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

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

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

IMPORTANCE

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

Evaluation of Anomalies and Neurodevelopment in Children Exposed to ZIKV during Pregnancy

Zika virus (ZIKV) infection in pregnancy is associated with birth and developmental alterations in infants. In this study, clinical records of 47 infants whose mothers had Zika during pregnancy or clinical manifestations compatible with Zika were reviewed. A description of the infants’ anomalies was established, and a neurodevelopmental assessment was performed on 18 infants, using the Evaluation of Infant Development (EDI for its initialism in Spanish) and DDST-II (Denver Developmental Screening Test II) tests. From his sample, 74.5% of the infants evaluated had major anomalies and 51.9% had minor anomalies. The incidence of major anomalies, related to trimester of pregnancy, was 84.2% for the first trimester, 77.8% for the second trimester, and 37.5% in the third trimester. A similar trend was observed in the frequency of infants without anomalies and was less evident in the incidence of minor anomalies (p = 0.016). Through neurodevelopmental assessments, EDI identified 27.8% of infants as having normal development, while 55.5% of affected infants had developmental delay, and 16.7% were at risk for developmental delay. The DDSST-II showed that 77.7% infants had delay in the gross motor and language area, 88.8% in the fine-adaptative motor area, and 72.2% in the personal–social area. In this work, children of mothers with ZIKV infection during pregnancy may have major or minor anomalies regardless of the trimester of pregnancy in which the infection occurred. The neurodevelopmental assessment shows that ZIKV can cause a developmental delay in infants with the fine-adaptative motor area being the most affected.

ATP-binding cassette (ABC) drug transporters in the developing blood-brain barrier: role in fetal brain protection

The blood-brain barrier (BBB) provides essential neuroprotection from environmental toxins and xenobiotics, through high expression of drug efflux transporters in endothelial cells of the cerebral capillaries. However, xenobiotic exposure, stress, and inflammatory stimuli have the potential to disrupt BBB permeability in fetal and post-natal life. Understanding the role and ability of the BBB in protecting the developing brain, particularly with respect to drug/toxin transport, is key to promoting long-term brain health. Drug transporters, particularly P-gp and BCRP are expressed in early gestation at the developing BBB and have a crucial role in developmental homeostasis and fetal brain protection. We have highlighted several factors that modulate drug transporters at the developing BBB, including synthetic glucocorticoid (sGC), cytokines, maternal infection, and growth factors. Some factors have the potential to increase expression and function of drug transporters and increase brain protection (e.g., sGC, transforming growth factor [TGF]-β). However, others inhibit drug transporters expression and function at the BBB, increasing brain exposure to xenobiotics (e.g., tumor necrosis factor [TNF], interleukin [IL]-6), negatively impacting brain development. This has implications for pregnant women and neonates, who represent a vulnerable population and may be exposed to drugs and environmental toxins, many of which are P-gp and BCRP substrates. Thus, alterations in regulated transport across the developing BBB may induce long-term changes in brain health and compromise pregnancy outcome. Furthermore, a large portion of neonatal adverse drug reactions are attributed to agents that target or access the nervous system, such as stimulants (e.g., caffeine), anesthetics (e.g., midazolam), analgesics (e.g., morphine) and antiretrovirals (e.g., Zidovudine); thus, understanding brain protection is key for the development of strategies to protect the fetal and neonatal brain.

Lack of Association between Adverse Pregnancy Outcomes and Zika Antibodies among Pregnant Women in Thailand between 1997 and 2015

Data about Zika virus infection and adverse pregnancy outcomes in Southeast Asia are scarce. We conducted an unmatched case-control study of Zika virus (ZIKV) serology in pregnant women enrolled in human immunodeficiency virus (HIV) or hepatitis B virus (HBV) perinatal prevention trials between 1997 and 2015 in Thailand. Case and control groups included women with and without adverse pregnancy outcomes. Plasma samples collected during the last trimester of pregnancy were tested for ZIKV IgG/IgM and Dengue IgG/IgM (Euroimmun, AG, Germany). Case newborn plasma samples were tested for ZIKV IgM and ZIKV RNA (Viasure, Spain). The case group included women with stillbirth (n = 22) or whose infants had microcephaly (n = 4), a head circumference below the first percentile (n = 14), neurological disorders (n = 36), or had died within 10 days after birth (n = 11). No women in the case group were positive for ZIKV IgM, and none of their live-born neonates were positive for ZIKV IgM or ZIKV RNA. The overall ZIKV IgG prevalence was 29%, 24% in the case and 34% in the control groups (Fisher's exact test; p = 0.13), while the dengue IgG seroprevalence was 90%. Neither neonatal ZIKV infections nor ZIKV-related adverse pregnancy outcomes were observed in these women with HIV and/or HBV during the 18-year study period.

Semisynthesis of Dolabellane Diterpenes: Oxygenated Analogues with Increased Activity against Zika and Chikungunya Viruses

Brown algae and soft corals represent the main marine sources of dolabellane diterpenes. The antiviral activity of dolabellanes has been studied for those isolated from algae, whereas dolabellanes isolated from soft corals have been barely studied. In this work, a collection of dolabellane diterpenes consisting of five natural and 21 semisynthetic derivatives was constructed, and their antiviral activities against Zika (ZIKV) and Chikungunya (CHIKV) viruses were tested. Dolabellatrienone (1) and (1R,7R,8R,11S)-7,8-epoxy-13-keto-dolabella-3,12(18)-diene (2), isolated from Eunicea genus soft corals, were employed to obtain 21 dolabellane and dolastane diterpenes by reactions such as allylic oxidations, reductions, acid-catalyzed epoxide ring opening, and acetylations. All of the compounds were identified by a combination of one- and two-dimensional NMR, mass spectrometry, and X-ray diffraction experiments. The cytotoxicites against Vero cells and the antiviral activities against ZIKV and CHIKV was tested to calculate the half-maximal effective concentration (EC₅₀) and selectivity indexes (SIs). In general, the addition of oxygen-containing functional groups improved the bioactivity of dolabellane and dolastane diterpenes against ZIKV and CHIKV replication. Compound 9 showed an EC₅₀ = 0.92 ± 0.08 μM and SI = 820 against ZIKV.

Case Report: Multiorgan Involvement with Congenital Zika Syndrome

We report the case of an infant born with congenital Zika syndrome (CZS). During the largest Zika virus (ZIKV) outbreak in Peru, the mother presented with fever and rash that were confirmed to be due to ZIKV by real-time PCR. The infant was born with severe microcephaly. Imaging revealed corpus callosum dysgenesis, lissencephaly, ventriculomegaly, and calcifications. Mild hypertrophic cardiomyopathy with diastolic dysfunction was reported in the echocardiogram. Valgus deviation of the lower extremities and a left clubfoot were diagnosed at birth. The hip ultrasound showed incipient signs of Graf type II dysplasia. The findings confirm that CZS is a multiorgan phenotype in which microcephaly is merely the tip of the iceberg. A multidisciplinary approach is needed for the evaluation of these children.

Risk factors of exposure to Aedes albopictus bites in mainland France using an immunological biomarker

In recent decades, the invasive Aedes albopictus vector has spread across Europe and is responsible for numerous outbreaks of autochthonous arboviral disease. The aim of this study was to identify epidemiological and sociological risk factors related to individual levels of exposure to Aedes albopictus bites. A multidisciplinary survey was conducted with volunteer blood donors living in areas either colonised or not by Aedes albopictus in mainland France. Individual levels of exposure were evaluated by measuring the IgG level specific to Aedes albopictus saliva. The most striking risk factors concerned the localisation and characteristics of the dwelling. Individuals living in areas colonised prior to 2009 or recently colonised (between 2010 and 2012) had higher anti-salivary gland extract IgG levels compared with those who were living in areas not yet colonised by Ae. albopictus. The type of dwelling did not seem to impact the level of exposure to Aedes bites. People living in apartments had a higher anti-salivary gland extract IgG level than those living in individual houses but the difference was not statistically significant. Interestingly, the presence of air conditioning or window nets was associated with a noticeable reduction in bite intensity.

A neonatal nonhuman primate model of gestational Zika virus infection with evidence of microencephaly, seizures and cardiomyopathy

Zika virus infection during pregnancy is associated with miscarriage and with a broad spectrum of fetal and neonatal developmental abnormalities collectively known as congenital Zika syndrome (CZS). Symptomology of CZS includes malformations of the brain and skull, neurodevelopmental delay, seizures, joint contractures, hearing loss and visual impairment. Previous studies of Zika virus in pregnant rhesus macaques (Macaca mulatta) have described injury to the developing fetus and pregnancy loss, but neonatal outcomes following fetal Zika virus exposure have yet to be characterized in nonhuman primates. Herein we describe the presentation of rhesus macaque neonates with a spectrum of clinical outcomes, including one infant with CZS-like symptoms including cardiomyopathy, motor delay and seizure activity following maternal infection with Zika virus during the first trimester of pregnancy. Further characterization of this neonatal nonhuman primate model of gestational Zika virus infection will provide opportunities to evaluate the efficacy of pre- and postnatal therapeutics for gestational Zika virus infection and CZS.

Route of Infection Influences Zika Virus Shedding in a Guinea Pig Model

Due to the recent epidemic of Zika virus (ZIKV) infection and resulting sequelae, as well as concerns about both the sexual and vertical transmission of the virus, renewed attention has been paid to the pathogenesis of this unique arbovirus. Numerous small animal models have been used in various ZIKV pathogenicity studies, however, they are often performed using immunodeficient or immunosuppressed animals, which may impact disease progression in a manner not relevant to immunocompetent humans. The use of immunocompetent animal models, such as macaques, is constrained by small sample sizes and the need for specialized equipment/staff. Here we report the establishment of ZIKV infection in an immunocompetent small animal model, the guinea pig, using both subcutaneous and vaginal routes of infection to mimic mosquito-borne and sexual transmission. Guinea pigs developed clinical signs consistent with mostly asymptomatic and mild disease observed in humans. We demonstrate that the route of infection does not significantly alter viral tissue tropism but does impact mucosal shedding mechanics. We also demonstrate persistent infection in sensory and autonomic ganglia, identifying a previously unrecognized niche of viral persistence that could contribute to viral shedding in secretions. We conclude that the guinea pig represents a useful and relevant model for ZIKV pathogenesis.

Auditory findings associated with Zika virus infection: an integrative review

INTRODUCTION

Possible associations between Zika virus infection and hearing loss were observed during the epidemic in the Americas.

OBJECTIVE

To describe the auditory alterations, pathogenesis and recommendations for follow-up in individuals with prenatal or acquired Zika virus infection.

METHODS

Bibliographic research conducted in March/2018-April/2019 at the main available databases. Article selection, data extraction and quality evaluation were carried out by two independent reviewers. Studies containing auditory evaluation of patients with congenital or acquired Zika virus infection; and/or hypotheses or evidences on the pathophysiology of auditory impairment associated with Zika virus; and/or recommendations on screening and follow-up of patients with auditory impairment by Zika virus were included.

RESULTS

A total of 27 articles were selected. Sensorineural and transient hearing loss were reported in six adults with acquired Zika virus infection. Of the 962 studied children, 482 had microcephaly and 145 had diagnostic confirmation of Zika virus; 515 of the 624 children with auditory evaluation performed only screening tests with otoacoustic emissions testing and/or automated click-stimuli auditory brainstem response testing. Studies in prenatally exposed children were very heterogeneous and great variations in the frequency of altered otoacoustic emissions and automated click-stimuli auditory brainstem response occurred across the studies. Altered otoacoustic emissions varied from 0% to 75%, while altered automated click-stimuli auditory brainstem response varied from 0% to 29.2%. Sensorineural, retrocochlear or central origin impairment could not be ruled out. One study with infected mice found no microscopic damage to cochlear hair cells. Studies on the pathogenesis of auditory changes in humans are limited to hypotheses and recommendations still include points of controversy.

CONCLUSION

The available data are still insufficient to understand the full spectrum of the involvement of the auditory organs by Zika virus, the pathogenesis of this involvement or even to confirm the causal association between auditory involvement and virus infection. The screening and follow-up recommendations still present points of controversy.

Interferon-stimulated gene 15 (ISG15) restricts Zika virus replication in primary human corneal epithelial cells

PURPOSE

Zika virus (ZIKV) has emerged as an important human pathogen causing ocular complications. There have been reports of the shedding of ZIKV in human as well as animal tears. In this study, we investigated the infectivity of ZIKV in corneal epithelial cells and their antiviral immune response.

METHODS

Primary human corneal epithelial cells (Pr. HCECs) and an immortalized cell line (HUCL) were infected with two different strains of ZIKV (PRVABC59 & BeH823339) or dengue virus (DENV, serotypes 1-4). Viral infectivity was assessed by immunostaining of viral antigen and plaque assay. qRT-PCR and immunoblot analyses were used to assess the expression of innate inflammatory and antiviral genes. Supplementation of recombinant ISG15 (rISG15) and gene silencing approaches were used to elucidate the role of ISG15 in corneal antiviral defense.

RESULTS

Pr. HCECs, but not the HUCL cells, were permissive to both ZIKV strains and specifically to DENV3 infection. ZIKV induced the expression of viral recognition receptors (TLR3, RIG-I, &MDA5), and genes involved in inflammatory (CXCL10 & CCL5) and antiviral (IFNs, MX1, OAS2, ISG15) responses in Pr. HCECs. Furthermore, ZIKV infection caused Pr. HCECs cell death, as evidenced by TUNEL staining. Silencing of ISG15 increased ZIKV infectivity while supplementation with rISG15 reduced ZIKV infection by direct inactivation of ZIKV and inhibiting its entry.

CONCLUSIONS

Our study demonstrates for the first time, that ZIKV can readily infect and replicate in Pr. HCECs. Therefore, ZIKV may persist in the cornea and pose the potential risk of transmission via corneal transplantation.

Zika Virus Infects Trabecular Meshwork and Causes Trabeculitis and Glaucomatous Pathology in Mouse Eyes

Zika virus (ZIKV) infection during pregnancy leads to devastating fetal outcomes, including neurological (microcephaly) and ocular pathologies such as retinal lesions, optic nerve abnormalities, chorioretinal atrophy, and congenital glaucoma. Only clinical case reports have linked ZIKV infection to causing glaucoma, a major blinding eye disease. In the present study, we have investigated the role of ZIKV in glaucoma pathophysiology using in vitro and in vivo experimental models. We showed that human primary trabecular meshwork (Pr. TM) cells, as well as a human GTM3 cell line, were permissive to ZIKV infection. ZIKV induced the transcription of various genes expressing pattern recognition receptors (TLR2, TLR3, and RIG-I), cytokines/chemokines (TNF-α, IL-1β, CCL5, and CXCL10), interferons (IFN-α2, IFN-β1, and IFN-γ), and interferon-stimulated genes (ISG15 and OAS2) in Pr. TM cells. ZIKV infection in IFNAR1-/- and wild-type (WT) mouse eyes resulted in increased intraocular pressure (IOP) and the development of chorioretinal atrophy. Anterior chamber (AC) inoculation of ZIKV caused infectivity in iridocorneal angle and TM, leading to the death of TM cells in the mouse eyes. Moreover, anterior segment tissue of infected eyes exhibited increased expression of inflammatory mediators and interferons. Furthermore, ZIKV infection in IFNAR1-/- mice resulted in retinal ganglion cell (RGC) death and loss, coinciding with optic nerve infectivity and disruption of anterograde axonal transport. Because of similarity in glaucomatous pathologies in our study and other experimental glaucoma models, ZIKV infection can be used to study infectious triggers of glaucoma, currently an understudied area of investigation.IMPORTANCE Ocular complications due to ZIKV infection remains a major public health concern because of their ability to cause visual impairment or blindness. Most of the previous studies have shown ZIKV-induced ocular pathology in the posterior segment (i.e., retina) of the eye. However, some recent clinical reports from affected countries highlighted the importance of ZIKV in affecting the anterior segment of the eye and causing congenital glaucoma. Because glaucoma is the second leading cause of blindness worldwide, it is imperative to study ZIKV infection in causing glaucoma to identify potential targets for therapeutic intervention. In this study, we discovered that ZIKV permissively infects human TM cells and evokes inflammatory responses causing trabeculitis. Using a mouse model, we demonstrated that ZIKV infection resulted in higher IOP, increased RGC loss, and optic nerve abnormalities, the classical hallmarks of glaucoma. Collectively, our study provides new insights into ocular ZIKV infection resulting in glaucomatous pathology.

The Unfolded Protein Response: A Key Player in Zika Virus-Associated Congenital Microcephaly

Zika virus (ZIKV) is a mosquito-borne virus that belongs to the Flaviviridae family, together with dengue, yellow fever, and West Nile viruses. In the wake of its emergence in the French Polynesia and in the Americas, ZIKV has been shown to cause congenital microcephaly. It is the first arbovirus which has been proven to be teratogenic and sexually transmissible. Confronted with this major public health challenge, the scientific and medical communities teamed up to precisely characterize the clinical features of congenital ZIKV syndrome and its underlying pathophysiological mechanisms. This review focuses on the critical impact of the unfolded protein response (UPR) on ZIKV-associated congenital microcephaly. ZIKV infection of cortical neuron progenitors leads to high endoplasmic reticulum (ER) stress. This results in both the stalling of indirect neurogenesis, and UPR-dependent neuronal apoptotic death, and leads to cortical microcephaly. In line with these results, the administration of molecules inhibiting UPR prevents ZIKV-induced cortical microcephaly. The discovery of the link between ZIKV infection and UPR activation has a broader relevance, since this pathway plays a crucial role in many distinct cellular processes and its induction by ZIKV may account for several reported ZIKV-associated defects.

Advances in Zika Virus⁻Host Cell Interaction: Current Knowledge and Future Perspectives

Emerging mosquito-transmitted RNA viruses, such as Zika virus (ZIKV) and Chikungunya represent human pathogens of an immense global health problem. In particular, ZIKV has emerged explosively since 2007 to cause a series of epidemics in the South Pacific and most recently in the Americas. Although typical ZIKV infections are asymptomatic, ZIKV infection during pregnancy is increasingly associated with microcephaly and other fetal developmental abnormalities. In the last few years, genomic and molecular investigations have established a remarkable progress on the pathogenic mechanisms of ZIKV infection using in vitro and in vivo models. Here, we highlight recent advances in ZIKV-host cell interaction studies, including cellular targets of ZIKV, ZIKV-mediated cell death mechanisms, host cell restriction factors that limit ZIKV replication, and immune evasion mechanisms utilized by ZIKV. Understanding of the mechanisms of ZIKV⁻host interaction at the cellular level will contribute crucial insights into the development of ZIKV therapeutics and vaccines.