Biology subjects

Wang, T. T.

Publications and source records attributed to Wang, T. T..

12 recordsLinked to original sources

bioRxiv2024

A connectomics-driven analysis reveals novel characterization of border regions in mouse visual cortex

Leveraging retinotopic maps to parcellate the visual cortex into its respective sub-regions has long been a canonical approach to characterizing the functional organization of visual areas in the mouse brain. However, with the advent of extensive connectomics datasets like MICrONS, we can now perform more granular analyses to better characterize the structure and function of the visual cortex. In this work, we propose a statistical framework for analyzing the MICrONS dataset, particularly the V1, RL, and AL visual areas. In addition to identifying several structural and functional differences between these regions, we focus on the borders between these regions. By comparing the V1-RL and RL-AL border regions, we show that different boundaries between visual regions are distinct in their structure and function. Additionally, we find that the V1-RL border region has greater synaptic connectivity and more synchronous neural activity than the V1 and RL regions individually. We further analyze structure and function in tandem by measuring information flow along synapses, observing that the V1-RL border appears to act as a bridge between the V1 and RL visual areas. Overall, we identify numerous measures that distinguish the V1-RL border from the larger V1-RL network, potentially motivating its characterization as a distinct region in the mouse visual cortex.

neuroscience↗

bioRxiv2024

Characterization of spike processing and entry mechanisms of seasonal human coronaviruses NL63, 229E and HKU1

Although much has been learned about the entry mechanism of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the details of entry mechanisms of seasonal human coronaviruses (HCoVs) remain less well understood. In the present study, we established that 293T cell lines that stably express angiotensin converting enzyme (ACE2), aminopeptidase N (APN), or transmembrane serine protease 2 (TMPRSS2) support high level transduction of lentiviral pseudoviruses bearing spike proteins of seasonal HCoVs, HCoV-NL63, -229E, or -HKU1, respectively. Our results showed that entry of HCoV-NL63, -229E and -HKU1 pseudoviruses is sensitive to endosomal acidification inhibitors (chloroquine and NH4Cl), indicating virus entry via the endocytosis route. Although HCoV-HKU1 pseudovirus infection requires TMPRSS2 expression on cell surface, endocytosis-mediated HCoV-HKU1 entry requires the serine protease domain but not the serine protease activity of TMPRSS2. We also show that amino acids in the predicted S1/S2 junctions of spike proteins of HCoV-NL63, and - 229E are essential for optimal entry but non-essential for spike-mediated entry of HCoV-HKU1. Our findings provide insights into entry mechanism of seasonal HCoVs that may support the development of novel treatment strategies. ImportanceDetails of the entry mechanisms of seasonal human coronaviruses (HCoVs) remain to be fully explored. To investigate the entry of HCoV-NL63, -229E and -HKU1 CoVs, we employed 293T cells that stably express angiotensin converting enzyme (ACE2) aminopeptidase N (APN), or transmembrane serine protease 2 (TMPRSS2) to study entry mechanisms of pseudoviruses bearing spike proteins of HCoV-NL63, -229E and - HKU1 respectively. Our results provide new insights into the predicted S1/S2 subunit junctions, cellular receptor, and protease requirements for seasonal HCoV pseudovirus entry via endocytic route and may support the development of novel treatment strategies.

microbiology↗

bioRxiv2024

Antigenic cartography using hamster sera identifies SARS-CoV-2 JN.1 evasion seen in human XBB.1.5 booster sera

Antigenic assessments of SARS-CoV-2 variants inform decisions to update COVID-19 vaccines. Primary infection sera are often used for assessments, but such sera are rare due to population immunity from SARS-CoV-2 infections and COVID-19 vaccinations. Here, we show that neutralization titers and breadth of matched human and hamster pre-Omicron variant primary infection sera correlate well and generate similar antigenic maps. The hamster antigenic map shows modest antigenic drift among XBB sub-lineage variants, with JN.1 and BA.4/BA.5 variants within the XBB cluster, but with five to six-fold antigenic differences between these variants and XBB.1.5. Compared to sera following only ancestral or bivalent COVID-19 vaccinations, or with post-vaccination infections, XBB.1.5 booster sera had the broadest neutralization against XBB sub-lineage variants, although a five-fold titer difference was still observed between JN.1 and XBB.1.5 variants. These findings suggest that antibody coverage of antigenically divergent JN.1 could be improved with a matched vaccine antigen.

microbiology↗

bioRxiv2024

Differential Patterns of Cross-Protection against Antigenically Distinct Variants in Small Animal Models of SARS-CoV-2 Infection

Continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will likely force more future updates of vaccine composition. Based on a series of studies carried out in human ACE2 transgenic mice (K18-hACE2) and Syrian hamsters, we show that immunity at the respiratory tract, acquired through either previous infection or vaccination with an in-house live attenuate virus, offers protection against antigenically distinct variants in the absence of variant spike-specific neutralizing antibodies. Interestingly, immunity acquired through infection of a modern variant (XBB.1.5) was insufficient in preventing brain infection by the ancestral virus (WA1/2020) in K18-hACE2 mice. Similarly, previous infection with WA1/2020 did not protect against brain infection by XBB.1.5. Our results highlight the importance of immune components other than neutralizing antibodies in maintaining protection against new variants in the respiratory tract, but also paint scenarios where a monovalent vaccine based on a contemporary variant may be less effective against the ancestral strain. ImportanceMany studies have assessed the cross neutralization of various SARS-CoV-2 variants induced by breakthrough infections or vaccine boosters. Few studies, however, have modeled a more severe type of breakthrough infection. Here, we show that immunity acquired through a previous infection by either a historical virus (WA1/2020) or a contemporary variant (XBB.1.5) failed to protect against brain infection of K18-hACE2 mice by an antigenically distinct virus, although it largely protected the respiratory tract. Our results provided a potential model to investigate the role of different immune components in curbing SARS-CoV-2 infection.

microbiology↗

bioRxiv2022

Durable protection against SARS-CoV-2 Omicron induced by an adjuvanted subunit vaccine

Despite the remarkable efficacy of COVID-19 vaccines, waning immunity, and the emergence of SARS-CoV-2 variants such as Omicron represents a major global health challenge. Here we present data from a study in non-human primates demonstrating durable protection against the Omicron BA.1 variant induced by a subunit SARS-CoV-2 vaccine, consisting of RBD (receptor binding domain) on the I53-50 nanoparticle, adjuvanted with AS03, currently in Phase 3 clinical trial (NCT05007951). Vaccination induced robust neutralizing antibody (nAb) titers that were maintained at high levels for at least one year after two doses (Pseudovirus nAb GMT: 2207, Live-virus nAb GMT: 1964) against the ancestral strain, but not against Omicron. However, a booster dose at 6-12 months with RBD-Wu or RBD-{beta} (RBD from the Beta variant) displayed on I53-50 elicited equivalent and remarkably high neutralizing titers against the ancestral as well as the Omicron variant. Furthermore, there were substantial and persistent memory T and B cell responses reactive to Beta and Omicron variants. Importantly, vaccination resulted in protection against Omicron infection in the lung (no detectable virus in any animal) and profound suppression of viral burden in the nares (median peak viral load of 7567 as opposed to 1.3x107 copies in unvaccinated animals) at 6 weeks post final booster. Even at 6 months post vaccination, there was significant protection in the lung (with 7 out of 11 animals showing no viral load, 3 out of 11 animals showing ~20-fold lower viral load than unvaccinated controls) and rapid control of virus in the nares. These results highlight the durable cross-protective immunity elicited by the AS03-adjuvanted RBD-I53-50 nanoparticle vaccine platform.

immunology↗

bioRxiv2022

Spike Protein-independent Attenuation of SARS-CoV-2 Omicron Variant in Laboratory Mice

Despite being more transmissible, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant was found to cause milder diseases in laboratory animals, often accompanied by a lower viral load compared to previous variants of concern. This study revealed the structural basis for a robust interaction between the receptor binding domain of the Omicron spike protein and mouse ACE2. Pseudovirus bearing the Omicron spike protein efficiently utilized mouse ACE2 for entry. By comparing viral load and disease severity among laboratory mice infected by a natural Omicron variant or recombinant ancestral viruses bearing either the entire Omicron Spike or only the N501Y/Q493R mutations in its spike, we found that mutations outside the spike protein in the Omicron variant may be responsible for the observed lower viral load. Together, our results indicated that a post-entry block to the Omicron variant exists in laboratory mice.

microbiology↗

bioRxiv2022

Identification of Salivary Gland Escape Barriers to Western Equine Encephalitis Virus in the Natural Vector, Culex tarsalis

Herein we describe a previously uninvestigated salivary gland escape barrier (SEB) in Culex tarsalis mosquitoes infected with two different strains of Western equine encephalitis virus (WEEV). The WEEV strains were originally isolated either from mosquitoes (IMP181) or a human patient (McMillan). Both IMP181 and McMillan viruses were fully able to infect the salivary glands of Culex tarsalis after intrathoracic injection as determined by expression of mCherry fluorescent protein. IMP181, however, was better adapted to transmission as measured by virus titer in saliva as well as transmission rates in infected mosquitoes. We used chimeric recombinant WEEV strains to show that inclusion of IMP181-derived structural genes partially circumvents the SEB. Author StatementDuring the first half of the previous century, WEEV was responsible for large outbreaks throughout the northern United States and Canada that caused severe disease in horses and people. Over the past 60 years, cases of WEEV have mysteriously faded and the pathogen is rarely encountered in the clinic today. Salivary gland escape barriers (SEB) are a relatively neglected field of study in arbovirology, and this study provides a valuable contribution to the field by describing a SEB found in otherwise vector competent Culex tarsalis mosquitoes. Although midgut barriers are well studied, less is known about barriers to transmission in the salivary glands. Although salivary gland infection occurs at a high rate following direct injection of virus into the hemocoel, we noticed that only [~]20-30% of infected mosquitoes transmit detectable infectious virus in their saliva. Additionally, although the more pathogenic patient-derived McMillan strain of WEEV infected salivary glands at a similar rate, its transmission was more severely restricted than the mosquito-derived but less pathogenic Imperial 181 strain. We were able to trace determinants of viral transmission to the 6K/E1 region of the gene encoding the viral structural polyprotein. WEEV is a valuable research model for the closely related Eastern equine encephalitis virus and Venezuelan equine encephalitis virus we believe that our findings are applicable to other members of Togaviridae.

microbiology↗

bioRxiv2021

Stable Cell Clones Harboring Self-Replicating SARS-CoV-2 RNAs for Drug Screen

The development of antivirals against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been hampered by the lack of efficient cell-based replication systems that are amenable to high-throughput screens in biosafety level 2 laboratories. Here we report that stable cell clones harboring autonomously replicating SARS-CoV-2 RNAs without S, M, E genes can be efficiently derived from the baby hamster kidney (BHK-21) cell line when a pair of mutations were introduced into the non-structural protein 1 (Nsp1) of SARS-CoV-2 to ameliorate cellular toxicity associated with virus replication. In a proof-of-concept experiment we screened a 273-compound library using replicon cells and identified three compounds as novel inhibitors of SARS-CoV-2 replication. Altogether, this work establishes a robust, cell-based system for genetic and functional analyses of SARS-CoV-2 replication and for the development of antiviral drugs. IMPORTANCESARS-CoV-2 replicon systems that have been reported up to date were unsuccessful in deriving stable cell lines harboring non-cytopathic replicons. The transient expression of viral sgmRNA or a reporter gene makes it impractical for industry-scale screening of large compound libraries using these systems. Here, for the first time, we derived stable cell clones harboring the SARS-CoV-2 replicon. These clones may now be conveniently cultured in a standard BSL-2 laboratory for high throughput screen of compound libraries. This achievement represents a ground-breaking discovery that will greatly accelerate the pace of developing treatments for COVID-19.

microbiology↗

bioRxiv2021

Divergent early antibody responses define COVID-19 disease trajectories

A damaging inflammatory response is strongly implicated in the pathogenesis of severe COVID-19 but mechanisms contributing to this response are unclear. In two prospective cohorts, early non-neutralizing, afucosylated, anti-SARS-CoV-2 IgG predicted progression from mild, to more severe COVID-19. In contrast to the antibody structures that predicted disease progression, antibodies that were elicited by mRNA SARS-CoV-2 vaccines were low in Fc afucosylation and enriched in sialylation, both modifications that reduce the inflammatory potential of IgG. To study the biology afucosylated IgG immune complexes, we developed an in vivo model which revealed that human IgG-Fc{gamma}R interactions can regulate inflammation in the lung. Afucosylated IgG immune complexes induced inflammatory cytokine production and robust infiltration of the lung by immune cells. By contrast, vaccine elicited IgG did not promote an inflammatory lung response. Here, we show that IgG-Fc{gamma}R interactions can regulate inflammation in the lung and define distinct lung activities associated with the IgG that predict severe COVID-19 and protection against SARS-CoV-2. One Sentence SummaryDivergent early antibody responses predict COVID-19 disease trajectory and mRNA vaccine response and are functionally distinct in vivo.

immunology↗

bioRxiv2020

FcRn, but not FcgRs, drives maternal-fetal transplacental transport of human IgGantibodies

The IgG Fc domain has the capacity to interact with diverse types of receptors, including FcRn and Fc{gamma}Rs, which confer pleiotropic biological activities. Whereas FcRn regulates IgG epithelial transport and recycling, Fc effector activities, such as ADCC and phagocytosis are mediated by Fc{gamma}Rs, which upon crosslinking transduce signals that modulate the function of effector leukocytes. Despite the well-defined and non-overlapping functional properties of FcRn and Fc{gamma}Rs, recent studies have suggested that Fc{gamma}Rs mediate transplacental IgG transport, as certain Fc glycoforms were reported to be enriched in fetal circulation. To determine the contribution of Fc{gamma}Rs and FcRn to the maternal-fetal transport of IgG, we characterized the IgG Fc glycosylation in paired maternal-fetal samples from patient cohorts from Uganda and Nicaragua. No differences in IgG1 Fc glycan profiles and minimal differences in IgG2 Fc glycans were noted, whereas the presence or absence of galactose on the Fc glycan of IgG1 did not alter Fc{gamma}RIIIA or FcRn binding, half-life, or their ability to deplete target cells in Fc{gamma}R/FcRn humanized mice. Modeling maternal/fetal transport in Fc{gamma}R/FcRn humanized mice confirmed that only FcRn contributed to transplacental transport of IgG; IgG selectively enhanced for FcRn binding resulted in enhanced accumulation of maternal antibody in the fetus. In contrast, enhancing Fc{gamma}RIIIA binding did not result in enhanced maternal/fetal transport. These results argue against a role for Fc{gamma}Rs in IgG transplacental transport, suggesting Fc engineering of maternally administered antibody to only enhance FcRn binding as a means to improve maternal/fetal transport of IgG. Significance StatementTransport of IgG antibodies from the maternal to the fetal circulation is a key process for neonatal immunity, as neonates cannot sufficiently generate IgG antibodies to reach protective levels during the first months after birth. In humans and other primates, maternal to fetal transport of IgG antibodies is largely mediated through the placental tissue. FcRn has been previously identified as the major driver of IgG transplacental transport. Here we examined whether other receptors, such as Fc{gamma}Rs, also contribute to the maternal-fetal IgG transfer. By characterizing the Fc domain structure of paired maternal-fetal IgG samples and modeling transplacental IgG transport in genetically engineered mouse strains, we determined that FcRn, but not Fc{gamma}Rs, is the major receptor that mediates transplacental IgG transport.

immunology↗

bioRxiv2019

TSC2-deficiency potentiates a catabolic signaling switch that differentiates neural and neural crest lineage development and progressive disease manifestations

Lymphangioleiomyomatosis (LAM) is a rare lung disease marked by cystic destruction caused by invasive LAM cells harboring loss-of-function mutations in TSC2 that exhibit dysregulated mTORC1 signaling. Rapamycin, the only approved treatment, is not curative. Therapeutic discovery has been limited by inadequate cell and animal models due to the unknown LAM cell of origin. We report a novel TSC2--/-- human pluripotent stem cell (hPSC)-derived neural crest cell (NCC) model, which replicates key LAM features. Leveraging this model, temporal RNA sequencing and genome-wide CRISPR knockout screens identified synthetic lethal genes including TWIST1 and SUN4. Antisense oligonucleotides (ASOs) targeting TWIST1 and SUN4 demonstrated selective TSC2 mutant NCC cytotoxicity and inhibited invasion. Using a "test-withdraw-monitor" clinical trial paradigm, TWIST1 and SUN4 ASOs profoundly suppressed tumor viability in a Tsc2--/-- mouse allograft model and eradicated 40% of tumors, outperforming standard of care rapamycin and highlighting their promise as novel cytoablative LAM therapeutics.

cancer biology↗

bioRxiv2019

Afucosylated maternal anti-dengue IgGs are a biomarker for susceptibility to dengue disease in their infants

Infant mortality from dengue disease is a devastating global health burden that could be minimized with the ability to identify susceptibility for severe disease prior to infection. While most primary infant dengue infections are asymptomatic, maternally derived anti-dengue IgGs present during infection can trigger progression to severe disease through antibody-dependent enhancement mechanisms. Importantly, specific characteristics of maternal IgGs that herald progression to severe infant dengue are unknown. Here, we define [≥]10% afucosylation of maternal anti-dengue IgGs as a biomarker for susceptibility of infants to symptomatic dengue infections. Mechanistic experiments show that anti-dengue afucosylation, a modification that enhances Fc affinity for the activating receptor Fc{gamma}RIIIa, promotes infection of Fc{gamma}RIIIa+ monocytes. Fc{gamma}RIIIa signaling, in turn, enhances a post-entry step of dengue virus replication. These studies identify a biomarker that can be applied to reduce mortality associated with dengue viruses and define a mechanism by which afucosylated antibodies and Fc{gamma}RIIIa enhance dengue infections.

immunology↗