Pathophysiology and Mechanisms of Zika Virus Infection in the Nervous System

NUBP2 deficiency disrupts the centrosome-check point in the brain and causes primary microcephaly

Microcephaly affects 1 in 2,500 babies per year. Primary microcephaly results from aberrant neurogenesis leading to a small brain at birth. This is due to altered patterns of proliferation and/or early differentiation of neurons. Premature differentiation of neurons is associated with defects in the centrosome and/or primary cilia. In this study, we report on the first patients identified with NUBP2 -deficiency and utilize a conditional mouse model to ascertain the molecular mechanisms associated with NUBP2 -deficient primary microcephaly. We identified homozygous NUBP2 variants in these patients who displayed profound primary microcephaly in addition to intrauterine growth restriction, cervical kyphosis, severe contractures of joints, and facial dysmorphia. We then generated a mouse model using Emx1-Cre to ablate Nubp2 from the forebrain. The mice presented with severe microcephaly starting at E18.5. Neurospheres generated from the forebrain of Emx1-Cre; Nubp2 flox/flox conditional deletion mice were used to support the pathogenicity of the patient variants. We show that loss of Nubp2 increases both canonical and non-canonical cell death, but that loss of p53 fails to rescue microcephaly in the mouse model. Examination of neurogenesis in Emx1-Cre; Nubp2 flox/flox mice revealed distinct alterations in proliferation and cellular migration accompanied by supernumerary centrosomes and cilia. We therefore propose that NUBP2 is a novel primary microcephaly-related gene and that the role of Nubp2 in centrosome and cilia regulation is crucial for proper neurogenesis.

Unraveling the Molecular Mechanisms of Mosquito Salivary Proteins: New Frontiers in Disease Transmission and Control

Mosquito-borne diseases are a group of illnesses caused by pathogens transmitted by mosquitoes, and they are globally prevalent, particularly in tropical and subtropical regions. Pathogen transmission occurs during mosquito blood feeding, a process in which mosquito saliva plays a crucial role. Mosquito saliva contains a variety of biologically active proteins that facilitate blood feeding by preventing blood clotting, promoting vasodilation, and modulating the host's immune and inflammatory responses. These effects create an environment conducive to pathogen invasion and dissemination. Specific mosquito salivary proteins (MSPs) can promote pathogen transmission through mechanisms that either regulate hosts' anti-infective immune responses or directly enhance pathogens' activity. Strategies targeting these MSPs have emerged as an innovative and promising approach for the control of mosquito-borne diseases. Meanwhile, the diversity of these proteins and their complex interactions with the host immune system necessitate further research to develop safer and more effective interventions. This review examines the functional diversity of MSPs and their roles in disease transmission, discusses the advantages and challenges of strategies targeting these proteins, and explores potential future directions for research in this area.

Protein kinase R induced by type I interferons is a main regulator of reactive microglia in Zika virus infection

Microglial cells are the phagocytic cells of the brain that under physiological conditions participate in brain homeostasis and surveillance. Under pathogenic states, microglia undergoes strong morphological and transcriptional changes potentially leading to sustained neuroinflammation, brain damage, and cognitive disorders. Postnatal and adult Zika virus (ZIKV) brain infection is characterized by the induction of reactive microglia associated with brain inflammation, synapse loss and neuropathogenesis. Contrary to neurons, microglial cells are not infected by ZIKV thus raising the question of the mechanism governing ZIKV-induced microglia's reactivity. In this work, we have questioned the role of exogenous, neuronal type I interferons (IFNs-I) in regulating ZIKV-induced microglia's reactivity. Primary cultured microglial cells were either treated with conditioned media from ZIKV-infected mature neurons or co-cultured with ZIKV-infected neurons. Using either an antibody directed against the IFNAR receptor that neutralizes the IFNs-I response or Ifnar-/-microglial cells, we demonstrate that IFNs-I produced by ZIKV-infected neurons are the main regulators of the phagocytic capacity and the pro-inflammatory gene expression profile of reactive, non-infected microglial cells. We identify protein kinase R (PKR), whose expression is activated by IFNs-I, as a major regulator of the phagocytic capacity, pro-inflammatory response, and morphological changes of microglia induced by IFNs-I while up-regulating STAT1 phosphorylation and IRF1 expression. Results obtained herein in vitro with primary cultured cells and in vivo in ZIKV-infected adult immunocompetent mice, unravel a role for IFNs-I and PKR in directly regulating microglia's reactivity that could be at work in other infectious and non-infectious brain pathologies.

Cerebral Malformations Related to Coronavirus Disease 2019 during Pregnancy

The pandemic of severe-acute-respiratory-syndrome-related coronavirus (SARS-CoV-2) has shown a wide spectrum of possible consequences in children, ranging from asymptomatic patients to the development of severe conditions, such as multisystem inflammatory syndrome in children and encephalopathies related to cytokine storm. Specifically, neurological and neuroimaging abnormalities, ranging from mild-to-the severe ones, have been documented in children as well, such as postinfectious immune-mediated acute disseminated encephalomyelitis, myelitis, neural enhancement, cranial nerve enhancement, and cortical injury, also without neurological symptoms. Considering the neurotropism of coronaviruses and SARS-CoV-2, which has been well described in the literature, we reviewed the literature reporting possible cerebral malformation in neonates due to the infection of SARS-CoV-2 in pregnancy. Coronavirus disease 2019 (COVID-19) during pregnancy might develop cerebral disorders in several ways. Articles in English in the literature were screened using the following search terms: (1) “brain malformations” AND “COVID-19”; (2) “cerebral malformations” AND “COVID-19”; (3) brain malformations AND “Sars-Cov-2”; (4) “cerebral malformations “AND “Sars-Cov-2.” Considering the congenital brain malformation found in newborns exposed to infection of SARS-Cov-2 pre- or neonatally, we identified one paper which reported three neonates with cerebral malformation. Although sporadic, cerebral malformations like atypical signals in white matter with delayed myelination, brain dysplasia/hypoplasia with delayed myelination, and unusual signals in the periventricular regions have been documented.

A review of CDKL: An underestimated protein kinase family

Cyclin-dependent kinase-like (CDKL) family proteins are serine/threonine protein kinases and is a specific branch of CMGC (including CDK, MAPK, GSK). Its name is due to the sequence similarity with CDK and it consists of 5 members. Their function in protein phosphorylation underpins their important role in cellular activities, including cell cycle, apoptosis, autophagy and microtubule dynamics. CDKL proteins have been demonstrated to regulate the length of primary cilium, which is a dynamic and diverse signaling hub and closely associated with multiple diseases. Furthermore, CDKL proteins have been shown to be involved in the development and progression of several diseases, including cancer, neurodegenerative diseases and kidney disease. In this review, we summarize the structural characteristics and discovered functions of CDKL proteins and their role in diseases, which might be helpful for the development of innovative therapeutic strategies for disease.

Clinical value of macrogenome next-generation sequencing on infections

Intracranial infection (ICI) is a frequent and serious complication after neurosurgery. Macrogenome next-generation sequencing (mNGS) technology can provide reference for clinical diagnosis and treatment of ICI. This work aimed to explore the application value of mNGS technology in analyzing the clinical characteristics of human immunodeficiency virus (HIV) infection and ICI after neurosurgery. A total of 60 patients with ICI were enrolled as the research objects, all patients underwent routine cerebrospinal fluid analysis and traditional pathogen detection, followed by mNGS genome analysis. Using clinical diagnosis of ICI as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value for both detection methods were calculated. Receiver operating characteristic curves were constructed to assess the area under the curve (AUC) for evaluating the clinical value of mNGS in suspected intracranial infectious pathogen diagnosis. Results showed a positivity rate of 71.67% (43 cases) with mNGS compared to 28.33% (17 cases) with traditional pathogen detection methods, demonstrating a significant difference (P < 0.05). The sensitivity of mNGS for detecting ICIs was 83.7%, significantly higher than the 34.88% observed with traditional methods (P < 0.05). The pathogen detection rate of mNGS was higher than traditional methods (P = 0.002), with an AUC of 0.856 (95% CI: 0.638-0.967), significantly greater than the AUC of 0.572 (95% CI: 0.350-0.792) for traditional methods (P < 0.05). mNGS successfully identified microorganisms such as Cryptococcus, Propionibacterium, Staphylococcus, Corynebacterium, Micrococcus, and Candida associated with ICIs. These findings underscore the clinical applicability of mNGS technology in analyzing the characteristics of HIV infection and ICI post-neurosurgical procedures. This technology enables more accurate diagnosis and treatment of ICIs, providing valuable insights for developing effective therapeutic strategies.

Fetal Zika virus inoculation in macaques revealed control of the fetal viral load during pregnancy

BACKGROUND

Early pregnancy Zika virus (ZIKV) infection is associated with major brain damage in fetuses, leading to microcephaly in 0.6-5.0% of cases, but the underlying mechanisms remain largely unknown.

METHODS

To understand the kinetics of ZIKV infection during fetal development in a nonhuman primate model, four cynomolgus macaque fetuses were exposed in utero through echo-guided intramuscular inoculation with 103 PFU of ZIKV at 70-80 days of gestation, 2 controls were mock inoculated. Clinical, immuno-virological and ultrasound imaging follow-ups of the mother/fetus pairs were performed until autopsy after cesarean section 1 or 2 months after exposure (n = 3 per group).

RESULTS

ZIKV was transmitted from the fetus to the mother and then replicate in the peripheral blood of the mother from week 1 to 4 postexposure. Infected fetal brains tended to be smaller than those of controls, but not the femur lengths. High level of viral RNA ws found after the first month in brain tissues and placenta. Thereafter, there was partial control of the virus in the fetus, resulting in a decreased number of infected tissue sections and a decreased viral load. Immune cellular and humoral responses were effectively induced.

CONCLUSIONS

ZIKV infection during the second trimester of gestation induces short-term brain injury, and although viral genomes persist in tissues, most of the virus is cleared before delivery.

Birth weight and head circumference discordance and outcome in preterms: results from the EPIPAGE-2 cohort

OBJECTIVE

To determine whether the relative measurement of birth weight (BW) and head circumference (HC) in preterm infants is associated with neurological outcomes.

METHODS

The EPIPAGE-2 Study included 3473 infants born before 32 weeks' gestation, classified based on their Z-score of BW and HC on the Fenton curves as concordant (≤1 SD apart) or discordant (>1 SD difference). We defined four mutually exclusive categories: discordant smaller BW (sBW) with BW-1SD and concordant small measurement (CsM) with BW and HC concordant and both ≤-1SD. Neurological outcomes at 5.5 years were evaluated with standard tests.

RESULTS

2592 (74.8%) preterm neonates were categorised as CM, 258 (7.4%) CsM, 378 (10.9%) sHC and 239 (6.9%) sBW. Compared with the CM children, those born with CsM had significantly higher risks of cognitive deficiency (adjusted OR (aOR) 1.3, 95% CI (1.0 to 2.0)), developmental coordination disorders (aOR 2.6 (1.5 to 4.4)) and need for special school services (aOR 2.3 (1.5 to 3.7)). Those born with sBW had significantly lower risk of cognitive deficiency (aOR 0.6 (0.4 to 0.9)) and the sHC group significantly higher risk of developmental coordination disorders (aOR 1.8 (1.0 to 3.2)).

CONCLUSIONS

The relative discordance of these preterm infants' BW and HC was associated with their neurological outcomes. It merits further exploration as an indirect indicator of development.

TRIAL REGISTRATION NUMBER

NCT03078439.

The ZIKV NS5 Protein Aberrantly Alters the Tubulin Cytoskeleton, Induces the Accumulation of Autophagic p62 and Affects IFN Production: HDAC6 Has Emerged as an Anti-NS5/ZIKV Factor

Zika virus (ZIKV) infection and pathogenesis are linked to the disruption of neurogenesis, congenital Zika syndrome and microcephaly by affecting neural progenitor cells. Nonstructural protein 5 (NS5) is the largest product encoded by ZIKV-RNA and is important for replication and immune evasion. Here, we studied the potential effects of NS5 on microtubules (MTs) and autophagy flux, together with the interplay of NS5 with histone deacetylase 6 (HDAC6). Fluorescence microscopy, biochemical cell-fractionation combined with the use of HDAC6 mutants, chemical inhibitors and RNA interference indicated that NS5 accumulates in nuclear structures and strongly promotes the acetylation of MTs that aberrantly reorganize in nested structures. Similarly, NS5 accumulates the p62 protein, an autophagic-flux marker. Therefore, NS5 alters events that are under the control of the autophagic tubulin-deacetylase HDAC6. HDAC6 appears to degrade NS5 by autophagy in a deacetylase- and BUZ domain-dependent manner and to control the cytoplasmic expression of NS5. Moreover, NS5 inhibits RNA-mediated RIG-I interferon (IFN) production, resulting in greater activity when autophagy is inhibited (i.e., effect correlated with NS5 stability). Therefore, it is conceivable that NS5 contributes to cell toxicity and pathogenesis, evading the IFN-immune response by overcoming HDAC6 functions. HDAC6 has emerged as an anti-ZIKV factor by targeting NS5.

Advances in Zika virus vaccines and therapeutics: A systematic review

Zika virus (ZIKV) is the causative agent of a viral infection that causes neurological complications in newborns and adults worldwide. Its wide transmission route and alarming spread rates are of great concern to the scientific community. Numerous trials have been conducted to develop treatment options for ZIKV infection. This review highlights the latest developments in the fields of vaccinology and pharmaceuticals developments for ZIKV infection. A systematic and comprehensive approach was used to gather relevant and up-to-date data so that inferences could be made about the gaps in therapeutic development. The results indicate that several therapeutic interventions are being tested against ZIKV infection, such as DNA vaccines, subunit vaccines, live-attenuated vaccines, virus-vector-based vaccines, inactivated vaccines, virus-like particles, and mRNA-based vaccines. In addition, approved anti-ZIKV drugs that can reduce the global burden are discussed. Although many vaccine candidates for ZIKV are at different stages of development, none of them have received Food and Drug Authority approval for use up to now. The issue of side effects associated with these drugs in vulnerable newborns and pregnant women is a major obstacle in the therapeutic pathway.

Insight into the Natural Biomolecules (BMs): Promising Candidates as Zika Virus Inhibitors

Zika virus (ZIKV) is among the relatively new infectious disease threats that include SARS-CoV-2, coronavirus, monkeypox (Mpox) virus, etc. ZIKV has been reported to cause severe health risks to the fetus. To date, satisfactory treatment is still not available for the treatment of ZIKV infection. This review examines the last five years of work using natural biomolecules (BMs) to counteract the ZIKV through virtual screening and in vitro investigations. Virtual screening has identified doramectin, pinocembrin, hesperidins, epigallocatechin gallate, pedalitin, and quercetin as potentially active versus ZIKV infection. In vitro, testing has shown that nordihydroguaiaretic acid, mefloquine, isoquercitrin, glycyrrhetinic acid, patentiflorin-A, rottlerin, and harringtonine can reduce ZIKV infections in cell lines. However, in vivo, testing is limited, fortunately, emetine, rottlerin, patentiflorin-A, and lycorine have shown in vivo anti- ZIKV potential. This review focuses on natural biomolecules that show a particularly high selective index (>10). There is limited in vivo and clinical trial data for natural BMs, which needs to be an active area of investigation. This review aims to compile the known reference data and discuss the barriers associated with discovering and using natural BM agents to control ZIKV infection.

The Antiviral Potential of AdipoRon, an Adiponectin Receptor Agonist, Reveals the Ability of Zika Virus to Deregulate Adiponectin Receptor Expression

Zika virus (ZIKV) is a pathogenic member of the flavivirus family, with several unique characteristics. Unlike any other arbovirus, ZIKV can be transmitted sexually and maternally, and thus produce congenital syndromes (CZS) due to its neurotropism. This challenges the search for safe active molecules that can protect pregnant women and their fetuses. In this context, and in the absence of any existing treatment, it seemed worthwhile to test whether the known cytoprotective properties of adiponectin and its pharmacological analog, AdipoRon, could influence the outcome of ZIKV infection. We showed that both AdipoRon and adiponectin could significantly reduce the in vitro infection of A549 epithelial cells, a well-known cell model for flavivirus infection studies. This effect was particularly observed when a pre-treatment was carried out. Conversely, ZIKV revealed an ability to downregulate adiponectin receptor expression and thereby limit adiponectin signaling.

Prenatal Zika virus exposure is associated with lateral geniculate nucleus abnormalities in juvenile rhesus macaques

Zika virus' neural tropism causes significant neural pathology, particularly in developing fetuses. One of the consistent findings from humans and animal models is that prenatal exposure to Zika virus (ZIKV) causes pathology in the eyes and visual pathways of the brain, although the extent to which this pathology persists over development is not clear. In the present report, we build upon our previous work which demonstrated that full-term rhesus monkey ( Macaca mulatta ) fetuses who were exposed to ZIKV early in gestation had significant pathological abnormalities to the organization of the lateral geniculate nucleus (LGN), a major hub of the visual network. The objective of the present work was to replicate those LGN findings and determine whether such pathology persisted across childhood development. We carried out histological analyses of the LGNs of two juvenile rhesus monkeys who were prenatally exposed to ZIKV and two age-matched controls. Pregnant rhesus monkeys were infected with ZIKV via the intravenous and intra-amniotic routes and tracked across development. Following sacrifice and perfusion, brains were subjected to quantitative neuroanatomical analyses with a focus on the size and structure of the LGN and its composite layers. Early fetal ZIKV exposure resulted in developmental abnormalities within the brains' visual pathway: specifically disorganization, blending of layers, laminar discontinuities, and regions of low cell density within the LGN. These abnormalities were not observed in the control animals. Our findings demonstrate that the ZIKV's damage to the LGN that occurs during fetal development persists into childhood.

Disease Transmission and Diagnosis of Zika Virus

An arbovirus belonging to the Flaviviridae family and the Flavivirus genus, the Zika virus (ZIKV), has profoundly transformed global health perception. Historically, ZIKV infections were considered infrequent, with generally mild manifestations. However, this perception changed dramatically when the virus quickly spread from Asia to the Americas, impacting many nations. It was alarming that there was a connection between ZIKV infection in pregnant women and the beginning of microcephaly in their offspring. ZIKV control and treatment are further complicated because Aedes mosquitoes, which primarily bite during the day, are the primary vectors of the virus. ZIKV diagnostic processes are complex since the virus shares symptoms with other illnesses like dengue and chikungunya. Despite the effectiveness of current diagnostic methods like real-time reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), there is a clear need for more accurate antibody tests. This is especially true given that many people undergo testing while asymptomatic or after the ideal detection window. The capacity of ZIKV to infect human-derived neural progenitor cells raises worrying possibilities for severe neurological effects. With all these characteristics and their connection to birth abnormalities, research efforts into the virus's efficient treatment and prevention have increased. Overall, the emergence of ZIKV has demonstrated the necessity of a comprehensive and team-based strategy to address its myriad problems. This entails comprehending its transmission dynamics, enhancing diagnostic accuracy, and creating efficient therapies and preventive measures, all crucial to lessening the threat that ZIKV poses to the world's health.

Zika virus infection leads to hormone deficiencies of the hypothalamic-pituitary-gonadal axis and diminished fertility in mice

IMPORTANCE

Zika virus (ZIKV) infection in pregnant women during the third trimester can cause neurodevelopmental delays and cryptorchidism in children without microcephaly. However, the consequences of congenital ZIKV infection on fertility in these children remain unclear. Here, using an immunocompetent mouse model, we reveal that congenital ZIKV infection can cause hormonal disorders of the hypothalamic-pituitary-gonadal axis, leading to reduced fertility and decreased sexual preference. Our study has for the first time linked the hypothalamus to the reproductive system and social behaviors after ZIKV infection. Although the extent to which these observations in mice translate to humans remains unclear, these findings did suggest that the reproductive health and hormone levels of ZIKV-exposed children should receive more attention to improve their living quality.

Investigation of the impact of AXL, TLR3, and STAT2 in congenital Zika syndrome through genetic polymorphisms and protein-protein interaction network analyses

INTRODUCTION

Zika virus (ZIKV) is a human teratogen that causes congenital Zika syndrome (CZS). AXL, TLR3, and STAT2 are proteins involved in the ZIKV's entry into cells (AXL) and host's immune response (TLR3 and STAT2). In this study, we evaluated the role of genetic polymorphisms in these three genes as risk factors to CZS, and highlighted which proteins that interact with them could be important for ZIKV infection and teratogenesis.

MATERIALS AND METHODS

We evaluate eighty-eight children exposed to ZIKV during the pregnancy, 40 with CZS and 48 without congenital anomalies. The evaluated polymorphisms in AXL (rs1051008), TLR3 (rs3775291), and STAT2 (rs2066811) were genotyped using TaqMan® Genotyping Assays. A protein-protein interaction network was created in STRING database and analyzed in Cytoscape software.

RESULTS

We did not find any statistical significant association among the polymorphisms and the occurrence of CZS. Through the analyses of the network composed by AXL, TLR3, STAT2 and their interactions targets, we found that EGFR and SRC could be important proteins for the ZIKV infection and its teratogenesis.

CONCLUSION

In summary, our results demonstrated that the evaluated polymorphisms do not seem to represent risk factors for CZS; however, EGFR and SRC appear to be important proteins that should be investigated in future studies.

Low CCL2 and CXCL8 Production and High Prevalence of Allergies in Children with Microcephaly Due to Congenital Zika Syndrome

Congenital Zika Syndrome (CZS) is associated with an increased risk of microcephaly in affected children. This study investigated the peripheral dysregulation of immune mediators in children with microcephaly due to CZS. Gene expression quantified by qPCR in whole blood samples showed an increase in IFNγ and IL-13 transcripts in children affected with microcephaly compared to the control group. The microcephaly group exhibited significantly decreased CCL2 and CXCL8 levels in serum, quantified by CBA assay. An allergic profile questionnaire revealed a high prevalence of allergies in the microcephaly group. In accordance, elevated serum IgE level measured by the Proquantum Immunoassay was observed in children affected with microcephaly compared to the control group. Altogether, these findings show a persistent systemic inflammation in children with microcephaly due to CZS and suggest a possible impairment in leukocyte migration caused by low production of CCL2 and CXCL8, in addition to high levels of IgE associated with high prevalence of allergies. The dysregulation of inflammatory genes and chemokines underscores the importance of understanding the immunological characteristics of CZS. Further investigation into the long-term consequences of systemic inflammation in these children is crucial for developing appropriate therapeutic strategies and tailored vaccination protocols.

Tracing down the Updates on Dengue Virus-Molecular Biology, Antivirals, and Vaccine Strategies

BACKGROUND

Nearly half of the world is at risk of developing dengue infection. Dengue virus is the causative agent behind this public healthcare concern. Millions of dengue cases are reported every year, leading to thousands of deaths. The scientific community is working to develop effective therapeutic strategies in the form of vaccines and antiviral drugs against dengue.

METHODS

In this review, a methodological approach has been used to gather data from the past five years to include the latest developments against the dengue virus.

RESULTS

Different therapeutics and antiviral targets against the dengue virus are at different stages of development, but none have been approved by the FDA. Moreover, various vaccination strategies have also been discussed, including attenuated virus vaccines, recombinant subunit vaccines, viral vector vaccines, DNA vaccines, nanotechnology, and plant-based vaccines, which are used to develop effective vaccines for the dengue virus. Many dengue vaccines pass the initial phases of evaluation, but only two vaccines have been approved for public use. DENGVAXIA is the only FDA-approved vaccine against all four stereotypes of the dengue virus, but it is licensed for use only in individuals 6-16 years of age with laboratory-confirmed previous dengue infection and living in endemic countries. Takeda is the second vaccine approved for use in the European Union, the United Kingdom, Brazil, Argentina, Indonesia, and Thailand. It produced sustained antibody responses against all four serotypes of dengue virus, regardless of previous exposure and dosing schedule. Other dengue vaccine candidates at different stages of development are TV-003/005, TDENV PIV, V180, and some DNA vaccines.

CONCLUSION

There is a need to put more effort into developing effective vaccines and therapeutics for dengue, as already approved vaccines and therapeutics have limitations. DENGVAXIA is approved for use in children and teenagers who are 6-16 years of age and have confirmed dengue infection, while Takeda is approved for use in certain countries, and it has withdrawn its application for FDA approval.

Single-cell RNA sequencing reveals the fragility of male spermatogenic cells to Zika virus-induced complement activation

Zika virus (ZIKV) is a potential threat to male reproductive health but the mechanisms underlying its influence on testes during ZIKV infection remain obscure. To address this question, we perform single-cell RNA sequencing using testes from ZIKV-infected mice. The results reveal the fragility of spermatogenic cells, especially spermatogonia, to ZIKV infection and show that the genes of the complement system are significantly upregulated mainly in infiltrated S100A4 + monocytes/macrophages. Complement activation and its contribution to testicular damage are validated by ELISA, RT‒qPCR and IFA and further verify in ZIKV-infected northern pigtailed macaques by RNA genome sequencing and IFA, suggesting that this might be the common response to ZIKV infection in primates. On this basis, we test the complement inhibitor C1INH and S100A4 inhibitors sulindac and niclosamide for their effects on testis protection. C1INH alleviates the pathological change in the testis but deteriorates ZIKV infection in general. In contrast, niclosamide effectively reduces S100A4 + monocyte/macrophage infiltration, inhibits complement activation, alleviates testicular damage, and rescues the fertility of male mice from ZIKV infection. This discovery therefore encourages male reproductive health protection during the next ZIKV epidemic.

Dynamic of Mayaro Virus Transmission in Aedes aegypti, Culex quinquefasciatus Mosquitoes, and a Mice Model

Mayaro virus (MAYV) is transmitted by Haemagogus spp. mosquitoes and has been circulating in Amazon areas in the North and Central West regions of Brazil since the 1980s, with an increase in human case notifications in the last 10 years. MAYV introduction in urban areas is a public health concern as infections can cause severe symptoms similar to other alphaviruses. Studies with Aedes aegypti have demonstrated the potential vector competence of the species and the detection of MAYV in urban populations of mosquitoes. Considering the two most abundant urban mosquito species in Brazil, we investigated the dynamics of MAYV transmission by Ae. aegypti and Culex quinquefasciatus in a mice model. Mosquito colonies were artificially fed with blood containing MAYV and infection (IR) and dissemination rates (DR) were evaluated. On the 7th day post-infection (dpi), IFNAR BL/6 mice were made available as a blood source to both mosquito species. After the appearance of clinical signs of infection, a second blood feeding was performed with a new group of non-infected mosquitoes. RT-qPCR and plaque assays were carried out with animal and mosquito tissues to determine IR and DR. For Ae. aegypti, we found an IR of 97.5-100% and a DR reached 100% in both 7 and 14 dpi. While IR and DR for Cx. quinquefasciatus was 13.1-14.81% and 60% to 80%, respectively. A total of 18 mice were used (test = 12 and control = 6) for Ae. aegypti and 12 (test = 8 and control = 4) for Cx. quinquefasciatus to evaluate the mosquito-mice transmission rate. All mice that were bitten by infected Ae. aegypti showed clinical signs of infection while all mice exposed to infected Cx. quinquefasciatus mosquitoes remained healthy. Viremia in the mice from Ae. aegypti group ranged from 2.5 × 10⁸ to 5 × 10⁹ PFU/mL. Ae. aegypti from the second blood feeding showed a 50% IR. Our study showed the applicability of an efficient model to complete arbovirus transmission cycle studies and suggests that the Ae. aegypti population evaluated is a competent vector for MAYV, while highlighting the vectorial capacity of Ae. aegypti and the possible introduction into urban areas. The mice model employed here is an important tool for arthropod-vector transmission studies with laboratory and field mosquito populations, as well as with other arboviruses.

Zika virus replication on endothelial cells and invasion into the central nervous system by inhibiting interferon β translation

The blood-brain barrier (BBB) is one of the tightest physical barriers to prevent pathogens from invading the central nervous system (CNS). However, the mechanism by which Zika virus (ZIKV) crossing the BBB remains unresolved. We found ZIKV induced high morbidity and mortality in newborn mice, accompanied by inflammatory injury on CNS. ZIKV was found to replicate primarily in the cortex and hippocampus in neonatal mouse brains. An in vitro model revealed that ZIKV had no impact on hBMECs permeability but led to endothelial activation, as shown by the enhancement of adhesion molecules expression and F-actin redistribution. ZIKV replication in hBMECs might be associated with the suppression of IFN-β translation via inhibiting RPS6 phosphorylation. On the other hand, ZIKV infection induced IFN-stimulated genes (ISGs), activated the mitogen-activated protein kinase (MAPK) signaling pathway, and promoted chemokine secretion. This study provides an understanding of virus replication and transmigration across the BBB during ZIKV infection.

Zika virus infection of mature neurons from immunocompetent mice generates a disease-associated microglia and a tauopathy-like phenotype in link with a delayed interferon beta response

BACKGROUND

Zika virus (ZIKV) infection at postnatal or adult age can lead to neurological disorders associated with cognitive defects. Yet, how mature neurons respond to ZIKV remains substantially unexplored.

METHODS

The impact of ZIKV infection on mature neurons and microglia was analyzed at the molecular and cellular levels, in vitro using immunocompetent primary cultured neurons and microglia, and in vivo in the brain of adult immunocompetent mice following intracranial ZIKV inoculation. We have used C57BL/6 and the genetically diverse Collaborative Cross mouse strains, displaying a broad range of susceptibility to ZIKV infection, to question the correlation between the effects induced by ZIKV infection on neurons and microglia and the in vivo susceptibility to ZIKV.

RESULTS

As a result of a delayed induction of interferon beta (IFNB) expression and response, infected neurons displayed an inability to stop ZIKV replication, a trait that was further increased in neurons from susceptible mice. Alongside with an enhanced expression of ZIKV RNA, we observed in vivo, in the brain of susceptible mice, an increased level of active Iba1-expressing microglial cells occasionally engulfing neurons and displaying a gene expression profile close to the molecular signature of disease-associated microglia (DAM). In vivo as well as in vitro, only neurons and not microglial cells were identified as infected, raising the question of the mechanisms underlying microglia activation following brain ZIKV infection. Treatment of primary cultured microglia with conditioned media from ZIKV-infected neurons demonstrated that type-I interferons (IFNs-I) secreted by neurons late after infection activate non-infected microglial cells. In addition, ZIKV infection induced pathological phosphorylation of Tau (pTau) protein, a hallmark of neurodegenerative tauopathies, in vitro and in vivo with clusters of neurons displaying pTau surrounded by active microglial cells.

CONCLUSIONS

We show that ZIKV-infected mature neurons display an inability to stop viral replication in link with a delayed IFNB expression and response, while signaling microglia for activation through IFNs-I secreted at late times post-infection. In the brain of ZIKV-infected susceptible mice, uninfected microglial cells adopt an active morphology and a DAM expression profile, surrounding and sometimes engulfing neurons while ZIKV-infected neurons accumulate pTau, overall reflecting a tauopathy-like phenotype.

Testosterone protects mice against zika virus infection and suppresses the inflammatory response in the brain

Testosterone is essential to human growth and development as well as immune regulation. Zika virus (ZIKV), an emerging arbovirus associated with neurological complications including neuroinflammation, can also cause testicular damage and decrease testosterone secretion. However, whether the dysregulation of testosterone plays a role in the process of neuroinflammation during ZIKV pathogenesis is still unclear. In this study, we found that ZIKV infection caused testicular damage and decreased testosterone secretion in male mice, and testosterone supplementation after ZIKV infection reduced their mortality and attenuated the pathological symptoms. Further investigation revealed that testosterone treatment after ZIKV infection alleviated inflammation and nerve injury in the mouse brain. Additionally, reduced CD8+ T cell infiltration and interferon-gamma production were observed in brains of testosterone-treated mice. Overall, our results demonstrated that testosterone plays a protective role in ZIKV-infected mice, and thus it can be developed as a potential therapeutic drug against ZIKV infection.

SUMOylation and Viral Infections of the Brain

The small ubiquitin-like modifier (SUMO) system regulates numerous biological processes, including protein localization, stability and/or activity, transcription, and DNA repair. SUMO also plays critical roles in innate immunity and antiviral defense by mediating interferon (IFN) synthesis and signaling, as well as the expression and function of IFN-stimulated gene products. Viruses including human immunodeficiency virus-1, Zika virus, herpesviruses, and coronaviruses have evolved to exploit the host SUMOylation system to counteract the antiviral activities of SUMO proteins and to modify their own proteins for viral persistence and pathogenesis. Understanding the exploitation of SUMO is necessary for the development of effective antiviral therapies. This review summarizes the interplay between viruses and the host SUMOylation system, with a special emphasis on viruses with neuro-invasive properties that have pathogenic consequences on the central nervous system.

Zika Virus Induces Mitotic Catastrophe in Human Neural Progenitors by Triggering Unscheduled Mitotic Entry in the Presence of DNA Damage While Functionally Depleting Nuclear PNKP

Vertical transmission of Zika virus (ZIKV) leads with high frequency to congenital ZIKV syndrome (CZS), whose worst outcome is microcephaly. However, the mechanisms of congenital ZIKV neurodevelopmental pathologies, including direct cytotoxicity to neural progenitor cells (NPC), placental insufficiency, and immune responses, remain incompletely understood. At the cellular level, microcephaly typically results from death or insufficient proliferation of NPC or cortical neurons. NPC replicate fast, requiring efficient DNA damage responses to ensure genome stability. Like congenital ZIKV infection, mutations in the polynucleotide 5′-kinase 3′-phosphatase (PNKP) gene, which encodes a critical DNA damage repair enzyme, result in recessive syndromes often characterized by congenital microcephaly with seizures (MCSZ). We thus tested whether there were any links between ZIKV and PNKP. Here, we show that two PNKP phosphatase inhibitors or PNKP knockout inhibited ZIKV replication. PNKP relocalized from the nucleus to the cytoplasm in infected cells, colocalizing with the marker of ZIKV replication factories (RF) NS1 and resulting in functional nuclear PNKP depletion. Although infected NPC accumulated DNA damage, they failed to activate the DNA damage checkpoint kinases Chk1 and Chk2. ZIKV also induced activation of cytoplasmic CycA/CDK1 complexes, which trigger unscheduled mitotic entry. Inhibition of CDK1 activity inhibited ZIKV replication and the formation of RF, supporting a role of cytoplasmic CycA/CDK1 in RF morphogenesis. In brief, ZIKV infection induces mitotic catastrophe resulting from unscheduled mitotic entry in the presence of DNA damage. PNKP and CycA/CDK1 are thus host factors participating in ZIKV replication in NPC, and pathogenesis to neural progenitor cells.

IMPORTANCE The 2015–2017 Zika virus (ZIKV) outbreak in Brazil and subsequent international epidemic revealed the strong association between ZIKV infection and congenital malformations, mostly neurodevelopmental defects up to microcephaly. The scale and global expansion of the epidemic, the new ZIKV outbreaks (Kerala state, India, 2021), and the potential burden of future ones pose a serious ongoing risk. However, the cellular and molecular mechanisms resulting in microcephaly remain incompletely understood. Here, we show that ZIKV infection of neuronal progenitor cells results in cytoplasmic sequestration of an essential DNA repair protein itself associated with microcephaly, with the consequent accumulation of DNA damage, together with an unscheduled activation of cytoplasmic CDK1/Cyclin A complexes in the presence of DNA damage. These alterations result in mitotic catastrophe of neuronal progenitors, which would lead to a depletion of cortical neurons during development.

Possible Routes for Zika Virus Vertical Transmission in Human Placenta: A Comprehensive Review

Zika virus (ZIKV) infections have gained notoriety due to congenital abnormalities. Pregnant women have a greater risk of ZIKV infection and consequent transmission to their progeny due to the immunological changes associated with pregnancy. ZIKV has been detected in amniotic fluid, as well as in fetal and neonatal tissues of infected pregnant women. However, the mechanism by which ZIKV reaches the fetus is not well understood. The four dengue virus serotypes have been the most widely used flaviviruses to elucidate the host-cell entry pathways. Nevertheless, it is of increasing interest to understand the specific interaction between ZIKV and the host cell, especially in the gestation period. Herein, the authors describe the mechanisms of prenatal vertical infection of ZIKV based on results from in vitro, in vivo, and ex vivo studies, including murine models and nonhuman primates. It also includes up-to-date knowledge from ex vivo and natural infections in pregnant women explaining the vertical transmission along four tracks: transplacental, paracellular, transcytosis mediated by extracellular vesicles, and paraplacental route and the antibody-dependent enhancement process. A global understanding of the diverse pathways used by ZIKV to cross the placental barrier and access the fetus, along with a better comprehension of the pathogenesis of ZIKV in pregnant females, may constitute a fundamental role in the design of antiviral drugs to reduce congenital disabilities associated with ZIKV.

Recapitulation of Retinal Damage in Zebrafish Larvae Infected with Zika Virus

Zebrafish are increasingly being utilized as a model to investigate infectious diseases and to advance the understanding of pathogen-host interactions. Here, we take advantage of the zebrafish to recapitulate congenital ZIKV infection and, for the first time, demonstrate that it can be used to model infection and reinfection and monitor anti-viral and inflammatory immune responses, as well as brain growth and eye abnormalities during embryonic development. By injecting a Brazilian strain of ZIKV into the yolk sac of one-cell stage embryos, we confirmed that, after 72 h, ZIKV successfully infected larvae, and the physical condition of the virus-infected hosts included gross morphological changes in surviving embryos (84%), with a reduction in larval head size and retinal damage characterized by increased thickness of the lens and inner nuclear layer. Changes in locomotor activity and the inability to perceive visual stimuli are a result of changes in retinal morphology caused by ZIKV. Furthermore, we demonstrated the ability of ZIKV to replicate in zebrafish larvae and infect new healthy larvae, impairing their visual and neurological functions. These data reinforce the deleterious activity of ZIKV in the brain and visual structures and establish the zebrafish as a model to study the molecular mechanisms involved in the pathology of the virus.

Flavivirus Entry Inhibitors

Flaviviruses, including Dengue virus, Zika virus, Yellow fever virus, Japanese encephalitis virus, West Nile virus, cause thousands of deaths and millions of illnesses each year. The large outbreak of ZIKV in 2016 reminds us that flaviviruses can pose a serious threat to human safety and public health as emerging and re-emerging viruses. However, there are no specific drugs approved for the treatment of flavivirus infections. Due to no need to enter the cells, viral entry inhibitors have the unique advantage in suppressing viral infections. Flaviviruses bind to receptors and attach to the cell surface, then enter the endosome in a clathrin-dependent manner and finalizes the viral entry process after fusion with the cell membrane in a low pH environment. Small molecules, antibodies or peptides can inhibit flavivirus entry by targeting the above processes. Here, we focus on flavivirus entry inhibitors with well-defined target and antiviral activity. We hope that our review will provide a theoretical basis for flavivirus treatment and drug research and help to accelerate the clinical application of flavivirus entry inhibitors.

Pathophysiological and molecular considerations of viral and bacterial infections during maternal-fetal and -neonatal interactions of SARS-CoV-2, Zika, and Mycoplasma infectious diseases

During pregnancy, a series of physiological changes are determined at the molecular, cellular and macroscopic level that make the mother and fetus more susceptible to certain viral and bacterial infections, especially the infections in this and the companion review. Particular situations increase susceptibility to infection in neonates. The enhanced susceptibility to certain infections increases the risk of developing particular diseases that can progress to become morbidly severe. For example, during the current pandemic caused by the SARS-CoV-2 virus, epidemiological studies have established that pregnant women with COVID-19 disease are more likely to be hospitalized. However, the risk for intensive care unit admission and mechanical ventilation is not increased compared with nonpregnant women. Although much remains unknown with this particular infection, the elevated risk of progression during pregnancy towards more severe manifestations of COVID-19 disease is not associated with an increased risk of death. In addition, the epidemiological data available in neonates suggest that their risk of acquiring COVID-19 is low compared with infants (<12 months of age). However, they might be at higher risk for progression to severe COVID-19 disease compared with older children. The data on clinical presentation and disease severity among neonates are limited and based on case reports and small case series. It is well documented the importance of the Zika virus infection as the main cause of several congenital anomalies and birth defects such as microcephaly, and also adverse pregnancy outcomes. Mycoplasma infections also increase adverse pregnancy outcomes. This review will focus on the molecular, pathophysiological and biophysical characteristics of the mother/placental-fetal/neonatal interactions and the possible mechanisms of these pathogens (SARS-CoV-2, ZIKV, and Mycoplasmas) for promoting disease at this level.

SARS-CoV-2, Zika viruses and mycoplasma: Structure, pathogenesis and some treatment options in these emerging viral and bacterial infectious diseases

The molecular evolution of life on earth along with changing environmental, conditions has rendered mankind susceptible to endemic and pandemic emerging infectious diseases. The effects of certain systemic viral and bacterial infections on morbidity and mortality are considered as examples of recent emerging infections. Here we will focus on three examples of infections that are important in pregnancy and early childhood: SARS-CoV-2 virus, Zika virus, and Mycoplasma species. The basic structural characteristics of these infectious agents will be examined, along with their general pathogenic mechanisms. Coronavirus infections, such as caused by the SARS-CoV-2 virus, likely evolved from zoonotic bat viruses to infect humans and cause a pandemic that has been the biggest challenge for humanity since the Spanish Flu pandemic of the early 20th century. In contrast, Zika Virus infections represent an expanding infectious threat in the context of global climate change. The relationship of these infections to pregnancy, the vertical transmission and neurological sequels make these viruses highly relevant to the topics of this special issue. Finally, mycoplasmal infections have been present before mankind evolved, but they were rarely identified as human pathogens until recently, and they are now recognized as important coinfections that are able to modify the course and prognosis of various infectious diseases and other chronic illnesses. The infectious processes caused by these intracellular microorganisms are examined as well as some general aspects of their pathogeneses, clinical presentations, and diagnoses. We will finally consider examples of treatments that have been used to reduce morbidity and mortality of these infections and discuss briefly the current status of vaccines, in particular, against the SARS-CoV-2 virus. It is important to understand some of the basic features of these emerging infectious diseases and the pathogens involved in order to better appreciate the contributions of this special issue on how infectious diseases can affect human pregnancy, fetuses and neonates.

Brevinin-2GHk, a Peptide Derived from the Skin of Fejervarya limnocharis, Inhibits Zika Virus Infection by Disrupting Viral Integrity

Several years have passed since the Zika virus (ZIKV) pandemic reoccurred in 2015–2016. However, there is still a lack of proved protective vaccines or effective drugs against ZIKV. The peptide brevinin-2GHk (BR2GK), pertaining to the brevinin-2 family of antimicrobial peptides, has been reported to exhibit only weak antibacterial activity, and its antiviral effects have not been investigated. Thus, we analyzed the effect of BR2GK on ZIKV infection. BR2GK showed significant inhibitory activity in the early and middle stages of ZIKV infection, with negligible cytotoxicity. Furthermore, BR2GK was suggested to bind with ZIKV E protein and disrupt the integrity of the envelope, thus directly inactivating ZIKV. In addition, BR2GK can also penetrate the cell membrane, which may contribute to inhibition of the middle stage of ZIKV infection. BR2GK blocked ZIKV E protein expression with an IC₅₀ of 3.408 ± 0.738 μΜ. In summary, BR2GK was found to be a multi-functional candidate and a potential lead compound for further development of anti-ZIKV drugs.

Modulating Neurological Complications of Emerging Infectious Diseases: Mechanistic Approaches to Candidate Phytochemicals

Growing studies are revealing the critical manifestations of influenza, dengue virus (DENV) infection, Zika virus (ZIKV) disease, and Ebola virus disease (EVD) as emerging infectious diseases. However, their corresponding mechanisms of major complications headed for neuronal dysfunction are not entirely understood. From the mechanistic point of view, inflammatory/oxidative mediators are activated during emerging infectious diseases towards less cell migration, neurogenesis impairment, and neuronal death. Accordingly, the virus life cycle and associated enzymes, as well as host receptors, cytokine storm, and multiple signaling mediators, are the leading players of emerging infectious diseases. Consequently, chemokines, interleukins, interferons, carbohydrate molecules, toll-like receptors (TLRs), and tyrosine kinases are leading orchestrates of peripheral and central complications which are in near interconnections. Some of the resulting neuronal manifestations have attracted much attention, including inflammatory polyneuropathy, encephalopathy, meningitis, myelitis, stroke, Guillain-Barré syndrome (GBS), radiculomyelitis, meningoencephalitis, memory loss, headaches, cranial nerve abnormalities, tremor, and seizure. The complex pathophysiological mechanism behind the aforementioned complications urges the need for finding multi-target agents with higher efficacy and lower side effects. In recent decades, the natural kingdom has been highlighted as promising neuroprotective natural products in modulating several dysregulated signaling pathways/mediators. The present study provides neuronal manifestations of some emerging infectious diseases and underlying pathophysiological mechanisms. Besides, a mechanistic-based strategy is developed to introduce candidate natural products as promising multi-target agents in combating major dysregulated pathways towards neuroprotection in influenza, DENV infection, ZIKV disease, and EVD.

Zika Virus: A New Therapeutic Candidate for Glioblastoma Treatment

Glioblastoma (GBM) is the most aggressive among the neurological tumors. At present, no chemotherapy or radiotherapy regimen is associated with a positive long-term outcome. In the majority of cases, the tumor recurs within 32-36 weeks of initial treatment. The recent discovery that Zika virus (ZIKV) has an oncolytic action against GBM has brought hope for the development of new therapeutic approaches. ZIKV is an arbovirus of the Flaviviridae family, and its infection during development has been associated with central nervous system (CNS) malformations, including microcephaly, through the targeting of neural stem/progenitor cells (NSCs/NPCs). This finding has led various groups to evaluate ZIKV's effects against glioblastoma stem cells (GSCs), supposedly responsible for GBM onset, progression, and therapy resistance. While preliminary data support ZIKV tropism toward GSCs, a more accurate study of ZIKV mechanisms of action is fundamental in order to launch ZIKV-based clinical trials for GBM patients.

Human host genetics and susceptibility to ZIKV infection

Managing emerging infectious diseases is a current challenge in the fields of microbiology and epidemiology. Indeed, among other environmental and human-related factors, climate change and global warming favor the emergence of new pathogens. The recent Zika virus (ZIKV) epidemic, of which the large and rapid spread surprised the scientific community, is a reminder of the importance to study viruses currently responsible for sporadic infections. Increasing our knowledge of key factors involved in emerging infections is essential to implement specific monitoring that can be oriented according to the pathogen, targeted population, or at-risk environment. Recent technological developments, such as high-throughput sequencing, genome-wide association studies and CRISPR screenings have allowed the identification of human single nucleotide polymorphisms (SNPs) involved in infectious disease outcome. This review focuses on the human genetic host factors that have been identified and shown to be associated with the pathogenesis of ZIKV infection and candidate SNP targets.

Overview of Pathogenesis, Diagnostics, and Therapeutics of Infectious Diseases: Dengue and Zika

The emergence of more virulent SARS virus has made scientists look back at other so-called neglected diseases such as dengue, Zika, and chikungunya, etc. Until recently these neglected diseases have not received much attention for their control or elimination from society. Over the past decade several attempts to investigate the pathogenicity, diagnostic, and therapeutic strategies for flavivirus caused diseases have been made. Herein we have reviewed the progress made toward the detection and treatment of two diseases-dengue and Zika. The above flavivirus related pathogenesis is concerned with the host immune system and known to be mediated through various receptors along with antibody-mediated disease enhancement. Moreover, researchers have been progressing toward discovering new drugs and therapeutic methods that target various stages of the flavivirus life cycle to minimize the above caused mortality and morbidity. The available diagnostics are based on serological, small molecule detection systems and point-of-care sensing devices. In this work, we have reviewed the advancements made toward understanding the pathogenesis, diagnostics, and therapeutics of the viral diseases caused by dengue and Zika.

Placental Autophagy and Viral Replication Co-localize in Human and Non-human Primate Placentae Following Zika Virus Infection: Implications for Therapeutic Interventions

Background

Multiple studies have shown both induction and inhibition of autophagy during Zika virus (ZIKV) infection. While some have proposed mechanisms by which autophagic dysregulation might facilitate ZIKV vertical transmission, there is a lack of in situ data in human and non-human primate models. This is an especially pertinent question as autophagy-inhibitors, such as hydroxychloroquine, have been proposed as potential therapeutic agents aimed at preventing vertical transmission of ZIKV and other RNA viruses.

Objectives

Given the paucity of pre-clinical data in support of either autophagic enhancement or inhibition of placental ZIKV viral infection, we sought to assess cellular, spatial, and temporal associations between placental ZIKV infection and measures of autophagy in human primary cell culture and congenital infection cases, as well as an experimental non-human primate (marmoset, Callithrix jacchus) model.

Study Design

Primary trophoblast cells were isolated from human placentae (n = 10) and infected in vitro with ZIKV. Autophagy-associated gene expression (ULK-1, BECN1, ATG5, ATG7, ATG12, ATG16L1, MAP1LC3A, MAP1LC3B, p62/SQSTM1) was then determined by TaqMan qPCR to determine fold-change with ZIKV-infection. In in vivo validation experiments, autophagy genes LC3B and p62/SQSTM1 were probed using in situ hybridization (ISH) in the placentae of human Congenital Zika Syndrome (CZS) cases (n = 3) and ZIKV-infected marmoset placenta (n = 1) and fetal tissue (n = 1). Infected and uninfected villi were compared for mean density and co-localization of autophagic protein markers.

Results

Studies of primary cultured human trophoblasts revealed decreased expression of autophagy genes ATG5 and p62/SQSTM1 in ZIKV-infected trophoblasts [ATG5 fold change (±SD) 0.734-fold (±0.722), p = 0.036; p62/SQSTM1 0.661-fold (±0.666), p = 0.029]. Histologic examination by ISH and immunohistochemistry confirmed spatial association of autophagy and ZIKV infection in human congenital infection cases, as well as marmoset placental and fetal tissue samples. When quantified by densitometric data, autophagic protein LC3B, and p62/SQSTM1 expression in marmoset placenta were significantly decreased in in situ ZIKV-infected villi compared to less-infected areas [LC3B mean 0.951 (95% CI, 0.930-0.971), p = 0.018; p62/SQSTM1 mean 0.863 (95% CI, 0.810-0.916), p = 0.024].

Conclusion

In the current study, we observed that in the non-transformed human and non-human primate placenta, disruption (specifically down-regulation) of autophagy accompanies later ZIKV replication in vitro, in vivo, and in situ. The findings collectively suggest that dysregulated autophagy spatially and temporally accompanies placental ZIKV replication, providing the first in situ evidence in relevant primate pre-clinical and clinical models for the importance of timing of human therapeutic strategies aimed at agonizing/antagonizing autophagy. These studies have likely further implications for other congenitally transmitted viruses, particularly the RNA viruses, given the ubiquitous nature of autophagic disruption and dysregulation in host responses to viral infection during pregnancy.

PPAR Gamma and Viral Infections of the Brain

Peroxisome Proliferator-Activated Receptor gamma (PPARγ) is a master regulator of metabolism, adipogenesis, inflammation and cell cycle, and it has been extensively studied in the brain in relation to inflammation or neurodegeneration. Little is known however about its role in viral infections of the brain parenchyma, although they represent the most frequent cause of encephalitis and are a major threat for the developing brain. Specific to viral infections is the ability to subvert signaling pathways of the host cell to ensure virus replication and spreading, as deleterious as the consequences may be for the host. In this respect, the pleiotropic role of PPARγ makes it a critical target of infection. This review aims to provide an update on the role of PPARγ in viral infections of the brain. Recent studies have highlighted the involvement of PPARγ in brain or neural cells infected by immunodeficiency virus 1, Zika virus, or human cytomegalovirus. They have provided a better understanding on PPARγ functions in the infected brain, and revealed that it can be a double-edged sword with respect to inflammation, viral replication, or neuronogenesis. They unraveled new roles of PPARγ in health and disease and could possibly help designing new therapeutic strategies.

Microglial Implications in SARS-CoV-2 Infection and COVID-19: Lessons From Viral RNA Neurotropism and Possible Relevance to Parkinson's Disease

Since December 2019, humankind has been experiencing a ravaging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak, the second coronavirus pandemic in a decade after the Middle East respiratory syndrome coronavirus (MERS-CoV) disease in 2012. Infection with SARS-CoV-2 results in Coronavirus disease 2019 (COVID-19), which is responsible for over 3.1 million deaths worldwide. With the emergence of a second and a third wave of infection across the globe, and the rising record of multiple reinfections and relapses, SARS-CoV-2 infection shows no sign of abating. In addition, it is now evident that SARS-CoV-2 infection presents with neurological symptoms that include early hyposmia, ischemic stroke, meningitis, delirium and falls, even after viral clearance. This may suggest chronic or permanent changes to the neurons, glial cells, and/or brain vasculature in response to SARS-CoV-2 infection or COVID-19. Within the central nervous system (CNS), microglia act as the central housekeepers against altered homeostatic states, including during viral neurotropic infections. In this review, we highlight microglial responses to viral neuroinfections, especially those with a similar genetic composition and route of entry as SARS-CoV-2. As the primary sensor of viral infection in the CNS, we describe the pathogenic and neuroinvasive mechanisms of RNA viruses and SARS-CoV-2 vis-à-vis the microglial means of viral recognition. Responses of microglia which may culminate in viral clearance or immunopathology are also covered. Lastly, we further discuss the implication of SARS-CoV-2 CNS invasion on microglial plasticity and associated long-term neurodegeneration. As such, this review provides insight into some of the mechanisms by which microglia could contribute to the pathophysiology of post-COVID-19 neurological sequelae and disorders, including Parkinson's disease, which could be pervasive in the coming years given the growing numbers of infected and re-infected individuals globally.

Implications of TORCH Diseases in Retinal Development-Special Focus on Congenital Toxoplasmosis

There are certain critical periods during pregnancy when the fetus is at high risk for exposure to teratogens. Some microorganisms, including Toxoplasma gondii, are known to exhibit teratogenic effects, interfering with fetal development and causing irreversible disturbances. T. gondii is an obligate intracellular parasite and the etiological agent of Toxoplasmosis, a zoonosis that affects one third of the world's population. Although congenital infection can cause severe fetal damage, the injury extension depends on the gestational period of infection, among other factors, like parasite genotype and host immunity. This parasite invades the Central Nervous System (CNS), forming tissue cysts, and can interfere with neurodevelopment, leading to frequent neurological abnormalities associated with T. gondii infection. Therefore, T. gondii is included in the TORCH complex of infectious diseases that may lead to neurological malformations (Toxoplasmosis, Others, Rubella, Cytomegalovirus, and Herpes). The retina is part of CNS, as it is derived from the diencephalon. Except for astrocytes and microglia, retinal cells originate from multipotent neural progenitors. After cell cycle exit, cells migrate to specific layers, undergo morphological and neurochemical differentiation, form synapses and establish their circuits. The retina is organized in nuclear layers intercalated by plexus, responsible for translating and preprocessing light stimuli and for sending this information to the brain visual nuclei for image perception. Ocular toxoplasmosis (OT) is a very debilitating condition and may present high severity in areas in which virulent strains are found. However, little is known about the effect of congenital infection on the biology of retinal progenitors/ immature cells and how this infection may affect the development of this tissue. In this context, this study reviews the effects that congenital infections may cause to the developing retina and the cellular and molecular aspects of these diseases, with special focus on congenital OT.

Differential gene expression elicited by ZIKV infection in trophoblasts from congenital Zika syndrome discordant twins

Zika virus (ZIKV) causes congenital Zika syndrome (CZS), which is characterized by fetal demise, microcephaly and other abnormalities. ZIKV in the pregnant woman circulation must cross the placental barrier that includes fetal endothelial cells and trophoblasts, in order to reach the fetus. CZS occurs in ~1-40% of cases of pregnant women infected by ZIKV, suggesting that mothers' infection by ZIKV during pregnancy is not deterministic for CZS phenotype in the fetus. Therefore, other susceptibility factors might be involved, including the host genetic background. We have previously shown that in three pairs of dizygotic twins discordant for CZS, neural progenitor cells (NPCs) from the CZS-affected twins presented differential in vitro ZIKV susceptibility compared with NPCs from the non-affected. Here, we analyzed human-induced-pluripotent-stem-cell-derived (hiPSC-derived) trophoblasts from these twins and compared by RNA-Seq the trophoblasts from CZS-affected and non-affected twins. Following in vitro exposure to a Brazilian ZIKV strain (ZIKVBR), trophoblasts from CZS-affected twins were significantly more susceptible to ZIKVBR infection when compared with trophoblasts from the non-affected. Transcriptome profiling revealed no differences in gene expression levels of ZIKV candidate attachment factors, IFN receptors and IFN in the trophoblasts, either before or after ZIKVBR infection. Most importantly, ZIKVBR infection caused, only in the trophoblasts from CZS-affected twins, the downregulation of genes related to extracellular matrix organization and to leukocyte activation, which are important for trophoblast adhesion and immune response activation. In addition, only trophoblasts from non-affected twins secreted significantly increased amounts of chemokines RANTES/CCL5 and IP10 after infection with ZIKVBR. Overall, our results showed that trophoblasts from non-affected twins have the ability to more efficiently activate genes that are known to play important roles in cell adhesion and in triggering the immune response to ZIKV infection in the placenta, and this may contribute to predict protection from ZIKV dissemination into fetuses' tissues.

A to Z of Zika Virus: A Comprehensive Review for Clinicians

Since its first outbreak in 2007 in the Pacific (Yap islands and Federal States of Micronesia), Zika virus has gradually and recently spread to the Americas in 2015. The neurotropic character of the virus was first noted during this outbreak in Brazil in 2015. Increasing number of infants born with microcephaly and other congenital deformities were identified through studies that have highlighted the importance of prevention of transmission of Zika virus in pregnant women. Long-term outcomes in infants born with this infection are now better understood than at the time of onset of this outbreak. Topics covered in this review include the history, modes of transmission, diagnosis of suspected cases, pathophysiology, complications, and prevention of Zika virus infection.