Global Alert: Zika Virus-an Emerging Arbovirus

Virus as Teratogenic Agents

Viral infectious diseases are important causes of reproductive disorders, as abortion, fetal mummification, embryonic mortality, stillbirth, and congenital abnormalities in animals and in humans. In this chapter, we provide an overview of some virus, as important agents in teratology.We begin by describing the Zika virus, whose infection in humans had a very significant impact in recent years and has been associated with major health problems worldwide. This virus is a teratogenic agent in humans and has been classified as a public health emergency of international concern (PHEIC).Then, some viruses associated with reproductive abnormalities on animals, which have a significant economic impact on livestock, are described, as bovine herpesvirus, bovine viral diarrhea virus, Schmallenberg virus, Akabane virus, and Aino virus.For all viruses mentioned in this chapter, the teratogenic effects and the congenital malformations associated with fetus and newborn are described, according to the most recent scientific publications.

Zika virus NS1 suppresses VE-cadherin via hsa-miR-29b-3p/DNMT3b/MMP-9 pathway in human brain microvascular endothelial cells

Zika virus infection has been reported to cause microcephaly in newborns. ZIKV exploits various strategies to cross the blood-brain barrier. ZIKV NS1 may compromise the barrier integrity of endothelial cells by regulating expression of junctional proteins. MicroRNAs play an important role in post-transcriptional gene regulations. We demonstrated that ZIKV-NS1 affected the adherence junction protein in human brain microvascular endothelial cells via hsa-miR-29b-3p/DNMT3b/MMP-9 pathway. The hCMEC/D3 cells were exposed to ZIKV-NS1 with different doses (500 ng/mL and 1000 ng/mL) for 24 h. The expression pattern of DNTM3b, MMP-9, and VE-cadherin were studied using immunoblotting and the distribution of DNMT3b and MMP-9 were studied using immunofluorescence. The quantification of hsa-miR-29b-3p was done through qRT-PCR. Direct regulation of DNMT3b by hsa-miR-29b-3p was demonstrated by overexpression of hsa-miR-29b-3p using hsa-miR-29b-3p mimic, and knockdown of hsa-miR-29b-3p by using hsa-miR-29b-3p inhibitors. The ZIKV-NS1 affected the barrier function of endothelial cells through the increased expression of hsa-miR29b-3p, which suppressed the DNMT3b, thus enhanced expression of MMP-9, which finally suppressed the expression of VE-cadherin. These findings suggested that ZIKV-NS1 alters the expression of Adherens Junction protein in human brain microvascular endothelial cells through hsa-miR-29b-3p/DNMT3b/MMP-9 pathway, which compromised the barrier function of human brain microvascular endothelial cells.

Evaluation of bladder and bowel functions in children with microcephaly and congenital zika syndrome

INTRODUCTION

Children with Congenital Zika Syndrome (CZS) present structural cortical changes that may compromise the integrity of their connections with urinary and digestive systems, causing bowel and bladder dysfunctions.

OBJECTIVE

To evaluate bladder and bowel dysfunction (BBD) in children with CZS.

STUDY DESIGN

This is an observational cross-sectional study of a series of CZS cases. Urinary tracts were investigated using a bladder function protocol consisting of clinical history, detailed physical examination, laboratory tests, ultrasound of the lower and upper urinary tracts, and urodynamic evaluation. The bowel function protocol expanded anamnesis with questions related to signs and symptoms of functional disorders, Bristol scale, and ultrasound of the rectal ampoule.

RESULTS

Forty children with CZS, aged between one and five years were included. The majority (80%) had bladder and bowel dysfunction (BBD), 12.5% had bladder dysfunction only, and 7.5% only bowel dysfunction. A reduced bladder capacity was confirmed in 36 patients (90%), while 15 (40%) presented postvoid residual greater than 20% of their cystometric capacity. Thirty-five patients (87.5%) presented four signs/symptoms of functional bowel disorders and the rectal ampoule ultrasound was >2.9 cm in 21 (52.5%). Moreover, 19 (47.5%) presented urinary tract infection, while 5 (12.5%) developed pyelonephritis and required hospitalization. Renal ultrasound showed nephrolithiasis in three (7.5%), one (2.5%) presented horseshoe kidney, and a duplicated collecting system was found in three patients. Cryptorchidism was presented in eight (34%).

DISCUSSION

Our study confirmed the presence of BBD in 80% of the children with CZS studied in this series. This is the first time that bowel dysfunction is confirmed in the settings of CZS. This recognition will facilitate early identification and appropriate therapies in an attempt to reduce complications. One limitation of the study is the absence of a control group. Due to the new aspects of CZS, it has been difficult to find a suitable group of patients with neurological disorders to compare and performing urodynamic studies in children without neurological or non-neurological voiding dysfunction is unethical. Appropriate control groups for future studies may be children with microcephaly due to other causes or older children with CZS who were not yet investigated or treated. Another limitation is the lack of a standard quantitative evaluation of bowel dysfunction in children with neurological disorders.

CONCLUSION

Bladder and bowel dysfunction was confirmed in 80% of the children with CZS. This is a new Zika virus-associated neuromuscular disorder that needs to be further investigated.

Gist of Zika Virus pathogenesis

Zika virus (ZIKV) is a mosquito-borne neurotropic flavivirus. ZIKV infection may lead to microcephaly in developing fetus and Guillain-Barré Syndrome (GBS) like symptoms in adults. ZIKV was first reported in humans in 1952 from Uganda and the United Republic of Tanzania. Later, ZIKV outbreak was reported in 2007 from the Yap Island. ZIKV re-emerged as major outbreak in the year 2013 from French Polynesia followed by second outbreak in the year 2015 from Brazil. ZIKV crosses the blood-tissue barriers to enter immune-privileged organs. Clinical manifestations in ZIKV disease includes rash, fever, conjunctivitis, muscle and joint pain, headache, transverse myelitis, meningoencephalitis, Acute Disseminated Encephalomyelitis (ADEM). The understanding of the molecular mechanism of ZIKV pathogenesis is very important to develop potential diagnostic and therapeutic interventions for ZIKV infected patients.

Different Gene Networks Are Disturbed by Zika Virus Infection in A Mouse Microcephaly Model

The association of Zika virus (ZIKV) infection with microcephaly has raised alarm worldwide. Their causal link has been confirmed in different animal models infected by ZIKV. However, the molecular mechanisms underlying ZIKV pathogenesis are far from clear. Hence, we performed global gene expression analysis of ZIKV-infected mouse brains to unveil the biological and molecular networks underpinning microcephaly. We found significant dysregulation of the sub-networks associated with brain development, immune response, cell death, microglial cell activation, and autophagy amongst others. We provided detailed analysis of the related complicated gene networks and the links between them. Additionally, we analyzed the signaling pathways that were likely to be involved. This report provides systemic insights into not only the pathogenesis, but also a path to the development of prophylactic and therapeutic strategies against ZIKV infection.

Structural Basis for Neutralization and Protection by a Zika Virus-Specific Human Antibody

We previously reported a human monoclonal antibody, ZK2B10, capable of protection against Zika virus (ZIKV) infection and microcephaly in developing mouse embryos. Here, we report the structural features and mechanism of action of ZK2B10. The crystal structure at a resolution of 2.32 Å revealed that the epitope is located on the lateral ridge of DIII of the envelope glycoprotein. Cryo-EM structure with mature ZIKV showed that the antibody binds to DIIIs around the icosahedral 2-fold, 3-fold, and 5-fold axes, a distinct feature compared to those reported for DIII-specific antibodies. The binding of ZK2B10 to ZIKV has no detectable effect on viral attachment to target cells or on conformational changes of the E glycoprotein in the acidic environment, suggesting that ZK2B10 functions at steps between the formation of the fusion intermediate and membrane fusion. These results provide structural and mechanistic insights into how ZK2B10 mediates protection against ZIKV infection.

Sleep findings in Brazilian children with congenital Zika syndrome

Study Objectives

Zika virus infection during pregnancy may result in congenital Zika syndrome (CZS), whose characteristics are being described.

Methods

The present study aimed to investigate the sleep characteristics of 136 infants/toddlers (88 with CZS and 48 with typical development (TD), age and gender matched, 60% girls and 40% boys in both groups) using the Brief Infant Sleep Questionnaire. The ages of children in both groups ranged from 5 to 24 months (CZS 15.9 ± 0.4 vs. TD 15.8 ± 1.0 months, P= 0.90).

Results

The results show that 34.1% of CZS and 2% of TD children were defined as poor sleepers, 15% of CZS and 2% of TD children remained awake at night for a period longer than 1 hour, and 24% of CZS and 2% of TD children slept less than 9 hours. The CZS group showed shorter total sleep time (CZS 11.24 ± 2.6 vs. TD 12.02 ± 1.9 hours, P= 0.03) and shorter nocturnal sleep duration than the TD group (CZS 8.2 ± 0.2 vs. TD 9.4 ± 0.2 hours, P= 0.0002). In contrast to the control group (P= 0.02, r= -0.34), in the CZS group, no correlation was found between age and nocturnal wakefulness. Future studies should explore these data in relation to the development and maturation of the central nervous system of these children.

Conclusions

Considering the well-known consequences of poor sleep quality on health in several populations, the presence of sleep disorders should be considered in CZS using multidisciplinary treatments.

Zika Virus Vaccines: Challenges and Perspectives

Zika virus is an arbovirus that has rapidly spread within the Americas since 2014, presenting a variety of clinical manifestations and neurological complications resulting in congenital malformation, microcephaly, and possibly, in male infertility. These significant clinical manifestations have led investigators to develop several candidate vaccines specific to Zika virus. In this review we describe relevant targets for the development of vaccines specific for Zika virus, the development status of various vaccine candidates and their different platforms, as well as their clinical progression.

Zika virus: epidemiology, clinical aspects, diagnosis, and control of infection

Zika virus (ZIKV) is an emerging pathogen of huge public health significance to human beings. Although majority of infections are benign with self-limiting symptoms, the recent outbreak has established an association with the increased incidence of some congenital anomalies such as microcephaly. In other words, due to the large extent of the virus and mosquito vectors, the infection has become a thoughtful health problem for human societies, though now, there are no antiviral therapies or vaccines against this virus. In spite of extensive research carried out by scientists, not so much information has been gathered about this viral infection. In the current review, we prepared an overview of the remarkable progress made in understanding about the epidemiology, immunology, clinical presentation, and diagnosis methods of ZIKV infection.

Disruption of glial cell development by Zika virus contributes to severe microcephalic newborn mice

The causal link between Zika virus (ZIKV) infection and microcephaly has raised alarm worldwide. Microglial hyperplasia, reactive gliosis, and myelination delay have been reported in ZIKV-infected microcephalic fetuses. However, whether and how ZIKV infection affects glial cell development remain unclear. Here we show that ZIKV infection of embryos at the later stage of development causes severe microcephaly after birth. ZIKV infects the glial progenitors during brain development. Specifically, ZIKV infection disturbs the proliferation and differentiation of the oligodendrocyte progenitor cells and leads to the abolishment of oligodendrocyte development. More importantly, a single intraperitoneal injection of pregnant mice with a human monoclonal neutralizing antibody provides full protection against ZIKV infection and its associated damages in the developing fetuses. Our results not only provide more insights into the pathogenesis of ZIKV infection, but also present a new model for the preclinical test of prophylactic and therapeutic agents against ZIKV infection.

Potential targets for therapeutic intervention and structure based vaccine design against Zika virus

Continuously increasing number of reports of Zika virus (ZIKV) infections and associated severe clinical manifestations, including autoimmune abnormalities and neurological disorders such as neonatal microcephaly and Guillain-Barré syndrome have created alarming situation in various countries. To date, no specific antiviral therapy or vaccine is available against ZIKV. This review provides a comprehensive insight into the potential therapeutic targets and describes viral epitopes of broadly neutralizing antibodies (bNAbs) in vaccine design perspective. Interactions between ZIKV envelope glycoprotein E and cellular receptors mediate the viral fusion and entry to the target cell. Blocking these interactions by targeting cellular receptors or viral structural proteins mediating these interactions or viral surface glycans can inhibit viral entry to the cell. Similarly, different non-structural proteins of ZIKV and un-translated regions (UTRs) of its RNA play essential roles in viral replication cycle and potentiate for therapeutic interventions. Structure based vaccine design requires identity and structural description of the epitopes of bNAbs. We have described different conserved bNAb epitopes present in the ZIKV envelope as potential targets for structure based vaccine design. This review also highlights successes, unanswered questions and future perspectives in relation to therapeutic and vaccine development against ZIKV.

Effects of climate change on the spread of zika virus: a public health threat

Zika is a vector-borne viral disease transmitted to humans primarily by Aedes aegypti mosquitoes. The increased climate instability has contributed to the emergence of infections carried by mosquitoes like dengue, chikungunya and zika. While infection with the zika virus is not new, the recent epidemic of microcephaly in Brazil and other countries in South America resulting from the infection of pregnant women with the zika virus raise a number of serious public health concerns. These include the question of how climate change affects the range of zika vectors, what can we do to shorten the length of mosquito season, how and why the symptoms of zika infection have changed and what can be done to reduce the burden of human disease from this infection? Another important question that needs to be answered is what are the factors that caused the zika virus to leave the non-human primates and/or other mammals and invade the human population?

Infection Elicited Autoimmunity and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: An Explanatory Model

Myalgic encephalomyelitis (ME) often also called chronic fatigue syndrome (ME/CFS) is a common, debilitating, disease of unknown origin. Although a subject of controversy and a considerable scientific literature, we think that a solid understanding of ME/CFS pathogenesis is emerging. In this study, we compiled recent findings and placed them in the context of the clinical picture and natural history of the disease. A pattern emerged, giving rise to an explanatory model. ME/CFS often starts after or during an infection. A logical explanation is that the infection initiates an autoreactive process, which affects several functions, including brain and energy metabolism. According to our model for ME/CFS pathogenesis, patients with a genetic predisposition and dysbiosis experience a gradual development of B cell clones prone to autoreactivity. Under normal circumstances these B cell offsprings would have led to tolerance. Subsequent exogenous microbial exposition (triggering) can lead to comorbidities such as fibromyalgia, thyroid disorder, and orthostatic hypotension. A decisive infectious trigger may then lead to immunization against autoantigens involved in aerobic energy production and/or hormone receptors and ion channel proteins, producing postexertional malaise and ME/CFS, affecting both muscle and brain. In principle, cloning and sequencing of immunoglobulin variable domains could reveal the evolution of pathogenic clones. Although evidence consistent with the model accumulated in recent years, there are several missing links in it. Hopefully, the hypothesis generates testable propositions that can augment the understanding of the pathogenesis of ME/CFS.

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

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