Ryan, L;Plötz, FB;van den Hoogen, A;Latour, JM;Degtyareva, M;Keuning, M;Klingenberg, C;Reiss, IKM;Giannoni, E;Roehr, C;Gale, C;Molloy, EJ;
PMID: 34961785 | DOI: 10.1038/s41390-021-01875-y
The SARS-CoV-2 pandemic has had a significant impact worldwide, particularly in middle- and low-income countries. While this impact has been well-recognized in certain age groups, the effects, both direct and indirect, on the neonatal population remain largely unknown. There are placental changes associated, though the contributions to maternal and fetal illness have not been fully determined. The rate of premature delivery has increased and SARS-CoV-2 infection is proportionately higher in premature neonates, which appears to be related to premature delivery for maternal reasons rather than an increase in spontaneous preterm labor. There is much room for expansion, including long-term data on outcomes for affected babies. Though uncommon, there has been evidence of adverse events in neonates, including Multisystem Inflammatory Syndrome in Children, associated with COVID-19 (MIS-C). There are recommendations for reduction of viral transmission to neonates, though more research is required to determine the role of passive immunization of the fetus via maternal vaccination. There is now considerable evidence suggesting that the severe visitation restrictions implemented early in the pandemic have negatively impacted the care of the neonate and the experiences of both parents and healthcare professionals alike. Ongoing collaboration is required to determine the full impact, and guidelines for future management. IMPACT: Comprehensive review of current available evidence related to impact of the COVID-19 pandemic on neonates, effects on their health, impact on their quality of care and indirect influences on their clinical course, including comparisons with other age groups. Reference to current evidence for maternal experience of infection and how it impacts the fetus and then neonate. Outline of the need for ongoing research, including specific areas in which there are significant gaps in knowledge.
The Journal of rheumatology
Iwamoto, T;Dorschner, JM;Selvaraj, S;Mezzano, V;Jensen, MA;Vsetecka, D;Amin, S;Makol, A;Osborn, T;Moder, K;Chowdhary, VR;Izmirly, P;Belmont, HM;Clancy, RM;Buyon, JP;Wu, M;Loomis, CA;Niewold, TB;
PMID: 34782453 | DOI: 10.3899/jrheum.210391
Previous studies suggest a link between high serum type I interferon (IFN) and lupus nephritis (LN). We determined whether serum IFN activity is associated with subtypes of LN and studied renal tissues and cells to understand the impact of IFN in LN.221 systemic lupus erythematosus (SLE) patients were studied. Serum IFN activity was measured by WISH bioassay. mRNA in-situ hybridization was used in renal tissue to measure expression of the representative IFN-induced gene, interferon-induced protein with tetratricopeptide repeats-1 (IFIT1), and the plasmacytoid dendritic cell (pDC) marker gene C-type lectin domain family-4 member C (CLEC4C or BDCA2). Podocyte cell line gene expression was measured by real-time PCR.Class III/IV LN prevalence was significantly increased in patients with high serum IFN compared with those with low IFN (OR=5.48, p=4.0x10-7). In multivariate regression models, type I IFN was a stronger predictor of class III/IV LN than complement C3 or anti-dsDNA antibody, and could account for the association of these variables with LN. IFIT1 expression was increased in all classes of LN, but most in the glomerular areas of active class III/IV LN kidneys. IFIT1 expression was not closely co-localized with pDCs. IFN directly activated podocyte cell lines to induce chemokines and proapoptotic molecules.Systemic high IFN is involved in the pathogenesis of severe LN. We do not find co-localization of pDCs with IFN signature in renal tissue, and instead observe the greatest intensity of IFN signature in glomerular areas, which could suggest a blood source of IFN.
Journal of immunology (Baltimore, Md. : 1950)
Silk, JD;Abbott, RJM;Adams, KJ;Bennett, AD;Brett, S;Cornforth, TV;Crossland, KL;Figueroa, DJ;Jing, J;O'Connor, C;Pachnio, A;Patasic, L;Peredo, CE;Quattrini, A;Quinn, LL;Rust, AG;Saini, M;Sanderson, JP;Steiner, D;Tavano, B;Viswanathan, P;Wiedermann, GE;Wong, R;Jakobsen, BK;Britten, CM;Gerry, AB;Brewer, JE;
PMID: 34853077 | DOI: 10.4049/jimmunol.2001357
Adoptive T cell therapy with T cells expressing affinity-enhanced TCRs has shown promising results in phase 1/2 clinical trials for solid and hematological tumors. However, depth and durability of responses to adoptive T cell therapy can suffer from an inhibitory tumor microenvironment. A common immune-suppressive agent is TGF-β, which is secreted by tumor cells and cells recruited to the tumor. We investigated whether human T cells could be engineered to be resistant to inhibition by TGF-β. Truncating the intracellular signaling domain from TGF-β receptor (TGFβR) II produces a dominant-negative receptor (dnTGFβRII) that dimerizes with endogenous TGFβRI to form a receptor that can bind TGF-β but cannot signal. We previously generated specific peptide enhanced affinity receptor TCRs recognizing the HLA-A*02-restricted peptides New York esophageal squamous cell carcinoma 1 (NY-ESO-1)157-165/l-Ag family member-1A (TCR: GSK3377794, formerly NY-ESO-1c259) and melanoma Ag gene A10254-262 (TCR: ADP-A2M10, formerly melanoma Ag gene A10c796). In this article, we show that exogenous TGF-β inhibited in vitro proliferation and effector functions of human T cells expressing these first-generation high-affinity TCRs, whereas inhibition was reduced or abolished in the case of second-generation TCRs coexpressed with dnTGFβRII (e.g., GSK3845097). TGF-β isoforms and a panel of TGF-β-associated genes are overexpressed in a range of cancer indications in which NY-ESO-1 is commonly expressed, particularly in synovial sarcoma. As an example, immunohistochemistry/RNAscope identified TGF-β-positive cells close to T cells in tumor nests and stroma, which had low frequencies of cells expressing IFN-γ in a non-small cell lung cancer setting. Coexpression of dnTGFβRII may therefore improve the efficacy of TCR-transduced T cells.
Yap Promotes Noncanonical Wnt Signals from Cardiomyocytes for Heart Regeneration
Liu, S;Tang, L;Zhao, X;Nguyen, B;Heallen, TR;Li, M;Wang, J;Wang, J;Martin, JF;
PMID: 34424032 | DOI: 10.1161/CIRCRESAHA.121.318966
Rationale: During neonatal heart regeneration, the fibrotic response, which is required to prevent cardiac rupture, resolves via poorly understood mechanisms. Deletion of the Hippo pathway gene Sav in adult CMs increases Yap activity and promotes cardiac regeneration, partly by inducing fibrosis resolution. Deletion of Yap in neonatal cardiomyocytes (CMs) leads to increased fibrosis and loss of neonatal heart regeneration, suggesting that Yap inhibits fibrosis by regulating intercellular signaling from CMs to cardiac fibroblasts (CFs). Objective: We investigated the role of Wntless (Wls), which is a direct target gene of Yap, in communication between CMs and CFs during neonatal heart regeneration. Methods and Results: We generated two mouse models to delete Wls specifically in CMs (Myh6-Cas9 combined with AAV9-Wls-gRNAs, and Myh6cre-ERT2/+; Wlsflox/flox mouse). Reanalysis of single-cell RNA-sequencing data revealed that Wnt ligands are expressed in CMs, whereas Wnt receptors are expressed in CFs, suggesting that Wnt signaling is directional from CMs to CFs during neonatal heart regeneration. Wls deletion in neonatal hearts disrupted Wnt signaling, showing as reduced noncanonical Wnt signaling in non-CMs. Four weeks after neonatal heart infarction, heart function was measured by echocardiography. Wls deletion in neonatal hearts after myocardial infarction impairs neonatal heart regeneration, marked by decreased contractile function and increased fibrosis. Wls mutant hearts display CF activation, characterized by increased extracellular matrix secretion, inflammation, and CF proliferation. Conclusions: These data indicate that during neonatal heart regeneration, intercellular signaling from CMs to CFs occurs via noncanonical Wnt signaling to rebuild cardiac architecture after myocardial infarction.
Integrative Functional Genomic Analysis of Human PTSD Molecular Pathology and Risk
Girgenti, M;Skarica, M;Zhang, J;Wang, J;Friedman, M;Zhao, H;Krystal, J;
| DOI: 10.1016/j.biopsych.2021.02.050
Background PTSD is a multigenic and multifactorial disorder occurring in the aftermath of significant trauma exposure. Recent GWAS have identified many high confidence loci as risk factors for PTSD, which have shed some light on impaired mechanisms. However, there are still fundamental gaps in our understanding of how these risk genes and pathways are interrelated in causing PTSD but are likely reflected in cell type-specific transcriptomic and epigenetic changes in the brain. Therefore, it is necessary to uncover the individual cell type contribution to the molecular pathology of PTSD. Methods We isolated nuclei from human postmortem dorsolateral prefrontal cortex (BA 9/46) from n=50 PTSD, MDD, and controls for single nucleus sequencing. We sequenced RNA from 10,000 nuclei per sample and used RNAscope fluorescence in situ hybridization to validate cell type specific gene expression changes. We performed snATAC-seq (Assay for Transposase-Accessible Chromatin using sequencing) on 5000 nuclei to generate disease and control open chromatin maps to compare DNA accessibility. Results These results implicate 19 cell types, in particular inhibitory interneurons and microglia as dysregulated in PTSD brain. Open chromatin profiles matched transcript levels and provided new genomic information and possible functional roles for PTSD risk loci identified by GWAS. Conclusions -Omics technologies have been instrumental in our understanding of the connection between the disruption of particular loci and final molecular pathology of neuropsychiatric disorders. Applying functional genomics approaches to characterize findings from multiple layers of single cell-type studies of postmortem brain tissue may therefore help determine which neurotypical processes are most impacted by PTSD.
The thrombin receptor modulates astroglia-neuron trophic coupling and neural repair after spinal cord injury
Kim, HN;Triplet, EM;Radulovic, M;Bouchal, S;Kleppe, LS;Simon, WL;Yoon, H;Scarisbrick, IA;
PMID: 33887067 | DOI: 10.1002/glia.24012
Excessive activation of the thrombin receptor, protease activated receptor 1 (PAR1) is implicated in diverse neuropathologies from neurodegenerative conditions to neurotrauma. PAR1 knockout mice show improved outcomes after experimental spinal cord injury (SCI), however information regarding the underpinning cellular and molecular mechanisms is lacking. Here we demonstrate that genetic blockade of PAR1 in female mice results in improvements in sensorimotor co-ordination after thoracic spinal cord lateral compression injury. We document improved neuron preservation with increases in Synapsin-1 presynaptic proteins and GAP43, a growth cone marker, after a 30 days recovery period. These improvements were coupled to signs of enhanced myelin resiliency and repair, including increases in the number of mature oligodendrocytes, their progenitors and the abundance of myelin basic protein. These significant increases in substrates for neural recovery were accompanied by reduced astrocyte (Serp1) and microglial/monocyte (CD68 and iNOS) pro-inflammatory markers, with coordinate increases in astrocyte (S100A10 and Emp1) and microglial (Arg1) markers reflective of pro-repair activities. Complementary astrocyte-neuron co-culture bioassays suggest astrocytes with PAR1 loss-of-function promote both neuron survival and neurite outgrowth. Additionally, the pro-neurite outgrowth effects of switching off astrocyte PAR1 were blocked by inhibiting TrkB, the high affinity receptor for brain derived neurotrophic factor. Altogether, these studies demonstrate unique modulatory roles for PAR1 in regulating glial-neuron interactions, including the capacity for neurotrophic factor signaling, and underscore its position at neurobiological intersections critical for the response of the CNS to injury and the capacity for regenerative repair and restoration of function.
PKN1 Is a Novel Regulator of Hippocampal GluA1 Levels
Frontiers in synaptic neuroscience
Safari, MS;Obexer, D;Baier-Bitterlich, G;Zur Nedden, S;
PMID: 33613259 | DOI: 10.3389/fnsyn.2021.640495
Alterations in the processes that control α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) expression, assembly and trafficking are closely linked to psychiatric and neurodegenerative disorders. We have recently shown that the serine/threonine kinase Protein kinase N1 (PKN1) is a developmentally active regulator of cerebellar synaptic maturation by inhibiting AKT and the neurogenic transcription factor neurogenic differentiation factor-2 (NeuroD2). NeuroD2 is involved in glutamatergic synaptic maturation by regulating expression levels of various synaptic proteins. Here we aimed to study the effect of Pkn1 knockout on AKT phosphorylation and NeuroD2 levels in the hippocampus and the subsequent expression levels of the NeuroD2 targets and AMPAR subunits: glutamate receptor 1 (GluA1) and GluA2/3. We show that PKN1 is expressed throughout the hippocampus. Interestingly, not only postnatal but also adult hippocampal phospho-AKT and NeuroD2 levels were significantly elevated upon Pkn1 knockout. Postnatal and adult Pkn1-/- hippocampi showed enhanced expression of the AMPAR subunit GluA1, particularly in area CA1. Surprisingly, GluA2/3 levels were not different between both genotypes. In addition to higher protein levels, we also found an enhanced GluA1 content in the membrane fraction of postnatal and adult Pkn1-/- animals, while GluA2/3 levels remained unchanged. This points toward a very specific regulation of GluA1 expression and/or trafficking by the novel PKN1-AKT-NeuroD2 axis. Considering the important role of GluA1 in hippocampal development as well as the pathophysiology of several disorders, ranging from Alzheimer's, to depression and schizophrenia, our results validate PKN1 for future studies into neurological disorders related to altered AMPAR subunit expression in the hippocampus.
Long noncoding RNA TINCR is a novel regulator of human bronchial epithelial cell differentiation state
Omote, N;Sakamoto, K;Li, Q;Schupp, JC;Adams, T;Ahangari, F;Chioccioli, M;DeIuliis, G;Hashimoto, N;Hasegawa, Y;Kaminski, N;
PMID: 33527707 | DOI: 10.14814/phy2.14727
Long-noncoding RNAs (lncRNAs) have numerous biological functions controlling cell differentiation and tissue development. The knowledge about the role of lncRNAs in human lungs remains limited. Here we found the regulatory role of the terminal differentiation-induced lncRNA (TINCR) in bronchial cell differentiation. RNA in situ hybridization revealed that TINCR was mainly expressed in bronchial epithelial cells in normal human lung. We performed RNA sequencing analysis of normal human bronchial epithelial cells (NHBECs) with or without TINCR inhibition and found the differential expression of 603 genes, which were enriched for cell adhesion and migration, wound healing, extracellular matrix organization, tissue development and differentiation. To investigate the role of TINCR in the differentiation of NHBECs, we employed air-liquid interface culture and 3D organoid formation assay. TINCR was upregulated during differentiation, loss of TINCR significantly induced an early basal-like cell phenotype (TP63) and a ciliated cell differentiation (FOXJ1) in late phase and TINCR overexpression suppressed basal cell phenotype and the differentiation toward to ciliated cells. Critical regulators of differentiation such as SOX2 and NOTCH genes (NOTCH1, HES1, and JAG1) were significantly upregulated by TINCR inhibition and downregulated by TINCR overexpression. RNA immunoprecipitation assay revealed that TINCR was required for the direct bindings of Staufen1 protein to SOX2, HES1, and JAG1 mRNA. Loss of Staufen1 induced TP63, SOX2, NOTCH1, HES1, and JAG1 mRNA expressions, which TINCR overexpression suppressed partially. In conclusion, TINCR is a novel regular of bronchial cell differentiation, affecting downstream regulators such as SOX2 and NOTCH genes, potentially in coordination with Staufen1.
Renal interstitial fibroblasts coproduce erythropoietin and renin under anaemic conditions
Miyauchi, K;Nakai, T;Saito, S;Yamamoto, T;Sato, K;Kato, K;Nezu, M;Miyazaki, M;Ito, S;Yamamoto, M;Suzuki, N;
PMID: 33508746 | DOI: 10.1016/j.ebiom.2021.103209
Erythrocyte mass contributes to maintaining systemic oxygen delivery and blood viscosity, with the latter being one of the determinants of blood pressure. However, the physiological response to blood pressure changes under anaemic conditions remain unknown. We show that anaemia decreases blood pressure in human patients and mouse models. Analyses of pathways related to blood pressure regulation demonstrate that anaemia enhances the expression of the gene encoding the vasopressor substance renin in kidneys. Although kidney juxtaglomerular cells are known to continuously produce renin, renal interstitial fibroblasts are identified in the present study as a novel site of renin induction under anaemic hypotensive conditions in mice and rats. Notably, some renal interstitial fibroblasts are found to simultaneously express renin and the erythroid growth factor erythropoietin in the anaemic mouse kidney. Antihypertensive agents but not hypoxic stimuli induced interstitial renin expression, suggesting that blood pressure reduction triggers interstitial renin induction in anaemic mice. The interstitial renin expression was also detected in injured fibrotic kidneys of the mouse and human, and the renin-expressing interstitial cells in murine fibrotic kidneys were identified as myofibroblasts originating from renal interstitial fibroblasts. Since the elevated expression levels of renin in fibrotic kidneys along with progression of renal fibrosis were well correlated to the systemic blood pressure increase, the renal interstitial renin production seemed to affect systemic blood pressure. Renal interstitial fibroblasts function as central controllers of systemic oxygen delivery by producing both renin and erythropoietin. Grants-in-Aid from Japan Society for the Promotion of Science (JSPS) KAKENHI (17K19680, 15H04691, and 26111002) and the Takeda Science Foundation.
Clinicopathological features of adult T-cell leukemia/lymphoma with HTLV-1–infected Hodgkin and Reed-Sternberg–like cells
Karube, K;Takatori, M;Sakihama, S;Tsuruta, Y;
| DOI: 10.1182/bloodadvances.2020003201
HBZ-ISH was performed to detect HTLV-1 in tissue specimens from 21 HTLV-1–seropositive cases with CHL-like morphology (supplemental Table 1). Three cases were nonevaluable due to negativity for the positive control (_PPIB_). HRS-like cells were negative for HBZ-ISH in 10 cases. Among them, 3 cases showed HRS-like cells positive for EBER-ISH and/or PAX5 as well as monoclonal TCR-γ chain gene rearrangement or loss of pan-T-cell antigens in the background cells, corresponding to the currently recognized pathological features of Hodgkin-like ATLL.16,17 Thus, 8 cases, including a recently described case (case 1)19 with a positive HBZ-ISH signal in HRS-like cells, were considered to be ATLL with HTLV-1–infected HRS-like cells. The clinical characteristics of these cases are shown in Table 1. The median age of the patients (4 males and 4 females) was 73 years (range, 55-81 years). All patients showed nodal or mediastinal lesions. Five patients (63%) were in an advanced stage of disease (Ann Arbor stage III or IV) at presentation. Bone marrow and hepatosplenic involvement was observed in 3 and 2 cases, respectively, but no other extranodal lesions were present in any of the cases. All patients except for case 6, who was treated with palliative care because of the co-occurrence of severe liver cirrhosis, received systemic combination chemotherapy. Two patients (cases 1 and 3) were mainly treated with ABVD, a standard therapy for CHL, and 5 patients were treated with a combination chemotherapy regimen such as CHOP. All cases, with enough follow-up period, treated with chemotherapy achieved complete remission, except for case 4, but a longer remission (>2 years) was achieved in 2 patients treated with CHOP. One patient (case 4) had been followed up for chronic-type ATLL before lymph node biopsy. This patient had very high serum levels of soluble interleukin-2 receptor, a prognostic biomarker for poor outcome,8 was refractory to systemic chemotherapy, and died 3 months after diagnosis (Table 1).
Upregulation of WNT Signaling in Lung Epithelial-Mesenchymal Crosstalk May Contribute to the Cystic Remodeling in Pulmonary Lymphangioleiomyomatosis (LAM)
TP108. TP108 CYSTIC FIBROSIS, LAM, SARCOID, AND RARE DISEASES
Obraztsova, K;Mukhitov, A;Lin, S;Smith, C;Basil, M;Katzen, J;Carl, J;Beers, M;Morrisey, E;Krymskaya, V;
| DOI: 10.1164/ajrccm-conference.2021.203.1_MeetingAbstracts.A4255
Rationale: Interstitial mesenchymal cells maintain alveolar epithelial (AT) cells (AT1 and AT2) homeostasis in health and disease. Human LAM is characterized by enlarged airspaces, cystic destruction of the lung parenchyma, and lung function decline, leading to respiratory failure. The exact mechanism behind the alveolar remodeling in LAM lung is still unknown. In the genetic mouse model of LAM, characterized by progressive enlargement of airspaces and female-specific lung function decline, we found that lung mesenchymal cells affect AT1/AT2 cell fitness through up-regulation of WNT signaling. We also discovered that genetic inhibition of the WNT pathway in mouse lung mesenchyme restored the observed disease phenotype. We utilized immunofluorescent histochemistry on the lung sections to study the differences in the architecture and cellular composition of the alveolar septal walls in human control and LAM lungs and found an increased number of transitional AT2/AT1 cells. We propose that LAM mesenchyme dysregulates the proliferation of the neighboring AT2 cells, which results in the abnormal architecture of LAM lung parenchyma.Methods: To study mesenchymal-epithelial interactions ex vivo we used 3D co-cultures of mesenchymal cells, isolated from multiple age-matched LAM and control human female lung, with primary AT2 cells isolated from control human female lungs. Results: LAM lung-derived mesenchyme supported increased colony-forming-efficiency (CFE), size, and structural complexity of AT2 organoids, compared to the control ones. LAM lung-derived mesenchymal support cells expressed increased levels of estrogen alphaencoding gene ESR1, as well as pro-mitotic gene WNT2. Using RNA-scope, we found the upregulation of the WNT pathway in the AT2 cells and in the LAM cells compared to the controls. In agreement with these findings, the CFE of LAM-based organoids was increased by estrogen stimulation and decreased by WNT-pathway inhibitors. Notably, control-lung-based organoids had simple monolayer organization, while LAM-based organoids formed highly organized and compartmentalized structures, composed of both AT2 and AT1 cells. LAM-based organoids also exhibited robust staining for AT1 cell marker – AQP5, specifically in the core of the organoid spheres, while AQP5+ cells lined up the walls of the internal organoid compartments. Conclusion: Our data demonstrate that upregulation of mTORC1-WNT signaling drives cystic airspace enlargement due to chronic activation of LAM cells and alveolar epithelial cells, promote abnormal epithelial-mesenchymal crosstalk, which affects the fitness of surrounding AT2 cells and potentially contributes to the cystic remodeling in the LAM lung through WNT pathway dysregulation.
He, MJ;Wang, HJ;Yan, XL;Lou, YN;Song, GY;Li, RT;Zhu, Z;Zhang, RR;Qin, CF;Li, XF;
PMID: 36840584 | DOI: 10.1128/jvi.01801-22
The Zika virus (ZIKV) represents an important global health threat due to its unusual association with congenital Zika syndrome. ZIKV strains are phylogenetically grouped into the African and Asian lineages. However, the viral determinants underlying the phenotypic differences between the lineages remain unknown. Here, multiple sequence alignment revealed a highly conserved residue at position 21 of the premembrane (prM) protein, which is glutamic acid and lysine in the Asian and African lineages, respectively. Using reverse genetics, we generated a recombinant virus carrying an E21K mutation based on the genomic backbone of the Asian lineage strain FSS13025 (termed E21K). The E21K mutation significantly increased viral replication in multiple neural cell lines with a higher ratio of M to prM production. Animal studies showed E21K exhibited increased neurovirulence in suckling mice, leading to more severe defects in mouse brains by causing more neural cell death and destruction of hippocampus integrity. Moreover, the E21K substitution enhanced neuroinvasiveness in interferon alpha/beta (IFN-α/β) receptor knockout mice, as indicated by the increased mortality, and enhanced replication in mouse brains. The global transcriptional analysis showed E21K infection profoundly altered neuron development networks and induced stronger antiviral immune response than wild type (WT) in both neural cells and mouse brains. More importantly, the reverse K21E mutation based on the genomic backbone of the African strain MR766 caused less mouse neurovirulence. Overall, our findings support the 21st residue of prM functions as a determinant for neurovirulence and neuroinvasiveness of the African lineage of ZIKV. IMPORTANCE The suspected link of Zika virus (ZIKV) to birth defects led the World Health Organization to declare ZIKV a Public Health Emergency of International Concern. ZIKV has been identified to have two dominant phylogenetic lineages, African and Asian. Significant differences exist between the two lineages in terms of neurovirulence and neuroinvasiveness in mice. However, the viral determinants underlying the phenotypic differences are still unknown. Here, combining reverse genetics, animal studies, and global transcriptional analysis, we provide evidence that a single E21K mutation of prM confers to the Asian lineage strain FSS130125 significantly enhanced replication in neural cell lines and more neurovirulent and neuroinvasiveness phenotypes in mice. Our findings support that the highly conserved residue at position 21 of prM functions as a determinant of neurovirulence and neuroinvasiveness of the African lineage of ZIKV in mice.