Zika virus (ZIKV) has evolved into a global health threat because of its unexpected causal link to microcephaly. Phylogenetic analysis reveals that contemporary epidemic strains have accumulated ...multiple substitutions from their Asian ancestor. Here we show that a single serine-to-asparagine substitution Ser139→Asn139 (S139N) in the viral polyprotein substantially increased ZIKV infectivity in both human and mouse neural progenitor cells (NPCs) and led to more severe microcephaly in the mouse fetus, as well as higher mortality rates in neonatal mice. Evolutionary analysis indicates that the S139N substitution arose before the 2013 outbreak in French Polynesia and has been stably maintained during subsequent spread to the Americas. This functional adaption makes ZIKV more virulent to human NPCs, thus contributing to the increased incidence of microcephaly in recent ZIKV epidemics.
The outbreak of Zika virus (ZIKV) and associated fetal microcephaly mandates efforts to understand the molecular processes of infection. Related flaviviruses produce noncoding subgenomic flaviviral ...RNAs (sfRNAs) that are linked to pathogenicity in fetal mice. These viruses make sfRNAs by co-opting a cellular exonudease via structured RNAs called xrRNAs. We found that ZIKV-infected monkey and human epithelial cells, mouse neurons, and mosquito cells produce sfRNAs. The RNA structure that is responsible for ZIKV sfRNA production forms a complex fold that is likely found in many pathogenic flaviviruses. Mutations that disrupt the structure affect exonudease resistance in vitro and sfRNA formation during infection. The complete ZIKV xrRNA structure clarifies the mechanism of exonudease resistance and identifies features that may modulate function in diverse flaviviruses.
Despite limited genomic diversity, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has shown a wide range of clinical manifestations in different patient populations. The mechanisms ...behind these host differences are still unclear. Here, we examined host response gene expression across infection status, viral load, age, and sex among shotgun RNA sequencing profiles of nasopharyngeal (NP) swabs from 430 individuals with PCR-confirmed SARS-CoV-2 and 54 negative controls. SARS-CoV-2 induced a strong antiviral response with up-regulation of antiviral factors such as OAS1-3 and IFIT1-3 and T helper type 1 (Th1) chemokines CXCL9/10/11, as well as a reduction in transcription of ribosomal proteins. SARS-CoV-2 culture in human airway epithelial (HAE) cultures replicated the in vivo antiviral host response 7 days post infection, with no induction of interferon-stimulated genes after 3 days. Patient-matched longitudinal specimens (mean elapsed time = 6.3 days) demonstrated reduction in interferon-induced transcription, recovery of transcription of ribosomal proteins, and initiation of wound healing and humoral immune responses. Expression of interferon-responsive genes, including ACE2, increased as a function of viral load, while transcripts for B cell-specific proteins and neutrophil chemokines were elevated in patients with lower viral load. Older individuals had reduced expression of the Th1 chemokines CXCL9/10/11 and their cognate receptor CXCR3, as well as CD8A and granzyme B, suggesting deficiencies in trafficking and/or function of cytotoxic T cells and natural killer (NK) cells. Relative to females, males had reduced B cell-specific and NK cell-specific transcripts and an increase in inhibitors of nuclear factor kappa-B (NF-κB) signaling, possibly inappropriately throttling antiviral responses. Collectively, our data demonstrate that host responses to SARS-CoV-2 are dependent on viral load and infection time course, with observed differences due to age and sex that may contribute to disease severity.
The explosive emergence of Zika virus has inspired a global effort to develop vaccines. Zika virus, which is a flavivirus primarily transmitted by mosquitoes, can cause devastating congenital ...syndrome in fetuses of pregnant women, including microcephaly, craniofacial disproportion, spasticity, ocular abnormalities, and miscarriage. In adults, Zika infection has been linked to the autoimmune disorder Guillain-Barré syndrome. Thus, despite the current waning in newly reported Zika infections, an efficacious vaccine is urgently needed to help limit the emergence of another detrimental epidemic. Here we summarize the current status of the Zika vaccine pipeline and highlight the challenges for clinical efficacy trials.
Shan et al. review the current status of the Zika virus vaccine pipeline, highlight the challenges for efficacy trial in humans, underline the knowledge gaps required for clinical development, and provide potential solutions to overcome the barriers toward licensure.
Abstract
The newly emerged Omicron SARS-CoV-2 has several distinct sublineages including BA.1, BA.2, and BA.3. BA.1 accounts for the initial surge and is being replaced by BA.2, whereas BA.3 is at a ...low prevalence at this time. Here we report the neutralization of BNT162b2-vaccinated sera (collected 1 month after dose 3) against the three Omicron sublineages. To facilitate the neutralization testing, we have engineered the complete BA.1, BA.2, or BA.3 spike into an mNeonGreen USA-WA1/2020 SRAS-CoV-2. All BNT162b2-vaccinated sera neutralize USA-WA1/2020, BA.1-, BA.2-, and BA.3-spike SARS-CoV-2s with titers of >20; the neutralization geometric mean titers (GMTs) against the four viruses are 1211, 336, 300, and 190, respectively. Thus, the BA.1-, BA.2-, and BA.3-spike SARS-CoV-2s are 3.6-, 4.0-, and 6.4-fold less efficiently neutralized than the USA-WA1/2020, respectively. Our data have implications in vaccine strategy and understanding the biology of Omicron sublineages.
Virus-host interactions determine an infection outcome. The Asian lineage of Zika virus (ZIKV), responsible for the recent epidemics, has fixed a mutation in the NS1 gene after 2012 that enhances ...mosquito infection. Here we report that the same mutation confers NS1 to inhibit interferon-β induction. This mutation enables NS1 binding to TBK1 and reduces TBK1 phosphorylation. Engineering the mutation into a pre-epidemic ZIKV strain debilitates the virus for interferon-β induction; reversing the mutation in an epidemic ZIKV strain invigorates the virus for interferon-β induction; these mutational effects are lost in IRF3-knockout cells. Additionally, ZIKV NS2A, NS2B, NS4A, NS4B, and NS5 can also suppress interferon-β production through targeting distinct components of the RIG-I pathway; however, for these proteins, no antagonistic difference is observed among various ZIKV strains. Our results support the mechanism that ZIKV has accumulated mutation(s) that increases the ability to evade immune response and potentiates infection and epidemics.
An Infectious cDNA Clone of SARS-CoV-2 Xie, Xuping; Muruato, Antonio; Lokugamage, Kumari G. ...
Cell host & microbe,
05/2020, Volume:
27, Issue:
5
Journal Article
Peer reviewed
Open access
The ongoing pandemic of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), underscores the urgency to develop experimental systems for studying this virus and ...identifying countermeasures. We report a reverse genetic system for SARS-CoV-2. Seven complimentary DNA (cDNA) fragments spanning the SARS-CoV-2 genome were assembled into a full-genome cDNA. RNA transcribed from the full-genome cDNA was highly infectious after electroporation into cells, producing 2.9 × 106 plaque-forming unit (PFU)/mL of virus. Compared with a clinical isolate, the infectious-clone-derived SARS-CoV-2 (icSARS-CoV-2) exhibited similar plaque morphology, viral RNA profile, and replication kinetics. Additionally, icSARS-CoV-2 retained engineered molecular markers and did not acquire other mutations. We generated a stable mNeonGreen SARS-CoV-2 (icSARS-CoV-2-mNG) by introducing this reporter gene into ORF7 of the viral genome. icSARS-CoV-2-mNG was successfully used to evaluate the antiviral activities of interferon (IFN). Collectively, the reverse genetic system and reporter virus provide key reagents to study SARS-CoV-2 and develop countermeasures.
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•A reverse genetic system has been established for SARS-CoV-2•Recombinant SARS-CoV-2 replicates as efficiently as the original clinical isolate•A stable mNeonGreen reporter SARS-CoV-2 has been developed•The mNeonGreen SARS-CoV-2 can be used to screen antiviral inhibitors
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a devastating global pandemic. Xie et al. generated an infectious cDNA clone of SARS-CoV-2 and a mNeonGreen reporter virus. Recombinant SARS-CoV-2 and reporter virus replicate as efficiently as the original clinical isolate.
A high-throughput platform would greatly facilitate coronavirus disease 2019 (COVID-19) serological testing and antiviral screening. Here we present a high-throughput nanoluciferase severe ...respiratory syndrome coronavirus 2 (SARS-CoV-2-Nluc) that is genetically stable and replicates similarly to the wild-type virus in cell culture. SARS-CoV-2-Nluc can be used to measure neutralizing antibody activity in patient sera within 5 hours, and it produces results in concordance with a plaque reduction neutralization test (PRNT). Additionally, using SARS-CoV-2-Nluc infection of A549 cells expressing human ACE2 receptor (A549-hACE2), we show that the assay can be used for antiviral screening. Using the optimized SARS-CoV-2-Nluc assay, we evaluate a panel of antivirals and other anti-infective drugs, and we identify nelfinavir, rupintrivir, and cobicistat as the most selective inhibitors of SARS-CoV-2-Nluc (EC
0.77 to 2.74 µM). In contrast, most of the clinically approved antivirals, including tenofovir alafenamide, emtricitabine, sofosbuvir, ledipasvir, and velpatasvir were inactive at concentrations up to 10 µM. Collectively, this high-throughput platform represents a reliable tool for rapid neutralization testing and antiviral screening for SARS-CoV-2.
In the past two decades, three highly pathogenic human coronaviruses severe acute respiratory syndrome coronavirus (SARS‐CoV), Middle East respiratory syndrome coronavirus, and, recently, SARS‐CoV‐2, ...have caused pandemics of severe acute respiratory diseases with alarming morbidity and mortality. Due to the lack of specific anti‐CoV therapies, the ongoing pandemic of coronavirus disease 2019 (COVID‐19) poses a great challenge to clinical management and highlights an urgent need for effective interventions. Drug repurposing is a rapid and feasible strategy to identify effective drugs for combating this deadly infection. In this review, we summarize the therapeutic CoV targets, focus on the existing small molecule drugs that have the potential to be repurposed for existing and emerging CoV infections of the future, and discuss the clinical progress of developing small molecule drugs for COVID‐19.
Abstract
Nowadays, energy-saving building materials are important for reducing indoor energy consumption by enabling better thermal insulation, promoting effective sunlight harvesting and offering ...comfortable indoor lighting. Here, we demonstrate a novel scalable aesthetic transparent wood (called aesthetic wood hereafter) with combined aesthetic features (e.g. intact wood patterns), excellent optical properties (an average transmittance of ~ 80% and a haze of ~ 93%), good UV-blocking ability, and low thermal conductivity (0.24 W m
−1
K
−1
) based on a process of spatially selective delignification and epoxy infiltration. Moreover, the rapid fabrication process and mechanical robustness (a high longitudinal tensile strength of 91.95 MPa and toughness of 2.73 MJ m
−3
) of the aesthetic wood facilitate good scale-up capability (320 mm × 170 mm × 0.6 mm) while saving large amounts of time and energy. The aesthetic wood holds great potential in energy-efficient building applications, such as glass ceilings, rooftops, transparent decorations, and indoor panels.
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