Biology subjects

Peng, B.-H.

Publications and source records attributed to Peng, B.-H..

9 recordsLinked to original sources

bioRxiv2025

VSA-2, a novel plant-derived adjuvant for SARS-CoV-2 subunit vaccine

QS-21, a key component of several licensed vaccines is facing limited supply, dose-limiting toxicity and other drawbacks which together limit its broader usage. Development of saponin alternatives to QS-21 that retain its desirable adjuvant activity without its drawbacks is in high need. Incorporating an amide side chain into the more sustainable Momordica saponins (MS) I and II led to the recent discovery of two semisynthetic immunostimulatory adjuvants VSA-1 and VSA-2. Here, we showed that the receptor-binding protein (RBD) of ancestral SARS-CoV-2 adjuvanted with VSA-2 (VSA-2-RBD) induced high titers of SARS-CoV-2-specific humoral and T helper-1 prone immune responses in mice comparable to that triggered by QS-21-RBD. Vaccination with VSA-2-RBD provided strong protection against SARS-COV-2, Delta and Omicron variants infection and the virus-induced lung inflammation and pathology similarly as QS-21-RBD vaccination. Overall, our results suggest that VSA-2 adjuvant can potentially complement the clinically proven saponin adjuvant QS-21 in vaccines against infectious diseases.

microbiology↗

bioRxiv2025

Crosstalk Among Disrupted Blood-Brain Barrier, Neuroinflammation, and Coagulopathy in AC70 hACE2 Tg Mice with Prolonged Neurological Manifestations Induced by the Omicron BA.1 Variant of SARS-CoV-2

Long COVID, or post-acute sequela of COVID (PASC), has emerged as a major post-pandemic challenge, with lasting neurological effects in a substantial number of patients. The underlying pathophysiological mechanisms of PASC remains elusive, largely due to the lack of suitable animal models that replicate key clinical and pathological features, especially in survivors of acute infection. Here, we employed the Omicron BA.1-infected AC70 hACE2 Tg mice to explore the pathogenesis of COVID-19. Our findings in the AC70/BA.1 model demonstrated that surviving mice developed lasting neurological sequelae of COVID-19, making it a promising platform for studying the pathogenesis of neuro- or long-COVID. Histopathological examinations revealed a transient pulmonary inflammatory response that correlated with the levels of live virus, whereas neuroinflammation within the brains persisted and progressed beyond the acute phase, without a clear linkage to direct virus effects. We showed that the severity of neurological sequelae directly correlated with the degree of blood-brain-barrier (BBB) disruption, alterations in tight junctions (TJs) and fibrinogen extravasation into the brain parenchyma. Additionally, BA.1-infected mice elicited a sustained systemic prothrombotic state, with dysregulated coagulation and fibrinolytic pathways in an organ-specific manner, as evidenced by distinct pattern of intracellular fibrin(ogen) depositions, elevated d-dimers, and tissue-plasminogen activator (t-PA) expression in the lungs and brains. We also found a positive correlation between progressive neuroinflammation and t-PA expression, which was closely co-localized with Iba-1-positive cells, indicating that activated microglia may serve as an additional source of t-PA in the CNS. Lastly, we showed that BA.1 variant triggered prolonged anti-Annexin A2 (ANXA2) autoantibody production. ANXA2 is essential for the neurovascular system, coordinating multiply dynamic processes within the endothelium, including cell surface fibrinolysis and TJ assembly. Our analysis revealed that impaired TJ structures coexisted with diminished ANXA2 levels around the brain vessels, suggesting its involvement in BBB dysfunction and neuroinflammation. Author SummaryLong COVID symptoms, especially neurological complications, remains a key public health concern worldwide. Alterations in the cerebrovascular system, along with ongoing coagulation disorders, may play a crucial role in the pathogenesis of this condition. Here, we established murine model for study post-acute sequela of COVID (PASC). We demonstrated that AC70 Tg mice infected with a high dose of BA.1 Omicron variant developed prolonged neurological symptoms, accompanied by progressive neuroinflammation in survivors. Our findings clearly showed the involvement of blood-brain-barrier (BBB) disfunction in the severity of neuropathology induced by SARS-CoV-2 infection. We also showed that the bidirectional interaction between dysregulated coagulation/ fibrinolysis and inflammatory systems may exhibit a distinct pattern in the CNC, significantly contributing to persistent neurological symptoms. Finally, we highlighted a potential role of malfunctioning Annexin A2 (ANXA2) in this phenomenon that may serve as a promising drug target for neuro-COVID interventions.

microbiology↗

bioRxiv2024

Characterizing neuroinvasion and neuropathology of SARS-CoV-2 by using AC70 human ACE2 transgenic mice

COVID-19 presents with a plethora of neurological signs and symptoms despite being characterized as a respiratory disease, including seizures, anxiety, depression, amnesia, attention deficits, and alterations in consciousness. The olfactory nerve is widely accepted as the neuroinvasive route by which the etiological agent SARS-CoV-2 enters the brain, but the trigeminal nerve is an often-overlooked additional route. Based on this consensus, we initially conducted a pilot experiment investigating the olfactory nerve route of SARS-CoV-2 neuroinvasion via intranasal inoculation in AC70 human ACE2 transgenic mice. Notably, we found that the trigeminal ganglion is an early and highly efficient site of viral replication, which then rapidly spread widely throughout the brain where neurons were primarily targeted. Despite the extensive viral infection across the brain, obvious evidence of tissue pathology including inflammatory infiltration, glial activation, and apoptotic cell deaths were not consistently observed, albeit inflammatory cytokines were significantly induced. However, the expression levels of different genes related to neuronal function, including the neurotransmitter dopamine pathway as well as synaptic function, and markers of neuronal damage were altered as compared to mock-infected mice. Our findings suggest that the trigeminal nerve can be a neuroinvasive route complementary to the olfactory nerve and that the ensuing neuroinvasion presented a unique neuropathological profile. This study provides insights into potential neuropathogenic mechanisms utilized by coronaviruses. IMPORTANCECOVID-19 presents with extrapulmonary signs and symptoms, the most notable of which involve the central nervous system, such as seizures and alterations in consciousness, and can eventually lead to death if severe enough. Some neurological signs and symptoms may continue to persist in some patients even after the resolution of active viral infection in the form of post-acute sequelae. Since the trigeminal nerve is a commonly under-studied route of entry into the brain in studies of coronaviruses and the neuropathogenic mechanisms of COVID-19 are not entirely elucidated, there is a need to thoroughly investigate this route of neuroinvasion. The significance of our research is in providing insights into the possible routes of SARS-CoV-2 neuroinvasion as well as the discovery of potential neuropathogenic mechanisms which may help guide the development of novel medical countermeasures.

pathology↗

bioRxiv2024

A Murine Model of Post-acute Neurological Sequelae Following SARS-CoV-2 Variant Infection

Viral variant is one known risk factor associated with post-acute sequelae of COVID-19 (PASC), yet the pathogenesis is largely unknown. Here, we studied SARS-CoV-2 Delta variant-induced PASC in K18-hACE2 mice. The virus replicated productively, induced robust inflammatory responses in lung and brain tissues, and caused weight loss and mortality during the acute infection. Longitudinal behavior studies in surviving mice up to 4 months post-acute infection revealed persistent abnormalities in neuropsychiatric state and motor behaviors, while reflex and sensory functions recovered over time. Surviving mice showed no detectable viral RNA in the brain and minimal neuroinflammation post-acute infection. Transcriptome analysis revealed persistent activation of immune pathways, including humoral responses, complement, and phagocytosis, and reduced levels of genes associated with ataxia telangiectasia, impaired cognitive function and memory recall, and neuronal dysfunction and degeneration. Furthermore, surviving mice maintained potent T helper 1 prone cellular immune responses and high neutralizing antibodies against Delta and Omicron variants in the periphery for months post-acute infection. Overall, infection in K18-hACE2 mice recapitulates the persistent clinical symptoms reported in long COVID patients and may be useful for future assessment of the efficacy of vaccines and therapeutics against SARS-CoV-2 variants.

microbiology↗

bioRxiv2023

Characterization of Unique Pathological Features of COVID-Associated Coagulopathy: Studies with AC70 hACE2 Transgenic Mice Highly Permissive to SARS-CoV-2 Infection

COVID-associated coagulopathy seemly plays a key role in post-acute sequelae of SARS-CoV-2 infection. However, the underlying pathophysiological mechanisms are poorly understood, largely due to the lack of suitable animal models that recapitulate key clinical and pathological symptoms. Here, we fully characterized AC70 line of human ACE2 transgenic (AC70 hACE2 Tg) mice for SARS-CoV-2 infection. We noted that this model is highly permissive to SARS-CoV-2 with values of 50% lethal dose and infectious dose as [~] 3 and [~] 0.5 TCID50 of SARS-CoV-2, respectively. Mice infected with 105 TCID50 of SARS-CoV-2 rapidly succumbed to infection with 100% mortality within 5 days. Lung and brain were the prime tissues harboring high viral titers, accompanied by histopathology. However, viral RNA and many inflammatory mediators could be readily detectable in other organs, suggesting the nature of a systemic infection. Lethal challenge of AC70 hACE2 Tg mice caused acute onset of leukopenia, lymphopenia, along with an increased neutrophil-to-lymphocyte ratio. Importantly, infected animals recapitulated key features of COVID-19-associated coagulopathy, including significantly elevated levels of D-dimer, t-PA, PAI-1, and circulating NETs, along with activated platelet/endothelium marker. Immunohistochemical staining with anti-PF4 antibody revealed profound platelet aggregates especially within blocked veins of the lungs. ANXA2 is known to interact with S100A10 to form heterotetrametric complexes, serving as coreceptors for t-PA to regulate membrane fibrinolysis. Thus, our results revealing elevated IgG type anti-ANXA2 antibody production, downregulated de novo ANXA2/S100A10 synthesis, and reduced AnxA2/S100A10 association in infected mice support an important role of this protein in the pathogenesis of acute COVID-19. In summary, we showed that acute SARS-CoV-2 infection of AC70 hACE2 Tg mice triggered a hypercoagulable state coexisting with ill-regulated fibrinolysis, accompanied by dysregulation of ANXA2 system, which might serve as druggable targets for development of antithrombotic and/or anti-fibrinolytic agents to attenuate pathogenesis of COVID-19. Author SummaryAccumulating evidence strongly suggests that COVID-associated coagulopathy characterized by dysregulation of the coagulation cascade, fibrinolysis system and pulmonary microvascular immune-thrombosis during different stages of SARS-CoV-2 infection may have a "yet-to-be fully defined" impact on the development of post-acute sequela of COVID-19. Herein we initially reported a comprehensively characterized AC70 hACE2 Tg mouse model for SARS-CoV-2 infection and disease. We next demonstrated the subsequent onset of imbalanced coagulation and fibrinolysis pathways in infected Tg mice, focusing on dysregulated formation of ANXA2/S100A10 complexes, key coreceptors for t-PA that regulates membrane fibrinolysis, in which elevated production of autoantibodies against ANXA2 induced by SARS-CoV-2 might play an intriguing role. Taken together, we demonstrated that AC70 hACE2 Tg mice lethally challenged with SARS-CoV-2 recapitulated several features of COVID-associated coagulopathy observed in patients and highlighted the potential role of ANXA2 in this phenomenon. Thus, ANXA2 might serve as a potentially novel druggable target to attenuate COVID-19-associated thrombotic events.

microbiology↗

bioRxiv2023

Design of SARS-CoV-2 protease inhibitors with improved affinity and reduced sensitivity to mutations

Inhibitors of the SARS-CoV-2 main protease (Mpro) such as nirmatrelvir (NTV) and ensitrelvir (ETV) have proven effective in reducing the severity of COVID-19, but the presence of resistance-conferring mutations in sequenced viral genomes raises concerns about future drug resistance. Second-generation oral drugs that retain function on these mutants are thus urgently needed. We hypothesized that the covalent HCV protease inhibitor boceprevir (BPV) could serve as the basis for orally bioavailable drugs that inhibit SARS-CoV-2 Mpro more tightly than existing drugs. Performing structure-guided modifications of BPV, we developed a picomolar-affinity inhibitor, ML2006a4, with antiviral activity, oral pharmacokinetics, and therapeutic efficacy similar or superior to NTV. A crucial feature of ML2006a4 is a novel derivatization of the ketoamide reactive group that improves cell permeability and oral bioavailability. Finally, ML2006a4 is less sensitive to several mutations that cause resistance to NTV or ETV and occur in the natural SARS-CoV-2 population. Thus, anticipatory drug design can preemptively address potential resistance mechanisms.

microbiology↗

bioRxiv2022

A pan-variant mRNA-LNP T cell vaccine protects HLA transgenic mice from mortality after infection with SARS-CoV-2 Beta

Clinically licensed COVID-19 vaccines ameliorate viral infection by inducing vaccinee production of neutralizing antibodies that bind to the SARS-CoV-2 Spike protein to inhibit viral cellular entry (Walsh et al., 2020; Baden et al., 2021), however the clinical effectiveness of these vaccines is transitory as viral variants arise that escape antibody neutralization (Tregoning et al., 2021; Willett et al., 2022). Vaccines that solely rely upon a T cell response to combat viral infection could be transformational because they can be based on highly conserved short peptide epitopes that hold the potential for pan-variant immunity, but a mRNA-LNP T cell vaccine has not been shown to be sufficient for effective antiviral prophylaxis. Here we show that a mRNA-LNP vaccine based on highly conserved short peptide epitopes activates a CD8+ and CD4+ T cell response that prevents mortality in HLA-A*02:01 transgenic mice infected with the SARS-CoV-2 Beta variant of concern (B.1.351). In mice vaccinated with the T cell vaccine, 24% of the nucleated cells in lung were CD8+ T cells on day 7 post infection. This was 5.5 times more CD8+ T cell infiltration of the lungs in response to infection compared to the Pfizer-BioNTech Comirnaty(R) vaccine. Between days 2 and 7 post infection, the number of CD8+ T cells in the lung increased in mice vaccinated with the T cell vaccine and decreased in mice vaccinated with Comirnaty(R). The T cell vaccine did not produce neutralizing antibodies, and thus our results demonstrate that SARS-CoV-2 viral infection can be controlled by a T cell response alone. Our results suggest that further study is merited for pan-variant T cell vaccines, and that T cell vaccines may be relevant for individuals that cannot produce neutralizing antibodies or to help mitigate Long COVID.

immunology↗

bioRxiv2021

Broad ultra-potent neutralization of SARS-CoV-2 variants by monoclonal antibodies specific to the tip of RBD

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) continue to wreak havoc across the globe. Higher transmissibility and immunologic resistance of VOCs bring unprecedented challenges to epidemic extinguishment. Here we describe a monoclonal antibody, 2G1, that neutralizes all current VOCs and has surprising tolerance to mutations adjacent to or within its interaction epitope. Cryo-electron microscopy structure showed that 2G1 bound to the tip of receptor binding domain (RBD) of spike protein with small contact interface but strong hydrophobic effect, which resulted in nanomolar to sub-nanomolar affinities to spike proteins. The epitope of 2G1 on RBD partially overlaps with ACE2 interface, which gives 2G1 ability to block interaction between RBD and ACE2. The narrow binding epitope but high affinity bestow outstanding therapeutic efficacy upon 2G1 that neutralized VOCs with sub-nanomolar IC50 in vitro. In SARS-CoV-2 and Beta- and Delta-variant-challenged transgenic mice and rhesus macaque models, 2G1 protected animals from clinical illness and eliminated viral burden, without serious impact to animal safety. Mutagenesis experiments suggest that 2G1 could be potentially capable of dealing with emerging SARS-CoV-2 variants in future. This report characterized the therapeutic antibodies specific to the tip of spike against SARS-CoV-2 variants and highlights the potential clinical applications as well as for developing vaccine and cocktail therapy.

cell biology↗

bioRxiv2020

Yeast-Expressed SARS-CoV Recombinant Receptor-Binding Domain (RBD219-N1) Formulated with Alum Induces Protective Immunity and Reduces Immune Enhancement

We developed a severe acute respiratory syndrome (SARS) subunit recombinant protein vaccine candidate based on a high-yielding, yeast-engineered, receptor-binding domain (RBD219-N1) of the SARS beta-coronavirus (SARS-CoV) spike (S) protein. When formulated with Alhydrogel®, RBD219-N1 induced high-level neutralizing antibodies against both pseudotyped virus and a clinical (mouse-adapted) isolate of SARS-CoV. Here, we report that mice immunized with RBD219-N1/Alhydrogel® were fully protected from lethal SARS-CoV challenge (0% mortality), compared to ∼ 30% mortality in mice when immunized with the SARS S protein formulated with Alhydrogel®, and 100% mortality in negative controls. An RBD219-N1 formulation Alhydrogel® was also superior to the S protein, unadjuvanted RBD, and AddaVax (MF59-like adjuvant)-formulated RBD in inducing specific antibodies and preventing cellular infiltrates in the lungs upon SARS-CoV challenge. Specifically, a formulation with a 1:25 ratio of RBD219-N1 to Alhydrogel® provided high neutralizing antibody titers, 100% protection with non-detectable viral loads with minimal or no eosinophilic pulmonary infiltrates. As a result, this vaccine formulation is under consideration for further development against SARS-CoV and potentially other emerging and re-emerging beta-CoVs such as SARS-CoV-2.Competing Interest StatementThe authors have declared no competing interest.View Full Text

immunology↗