals to serve as an effective strategy to prevent sexual transmission. Male AG129 mice infected with a ZIKV isolate from Suriname were treated with the nucleoside analog, 7-deaza-2′-C-methyladenosine (7DMA), that was previously shown to be efficacious in reducing ZIKV viremia and delaying ZIKV-induced disease in mice. Following treatment, viral RNA and infectious virus titers were consistently reduced in the male reproductive organs compared to vehicle-treated mice. This reduction of ZIKV loads in the testis was confirmed by the detection of lower levels of ZIKV antigens. Our data illustrate the value of this mouse model to validate the efficacy of new potential ZIKV drugs at the level of the male reproductive system.

Immunogenicity and protection conferred by an optimized purified inactivated Zika vaccine in mice

After decades of inconsequential infections, and sporadic outbreaks in the Asia-Pacific region between 2007 and 2013, Zika virus caused a widespread epidemic in South America in 2015 that was complicated by severe congenital infections. After the WHO declared a Public Health Emergency of International Concern in February 2016, vaccine development efforts based on different platforms were initiated. Several candidates have since been evaluated in clinical phase I studies. Of these, a Zika purified inactivated vaccine (ZPIV), adjuvanted with aluminum hydroxide, developed by the Walter Reed Army Institute of Research (WRAIR), yielded high seroconversion rates. Sanofi Pasteur further optimized the vaccine in terms of production scale, purification conditions and regulatory compliance, using its experience in flavivirus vaccine development. Here we report that the resulting optimized vaccine (ZPIV-SP) elicited robust seroneutralizing antibody responses and provided complete protection from homologous Zika virus strain challenge in immunocompetent BALB/c mice. ZPIV-SP also showed improved immunogenicity compared with the first-generation vaccine, and improved efficacy in the more permissive interferon receptor-deficient A129 mice. Finally, analysis of the IgG response directed towards nonstructural protein 1 (NS1) suggests that viral NS1 was efficiently removed during the optimized purification process of ZPIV-SP. Together, these results suggest that the optimized vaccine is well suited for further evaluation in larger animal models and late-stage clinical studies.

Zika Virus: Relevance to the State of Hawai'i

Zika virus (ZIKV) is spread among human populations primarily through the bite of Aedes mosquitoes. While most ZIKV infections are asymptomatic or cause self-limited symptoms, the major concerns are its association with Guillain-Barré Syndrome and fetal microcephaly together with other birth defects, known as congenital Zika syndrome (CZS). This article reviews the confirmed Zika cases in the continental United States (U.S.) and Hawai'i thus far, as well as literature of Zika research relevant to Hawai'i. The first case of CZS within the U.S. was reported in Hawai'i, highlighting the unique position of Hawai'i for emerging and re-emerging infectious diseases. Recent studies of the Zika outbreak in Florida demonstrate the key role of Ae. aegypti mosquito in transmission; continuous and proactive vector surveillance in Hawai'i is warranted. Additionally, an updated interim pregnancy guidance for pregnant women with possible ZIKV exposure was summarized. Due to recent decline of ZIKV transmission in the Americas, the risk of ZIKV importation to Hawai'i has been greatly reduced. However, given the presence of Aedes mosquitoes, climate condition, and status of Hawai'i as a travel destination and foreign import market, public health officials and healthcare providers should remain vigilant for a potential outbreak of mosquito-borne diseases in the future.

Zika virus infection in travellers returning to the United Kingdom during the period of the outbreak in the Americas (2016-17): A retrospective analysis

BACKGROUND

In 2016, Zika virus (ZIKV) spread rapidly throughout the Americas and Caribbean in an explosive outbreak. In the UK, testing for ZIKV infection is performed at Public Health England's Rare and Imported Pathogens Laboratory. Here we present the UK's experience of imported ZIKV during the epidemic.

METHOD

A retrospective review was performed on the laboratory computer system searching by orders for ZIKV PCR and/or ELISA serology tests between 1st January 2016 and 31st December 2017. Each individual request form and result was reviewed.

RESULTS

Of 6333 symptomatic patients tested for ZIKV, 374 (6%) had molecular or serological evidence consistent with recent infection; most of these had travelled to the Caribbean in 2016. On follow-up of PCR-confirmed cases, ZIKV IgM disappeared within 6 weeks and often didn't appear in patients with previous dengue infection. Rash was the commonest symptom in PCR-confirmed infection (93%). There were only single cases of presumed sexual transmission and of in-utero transmission.

CONCLUSIONS

The rise and fall in numbers of imported ZIKV cases largely reflected the temporal course of the outbreak in the Caribbean. ZIKV serology is difficult to interpret but the absence of antibodies to ZIKV 14 days after symptom onset makes infection very unlikely.

Impact of pre-existing dengue immunity on human antibody and memory B cell responses to Zika

Little is known about enduring memory B cell (MBC) responses to Zika virus (ZIKV) and their relationship with circulating antibodies. Here we comprehensively assess MBC frequency and specificity alongside serum binding and neutralizing antibody responses to ZIKV ~2 weeks and ~8 months postinfection in 31 pediatric subjects with 0, 1 or >1 prior infections with the related dengue virus (DENV). ZIKV infection elicits a robust type-specific MBC response, and the majority of late convalescent anti-ZIKV serum neutralizing activity is attributable to ZIKV-specific antibodies. The number of prior DENV infections does not influence type-specific or cross-reactive MBC responses, although ZIKV has the highest cross-reactivity with DENV3. DENV cross-reactive MBCs expanded by ZIKV infection decline in number and proportion by late convalescence. Finally, ZIKV induces greater cross-reactivity in the MBC pool than in serum antibodies. Our data suggest immunity to DENV only modestly shapes breadth and magnitude of enduring ZIKV antibody responses.

The Application and Interpretation of IgG Avidity and IgA ELISA Tests to Characterize Zika Virus Infections

In the absence of viremia, the diagnostics of Zika virus (ZIKV) infections must rely on serological techniques. In order to improve the serological diagnosis of ZIKV, ZIKV-IgA and ZIKV-IgG avidity assays were evaluated. Forty patients returning from ZIKV endemic areas, with confirmed or suspected ZIKV infections were studied. Samples were classified as early acute, acute and late acute according to the number of days post illness onset. Low avidity IgG was only detected at acute and late acute stages and IgA mostly at the early acute and acute stages. The date of sampling provides useful information and can help to choose the best technique to use at a determined moment in time and to interpret low avidity IgG and IgA results, improving the serological diagnosis of ZIKV.

Combination of Nonstructural Protein 1-Based Enzyme-Linked Immunosorbent Assays Can Detect and Distinguish Various Dengue Virus and Zika Virus Infections

The recent outbreaks of Zika virus (ZIKV) and associated birth defects in regions of dengue virus (DENV) endemicity emphasize the need for sensitive and specific serodiagnostic tests. We reported previously that enzyme-linked immunosorbent assays (ELISAs) based on the nonstructural protein 1 (NS1) of DENV serotype 1 (DENV1) and ZIKV can distinguish primary DENV1, secondary DENV, and ZIKV infections. Whether ELISAs based on NS1 proteins of other DENV serotypes can discriminate various DENV and ZIKV infections remains unknown. We herein developed DENV2, DENV3, and DENV4 NS1 IgG ELISAs to test convalescent- and postconvalescent-phase samples from reverse transcription-PCR-confirmed cases, including 25 primary DENV1, 24 primary DENV2, 10 primary DENV3, 67 secondary DENV, 36 primary West Nile virus, 38 primary ZIKV, and 35 ZIKV with previous DENV infections as well as 55 flavivirus-naive samples. Each ELISA detected primary DENV infection with a sensitivity of 100% for the same serotype and 23.8% to 100% for different serotypes. IgG ELISA using a mixture of DENV1-4 NS1 proteins detected different primary and secondary DENV infections with a sensitivity of 95.6% and specificity of 89.5%. The ZIKV NS1 IgG ELISA detected ZIKV infection with a sensitivity of 100% and specificity of 82.9%. On the basis of the relative optical density ratio, the combination of DENV1-4 and ZIKV NS1 IgG ELISAs distinguished ZIKV with previous DENV and secondary DENV infections with a sensitivity of 91.7% to 94.1% and specificity of 87.0% to 95.0%. These findings have important applications to serodiagnosis, serosurveillance, and monitoring of both DENV and ZIKV infections in regions of endemicity.

Transfusion-Transmitted Zika Virus Infection in Pregnant Mice Leads to Broad Tissue Tropism With Severe Placental Damage and Fetal Demise

Zika virus (ZIKV) infection during pregnancy can cause significant problems, particularly congenital Zika syndrome. Nevertheless, the potential deleterious consequences and associated mechanisms of transfusion-transmitted ZIKV infection on pregnant individuals and their fetuses and babies have not been investigated. Here we examined transmissibility of ZIKV through blood transfusion in ZIKV-susceptible pregnant A129 mice. Our data showed that transfused-transmitted ZIKV at the early infection stage led to significant viremia and broad tissue tropism in the pregnant recipient mice, which were not seen in those transfused with ZIKV-positive (ZIKV⁺) plasma at later infection stages. Importantly, pregnant mice transfused with early-stage, but not later stages, ZIKV⁺ plasma also exhibited severe placental infection with vascular damage and apoptosis, fetal infection and fetal damage, accompanied by fetal and pup death. Overall, this study suggests that transfusion-related transmission of ZIKV during initial stage of infection, which harbors high plasma viral titers, can cause serious adverse complications in the pregnant recipients and their fetuses and babies.

Fetal and neonatal neurogenetics

Disorders of the developing nervous system may be of genetic origin, comprising congenital malformations of spine and brain as well as metabolic or vascular disorders that affect normal brain development. Acquired causes include congenital infections, hypoxic-ischemic or traumatic brain injury, and a number of rare neoplasms. This chapter focuses on the clinical presentation and workup of neurogenetic disorders presenting in the fetal or neonatal period. After a summary of the most frequent clinical presentations, clues from history taking and clinical examination are illustrated with short case reports. This is followed by a discussion of the different tools available for the workup of neurogenetic disorders, including the various genetic techniques with their advantages and disadvantages. The implications of a molecular genetic diagnosis for the patient and family are addressed in the section on counseling. The chapter concludes with a proposed workflow that may help the clinician when confronted with a potential neurogenetic disorder in the fetal or neonatal period.

Microcefalia relacionada ao vírus Zika e dinâmica familiar: perspectiva da mãe

Objetivo: compreender como os familiares de crianças diagnosticadas com microcefalia pelo vírus Zika (ZIKV) reagiram emocionalmente ao diagnóstico e qual é o impacto desse evento na dinâmica familiar.Metodologia: estudo descritivo-exploratório de cunho qualitativo realizado em um município de médio porte de Minas Gerais (Brasil). Para a coleta de dados foi utilizada a entrevista semiestruturada gravada e transcrita. O corpus foi submetido à análise de conteúdo conforme o preconizado por Bardin.Resultados: verificou-se que as mães demonstraram preocupação diante da hipossuficiência de informações sobre a condição dos filhos. O diagnóstico trouxe uma sensação de desconstrução do filho idealizado e desencadeou reações de choque emocional. As mães demonstraram possuir grandes incertezas em relação ao futuro dos filhos. Foi relatado que os pais participam ativamente no cuidado.Conclusão: evidencia-se, nas narrativas das mães, a necessidade de maior eficiência dos serviços públicos de assistência, notadamente os de saúde, no acompanhamento das crianças e orientação das famílias.

Prior dengue virus infection and risk of Zika: A pediatric cohort in Nicaragua

BACKGROUND

Zika virus (ZIKV) emerged in northeast Brazil in 2015 and spread rapidly across the Americas, in populations that have been largely exposed to dengue virus (DENV). The impact of prior DENV infection on ZIKV infection outcome remains unclear. To study this potential impact, we analyzed the large 2016 Zika epidemic in Managua, Nicaragua, in a pediatric cohort with well-characterized DENV infection histories.

METHODS AND FINDINGS

Symptomatic ZIKV infections (Zika cases) were identified by real-time reverse transcription PCR and serology in a community-based cohort study that follows approximately 3,700 children aged 2-14 years old. Annual blood samples were used to identify clinically inapparent ZIKV infections using a novel, well-characterized serological assay. Multivariable Poisson regression was used to examine the relation between prior DENV infection and incidence of symptomatic and inapparent ZIKV infection. The generalized-growth method was used to estimate the effective reproduction number. From January 1, 2016, to February 28, 2017, 560 symptomatic ZIKV infections and 1,356 total ZIKV infections (symptomatic and inapparent) were identified, for an overall incidence of 14.0 symptomatic infections (95% CI: 12.9, 15.2) and 36.5 total infections (95% CI: 34.7, 38.6) per 100 person-years. Effective reproduction number estimates ranged from 3.3 to 3.4, depending on the ascending wave period. Incidence of symptomatic and total ZIKV infections was higher in females and older children. Analysis of the effect of prior DENV infection was performed on 3,027 participants with documented DENV infection histories, of which 743 (24.5%) had experienced at least 1 prior DENV infection during cohort follow-up. Prior DENV infection was inversely associated with risk of symptomatic ZIKV infection in the total cohort population (incidence rate ratio [IRR]: 0.63; 95% CI: 0.48, 0.81; p < 0.005) and with risk of symptomatic presentation given ZIKV infection (IRR: 0.62; 95% CI: 0.44, 0.86) when adjusted for age, sex, and recent DENV infection (1-2 years before ZIKV infection). Recent DENV infection was significantly associated with decreased risk of symptomatic ZIKV infection when adjusted for age and sex, but not when adjusted for prior DENV infection. Prior or recent DENV infection did not affect the rate of total ZIKV infections. Our findings are limited to a pediatric population and constrained by the epidemiology of the site.

CONCLUSIONS

These findings support that prior DENV infection may protect individuals from symptomatic Zika. More research is needed to address the possible immunological mechanism(s) of cross-protection between ZIKV and DENV and whether DENV immunity also modulates other ZIKV infection outcomes such as neurological or congenital syndromes.

Reassessing Serosurvey-Based Estimates of the Symptomatic Proportion of Zika Virus Infections

Since the 2007 Zika epidemic in the Micronesian state of Yap, it has been apparent that not all people infected with Zika virus (ZIKV) experience symptoms. However, the proportion of infections that result in symptoms remains unclear. Existing estimates have varied in their interpretation of symptoms due to other causes and the case definition used, and they have assumed perfect test sensitivity and specificity. Using a Bayesian model and data from ZIKV serosurveys in Yap (2007), French Polynesia (2013-2014), and Puerto Rico (2016), we found that assuming perfect sensitivity and specificity generally led to lower estimates of the symptomatic proportion. Incorporating reasonable assumptions for assay sensitivity and specificity, we estimated that 27% (95% credible interval (CrI): 15, 37) (Yap), 44% (95% CrI: 26, 66) (French Polynesia), and 50% (95% CrI: 34, 92) (Puerto Rico) of infections were symptomatic, with variation due to differences in study populations, study designs, and case definitions. The proportion of ZIKV infections causing symptoms is critical for surveillance system design and impact assessment. Here, we accounted for key uncertainties in existing seroprevalence data and found that estimates for the symptomatic proportion ranged from 27% to 50%, suggesting that while the majority of infections are asymptomatic or mildly symptomatic, symptomatic infections might be more common than previously estimated.

Microcephaly caused by the Zika virus: dental care

ABSTRACT Zika virus infection was declared a public health emergency at national and international levels due to the high incidence of the virus infection and its relationship with the birth of children with microcephaly. Patients with microcephaly present significant clinical neuropsychomotor disorders, therefore, dental surgeons should be prepared to treat such patients, observing the possible alterations associated with this condition, as well as the oral diseases. Thus, the purpose of this research study was to inform dental surgeons about the microcephaly associated with the Zika virus, as well as instructing them about the dental care necessary for such condition and its management during the consultations.

Prevalence and outcomes of Guillain-Barré syndrome among pediatrics in Saudi Arabia: a 10-year retrospective study

BACKGROUND

Guillain-Barré syndrome (GBS) is a progressive acute form of paralysis most probably secondary to an immune-mediated process. GBS among Saudis has been seldom investigated, which leaves both clinicians and researchers with scarcity in knowledge. Therefore, this study aims to assess the prevalence and clinical prognosis of GBS among pediatrics admitted with acute paralysis at a large healthcare facility in Riyadh, Saudi Arabia.

METHODS

This retrospective study reviewed patients' medical records between 2005 and 2015. Eligible cases were children (<14 years old) admitted to the hospital complaining of acute paralysis and later diagnosed with one form or variant of GBS. Pearson's chi-square, Fisher's exact test, and binary logistic regression were employed to analyze the collected data.

RESULTS

The prevalence of GBS was 49%. The male-to-female ratio was 1.45:1. The mean ± standard deviation age was 7±3.7 years. There were 34 (69.4%) cases with progression to maximum paralysis in ≤2 weeks, while 15 (30.6%) cases occurred beyond 2 weeks. Males (n=24, 82.8%) were more likely to endure progression to maximum paralysis in ≤2 weeks after the disease onset, compared to females (n=10, 50%), P=0.014. All cases complaining of respiratory problems exhibited a progression to maximum paralysis in ≤2 weeks, compared to those with no respiratory problems, P=0.027. Residual paralysis at 60 days post disease onset was highly associated with GBS patients of age 8-14 years (n=15, 65.2%), compared to younger patients (n=8, 30.8%), P=0.016. Patients admitted in colder seasons (n=14, 63.6%) were more likely to suffer residual paralysis too, compared to those in warmer seasons (n=9, 33.3%), P=0.035. GBS cases who complained of facial weakness (n=9, 75%) and ocular abnormalities (n=10, 71.4%) were also more likely to endure residual paralysis at 60 days post disease onset, P=0.025 and P=0.03, respectively.

CONCLUSION

Male gender could be a determinant of rapid progression to maximum paralysis, while the older age group in pediatrics is expected to endure residual paralysis at 60 days post disease onset. GBS can be accounted as a rare disease, especially in pediatrics, so confirmed cases should be investigated comprehensively for research purposes.

Pre-Existing Dengue Immunity Drives a DENV-Biased Plasmablast Response in ZIKV-Infected Patient

The re-emergence of Zika virus (ZIKV) in the western hemisphere has most significantly affected dengue virus (DENV) endemic regions. Due to the geographical overlap between these two closely related flaviviruses, numerous individuals who suffered ZIKV infection during recent outbreaks may have also previously been exposed to DENV. As such, the impact of pre-existing dengue immunity on immune responses to ZIKV has been an area of focused research and interest. To understand how B cell responses to a ZIKV infection may be modulated by prior dengue exposures, we compared and contrasted plasmablast repertoire and specificity between two ZIKV-infected individuals, one dengue-naïve (ZK018) and the other dengue-experienced (ZK016). In addition to examining serological responses, we generated 59 patient plasmablast-derived monoclonal antibodies (mAbs) to define the heterogeneity of the early B cell response to ZIKV. Both donors experienced robust ZIKV-induced plasmablast expansions early after infection, with comparable mutational frequencies in their antibody variable genes. However, notable differences were observed in plasmablast clonality and functional reactivity. Plasmablasts from the dengue-experienced donor ZK016 included cells with shared clonal origin, while ZK018 mAbs were entirely clonally unrelated. Both at the mAb and plasma level, ZK016 antibodies displayed extensive cross-reactivity to DENV1-4, and preferentially neutralized DENV compared to ZIKV. In contrast, the neutralization activity of ZK018 mAbs was primarily directed towards ZIKV, and fewer mAbs from this donor were cross-reactive, with the cross-reactive phenotype largely limited to fusion loop-specific mAbs. ZK016 antibodies caused greater enhancement of DENV2 infection of FcRγ-expressing cells overall compared to ZK018, with a striking difference at the plasma level. Taken together, these data strongly suggest that the breadth and protective capacity of the initial antibody responses after ZIKV infection may depend on the dengue immune status of the individual. These findings have implications for vaccine design, given the likelihood that future epidemics will involve both dengue-experienced and naïve populations.

Systematic review of factors associated with the development of Guillain-Barré syndrome 2007-2017: what has changed?

OBJECTIVE

The objective of this study was to describe the factors associated with the development of Guillain-Barré syndrome, both infectious and non-infectious, during and after the A(H1N1) influenza pandemic in 2009 and the recent Zika virus epidemic in the Americas.

METHOD

Systematic review of literature on factors associated with the development of the Guillain-Barré syndrome published between 2007 and 2017 listed in EBSCO, MEDLINE and LILACS databases. The quality of the studies was evaluated using the Newcastle Ottawa Scale.

RESULTS

Thirty-four articles met inclusion criteria and were selected for analysis. Their quality was considered good in relation to most of the items evaluated. Many aetiological agents had the results of association with Guillain-Barré syndrome, among them Campylobacter jejuni, influenza vaccine - both pandemic and seasonal vaccines, respiratory infection, gastrointestinal infection among others. The aetiological agents found are, in most part, the same reported prior to the study period. The association with surgeries, chikungunya virus (CHIKV), Zika virus and quadrivalent human papillomavirus vaccine stand out as new aetiological agents in the list of the various possible agents that trigger Guillain-Barré syndrome reported in the study period. There were no Brazilian studies identified during this period.

CONCLUSIONS

The results of the review reaffirmed C. jejuni as the major trigger of GBS, whereas the association of influenza vaccines and GBS is less clear; Zika virus infection in association with GBS was found in only one study.

Routes of Zika virus dissemination in the testis and epididymis of immunodeficient mice

Sexual transmission and persistence of Zika virus (ZIKV) in the male reproductive tract (MRT) poses new challenges for controlling virus outbreaks and developing live-attenuated vaccines. To elucidate routes of ZIKV dissemination in the MRT, we here generate microRNA-targeted ZIKV clones that lose the infectivity for (1) the cells inside seminiferous tubules of the testis, or (2) epithelial cells of the epididymis. We trace ZIKV dissemination in the MRT using an established mouse model of ZIKV pathogenesis. Our results support a model in which ZIKV infects the testis via a hematogenous route, while infection of the epididymis can occur via two routes: (1) hematogenous/lymphogenous and (2) excurrent testicular. Co-targeting of the ZIKV genome with brain-, testis-, and epididymis-specific microRNAs restricts virus infection of these organs, but does not affect virus-induced protective immunity in mice and monkeys. These defined alterations of ZIKV tropism represent a rational design of a safe live-attenuated ZIKV vaccine.

Suppression of Type I Interferon Signaling by Flavivirus NS5

Type I interferon (IFN-I) is the first line of mammalian host defense against viral infection. To counteract this, the flaviviruses, like other viruses, have encoded a variety of antagonists, and use a multi-layered molecular defense strategy to establish their infections. Among the most potent antagonists is non-structural protein 5 (NS5), which has been shown for all disease-causing flaviviruses to target different steps and players of the type I IFN signaling pathway. Here, we summarize the type I IFN antagonist mechanisms used by flaviviruses with a focus on the role of NS5 in regulating one key regulator of type I IFN, signal transducer and activator of transcription 2 (STAT2).

Potential inconsistencies in Zika surveillance data and our understanding of risk during pregnancy

Background

A significant increase in microcephaly incidence was reported in Northeast Brazil at the end of 2015, which has since been attributed to an epidemic of Zika virus (ZIKV) infections earlier that year. Further incidence of congenital Zika syndrome (CZS) was expected following waves of ZIKV infection throughout Latin America; however, only modest increases in microcephaly and CZS incidence have since been observed. The quantitative relationship between ZIKV infection, gestational age and congenital outcome remains poorly understood.

Methodology/Principle findings

We characterised the gestational-age-varying risk of microcephaly given ZIKV infection using publicly available incidence data from multiple locations in Brazil and Colombia. We found that the relative timings and shapes of ZIKV infection and microcephaly incidence curves suggested different gestational risk profiles for different locations, varying in both the duration and magnitude of gestational risk. Data from Northeast Brazil suggested a narrow window of risk during the first trimester, whereas data from Colombia suggested persistent risk throughout pregnancy. We then used the model to estimate which combination of behavioural and reporting changes would have been sufficient to explain the absence of a second microcephaly incidence wave in Bahia, Brazil; a population for which we had two years of data. We found that a 18.9-fold increase in ZIKV infection reporting rate was consistent with observed patterns.

Conclusions

Our study illustrates how surveillance data may be used in principle to answer key questions in the absence of directed epidemiological studies. However, in this case, we suggest that currently available surveillance data are insufficient to accurately estimate the gestational-age-varying risk of microcephaly from ZIKV infection. The methods used here may be of use in future outbreaks and may help to inform improved surveillance and interpretation in countries yet to experience an outbreak of ZIKV infection.

Zika virus (ZIKV) infection is associated with the rise of microcephaly cases observed in Northeast Brazil at the end of 2015. For women in endemic or at-risk areas, understanding how the relationship between time of infection and microcephaly risk varies through pregnancy is important in informing family planning. However, a relatively modest number of congenital Zika syndrome cases have been observed following subsequent waves of ZIKV infection, limiting our understanding of gestational risk. We used a mathematical model to quantify the shape and magnitude of the gestational-age-varying risk to a fetus. Although the risk profile should be conserved regardless of location, we estimated different profiles when using surveillance data from locations in Northeast Brazil and Colombia. Our results suggest that time-dependent reporting changes likely confound the interpretation of currently available surveillance data. Furthermore, we investigated a range of behavioural and reporting rate changes that could explain two waves of ZIKV infection in Bahia, Brazil despite only one wave of microcephaly. Plausible changes in reporting could explain these data whilst remaining consistent with the hypothesis that ZIKV infection carries a significant risk of microcephaly. Further evidence is needed to disentangle the true risk of congenital Zika syndrome from time-varying reporting changes.

Tet-Inducible Production of Infectious Zika Virus from the Full-Length cDNA Clones of African- and Asian-Lineage Strains

Zika virus (ZIKV) is a mosquito-borne flavivirus that has emerged as an important human viral pathogen, causing congenital malformation including microcephaly among infants born to mothers infected with the virus during pregnancy. Phylogenetic analysis suggested that ZIKV can be classified into African and Asian lineages. In this study, we have developed a stable plasmid-based reverse genetic system for robust production of both ZIKV prototype African-lineage MR766 and clinical Asian-lineage FSS13025 strains using a tetracycline (Tet)-controlled gene expression vector. Transcription of the full-length ZIKV RNA is under the control of the Tet-responsive P_tight promoter at the 5′ end and an antigenomic ribozyme of hepatitis delta virus at the 3′ end. The transcription of infectious ZIKV RNA genome was efficiently induced by doxycycline. This novel ZIKV reverse genetics system will be valuable for the study of molecular viral pathogenesis of ZIKV and the development of new vaccines against ZIKV infection.

An Evolutionary Insight into Zika Virus Strains Isolated in the Latin American Region

Zika virus (ZIKV) is an emerging pathogen member of the Flaviviridae family. ZIKV has spread rapidly in the Latin American region, causing hundreds of thousands of cases of ZIKV disease, as well as microcephaly in congenital infections. Detailed studies on the pattern of evolution of ZIKV strains have been extremely important to our understanding of viral survival, fitness, and evasion of the host’s immune system. For these reasons, we performed a comprehensive phylogenetic analysis of ZIKV strains recently isolated in the Americas. The results of these studies revealed evidence of diversification of ZIKV strains circulating in the Latin American region into at least five different genetic clusters. This diversification was also reflected in the different trends in dinucleotide bias and codon usage variation. Amino acid substitutions were found in E and prM proteins of the ZIKV strains isolated in this region, revealing the presence of novel genetic variants circulating in Latin America.

Fragile X mental retardation protein is a Zika virus restriction factor that is antagonized by subgenomic flaviviral RNA

Subgenomic flaviviral RNA (sfRNA) accumulates during infection due to incomplete degradation of viral genomes and interacts with cellular proteins to promote infection. Here we identify host proteins that bind the Zika virus (ZIKV) sfRNA. We identified fragile X mental retardation protein (FMRP) as a ZIKV sfRNA-binding protein and confirmed this interaction in cultured cells and mouse testes. Depletion of FMRP elevated viral translation and enhanced ZIKV infection, indicating that FMRP is a ZIKV restriction factor. We further observed that an attenuated ZIKV strain compromised for sfRNA production was disproportionately stimulated by FMRP knockdown, suggesting that ZIKV sfRNA antagonizes FMRP activity. Importantly, ZIKV infection and expression of ZIKV sfRNA upregulated endogenous FMRP target genes in cell culture and ZIKV-infected mice. Together, our observations identify FMRP as a ZIKV restriction factor whose activity is antagonized by the sfRNA. Interaction between ZIKV and FMRP has significant implications for the pathogenesis of ZIKV infections.

The Diversification of Zika Virus: Are There Two Distinct Lineages?

Zika virus (ZIKV) has caused explosive epidemics in the Pacific and the Americas, posing a serious threat to public health. Conventional opinion advocates that ZIKV evolved into two distinct lineages, namely, African and Asian. Descendants of this latter lineage dispersed globally causing major epidemics. However, based on shared amino acid replacements and phylogenetic analyses, it was recently contentiously proposed that the Asian lineage was a direct descendant of the African lineage. To address this contentious issue, we reconstructed a phylogenetic tree of ZIKV using the method based on shared amino acid replacements and found that ZIKV evolved into two distinct lineages. This supports the conventional phylogenetic divergence pattern of ZIKV. Evidence of recombination and sequencing errors was identified among the large collection of ZIKV. As such problematic sequences could confound the phylogenetic analyses, they were removed. Bayesian phylogenetic analyses using the improved sequence data enabled estimates for the divergence time in the past of the African and Asian lineages of ∼180 years ago. Moreover, we found that the Asian lineage viruses did not evolve at an elevated rate. Our findings provide additional support for the conventional opinion that the Asian lineage of ZIKV diverged from the African lineage.

Recent Advances in Zika Virus Vaccines

The recent outbreaks of Zika virus (ZIKV) infections and associated microcephaly in newborns has resulted in an unprecedented effort by researchers to target this virus. Significant advances have been made in developing vaccine candidates, treatment strategies and diagnostic assays in a relatively short period of time. Being a preventable disease, the first line of defense against ZIKV would be to vaccinate the highly susceptible target population, especially pregnant women. Along those lines, several vaccine candidates including purified inactivated virus (PIV), live attenuated virus (LAV), virus like particles (VLP), DNA, modified RNA, viral vectors and subunit vaccines have been in the pipeline with several advancing to clinical trials. As the primary objective of Zika vaccination is the prevention of vertical transmission of the virus to the unborn fetus, the safety and efficacy requirements for this vaccine remain unique when compared to other diseases. This review will discuss these recent advances in the field of Zika vaccine development.

Human antibodies targeting Zika virus NS1 provide protection against disease in a mouse model

Zika virus is a mosquito-borne flavivirus closely related to dengue virus that can cause severe disease in humans, including microcephaly in newborns and Guillain-Barré syndrome in adults. Specific treatments and vaccines for Zika virus are not currently available. Here, we isolate and characterize four monoclonal antibodies (mAbs) from an infected patient that target the non-structural protein NS1. We show that while these antibodies are non-neutralizing, NS1-specific mAbs can engage FcγR without inducing antibody dependent enhancement (ADE) of infection in vitro. Moreover, we demonstrate that mAb AA12 has protective efficacy against lethal challenges of African and Asian lineage strains of Zika virus in Stat2^–/– mice. Protection is Fc-dependent, as a mutated antibody unable to activate known Fc effector functions or complement is not protective in vivo. This study highlights the importance of the ZIKV NS1 protein as a potential vaccine antigen.

Zika virus infection can cause severe disease in humans and there are currently no specific treatments or vaccines. Here, Bailey et al. isolate antibodies recognizing non-structural protein NS1 and show that they protect mice from disease by an Fc-dependent, non-neutralizing mechanism.

Reverse Genetic Approaches for the Generation of Recombinant Zika Virus

Zika virus (ZIKV) is an emergent mosquito-borne member of the Flaviviridae family that was responsible for a recent epidemic in the Americas. ZIKV has been associated with severe clinical complications, including neurological disorder such as Guillain-Barré syndrome in adults and severe fetal abnormalities and microcephaly in newborn infants. Given the significance of these clinical manifestations, the development of tools and reagents to study the pathogenesis of ZIKV and to develop new therapeutic options are urgently needed. In this respect, the implementation of reverse genetic techniques has allowed the direct manipulation of the viral genome to generate recombinant (r)ZIKVs, which have provided investigators with powerful systems to answer important questions about the biology of ZIKV, including virus-host interactions, the mechanism of transmission and pathogenesis or the function of viral proteins. In this review, we will summarize the different reverse genetic strategies that have been implemented, to date, for the generation of rZIKVs and the applications of these platforms for the development of replicon systems or reporter-expressing viruses.

Potential role of dengue virus, chikungunya virus and Zika virus in neurological diseases

This study showed that laboratory markers of recent infection by dengue, Zika or chikungunya arboviruses were detected in the biological samples of approximately one-third of patients with encephalitis, myelitis, encephalomyelitis or Guillain-Barré syndrome, in a surveillance programme in Piauí state, Brazil, between 2015-2016. Fever and myalgia had been associated with these cases. Since in non-tropical countries most infections or parainfectious diseases associated with the nervous system are attributed to herpesviruses, enteroviruses, and Campylobacter jejuni, the present findings indicate that in tropical countries, arboviruses may now play a more important role and reinforce the need for their surveillance and systematic investigation in the tropics.

Zika virus NS2B/NS3 proteinase: A new target for an old drug - Suramin a lead compound for NS2B/NS3 proteinase inhibition

Zika virus infection is the focus of much research due to the medical and social repercussions. Due the role of the viral NS2B/NS3 proteinase in maturation of the viral proteins, it had become an attractive antiviral target. Numerous investigations on viral epidemiology, structure and function analysis, vaccines, and therapeutic drugs have been conducted around the world. At present, no approved vaccine or even drugs have been reported. Thus, there is an urgent need to develop therapeutic agents to cure this epidemic disease. In the present study, we identified the polyanion suramin, an approved antiparasitic drug with antiviral properties, as a potential inhibitor of Zika virus complex NS2B/NS3 proteinase with IC₅₀ of 47 μM. Using fluorescence spectroscopy results we could determine a k_d value of 28 μM and had shown that the ligand does not affect the thermal stability of the protein. STD NMR spectroscopy experiments and molecular docking followed by molecular dynamics simulation identified the binding epitopes of the molecule and shows the mode of interaction, respectively. The computational analysis showed that suramin block the Ser135 residue and interact with the catalytically histidine residue.

[Andrology in oncological diseases]

In dermato-oncological treatment there are many gonadotoxic interventions. Alkylating and hormonally active substances as well as gonadal irradiation, in particular, are known to have a fertilization-limiting effect in men. Since 2017 certified skin cancer centers in Germany therefore have the task to implement counselling on preservation of fertility. This is supported by the S2k guidelines on preservation of fertility in oncological treatment. Because recommendation of the various interventions from the dermato-oncological guidelines are dependent on the stage, the authors advocate at least the question "Is the desire to have children of interest to you?" when patients reach the appropriate stage. Fertility protection of men via cryopreservation of ejaculates or testicular tissue is then a simple and safe option. The procedure is standardized and usually available. In addition, the possibility of cryopreservation of testicular tissue from prepubertal male children and infants is now available via the new Androprotect project. If signs of hypogonadism occur during therapy, a treatment can be considered by weighing up the effects of testosterone but in this case it is important to take the anabolic and immunomodulating effects into account.

Revisiting Key Entry Routes of Human Epidemic Arboviruses into the Mainland Americas through Large-Scale Phylogenomics

The rapid worldwide spread of chikungunya (CHIKV), dengue (DENV), and Zika (ZIKV) viruses have raised great international concern. Knowledge about the entry routes and geographic expansion of these arboviruses to the mainland Americas remain incomplete and controversial. Epidemics caused by arboviruses continue to cause socioeconomic burden globally, particularly in countries where vector control is difficult due to climatic or infrastructure factors. Understanding how the virus circulates and moves from one country to another is of paramount importance to assist government and health officials in anticipating future epidemics, as well as to take steps to help control or mitigate the spread of the virus. Through the analyses of the sequences of arbovirus genomes collected at different locations over time, we identified patterns of accumulated mutations, being able to trace routes of dispersion of these viruses. Here, we applied robust phylogenomic methods to trace the evolutionary dynamics of these arboviruses with special focus on Brazil, the epicenter of these triple epidemics. Our results show that CHIKV, DENV-1–4, and ZIKV followed a similar path prior to their first introductions into the mainland Americas, underscoring the need for systematic arboviral surveillance at major entry points of human population movement between countries such as airports and seaports.

Zika virus exposure in pregnancy and its association with newborn visual anomalies and hearing loss

Exposure to Zika virus (ZIKV) in pregnancy leads to a spectrum of congenital effects in the newborn. Recent studies have begun to evaluate the impact of ZIKV during pregnancy. Among 39 relevant studies, nine were related specifically to clinical studies of ophthalmologic disorders and one was related to hearing loss impairment; most of these studies were case reports and case series reports. Importantly, congenital toxoplasmosis was ruled out in all studies. The data show that, in addition to microcephaly, ZIKV exposure in pregnancy may result in subtle ocular impairments in the newborn. The most common anomalies are macular pigment mottling and/or chorioretinal atrophy, and optic nerve disorders. Sensorineural hearing loss has also been noted in 5.8% of infants with microcephaly. The effects of ZIKV infection during pregnancy are potentially devastating to the fetus and newborn. Although microcephaly is an important signal, the current information emphasizes the importance of ocular and auditory screenings, otherwise sight and hearing anomalies may be underestimated. Healthcare providers should fully understand the spectrum of anomalies related to ZIKV exposure in pregnancy in order to counsel pregnant women living in high-risk areas, in addition to those wanting to become pregnant.

New therapies for human cytomegalovirus infections

The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.

Seroprevalence, risk factor, and spatial analyses of Zika virus infection after the 2016 epidemic in Managua, Nicaragua

In 2015, a Zika epidemic in Brazil began spreading throughout the Americas. Zika virus (ZIKV) entered Managua, Nicaragua, in January 2016 and caused an epidemic that peaked in July-September 2016. ZIKV seropositivity was estimated among participants of pediatric (n = 3,740) and household (n = 2,147) cohort studies, including an adult-only subset from the household cohort (n = 1,074), in Managua. Seropositivity was based on a highly sensitive and specific assay, the Zika NS1 blockade-of-binding ELISA, which can be used in dengue-endemic populations. Overall seropositivity for the pediatric (ages 2-14), household (ages 2-80), and adult (ages 15-80) cohorts was 36, 46, and 56%, respectively. Trend, risk factor, and contour mapping analyses demonstrated that ZIKV seroprevalence increased nonlinearly with age and that body surface area was statistically associated with increasing seroprevalence in children. ZIKV seropositivity was higher in females than in males across almost all ages, with adjusted prevalence ratios in children and adults of 1.11 (95% CI: 1.02-1.21) and 1.14 (95% CI: 1.01-1.28), respectively. No household-level risk factors were statistically significant in multivariate analyses. A spatial analysis revealed a 10-15% difference in the risk of ZIKV infections across our 3-km-wide study site, suggesting that ZIKV infection risk varies at small spatial scales. To our knowledge, this is the largest ZIKV seroprevalence study reported in the Americas, and the only one in Central America and in children to date. It reveals a high level of immunity against ZIKV in Managua as a result of the 2016 epidemic, making a second large Zika epidemic unlikely in the near future.

Readiness for an Increase in Congenital Zika Virus Infections in the United States: Geographic Distance to Pediatric Subspecialist Care

OBJECTIVE

The study's purpose was to investigate readiness for an increase in the congenital Zika infection (CZI) by describing the distribution of pediatric subspecialists needed for the care of children with CZI.

METHODS

We applied county-level subspecialist counts to US maps, overlaying the geocoded locations of children's hospitals to assess the correlation of hospital and subspecialist locations. We calculated travel distance from census tract centroids to the nearest in-state children's hospital by state (with/without &gt; 100 reported adult Zika virus cases) and by regions corresponding to the likely local Zika virus transmission area and to the full range of the mosquito vector. Travel distance percentiles reflect the population of children 100 miles.

CONCLUSION

The travel distance to pediatric subspecialty care varies widely by state and is likely to be an access barrier in some areas, particularly states bordering the Gulf of Mexico, which may have increasing numbers of CZI cases. (Disaster Med Public Health Preparedness. 2019;13:476-486).

Zika might not be acting alone: Using an ecological study approach to investigate potential co-acting risk factors for an unusual pattern of microcephaly in Brazil

Zika virus infections can cause a range of neurologic disorders including congenital microcephaly. However, while Zika infections have been notified across all regions in Brazil, there has been an unusual number of congenital microcephaly case notifications concentrated in the Northeast of the country. To address this observation, we investigated epidemiological data (2014–2016) on arbovirus co-distribution, environmental and socio-economic factors for each region in Brazil. Data on arbovirus reported cases and microcephaly were collected from several Brazilian Ministry of Health databases for each Federal unit. These were complemented by environmental management, social economic and Aedes aegypti infestation index data, extracted from multiple databases. Spatial time “ecological” analysis on the number of arboviruses transmitted by Aedes mosquitoes in Brazil show that the distribution of dengue and Zika was widespread in the whole country, with higher incidence in the West-Central region. However, reported chikungunya cases were higher in the Northeast, the region also with the highest number of microcephaly cases registered. Social economic factors (human development index and poverty index) and environmental management (water supply/storage and solid waste management) pointed the Northeast as the less wealthy region. The Northeast is also the region with the highest risk of Aedes aegypti house infestation due to the man-made larval habitats. In summary, the results of our ecological analysis support the hypothesis that the unusual distribution of microcephaly might not be due to Zika infection alone and could be accentuated by poverty and previous or co-infection with other pathogens. Our study reinforces the link between poverty and the risk of disease and the need to understand the effect on pathogenesis of sequential exposure to arboviruses and co-viral infections. Comprehensive large-scale cohort studies are required to corroborate our findings. We recommend that the list of infectious diseases screened, particularly during pregnancy, be regularly updated to include and effectively differentiate all viruses from ongoing outbreaks.

Astrogliopathology in the infectious insults of the brain

Astroglia, a heterogeneous type of neuroglia, play key homeostatic functions in the central nervous system (CNS) and represent an important defence system. Impaired homeostatic capacity of astrocytes manifests in diseases and this is mirrored in various astrocyte-based pathological features including reactive astrogliosis, astrodegeneration with astroglial atrophy and pathological remodelling of astrocytes. All of these manifestations are most prominently associated with infectious insults, mediated by bacteria, protozoa and viruses. Here we focus onto neurotropic viruses such as tick-borne encephalitis (TBEV) and Zika virus (ZIKV), both belonging to Flaviviridae and both causing severe neurological impairments. We argue that astrocytes provide a route through which neurotropic infectious agents attack the CNS, since they are anatomically associated with the blood-brain barrier and exhibit aerobic glycolysis, a metabolic specialisation of highly morphologically dynamic cells, which may provide a suitable metabolic milieu for proliferation of infectious agents, including viral bodies.

T Cell Responses to Nonstructural Protein 3 Distinguish Infections by Dengue and Zika Viruses

The 2015–2016 Zika virus (ZIKV) epidemic in the Americas and the Caribbean demonstrated that clinical assays to detect, distinguish, and characterize immune responses to flaviviral infections are needed. ZIKV and dengue virus (DENV) are mosquito-transmitted flaviviruses sharing overlapping geographic distributions and have significant sequence similarities that can increase the potential for antibody and T cell cross-reaction. Using nonstructural protein 1-based enzyme-linked immunosorbent assays (ELISAs), we determined the serostatus of individuals living in a region of DENV and ZIKV endemicity in Brazil, identifying individuals with primary DENV (pDENV) and primary ZIKV (pZIKV), ZIKV with primary DENV (ZIKVwpDENV), and secondary DENV (sDENV) infections; the presence of pDENV and pZIKV was further confirmed by neutralization tests. Development of an enzyme-linked immunosorbent spot (ELISPOT) assay for DENV and ZIKV structural and nonstructural (NS) protein antigens enabled us to distinguish infections by these viruses based on T cell responses and to characterize those responses. We found that gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) T cell responses to NS3 differentiated DENV and ZIKV infections with 94% sensitivity and 92% specificity. In general, we also showed that pDENV and sDENV cases and pZIKV and ZIKVwpDENV cases elicit similar T cell response patterns and that HIV-infected individuals show T cell responses that are lower than those shown by HIV-negative individuals. These results have important implications for DENV and ZIKV diagnostic and vaccine development and provide critical insights into the T cell response in individuals with multiple flaviviral infections.

The potential for antibody and T cell cross-reactions to DENV and ZIKV, flaviviruses that cocirculate and can sequentially infect individuals, has complicated diagnostic and vaccine development. Our serological data show that antibodies to nonstructural protein 1 can distinguish sequential human infections by DENV and ZIKV. The development of a simple and inexpensive assay also enables the differentiation of DENV and ZIKV infections based on characterization of T cell responses. Our T cell data reveal strong response patterns that are similar in nature to those seen with individuals with one or multiple DENV infections and with individuals with only primary ZIKV infection and ZIKV-infected individuals with previous DENV exposure. The characterization of T cell responses in a serologically validated group of individuals is of relevance to the development of vaccines and immunotherapeutics against these global threats.

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.

Role of Zika Virus prM Protein in Viral Pathogenicity and Use in Vaccine Development

Recent Zika virus (ZIKV) epidemics necessitate the urgent development of effective drugs and vaccines, which can be accelerated by an enhanced understanding of ZIKV biology. One of the ZIKV structural proteins, precursor membrane (prM), plays an important role in the assembly of mature virions through cleavage of prM into M protein. Recent studies have suggested that prM protein might be implicated in the neurovirulence of ZIKV. Most vaccines targeting ZIKV include prM as the immunogen. Here, we review progress in our understanding of ZIKV prM protein and its application in ZIKV vaccine development.

A low-cost, battery-powered acoustic trap for surveilling male Aedes aegypti during rear-and-release operations

The Aedes aegypti mosquito is a primary vector of several serious arboviruses throughout the world and is therefore of great concern to many public health organizations. With vector control methodology pivoting towards rearing and releasing large numbers of genetically modified, sterilized, or Wolbachia-infected male mosquitoes to control vector populations, economical surveillance methods for release tracking becomes increasingly necessary. Previous work has identified that male Ae. aegypti are attracted to female wingbeat frequencies and can be captured through artificial playback of these frequencies, but the tested systems are cost-prohibitive for wide-scale monitoring. Thus, we have developed a simple, low-cost, battery-powered, microcontroller-based sound lure which mimics the wingbeat frequency of female Ae. aegypti, thereby attracting males. We then tested the efficacy of this lure in combination with a passive (non-powered) gravid Aedes trap (GAT) against the current gold-standard, the Biogents Sentinel (BGS) trap, which requires main power (household power) and costs several times what the GAT does. Capture rates of male Ae. aegypti in sound-baited GATs (Sound-GATs) in these field tests were comparable to that of the BGS with no inhibitory effects of sound playback on female capture. We conclude that the Sound-GAT is an effective replacement of the costly BGS for surveillance of male Ae. aegypti mosquitoes, particularly in the developing countries where funding is limited, and has the potential to be adapted to target males of other medically important species.

Point-of-care diagnostic assay for the detection of Zika virus using the recombinase polymerase amplification method

The sudden and explosive expansion of Zika virus (ZIKV) from the African continent through Oceania and culminating in the outbreak in South America has highlighted the importance of new rapid point-of-care diagnostic tools for the control and prevention of transmission. ZIKV infection has devastating consequences, such as neurological congenital malformations in infants born to infected mothers and Guillain-Barré syndrome in adults. Additionally, its potential for transmission through vector bites, as well as from person to person through blood transfusions and sexual contact, are important considerations for prompt diagnosis. Recombinase polymerase amplification (RPA), an isothermal method, was developed as an alternative field-applicable assay to PCR. Here we report the development of a novel ZIKV real-time reverse transcriptase RPA (RT-RPA) assay capable of detecting a range of different ZIKV strains from a variety of geographical locations. The ZIKV RT-RPA was shown to be highly sensitive, being capable of detecting as few as five copies of target nucleic acid per reaction, and suitable for use with a battery-operated portable device. The ZIKV RT-RPA demonstrated 100 % specificity and 83 % sensitivity in clinical samples. Furthermore, we determined that the ZIKV RT-RPA is a versatile assay that can be applied to crude samples, such as saliva and serum, and can be used as a vector surveillance tool on crude mosquito homogenates. Therefore, the developed ZIKV RT-RPA is a useful diagnostic tool that can be transferred to a resource-limited location, eliminating the need for a specialized and sophisticated laboratory environment and highly trained staff.

Zika virus vaccines: immune response, current status, and future challenges

Zika virus (ZIKV) is the most recent mosquito-transmitted virus to cause a global health crisis following its entrance into a naïve population in the Western Hemisphere. Once the ZIKV outbreak began investigators rapidly established small and large animal models of pathogenesis, developed a number candidate vaccines using different platforms, and defined mechanisms of protection. In this review, we characterize the adaptive immune response elicited by ZIKV infections and vaccines, the status of ongoing clinical trials in humans, and discuss future challenges within the field.

Seroepidemiology of Dengue, Zika, and Yellow Fever Viruses among Children in the Democratic Republic of the Congo

Flaviviruses such as Zika, dengue, and yellow fever cause epidemics throughout the tropics and account for substantial global morbidity and mortality. Although malaria and other vector-borne diseases have long been appreciated in Africa, flavivirus epidemiology is incompletely understood. Despite the existence of an effective vaccine, yellow fever continues to cause outbreaks and deaths, including at least 42 fatalities in the Democratic Republic of the Congo (DRC) in 2016. Here, we leveraged biospecimens collected as part of the nationally representative 2013-2014 Demographic and Health Survey in the DRC to examine serological evidence of flavivirus infection or vaccination in children aged 6 months to 5 years. Even in this young stratum of the Congolese population, we find evidence of infection by dengue and Zika viruses based on results from enzyme-linked immunosorbent assay and neutralization assay. Surprisingly, there was remarkable discordance between reported yellow fever vaccination status and results of serological assays. The estimated seroprevalences of neutralizing antibodies against each virus are yellow fever, 6.0% (95% confidence interval [CI] = 4.6-7.5%); dengue, 0.4% (0.1-0.9%); and Zika, 0.1% (0.0-0.5%). These results merit targeted, prospective studies to assess effectiveness of yellow fever vaccination programs, determine flavivirus seroprevalence across a broader age range, and investigate how these emerging diseases contribute to the burden of acute febrile illness in the DRC.

Zika Virus Replication in Dorsal Root Ganglia Explants from Interferon Receptor1 Knockout Mice Causes Myelin Degeneration

Zika virus (ZIKV) is a neurotropic agent that targets the developing fetal brain in women infected during pregnancy. In addition to the developing central nervous system, ZIKV has been recently shown to infect cells of the peripheral nervous system (PNS), highlighting its potential to cause acute peripheral neuropathies in adults, such as Guillain-Barré Syndrome (GBS). Here we show that myelinating dorsal root ganglia (DRG) explants obtained from interferon-alpha/beta receptor knock-out mice are productively infected by ZIKV. Virus replication is cytopathic in both peripheral neurons and myelinating Schwann cells leading to myelin disruption. These results confirm and extend previous observations suggesting that the PNS is indeed a potential site of ZIKV infection, replication and cytopathicity.

Cost-effectiveness of a potential Zika vaccine candidate: a case study for Colombia

BACKGROUND

A number of Zika vaccine platforms are currently being investigated, some of which have entered clinical trials. We sought to evaluate the cost-effectiveness of a potential Zika vaccine candidate under the WHO Vaccine Target Product Profile for outbreak response, prioritizing women of reproductive age to prevent microcephaly and other neurological disorders.

METHODS

Using an agent-based simulation model of ZIKV transmission dynamics in a Colombian population setting, we conducted cost-effectiveness analysis with and without pre-existing herd immunity. The model was parameterized with estimates associated with ZIKV infection, risks of microcephaly in different trimesters, direct medical costs, and vaccination costs. We assumed that a single dose of vaccine provides a protection efficacy in the range 60% to 90% against infection. Cost-effectiveness analysis was conducted from a government perspective.

RESULTS

Under a favorable scenario when the reproduction number is relatively low (R₀ = 2.2) and the relative transmissibility of asymptomatic infection is 10% compared with symptomatic infection, a vaccine is cost-saving (with negative incremental cost-effective ratio; ICER) for vaccination costs up to US$6 per individual without herd immunity, and up to US$4 per individual with 8% herd immunity. For positive ICER values, vaccination is highly cost-effective for vaccination costs up to US$10 (US$7) in the respective scenarios with the willingness-to-pay of US$6610 per disability-adjusted life-year, corresponding to the average per capita GDP of Colombia between 2013 and 2017. Our results indicate that the effect of other control measures targeted to reduce ZIKV transmission decreases the range of vaccination costs for cost-effectiveness due to reduced returns of vaccine-induced herd immunity. In all scenarios investigated, the median reduction of microcephaly exceeded 64% with vaccination.

CONCLUSIONS

Our study suggests that a Zika vaccine with protection efficacy as low as 60% could significantly reduce the incidence of microcephaly. From a government perspective, Zika vaccination is highly cost-effective, and even cost-saving in Colombia if vaccination costs per individual is sufficiently low. Efficacy data from clinical trials and number of vaccine doses will be important requirements in future studies to refine our estimates, and conduct similar studies in other at-risk populations.