Biology subjects

Huang, A.

Publications and source records attributed to Huang, A..

At least 91 records · Page 5Linked to original sources

bioRxiv2022

A patterned human heart tube organoid model generated by pluripotent stem cell self-assembly

Human pluripotent stem cells can recapitulate significant features of mammalian organ development in vitro, including key aspects of heart development. We hypothesized that the organoids thus created can be made substantially more relevant by mimicking aspects of in utero gestation, leading to higher physiological and anatomical resemblance to their in vivo counterparts. Here, we report steps towards generating developmentally inspired maturation methodologies to differentiate early human heart organoids into patterned heart-tube-like structures in a reproducible and high-throughput fashion by complete self-organization. The maturation strategy consists of the controlled and stepwise exposure to metabolic (glucose, fatty acids) and hormonal signals (T3, IGF-1) as present during early heart development. These conditions elicit important transcriptomic, cellular, morphological, metabolomic, and functional changes over a 10-day period consistent with continuously increasing heart complexity, maturation, and patterning. Our data reveals the emergence of atrial and ventricular cardiomyocyte populations, valvular cells, epicardial cells, proepicardial-derived cells, endothelial cells, stromal cells, conductance cells, and cardiac progenitors, all of them cell types present in the primitive heart tube. Anatomically, the organoids elongate and develop well-differentiated atrial and ventricular chambers with compacted myocardial muscle walls and a proepicardial organ. For the first time in a completely self-organizing heart organoid, we show anterior-posterior patterning due to an endogenous retinoic acid gradient originating at the atrial pole, where proepicardial and atrial populations reside, mimicking the developmental process present within the primitive heart tube. Collectively, these findings highlight the ability of self-organization and developmental maturation strategies to recapitulate human heart development. Our patterned human heart tube model constitutes a powerful in vitro tool for dissecting the role of different cell types and genes in human heart development, as well as disease modeling congenital heart defects, and represents a step forward in creating fully synthetic human hearts.

bioengineering↗

bioRxiv2022

Evidence for a travel direction signal in humans that is independent of head direction

We often assume that travel direction is redundant with head direction, but from first principles these two factors provide differing spatial information. Although head direction has been found to be a fundamental component of human navigation, it is unclear how self-motion signals for travel direction contribute to forming a travel trajectory. Employing a novel motion adaptation paradigm from visual neuroscience designed to preclude a contribution of head direction, we found high-level aftereffects of perceived travel direction, indicating that travel direction is a fundamental component of human navigation. Interestingly, we discovered a higher frequency of reporting perceived travel toward the adapted direction compared to a no-adapt control - an aftereffect that runs contrary to low-level motion aftereffects. This travel aftereffect was maintained after controlling for possible response biases and approaching effects, and it scaled with adaptation duration. These findings demonstrate the first evidence of how a pure travel direction signal might be represented in humans, independent of head direction.

neuroscience↗

bioRxiv2022

Extreme sex chromosome differentiation, likely driven by inversion, contrasts with mitochondrial paraphyly between species of crowned sparrows

Sympatric species pairs provide researchers with the opportunity to study patterns of genomic differentiation during the late stages of speciation and to identify the genomic regions underlying reproductive isolation. The Golden-crowned Sparrow (Zonotrichia atricapilla) and the White-crowned Sparrow (Zonotrichia leucophrys) are broadly sympatric songbirds found in western North America. These sister species are phenotypically differentiated and largely reproductively isolated despite possessing similar mitochondrial genomes, likely due to recent mitochondrial introgression. We used a genotyping-by-sequencing (GBS) approach to determine the structure of nuclear genomic differentiation between these species and also between two hybridizing subspecies of Z. leucophrys, across more than 45,000 single nucleotide polymorphisms (SNPs). The two Z. leucophrys subspecies showed moderate levels of relative differentiation, as well as patterns consistent with a history of recurrent selection in both ancestral and daughter populations. Z. leucophrys and Z. atricapilla show high levels of relative differentiation and strong heterogeneity in the level of differentiation among different chromosomal regions, with a large portion of the Z chromosome showing highly elevated differentiation. Patterns of relative and absolute differentiation and linkage disequilibrium suggest a large inversion on the Z chromosome, with inversion haplotypes that segregate between Z. atricapilla and Z. leucophrys. While mitochondrial DNA differentiation is often emphasized in studies of speciation, differentiation between these Zonotrichia sparrows appears to have occurred first in the Z chromosome and secondarily in autosomes, followed by mitochondrial introgression. This putative inversion has implications for reproductive isolation between these species and adds to a growing body of evidence for the importance of inversions and the Z chromosome in speciation.

evolutionary biology↗

bioRxiv2022

Small cytosolic dsDNAs repress cGAS activation and induce autophagy

Cyclic GMP-AMP (cGAMP) synthase (cGAS), a major cytosolic DNA sensor, activates innate immune responses by producing cGAMP, which activates stimulator of interferon genes (STING)1. Cytosolic DNA induces autophagy in a cGAS-dependent manner to avoid persistent immune stimulation. Although dsDNAs < 20 bp can bind to cGAS, robust cGAS activation requires dsDNAs > 45 bp 2-4. However, whether cytosolic dsDNAs < 45 bp exist in mammalian cells remains unclear. Here, we identified a class of small cytosolic DNAs (scDNAs) of [~]20-40 bp in human and mouse cell lines. scDNAs competed with herring testis DNA (HT-DNA, [~]200-1500 bp) for binding to cGAS, and repressing HT-DNA-induced cGAS activation and the associated interferon {beta} (IFN{beta}) production. Moreover, scDNAs promoted cGAS and Beclin-1 interaction, triggering the release of Rubicon, a negative regulator of phosphatidylinositol 3-kinase class III (PI3KC3)5,6, from the Beclin-1-PI3KC3 complex, activating PI3KC3 and inducing autophagy. DNA damage decreased and autophagy inducers increased scDNA levels. scDNA transfection or autophagy induction attenuated DNA damage-induced cGAS-STING activation and IFN{beta} expression. Thus, scDNAs acted as molecular brakes of cGAS activation, preventing excessive inflammatory cytokine production following DNA damage. Our findings lay foundations for understanding the physiological and pathological functions of scDNAs.

molecular biology↗

bioRxiv2022

Tubule jamming in the developing kidney creates cyclical mechanical stresses instructive to nephron formation

The kidney develops through branching of progressively crowded ureteric bud (UB) tubules at the organ surface. The elongating tubule tips are surrounded by traveling cap mesenchyme niches consisting of nephron progenitors and separated by stromal boundaries. Dynamic interactions between these tissues coordinate a balance between UB tip branching, elongation, and nephron induction that sets nephron numbers for life, impacting the likelihood of adult disease. Such a crowded tissue environment could place geometric limits on the number of niches that can be formed while maintaining mechanical integrity of the tissue. Since space is at a premium, crowding could also force a given niche to prioritize between nephron formation or UB branching differently depending on its spatial context. Here we study the geometric and mechanical consequences of tubule tip crowding at the embryonic kidney surface. Organ curvature reduces and tubule tip domain niches pack more closely over developmental time. These together create a semi-crystalline geometry of tips at the kidney surface and a rigidity transition to more solid-like tissue properties at later developmental stages. To infer mechanical dynamics over the branching timescale, we define a new method to infer tip domain ages relative to their most recent branch events from fixed kidneys. We find that new tip domains overcome mechanical resistance as they branch and displace close-packed neighbors, transiently increasing mechanical stress in the niche. Ongoing efforts to understand geometric and mechanical effects on niche regulation will clarify variation in kidney tissue composition and advance engineering control strategies for synthetic regenerative tissues.

bioengineering↗

bioRxiv2022

Chemical genetic screening identifies nalacin as an inhibitor of GH3 amido synthetase for auxin conjugation

Root system is critical for plant growth and development. To develop plant growth regulators functioning in root development, we performed a phenotype-based chemical screen in Arabidopsis and identified a chemical, nalacin, that mimicked the effects of auxin on root development. Genetic, pharmacological and biochemical approaches demonstrated that nalacin exerts its auxin-like activities by inhibiting indole-3-acetic acid (IAA) conjugation that is mediated by Gretchen Hagen 3 (GH3) acyl acid amido synthetases. The crystal structure of Arabidopsis GH3.6 in complex with D4 (a derivative of nalacin) together with docking simulation analysis revealed the molecular basis of the inhibition of group II GH3 by nalacin. Sequence alignment analysis indicated broad bioactivities of nalacin and D4 as inhibitors of GH3s in vascular plants, which were confirmed, at least, in tomato and rice. In summary, our work identifies nalacin as a potent inhibitor of IAA conjugation mediated by group II GH3 that plays versatile roles in hormone-regulated plant development and has potential applications in both basic research and agriculture.

plant biology↗

bioRxiv2022

A cocktail containing two synergetic antibodies broadly neutralizes SARS-CoV-2 and its variants including Omicron BA.1 and BA.2

Neutralizing antibodies (NAbs) can prevent and treat infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, continuously emerging variants, such as Omicron, have significantly reduced the potency of most known NAbs. The selection of NAbs with broad neutralizing activities and the identification of conserved critical epitopes are still urgently needed. Here, we identified an extremely potent antibody (55A8) by single B-cell sorting from convalescent SARS-CoV-2-infected patients that recognized the receptor-binding domain (RBD) in the SARS-CoV-2 spike (S) protein. 55A8 could bind to wild-type SARS-CoV-2, Omicron BA.1 and Omicron BA.2 simultaneously with 58G6, a NAb previously identified by our group. Importantly, an antibody cocktail containing 55A8 and 58G6 (2-cocktail) showed synergetic neutralizing activity with a half-maximal inhibitory concentration (IC50) in the picomolar range in vitro and prophylactic efficacy in hamsters challenged with Omicron (BA.1) through intranasal delivery at an extraordinarily low dosage (25 g of each antibody daily) at 3 days post-infection. Structural analysis by cryo-electron microscopy (cryo-EM) revealed that 55A8 is a Class III NAb that recognizes a highly conserved epitope. It could block angiotensin-converting enzyme 2 (ACE2) binding to the RBD in the S protein trimer via steric hindrance. The epitopes in the RBD recognized by 55A8 and 58G6 were found to be different and complementary, which could explain the synergetic mechanism of these two NAbs. Our findings not only provide a potential antibody cocktail for clinical use against infection with current SARS-CoV-2 strains and future variants but also identify critical epitope information for the development of better antiviral agents.

immunology↗

bioRxiv2022

Extensive neutralization against SARS-CoV-2 variants elicited by Omicron-specific subunit vaccine booster

The currently dominant variant of SARS-CoV-2 Omicron, carrying a great number of mutations, has been verified its strong capacity of immune escape in COVID-19 convalescents and vaccinated individuals. An increased risk of SARS-CoV-2 reinfection or breakthrough infection should be concerned. Here we reported higher humoral immune response elicited by Delta and Omicron variants after breaking through previous infection and cross-neutralization against VOCs, compared to the ancestral wild-type (WT) virus infection. To overcome the immune escape of Omicron, Omicron-specific vaccine was considered as a novel and potential strategy. Mouse models were used to verify whether Omicron-specific RBD subunit boost immune response by immunizing Omicron-RBD recombinant proteins. Three doses of Omicron-RBD immunization elicit comparable neutralizing antibody (NAb) titers with three doses of WT-RBD immunization, but the neutralizing activity was not cross-active. By contrast, two doses of WT-RBD with an Omicron-RBD booster increased the NAb geometric mean titers against Omicron by 9 folds. Moreover, an additional boost vaccination with Omicron-RBD protein could increase humoral immune response against both WT and current VOCs. These results suggest that the Omicron-specific subunit booster shows its advantages in the immune protection from both WT and current VOCs, and that SARS-CoV-2 vaccines administration using two or more virus lineages as antigens might improve the NAb response.

microbiology↗

bioRxiv2022

The mycotoxin Beauvericin exhibits immunostimulatory effects on dendritic cells via activating the TLR4 signaling pathway

Beauvericin (BEA), a mycotoxin of the enniatin family produced by various toxigenic fungi, has been attributed multiple biological activities such as anti-cancer, anti-inflammatory, and anti-microbial functions. However, effects of BEA on dendritic cells remain unknown so far. Here, we identified effects of BEA on murine granulocyte-macrophage colony-stimulating factor (GM-CSF)-cultured bone marrow derived dendritic cells (BMDCs) and the underlying molecular mechanisms. BEA potently activates BMDCs as signified by elevated IL-12 and CD86 expression. Multiplex immunoassays performed on myeloid differentiation primary response 88 (MyD88) and toll/interleukin-1 receptor (TIR) domain containing adaptor inducing interferon beta (TRIF) single or double deficient BMDCs indicate that BEA induces inflammatory cytokine and chemokine production in a MyD88/TRIF dependent manner. Furthermore, we found that BEA was not able to induce IL-12 or IFN{beta} production in Toll-like receptor 4 (Tlr4)-deficient BMDCs, whereas induction of these cytokines was not compromised in Tlr3/7/9 deficient BMDCs. This suggests that TLR4 might be the functional target of BEA on BMDCs. Consistently, in luciferase reporter assays BEA stimulation significantly promotes NF-{kappa}B activation in mTLR4/CD14/MD2 overexpressing but not control HEK-293 cells. RNA-sequencing analyses further confirmed that BEA induces transcriptional changes associated with the TLR4 signaling pathway. Together, these results identify TLR4 as a cellular BEA sensor and define BEA as a potent activator of BMDCs, implying that this compound can be exploited as a promising candidate structure for vaccine adjuvants or cancer immunotherapies.

immunology↗

bioRxiv2022

VRK1 is a Paralog Synthetic Lethal Target in VRK2-methylated Glioblastoma

Synthetic lethality -- a genetic interaction that results in cell death when two genetic deficiencies co-occur but not when either deficiency occurs alone -- can be co-opted for cancer therapeutics. A pair of paralog genes is among the most straightforward synthetic lethal interaction by virtue of their redundant functions. Here we demonstrate a paralog-based synthetic lethality by targeting Vaccinia-Related Kinase 1 (VRK1) in Vaccinia-Related Kinase 2 (VRK2)-methylated glioblastoma (GBM). VRK2 is silenced by promoter methylation in approximately two-thirds of GBM, an aggressive cancer with few available targeted therapies. Genetic knockdown of VRK1 in VRK2-null or VRK2-methylated cells results in decreased activity of the downstream substrate Barrier to Autointegration Factor (BAF), a regulator of post-mitotic nuclear envelope formation. VRK1 knockdown, and thus reduced BAF activity, causes nuclear lobulation, blebbing and micronucleation, which subsequently results in G2/M arrest and DNA damage. The VRK1-VRK2 synthetic lethal interaction is dependent on VRK1 kinase activity and is rescued by ectopic VRK2 expression. Knockdown of VRK1 leads to robust tumor growth inhibition in VRK2-methylated GBM xenografts. These results indicate that inhibiting VRK1 kinase activity could be a viable therapeutic strategy in VRK2-methylated GBM.

cancer biology↗

bioRxiv2021

Molecular probes of spike ectodomain and its subdomains for SARS-CoV-2 variants, Alpha through Omicron

Since the outbreak of the COVID-19 pandemic, widespread infections have allowed SARS-CoV-2 to evolve in human, leading to the emergence of multiple circulating variants. Some of these variants show increased resistance to vaccines, convalescent plasma, or monoclonal antibodies. In particular, mutations in the SARS-CoV-2 spike have drawn attention. To facilitate the isolation of neutralizing antibodies and the monitoring the vaccine effectiveness against these variants, we designed and produced biotin-labeled molecular probes of variant SARS-CoV-2 spikes and their subdomains, using a structure-based construct design that incorporated an N-terminal purification tag, a specific amino acid sequence for protease cleavage, the variant spike-based region of interest, and a C-terminal sequence targeted by biotin ligase. These probes could be produced by a single step using in-process biotinylation and purification. We characterized the physical properties and antigenicity of these probes, comprising the N-terminal domain (NTD), the receptor-binding domain (RBD), the RBD and subdomain 1 (RBD-SD1), and the prefusion-stabilized spike ectodomain (S2P) with sequences from SARS-CoV-2 variants of concern or of interest, including variants Alpha, Beta, Gamma, Epsilon, Iota, Kappa, Delta, Lambda, Mu, and Omicron. We functionally validated probes by using yeast expressing a panel of nine SARS-CoV-2 spike-binding antibodies and confirmed sorting capabilities of variant probes using yeast displaying libraries of plasma antibodies from COVID-19 convalescent donors. We deposited these constructs to Addgene to enable their dissemination. Overall, this study describes a matrix of SARS-CoV-2 variant molecular probes that allow for assessment of immune responses, identification of serum antibody specificity, and isolation and characterization of neutralizing antibodies.

immunology↗

bioRxiv2021

HBV enveloped particle secretion is positively regulated by GRP78 through direct interaction with preS1

Hepatitis B virus (HBV) infection is a common cause of liver diseases worldwide. Existing drugs do not effectively eliminate HBV from infected hepatocytes; thus, novel curative therapies are needed. Enveloped-particle secretion is a key but poorly studied aspect of the viral life cycle. Here, we report that GRP78 positively regulates HBV enveloped-particle secretion. GRP78 is the specific target of preS1 binding; HBV can upregulate GRP78 in liver cell lines and sera from chronic hepatitis B patients. GRP78 promoted intact HBV-particle secretion in liver cell lines and an HBV transgenic-mouse model. Some peptides screened from preS1 via phage display could inhibit viral-particle secretion by interacting with GRP78 via hydrogen bonds and hydrophobic interactions, thereby disturbing the interaction with HBV particles. These results provide insight into enveloped-particle secretion in the HBV life cycle. GRP78 might be a potential target for HBV-infection treatment via restricting GRP78-preS1 interactions to block viral-particle secretion. IMPORTANCEHBV is a major human pathogen. The virus More than 250 million n individuals globally are chronically infected with HBV and can result in the infected personsabout 800,000 die for HBV-related disease annually. The mature HBV enveloped particles containing HBs and the relaxed circular (RC) DNA genome could secreted extracellularly as virions. And these enveloped virions serves as the infectious HBV particles for initiating a complete life cycle of the virus. Here, we show the GRP78 is the specific target of preS1 binding, and it could positive regulate HBV enveloped particle secretion in cell and HBV transgenic mice model. Furthermore, several peptides screened from preS1 and Phage screening could inhibit viral particle secretion by interacting with GRP78 and disturbing its interaction with HBV, and then block the life cycle of the virus. This has important implications for our understanding of the mechanisms of antivirals that target intact HBV particles secretion.

microbiology↗

bioRxiv2021

CTCF blocks anti-sense transcription initiation at divergent gene promoters

Transcription at most promoters is divergent, initiating at closely spaced oppositely oriented core promoters to produce sense transcripts along with often unstable upstream antisense (uasTrx). How antisense transcription is regulated and to what extent it is coordinated with sense transcription is largely unknown. Here by combining acute degradation of the multi-functional transcription factor CTCF and nascent transcription measurements, we find that CTCF specifically suppresses antisense but not sense transcription at hundreds of divergent promoters, the great majority of which bear proximal CTCF binding sites. Genome editing, chromatin conformation studies, and high-resolution transcript mapping revealed that precisely positioned CTCF directly suppresses the initiation of uasTrx, in a manner independent of its chromatin architectural function. Primary transcript RNA FISH revealed co-bursting of sense and anti-sense transcripts is disfavored, suggesting CTCF-regulated competition for transcription initiation. In sum, CTCF shapes the transcriptional landscape in part by suppressing upstream antisense transcription.

molecular biology↗

bioRxiv2021

Spatially-resolved transcriptomics analyses of invasive fronts in solid tumors

Solid tumors are complex ecosystems, and heterogeneity is the major challenge for overcoming tumor relapse and metastasis. Uncovering the spatial heterogeneity of cell types and functional states in tumors is essential for developing effective treatment, especially in invasive fronts of tumor, the most active region for tumor cells infiltration and invasion. We firstly used SpaTial Enhanced REsolution Omics-sequencing (Stereo-seq) with a nanoscale resolution to characterize the tumor microenvironment of intrahepatic cholangiocarcinoma (ICC). Enrichment of distinctive immune cells, suppressive immune microenvironment and metabolic reprogramming of tumor cells were identified in the 500{micro}m-wide zone centered bilaterally on the tumor boundary, namely invasive fronts of tumor. Furthermore, we found the damaged states of hepatocytes with overexpression of Serum Amyloid A (SAA) in invasive fronts, recruiting macrophages for facilitating further tumor invasion, and thus resulting in a worse prognosis. We also confirmed these findings in hepatocellular carcinoma and other liver metastatic cancers. Our work highlights the remarkable potential of high-resolution-spatially resolved transcriptomic approaches to provide meaningful biological insights for comprehensively dissecting the tumor ecosystem and guiding the development of novel therapeutic strategies for solid tumors.

cancer biology↗

bioRxiv2021

Characterization of SARS-CoV-2 variants B.1.617.1 (Kappa), B.1.617.2 (Delta) and B.1.618 on cell entry, host range, and sensitivity to convalescent plasma and ACE2 decoy receptor

Recently, highly transmissible SARS-CoV-2 variants B.1.617.1 (Kappa), B.1.617.2 (Delta) and B.1.618 were identified in India with mutations within the spike proteins. The spike protein of Kappa contains four mutations E154K, L452R, E484Q and P681R, and Delta contains L452R, T478K and P681R, while B.1.618 spike harbors mutations {Delta}145-146 and E484K. However, it remains unknown whether these variants have altered in their entry efficiency, host tropism, and sensitivity to neutralizing antibodies as well as entry inhibitors. In this study, we found that Kappa, Delta or B.1.618 spike uses human ACE2 with no or slightly increased efficiency, while gains a significantly increased binding affinity with mouse, marmoset and koala ACE2 orthologs, which exhibits limited binding with WT spike. Furthermore, the P618R mutation leads to enhanced spike cleavage, which could facilitate viral entry. In addition, Kappa, Delta and B.1.618 exhibits a reduced sensitivity to neutralization by convalescent sera owning to the mutation of E484Q, T478K, {Delta}145-146 or E484K, but remains sensitive to entry inhibitors-ACE2-lg decoy receptor. Collectively, our study revealed that enhanced human and mouse ACE2 receptor engagement, increased spike cleavage and reduced sensitivity to neutralization antibodies of Kappa, Delta and B.1.618 may contribute to the rapid spread of these variants and expanded host range. Furthermore, our result also highlighted that ACE2-lg could be developed as broad-spectrum antiviral strategy against SARS-CoV-2 variants.

microbiology↗

bioRxiv2021

Mutation Y453F in the spike protein of SARS-CoV-2 enhances interaction with the mink ACE2 receptor for host adaption

COVID-19 patients transmitted SARS-CoV-2 to minks in the Netherlands in April 2020. Subsequently, the mink-associated virus (miSARS-CoV-2) spilled back over into humans. Genetic sequences of the miSARS-CoV-2 identified a new genetic variant known as "Cluster 5" that contained mutations in the spike protein. However, the functional properties of these "Cluster 5" mutations have not been well established. In this study, we found that the Y453F mutation located in the RBD domain of miSARS-CoV-2 is an adaptive mutation that enhances binding to mink ACE2 and other orthologs of Mustela species without compromising, and even enhancing, its ability to utilize human ACE2 as a receptor for entry. Structural analysis suggested that despite the similarity in the overall binding mode of SARS-CoV-2 RBD to human and mink ACE2, Y34 of mink ACE2 was better suited to interact with a Phe rather than a Tyr at position 453 of the viral RBD due to less steric clash and tighter hydrophobic-driven interaction. Additionally, the Y453F spike exhibited resistance to convalescent serum, posing a risk for vaccine development. Thus, our study suggests that since the initial transmission from humans, SARS-CoV-2 evolved to adapt to the mink host, leading to widespread circulation among minks while still retaining its ability to efficiently utilize human ACE2 for entry, thus allowing for transmission of the miSARS-CoV-2 back into humans. These findings underscore the importance of active surveillance of SARS-CoV-2 evolution in Mustela species and other susceptible hosts in order to prevent future outbreaks.

microbiology↗

bioRxiv2021

Reduced neutralization of SARS-CoV-2 B.1.617 variant by inactivated and RBD-subunit vaccine

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The Spike protein that mediates coronavirus entry into host cells is a major target for COVID-19 vaccines and antibody therapeutics. However, multiple variants of SARS-CoV-2 have emerged, which may potentially compromise vaccine effectiveness. Using a pseudovirus-based assay, we evaluated SARS-CoV-2 cell entry mediated by the viral Spike B.1.617 and B.1.1.7 variants. We also compared the neutralization ability of monoclonal antibodies from convalescent sera and neutralizing antibodies (NAbs) elicited by CoronaVac (inactivated vaccine) and ZF2001 (RBD-subunit vaccine) against B.1.617 and B.1.1.7 variants. Our results showed that, compared to D614G and B.1.1.7 variants, B.1.617 shows enhanced viral entry and membrane fusion, as well as more resistant to antibody neutralization. These findings have important implications for understanding viral infectivity and for immunization policy against SARS-CoV-2 variants.

microbiology↗

bioRxiv2021

Ultrapotent SARS-CoV-2 neutralizing antibodies with protective efficacy against newly emerged mutational variants

Accumulating mutations in the SARS-CoV-2 Spike (S) protein can increase the possibility of immune escape, challenging the present COVID-19 prophylaxis and clinical interventions. Here, 3 receptor binding domain (RBD) specific monoclonal antibodies (mAbs), 58G6, 510A5 and 13G9, with high neutralizing potency blocking authentic SARS-CoV-2 virus displayed remarkable efficacy against authentic B.1.351 virus. Each of these 3 mAbs in combination with one neutralizing Ab recognizing non-competing epitope exhibited synergistic effect against authentic SARS-CoV-2 virus. Surprisingly, structural analysis revealed that 58G6 and 13G9, encoded by the IGHV1-58 and the IGKV3-20 germline genes, both recognized the steric region S470-495 on the RBD, overlapping the E484K mutation presented in B.1.351. Also, 58G6 directly bound to another region S450-458 in the RBD. Significantly, 58G6 and 510A5 both demonstrated prophylactic efficacy against authentic SARS-CoV-2 and B.1.351 viruses in the transgenic mice expressing human ACE2 (hACE2), protecting weight loss and reducing virus loads. These 2 ultrapotent neutralizing Abs can be promising candidates to fulfill the urgent needs for the prolonged COVID-19 pandemic.

immunology↗