Chris Chan - Academia.edu (original) (raw)

Papers by Chris Chan

Research paper thumbnail of A molecularly engineered, broad-spectrum anti-coronavirus lectin inhibits SARS-CoV-2 and MERS-CoV infection in vivo

Coronaviruses have repeatedly crossed species barriers to cause epidemics1. “Pan-coronavirus” ant... more Coronaviruses have repeatedly crossed species barriers to cause epidemics1. “Pan-coronavirus” antivirals targeting conserved viral components involved in coronavirus replication, such as the extensively glycosylated spike protein, can be designed. Here we show that the rationally engineered H84T-banana lectin (H84T-BanLec), which specifically recognizes high-mannose found on viral proteins but seldom on healthy human cells2, potently inhibits the highly virulent MERS-CoV, pandemic SARS-CoV-2 and its variants, and other human-pathogenic coronaviruses at nanomolar concentrations. MERS-CoV-infected human DPP4-transgenic mice treated by H84T-BanLec have significantly higher survival, lower viral burden, and reduced pulmonary damage. Similarly, prophylactic or therapeutic H84T-BanLec is effective against SARS-CoV-2 in hamsters. Importantly, intranasally and intraperitoneally administered H84T-BanLec are comparably effective. Time-of-drug-addition assay shows that H84T-BanLec targets viru...

Research paper thumbnail of Emerging SARS-CoV-2 variants expand species tropism to rodents

Mice are not susceptible to wildtype SARS-CoV-2 infection. Emerging SARS-CoV-2 variants including... more Mice are not susceptible to wildtype SARS-CoV-2 infection. Emerging SARS-CoV-2 variants including B.1.1.7, B.1.351, P.1, and P.3 contain mutations in spike, which have been suggested to associate with an increased recognition of mouse ACE2, raising the postulation that they may have evolved to expand species tropism to rodents. Here, we investigated the capacity of B.1.1.7 and other emerging SARS-CoV-2 variants in infecting mouse (Mus musculus) and rats (Rattus norvegicus) under in vitro and in vivo settings. Our results show that B.1.1.7 and P.3, but not B.1 or wildtype SARS-CoV-2, can utilize mouse and rat ACE2 for virus entry in vitro. High infectious virus titers, abundant viral antigen expression, and pathological changes are detected in the nasal turbinate and lung of B.1.1.7-inocluated mice and rats. Together, these results reveal that the current predominant circulating SARS-CoV-2 variant, B.1.1.7, has gained the capability to expand species tropism to rodents.

Research paper thumbnail of CL-385319 inhibits H5N1 avian influenza A virus infection by blocking viral entry

European Journal of Pharmacology, 2011

CL-385319, an N-substituted piperidine, is effective in inhibiting infection of H1-, H2-, and to ... more CL-385319, an N-substituted piperidine, is effective in inhibiting infection of H1-, H2-, and to a lesser extent, H3-typed influenza A viruses by interfering with the fusogenic function of the viral hemagglutinin. Here we show that CL-385319 is effective in inhibiting infection of highly pathogenic H5N1 influenza A virus in Madin-Darby Canine Kidney (MDCK) cells with an IC 50 of 27.03 ± 2.54 μM. This compound with low cytotoxicity (CC 50 = 1.48 ± 0.01 mM) could also inhibit entry of pseudoviruses carrying hemagglutinins from H5N1 strains that were isolated from different places at different times, while it had no inhibitory activity on the entry of VSV-G pseudotyped particles. CL385319 could not inhibit N1-typed neuraminidase activity and the adsorption of H5-typed HA to chicken erythrocytes at the concentration as high as 1 mg/ml (2.8 mM). Computer-aid molecular docking analysis suggested that CL-385319 might bind to the cavity of HA2 stem region which was known to undergo significant rearrangement during membrane fusion. Pseudoviruses with M24A mutation in HA1 or F110S mutation in HA2 were resistant to CL-385319, indicating that these two residues in the cavity region may be critical for CL-385319 bindings. These findings suggest that CL-385319 can serve as a lead for development of novel virus entry inhibitors for preventing and treating H5N1 influenza A virus infection.

Research paper thumbnail of Coronaviruses exploit a host cysteine-aspartic protease for efficient replication

Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-C... more Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1,2, Middle East respiratory syndrome coronavirus (MERS-CoV)3,4, and SARS-CoV-15 vary in their transmissibility and pathogenicity. However, infection by all three viruses result in substantial apoptosis in cell culture6-8 and in patient samples9-11, suggesting a potential link between apoptosis and the pathogenesis of coronaviruses. To date, the underlying mechanism of how apoptosis modulates coronavirus pathogenesis is unknown. Here we show that a cysteine-aspartic protease of the apoptosis cascade, caspase-6, serves as an essential host factor for efficient coronavirus replication. We demonstrate that caspase-6 cleaves coronavirus nucleocapsid (N) proteins, generating N fragments that serve as interferon (IFN) antagonists, thus facilitating virus replication. Inhibition of caspase-6 substantially attenuates the lung pathology and body weight loss of SARS-CoV-2-infected golden Syri...

Research paper thumbnail of Coronaviruses exploit a host cysteine-aspartic protease for efficient replication

Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-C... more Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1,2, Middle East respiratory syndrome coronavirus (MERS-CoV)3,4, and SARS-CoV-15 vary in their transmissibility and pathogenicity. However, infection by all three viruses result in substantial apoptosis in cell culture6-8 and in patient samples9-11, suggesting a potential link between apoptosis and the pathogenesis of coronaviruses. To date, the underlying mechanism of how apoptosis modulates coronavirus pathogenesis is unknown. Here we show that a cysteine-aspartic protease of the apoptosis cascade, caspase-6, serves as an essential host factor for efficient coronavirus replication. We demonstrate that caspase-6 cleaves coronavirus nucleocapsid (N) proteins, generating N fragments that serve as interferon (IFN) antagonists, thus facilitating virus replication. Inhibition of caspase-6 substantially attenuates the lung pathology and body weight loss of SARS-CoV-2-infected golden Syri...

Research paper thumbnail of Cross-linking peptide and repurposed drugs inhibit both entry pathways of SARS-CoV-2

Nature Communications, 2021

Up to date, effective antivirals have not been widely available for treating COVID-19. In this st... more Up to date, effective antivirals have not been widely available for treating COVID-19. In this study, we identify a dual-functional cross-linking peptide 8P9R which can inhibit the two entry pathways (endocytic pathway and TMPRSS2-mediated surface pathway) of SARS-CoV-2 in cells. The endosomal acidification inhibitors (8P9R and chloroquine) can synergistically enhance the activity of arbidol, a spike-ACE2 fusion inhibitor, against SARS-CoV-2 and SARS-CoV in cells. In vivo studies indicate that 8P9R or the combination of repurposed drugs (umifenovir also known as arbidol, chloroquine and camostat which is a TMPRSS2 inhibitor), simultaneously interfering with the two entry pathways of coronaviruses, can significantly suppress SARS-CoV-2 replication in hamsters and SARS-CoV in mice. Here, we use drug combination (arbidol, chloroquine, and camostat) and a dual-functional 8P9R to demonstrate that blocking the two entry pathways of coronavirus can be a promising and achievable approach fo...

Research paper thumbnail of Cross-linking peptide and repurposed drugs inhibit both entry pathways of SARS-CoV-2

Nature Communications, 2021

Up to date, effective antivirals have not been widely available for treating COVID-19. In this st... more Up to date, effective antivirals have not been widely available for treating COVID-19. In this study, we identify a dual-functional cross-linking peptide 8P9R which can inhibit the two entry pathways (endocytic pathway and TMPRSS2-mediated surface pathway) of SARS-CoV-2 in cells. The endosomal acidification inhibitors (8P9R and chloroquine) can synergistically enhance the activity of arbidol, a spike-ACE2 fusion inhibitor, against SARS-CoV-2 and SARS-CoV in cells. In vivo studies indicate that 8P9R or the combination of repurposed drugs (umifenovir also known as arbidol, chloroquine and camostat which is a TMPRSS2 inhibitor), simultaneously interfering with the two entry pathways of coronaviruses, can significantly suppress SARS-CoV-2 replication in hamsters and SARS-CoV in mice. Here, we use drug combination (arbidol, chloroquine, and camostat) and a dual-functional 8P9R to demonstrate that blocking the two entry pathways of coronavirus can be a promising and achievable approach fo...

Research paper thumbnail of Immunization with a Novel Human type 5 Adenovirus-Vectored Vaccine Expressing the Premembrane and Envelope Proteins of Zika Virus Provides Consistent and Sterilizing Protection in Multiple Immunocompetent and Immunocompromised Animal Models

The Journal of infectious diseases, Jan 29, 2018

Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both... more Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both vector-borne and non-vector-borne routes. Adenovirus-vectored vaccines represent a favorable controlling measure for the ZIKV epidemic as they have been shown to be safe, immunogenic, and rapidly generable for other emerging viral infections. Evaluations of two previously reported adenovirus-vectored ZIKV vaccines were performed using non-lethal animal models and/or non-epidemic ZIKV strain. We constructed and evaluated two human adenovirus-5-vectored vaccines containing the ZIKV premembrane-envelope(Ad5-Sig-prM-Env) and envelope(Ad5-Env) proteins, respectively, in multiple non-lethal and lethal animal models using epidemic ZIKV strains. Both vaccines elicited robust humoral and cellular immune responses in immunocompetent BALB/c mice. Dexamethasone-immunosuppressed mice vaccinated with either vaccine demonstrated robust and durable antibody responses and significantly lower blood/tissu...

Research paper thumbnail of The celecoxib derivative kinase inhibitor AR-12 (OSU-03012) inhibits Zika virus via down-regulation of the PI3K/Akt pathway and protects Zika virus-infected A129 mice: A host-targeting treatment strategy

Antiviral research, Jan 13, 2018

Zika virus (ZIKV) is a human-pathogenic flavivirus that has recently emerged as a global public h... more Zika virus (ZIKV) is a human-pathogenic flavivirus that has recently emerged as a global public health threat. ZIKV infection may be associated with congenital malformations in infected fetuses and severe neurological and systemic complications in infected adults. There are currently limited treatment options for ZIKV infection. AR-12 (OSU-03012) is a celecoxib derivative cellular kinase inhibitor that has broad-spectrum antiviral activities. In this study, we investigated the antiviral activity and mechanism of AR-12 against ZIKV. We evaluated the in vitro anti-ZIKV activity of AR-12, using cell protection and virus yield reduction assays, in multiple clinically relevant cell lines, and the in vivo treatment effects of AR-12 in a lethal mouse model using type I interferon receptor-deficient A129 mice. AR-12 inhibited ZIKV strains belonging to both the African and Asian/American lineages in Huh-7 and/or neuronal cells. AR12's IC against ZIKV was consistently <2 μM in these ce...

Research paper thumbnail of Priming with rAAV encoding RBD of SARS-CoV S protein and boosting with RBD-specific peptides for T cell epitopes elevated humoral and cellular immune responses against SARS-CoV infection

Vaccine, 2008

Development of vaccines against severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) i... more Development of vaccines against severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) is crucial in the prevention of SARS reemergence. The receptor-binding domain (RBD) of SARS-CoV spike (S) protein is an important target in developing safe and effective SARS vaccines. Our previous study has demonstrated that vaccination with adenoassociated virus encoding RBD (RBD-rAAV) induces high titer of neutralizing antibodies. In this study, we further assessed the immune responses and protective effect of the immunization with RBD-rAAV prime/RBD-specific T cell peptide boost. Compared with the RBD-rAAV prime/boost vaccination, RBD-rAAV prime/RBD-peptide (RBD-Pep) boost induced similar levels of Th1 and neutralizing antibody responses that protected the vaccinated mice from subsequent SARS-CoV challenge, but stronger Th2 and CTL responses. No significant immune responses and protective effects were detected in mice vaccinated with RBD-Pep or blank AAV alone. Since T cell epitopes are highly conserved and boosting with peptides may induce the production of effector memory T cells, which may be effective against viruses with mutations in the neutralizing epitopes, our results suggest that the vaccination protocol used may be ideal for providing effective, broad and long-term protection against SARS-CoV infection.

Research paper thumbnail of Delayed antiviral plus immunomodulator treatment still reduces mortality in mice infected by high inoculum of influenza A/H5N1 virus

Proceedings of the National Academy of Sciences, 2008

The mortality of human infection by influenza A/H5N1 virus can exceed 80%. The high mortality and... more The mortality of human infection by influenza A/H5N1 virus can exceed 80%. The high mortality and its poor response to the neuraminidase inhibitor oseltamivir have been attributed to uncontrolled virus-induced cytokine storm. We challenged BALB/c mice with 1,000 LD 50 of influenza A/Vietnam/1194/04. Survival, body weight, histopathology, inflammatory markers, viral loads, T lymphocyte counts, and neutralizing antibody response were documented in infected mice treated individually or in combination with zanamvir, celecoxib, gemfibrozil, and mesalazine. To imitate the real-life scenario, treatment was initiated at 48 h after viral challenge. There were significant improvements in survival rate ( P = 0.02), survival time ( P < 0.02), and inflammatory markers ( P < 0.01) in the group treated with a triple combination of zanamivir, celecoxib, and mesalazine when compared with zanamivir alone. Zanamivir with or without immunomodulators reduced viral load to a similar extent. Insigni...

Research paper thumbnail of Immunization with a Novel Human type 5 Adenovirus-Vectored Vaccine Expressing the Premembrane and Envelope Proteins of Zika Virus Provides Consistent and Sterilizing Protection in Multiple Immunocompetent and Immunocompromised Animal Models

The Journal of infectious diseases, Jan 29, 2018

Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both... more Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both vector-borne and non-vector-borne routes. Adenovirus-vectored vaccines represent a favorable controlling measure for the ZIKV epidemic as they have been shown to be safe, immunogenic, and rapidly generable for other emerging viral infections. Evaluations of two previously reported adenovirus-vectored ZIKV vaccines were performed using non-lethal animal models and/or non-epidemic ZIKV strain. We constructed and evaluated two human adenovirus-5-vectored vaccines containing the ZIKV premembrane-envelope(Ad5-Sig-prM-Env) and envelope(Ad5-Env) proteins, respectively, in multiple non-lethal and lethal animal models using epidemic ZIKV strains. Both vaccines elicited robust humoral and cellular immune responses in immunocompetent BALB/c mice. Dexamethasone-immunosuppressed mice vaccinated with either vaccine demonstrated robust and durable antibody responses and significantly lower blood/tissu...

Research paper thumbnail of Improved detection of Zika virus RNA in human and animal specimens by a novel, highly sensitive and specific real-time RT-PCR assay targeting the 5'-untranslated region of Zika virus

Tropical medicine & international health : TM & IH, May 18, 2017

We developed and evaluated five novel real-time RT-PCR assays targeting conserved regions in the ... more We developed and evaluated five novel real-time RT-PCR assays targeting conserved regions in the 5'-untranslated region (5'-UTR), envelope (E'), non-structural protein 2A (NS2A), NS5, and 3'-UTR of the ZIKV genome. The ZIKV-5'-UTR assay exhibited the lowest in-vitro limit of detection (5-10 RNA copies/reaction and 3.0×10(-1) plaque-forming units/ml). Compared to the modified version of a widely adopted RT-PCR assay targeting the ZIKV-E gene, the ZIKV-5'-UTR assay showed better sensitivity in human clinical specimens, and representative mouse specimens, including many organs which are known to be involved in human ZIKV infection but difficult to obtain in clinical settings. The ZIKV-5'-UTR assay detected ZIKV RNA in 84/84 (100.0%) ZIKV-E'-positive and an additional 30/296 (10.1%, P<0.01) ZIKV-E'-negative mouse specimens. The higher sensitivity of the ZIKV-5'-UTR assay was most significant in kidney and testis/epididymis specimens (P<0.01)...

Research paper thumbnail of Intranasal vaccination of recombinant adeno-associated virus encoding receptor-binding domain of severe acute respiratory syndrome coronavirus (SARS-CoV) spike …

The Journal of …, 2008

We have previously reported that a subunit protein vaccine based on the receptor-binding domain (... more We have previously reported that a subunit protein vaccine based on the receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus (SARS-CoV) spike protein and a recombinant adeno-associated virus (rAAV)-based RBD (RBD-rAAV) vaccine could induce highly ...

Research paper thumbnail of Zika Virus Infection in Dexamethasone-immunosuppressed Mice Demonstrating Disseminated Infection with Multi-organ Involvement Including Orchitis Effectively Treated by Recombinant Type I Interferons

EBioMedicine, 2016

Disseminated or fatal Zika virus (ZIKV) infections were reported in immunosuppressed patients. Ex... more Disseminated or fatal Zika virus (ZIKV) infections were reported in immunosuppressed patients. Existing interferon-signaling/receptor-deficient mouse models may not be suitable for evaluating treatment effects of recombinant interferons. We developed a novel mouse model for ZIKV infection by immunosuppressing BALB/c mice with dexamethasone. Dexamethasone-immunosuppressed male mice (6-8weeks) developed disseminated infection as evidenced by the detection of ZIKV-NS1 protein expression and high viral loads in multiple organs. They had ≥10% weight loss and high clinical scores soon after dexamethasone withdrawal (10dpi), which warranted euthanasia at 12dpi. Viral loads in blood and most tissues at 5dpi were significantly higher than those at 12dpi (P<0.05). Histological examination revealed prominent inflammatory infiltrates in multiple organs, and CD45+ and CD8+ inflammatory cells were seen in the testis. These findings suggested that clinical deterioration occurred during viral cl...

Research paper thumbnail of Differential cell line susceptibility to the emerging Zika virus: implications for disease pathogenesis, non-vector-borne human transmission and animal reservoirs

Emerging microbes & infections, Jan 24, 2016

Zika virus (ZIKV) is unique among human-pathogenic flaviviruses by its association with congenita... more Zika virus (ZIKV) is unique among human-pathogenic flaviviruses by its association with congenital anomalies and trans-placental and sexual human-to-human transmission. Although the pathogenesis of ZIKV-associated neurological complications has been reported in recent studies, key questions on the pathogenesis of the other clinical manifestations, non-vector-borne transmission and potential animal reservoirs of ZIKV remain unanswered. We systematically characterized the differential cell line susceptibility of 18 human and 15 nonhuman cell lines to two ZIKV isolates (human and primate) and dengue virus type 2 (DENV-2). Productive ZIKV replication (⩾2 log increase in viral load, ZIKV nonstructural protein-1 (NS1) protein expression and cytopathic effects (CPE)) was found in the placental (JEG-3), neuronal (SF268), muscle (RD), retinal (ARPE19), pulmonary (Hep-2 and HFL), colonic (Caco-2),and hepatic (Huh-7) cell lines. These findings helped to explain the trans-placental transmission...

Research paper thumbnail of A novel peptide with potent and broad-spectrum antiviral activities against multiple respiratory viruses

Scientific reports, Jan 25, 2016

A safe, potent and broad-spectrum antiviral is urgently needed to combat emerging respiratory vir... more A safe, potent and broad-spectrum antiviral is urgently needed to combat emerging respiratory viruses. In light of the broad antiviral activity of β-defensins, we tested the antiviral activity of 11 peptides derived from mouse β-defensin-4 and found that a short peptide, P9, exhibited potent and broad-spectrum antiviral effects against multiple respiratory viruses in vitro and in vivo, including influenza A virus H1N1, H3N2, H5N1, H7N7, H7N9, SARS-CoV and MERS-CoV. The antiviral activity of P9 was attributed to its high-affinity binding to viral glycoproteins, as well as the abundance of basic amino acids in its composition. After binding viral particles through viral surface glycoproteins, P9 entered into cells together with the viruses via endocytosis and prevented endosomal acidification, which blocked membrane fusion and subsequent viral RNA release. This study has paved the avenue for developing new prophylactic and therapeutic agents with broad-spectrum antiviral activities.

Research paper thumbnail of An H5N1-based matrix protein 2 ectodomain tetrameric peptide vaccine provides cross-protection against lethal infection with H7N9 influenza virus

Emerging Microbes & Infections, 2015

In March 2013, a patient infected with a novel avian influenza A H7N9 virus was reported in China... more In March 2013, a patient infected with a novel avian influenza A H7N9 virus was reported in China. Since then, there have been 458 confirmed infection cases and 177 deaths. The virus contains several human-adapted markers, indicating that H7N9 has pandemic potential. The outbreak of this new influenza virus highlighted the need for the development of universal influenza vaccines. Previously, we demonstrated that a tetrameric peptide vaccine based on the matrix protein 2 ectodomain (M2e) of the H5N1 virus (H5N1-M2e) could protect mice from lethal infection with different clades of H5N1 and 2009 pandemic H1N1 influenza viruses. In this study, we investigated the cross-protection of H5N1-M2e against lethal infection with the new H7N9 virus. Although five amino acid differences existed at positions 13, 14, 18, 20, and 21 between M2e of H5N1 and H7N9, H5N1-M2e vaccination with either Freund's adjuvant or the Sigma adjuvant system (SAS) induced a high level of anti-M2e antibody, which cross-reacted with H7N9-M2e peptide. A mouse-adapted H7N9 strain, A/Anhui/01/2013m, was used for lethal challenge in animal experiments. H5N1-M2e vaccination provided potent cross-protection against lethal challenge of the H7N9 virus. Reduced viral replication and histopathological damage of mouse lungs were also observed in the vaccinated mice. Our results suggest that the tetrameric H5N1-M2e peptide vaccine could protect against different subtypes of influenza virus infections. Therefore, this vaccine may be an ideal candidate for developing a universal vaccine to prevent the reemergence of avian influenza A H7N9 virus and the emergence of potential novel reassortants of influenza virus.

Research paper thumbnail of A critical role of IL-17 in modulating the B-cell response during H5N1 influenza virus infection

Cellular & Molecular …, 2011

Cellular and Molecular Immunology aims to report the dynamic progress being made in China and abr... more Cellular and Molecular Immunology aims to report the dynamic progress being made in China and abroad in immunological research, and welcomes high-quality Research Articles, Reviews and Brief Reports across a broad range of topics including, but not limited to, clinical immunology ...

Research paper thumbnail of A 219-mer CHO-Expressing Receptor-Binding Domain of SARS-CoV S Protein Induces Potent Immune Responses and Protective Immunity

Viral …, 2010

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Research paper thumbnail of A molecularly engineered, broad-spectrum anti-coronavirus lectin inhibits SARS-CoV-2 and MERS-CoV infection in vivo

Coronaviruses have repeatedly crossed species barriers to cause epidemics1. “Pan-coronavirus” ant... more Coronaviruses have repeatedly crossed species barriers to cause epidemics1. “Pan-coronavirus” antivirals targeting conserved viral components involved in coronavirus replication, such as the extensively glycosylated spike protein, can be designed. Here we show that the rationally engineered H84T-banana lectin (H84T-BanLec), which specifically recognizes high-mannose found on viral proteins but seldom on healthy human cells2, potently inhibits the highly virulent MERS-CoV, pandemic SARS-CoV-2 and its variants, and other human-pathogenic coronaviruses at nanomolar concentrations. MERS-CoV-infected human DPP4-transgenic mice treated by H84T-BanLec have significantly higher survival, lower viral burden, and reduced pulmonary damage. Similarly, prophylactic or therapeutic H84T-BanLec is effective against SARS-CoV-2 in hamsters. Importantly, intranasally and intraperitoneally administered H84T-BanLec are comparably effective. Time-of-drug-addition assay shows that H84T-BanLec targets viru...

Research paper thumbnail of Emerging SARS-CoV-2 variants expand species tropism to rodents

Mice are not susceptible to wildtype SARS-CoV-2 infection. Emerging SARS-CoV-2 variants including... more Mice are not susceptible to wildtype SARS-CoV-2 infection. Emerging SARS-CoV-2 variants including B.1.1.7, B.1.351, P.1, and P.3 contain mutations in spike, which have been suggested to associate with an increased recognition of mouse ACE2, raising the postulation that they may have evolved to expand species tropism to rodents. Here, we investigated the capacity of B.1.1.7 and other emerging SARS-CoV-2 variants in infecting mouse (Mus musculus) and rats (Rattus norvegicus) under in vitro and in vivo settings. Our results show that B.1.1.7 and P.3, but not B.1 or wildtype SARS-CoV-2, can utilize mouse and rat ACE2 for virus entry in vitro. High infectious virus titers, abundant viral antigen expression, and pathological changes are detected in the nasal turbinate and lung of B.1.1.7-inocluated mice and rats. Together, these results reveal that the current predominant circulating SARS-CoV-2 variant, B.1.1.7, has gained the capability to expand species tropism to rodents.

Research paper thumbnail of CL-385319 inhibits H5N1 avian influenza A virus infection by blocking viral entry

European Journal of Pharmacology, 2011

CL-385319, an N-substituted piperidine, is effective in inhibiting infection of H1-, H2-, and to ... more CL-385319, an N-substituted piperidine, is effective in inhibiting infection of H1-, H2-, and to a lesser extent, H3-typed influenza A viruses by interfering with the fusogenic function of the viral hemagglutinin. Here we show that CL-385319 is effective in inhibiting infection of highly pathogenic H5N1 influenza A virus in Madin-Darby Canine Kidney (MDCK) cells with an IC 50 of 27.03 ± 2.54 μM. This compound with low cytotoxicity (CC 50 = 1.48 ± 0.01 mM) could also inhibit entry of pseudoviruses carrying hemagglutinins from H5N1 strains that were isolated from different places at different times, while it had no inhibitory activity on the entry of VSV-G pseudotyped particles. CL385319 could not inhibit N1-typed neuraminidase activity and the adsorption of H5-typed HA to chicken erythrocytes at the concentration as high as 1 mg/ml (2.8 mM). Computer-aid molecular docking analysis suggested that CL-385319 might bind to the cavity of HA2 stem region which was known to undergo significant rearrangement during membrane fusion. Pseudoviruses with M24A mutation in HA1 or F110S mutation in HA2 were resistant to CL-385319, indicating that these two residues in the cavity region may be critical for CL-385319 bindings. These findings suggest that CL-385319 can serve as a lead for development of novel virus entry inhibitors for preventing and treating H5N1 influenza A virus infection.

Research paper thumbnail of Coronaviruses exploit a host cysteine-aspartic protease for efficient replication

Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-C... more Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1,2, Middle East respiratory syndrome coronavirus (MERS-CoV)3,4, and SARS-CoV-15 vary in their transmissibility and pathogenicity. However, infection by all three viruses result in substantial apoptosis in cell culture6-8 and in patient samples9-11, suggesting a potential link between apoptosis and the pathogenesis of coronaviruses. To date, the underlying mechanism of how apoptosis modulates coronavirus pathogenesis is unknown. Here we show that a cysteine-aspartic protease of the apoptosis cascade, caspase-6, serves as an essential host factor for efficient coronavirus replication. We demonstrate that caspase-6 cleaves coronavirus nucleocapsid (N) proteins, generating N fragments that serve as interferon (IFN) antagonists, thus facilitating virus replication. Inhibition of caspase-6 substantially attenuates the lung pathology and body weight loss of SARS-CoV-2-infected golden Syri...

Research paper thumbnail of Coronaviruses exploit a host cysteine-aspartic protease for efficient replication

Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-C... more Highly pathogenic coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1,2, Middle East respiratory syndrome coronavirus (MERS-CoV)3,4, and SARS-CoV-15 vary in their transmissibility and pathogenicity. However, infection by all three viruses result in substantial apoptosis in cell culture6-8 and in patient samples9-11, suggesting a potential link between apoptosis and the pathogenesis of coronaviruses. To date, the underlying mechanism of how apoptosis modulates coronavirus pathogenesis is unknown. Here we show that a cysteine-aspartic protease of the apoptosis cascade, caspase-6, serves as an essential host factor for efficient coronavirus replication. We demonstrate that caspase-6 cleaves coronavirus nucleocapsid (N) proteins, generating N fragments that serve as interferon (IFN) antagonists, thus facilitating virus replication. Inhibition of caspase-6 substantially attenuates the lung pathology and body weight loss of SARS-CoV-2-infected golden Syri...

Research paper thumbnail of Cross-linking peptide and repurposed drugs inhibit both entry pathways of SARS-CoV-2

Nature Communications, 2021

Up to date, effective antivirals have not been widely available for treating COVID-19. In this st... more Up to date, effective antivirals have not been widely available for treating COVID-19. In this study, we identify a dual-functional cross-linking peptide 8P9R which can inhibit the two entry pathways (endocytic pathway and TMPRSS2-mediated surface pathway) of SARS-CoV-2 in cells. The endosomal acidification inhibitors (8P9R and chloroquine) can synergistically enhance the activity of arbidol, a spike-ACE2 fusion inhibitor, against SARS-CoV-2 and SARS-CoV in cells. In vivo studies indicate that 8P9R or the combination of repurposed drugs (umifenovir also known as arbidol, chloroquine and camostat which is a TMPRSS2 inhibitor), simultaneously interfering with the two entry pathways of coronaviruses, can significantly suppress SARS-CoV-2 replication in hamsters and SARS-CoV in mice. Here, we use drug combination (arbidol, chloroquine, and camostat) and a dual-functional 8P9R to demonstrate that blocking the two entry pathways of coronavirus can be a promising and achievable approach fo...

Research paper thumbnail of Cross-linking peptide and repurposed drugs inhibit both entry pathways of SARS-CoV-2

Nature Communications, 2021

Up to date, effective antivirals have not been widely available for treating COVID-19. In this st... more Up to date, effective antivirals have not been widely available for treating COVID-19. In this study, we identify a dual-functional cross-linking peptide 8P9R which can inhibit the two entry pathways (endocytic pathway and TMPRSS2-mediated surface pathway) of SARS-CoV-2 in cells. The endosomal acidification inhibitors (8P9R and chloroquine) can synergistically enhance the activity of arbidol, a spike-ACE2 fusion inhibitor, against SARS-CoV-2 and SARS-CoV in cells. In vivo studies indicate that 8P9R or the combination of repurposed drugs (umifenovir also known as arbidol, chloroquine and camostat which is a TMPRSS2 inhibitor), simultaneously interfering with the two entry pathways of coronaviruses, can significantly suppress SARS-CoV-2 replication in hamsters and SARS-CoV in mice. Here, we use drug combination (arbidol, chloroquine, and camostat) and a dual-functional 8P9R to demonstrate that blocking the two entry pathways of coronavirus can be a promising and achievable approach fo...

Research paper thumbnail of Immunization with a Novel Human type 5 Adenovirus-Vectored Vaccine Expressing the Premembrane and Envelope Proteins of Zika Virus Provides Consistent and Sterilizing Protection in Multiple Immunocompetent and Immunocompromised Animal Models

The Journal of infectious diseases, Jan 29, 2018

Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both... more Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both vector-borne and non-vector-borne routes. Adenovirus-vectored vaccines represent a favorable controlling measure for the ZIKV epidemic as they have been shown to be safe, immunogenic, and rapidly generable for other emerging viral infections. Evaluations of two previously reported adenovirus-vectored ZIKV vaccines were performed using non-lethal animal models and/or non-epidemic ZIKV strain. We constructed and evaluated two human adenovirus-5-vectored vaccines containing the ZIKV premembrane-envelope(Ad5-Sig-prM-Env) and envelope(Ad5-Env) proteins, respectively, in multiple non-lethal and lethal animal models using epidemic ZIKV strains. Both vaccines elicited robust humoral and cellular immune responses in immunocompetent BALB/c mice. Dexamethasone-immunosuppressed mice vaccinated with either vaccine demonstrated robust and durable antibody responses and significantly lower blood/tissu...

Research paper thumbnail of The celecoxib derivative kinase inhibitor AR-12 (OSU-03012) inhibits Zika virus via down-regulation of the PI3K/Akt pathway and protects Zika virus-infected A129 mice: A host-targeting treatment strategy

Antiviral research, Jan 13, 2018

Zika virus (ZIKV) is a human-pathogenic flavivirus that has recently emerged as a global public h... more Zika virus (ZIKV) is a human-pathogenic flavivirus that has recently emerged as a global public health threat. ZIKV infection may be associated with congenital malformations in infected fetuses and severe neurological and systemic complications in infected adults. There are currently limited treatment options for ZIKV infection. AR-12 (OSU-03012) is a celecoxib derivative cellular kinase inhibitor that has broad-spectrum antiviral activities. In this study, we investigated the antiviral activity and mechanism of AR-12 against ZIKV. We evaluated the in vitro anti-ZIKV activity of AR-12, using cell protection and virus yield reduction assays, in multiple clinically relevant cell lines, and the in vivo treatment effects of AR-12 in a lethal mouse model using type I interferon receptor-deficient A129 mice. AR-12 inhibited ZIKV strains belonging to both the African and Asian/American lineages in Huh-7 and/or neuronal cells. AR12's IC against ZIKV was consistently <2 μM in these ce...

Research paper thumbnail of Priming with rAAV encoding RBD of SARS-CoV S protein and boosting with RBD-specific peptides for T cell epitopes elevated humoral and cellular immune responses against SARS-CoV infection

Vaccine, 2008

Development of vaccines against severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) i... more Development of vaccines against severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) is crucial in the prevention of SARS reemergence. The receptor-binding domain (RBD) of SARS-CoV spike (S) protein is an important target in developing safe and effective SARS vaccines. Our previous study has demonstrated that vaccination with adenoassociated virus encoding RBD (RBD-rAAV) induces high titer of neutralizing antibodies. In this study, we further assessed the immune responses and protective effect of the immunization with RBD-rAAV prime/RBD-specific T cell peptide boost. Compared with the RBD-rAAV prime/boost vaccination, RBD-rAAV prime/RBD-peptide (RBD-Pep) boost induced similar levels of Th1 and neutralizing antibody responses that protected the vaccinated mice from subsequent SARS-CoV challenge, but stronger Th2 and CTL responses. No significant immune responses and protective effects were detected in mice vaccinated with RBD-Pep or blank AAV alone. Since T cell epitopes are highly conserved and boosting with peptides may induce the production of effector memory T cells, which may be effective against viruses with mutations in the neutralizing epitopes, our results suggest that the vaccination protocol used may be ideal for providing effective, broad and long-term protection against SARS-CoV infection.

Research paper thumbnail of Delayed antiviral plus immunomodulator treatment still reduces mortality in mice infected by high inoculum of influenza A/H5N1 virus

Proceedings of the National Academy of Sciences, 2008

The mortality of human infection by influenza A/H5N1 virus can exceed 80%. The high mortality and... more The mortality of human infection by influenza A/H5N1 virus can exceed 80%. The high mortality and its poor response to the neuraminidase inhibitor oseltamivir have been attributed to uncontrolled virus-induced cytokine storm. We challenged BALB/c mice with 1,000 LD 50 of influenza A/Vietnam/1194/04. Survival, body weight, histopathology, inflammatory markers, viral loads, T lymphocyte counts, and neutralizing antibody response were documented in infected mice treated individually or in combination with zanamvir, celecoxib, gemfibrozil, and mesalazine. To imitate the real-life scenario, treatment was initiated at 48 h after viral challenge. There were significant improvements in survival rate ( P = 0.02), survival time ( P < 0.02), and inflammatory markers ( P < 0.01) in the group treated with a triple combination of zanamivir, celecoxib, and mesalazine when compared with zanamivir alone. Zanamivir with or without immunomodulators reduced viral load to a similar extent. Insigni...

Research paper thumbnail of Immunization with a Novel Human type 5 Adenovirus-Vectored Vaccine Expressing the Premembrane and Envelope Proteins of Zika Virus Provides Consistent and Sterilizing Protection in Multiple Immunocompetent and Immunocompromised Animal Models

The Journal of infectious diseases, Jan 29, 2018

Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both... more Zika virus (ZIKV) infection may be associated with severe complications and disseminated via both vector-borne and non-vector-borne routes. Adenovirus-vectored vaccines represent a favorable controlling measure for the ZIKV epidemic as they have been shown to be safe, immunogenic, and rapidly generable for other emerging viral infections. Evaluations of two previously reported adenovirus-vectored ZIKV vaccines were performed using non-lethal animal models and/or non-epidemic ZIKV strain. We constructed and evaluated two human adenovirus-5-vectored vaccines containing the ZIKV premembrane-envelope(Ad5-Sig-prM-Env) and envelope(Ad5-Env) proteins, respectively, in multiple non-lethal and lethal animal models using epidemic ZIKV strains. Both vaccines elicited robust humoral and cellular immune responses in immunocompetent BALB/c mice. Dexamethasone-immunosuppressed mice vaccinated with either vaccine demonstrated robust and durable antibody responses and significantly lower blood/tissu...

Research paper thumbnail of Improved detection of Zika virus RNA in human and animal specimens by a novel, highly sensitive and specific real-time RT-PCR assay targeting the 5'-untranslated region of Zika virus

Tropical medicine & international health : TM & IH, May 18, 2017

We developed and evaluated five novel real-time RT-PCR assays targeting conserved regions in the ... more We developed and evaluated five novel real-time RT-PCR assays targeting conserved regions in the 5'-untranslated region (5'-UTR), envelope (E'), non-structural protein 2A (NS2A), NS5, and 3'-UTR of the ZIKV genome. The ZIKV-5'-UTR assay exhibited the lowest in-vitro limit of detection (5-10 RNA copies/reaction and 3.0×10(-1) plaque-forming units/ml). Compared to the modified version of a widely adopted RT-PCR assay targeting the ZIKV-E gene, the ZIKV-5'-UTR assay showed better sensitivity in human clinical specimens, and representative mouse specimens, including many organs which are known to be involved in human ZIKV infection but difficult to obtain in clinical settings. The ZIKV-5'-UTR assay detected ZIKV RNA in 84/84 (100.0%) ZIKV-E'-positive and an additional 30/296 (10.1%, P<0.01) ZIKV-E'-negative mouse specimens. The higher sensitivity of the ZIKV-5'-UTR assay was most significant in kidney and testis/epididymis specimens (P<0.01)...

Research paper thumbnail of Intranasal vaccination of recombinant adeno-associated virus encoding receptor-binding domain of severe acute respiratory syndrome coronavirus (SARS-CoV) spike …

The Journal of …, 2008

We have previously reported that a subunit protein vaccine based on the receptor-binding domain (... more We have previously reported that a subunit protein vaccine based on the receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus (SARS-CoV) spike protein and a recombinant adeno-associated virus (rAAV)-based RBD (RBD-rAAV) vaccine could induce highly ...

Research paper thumbnail of Zika Virus Infection in Dexamethasone-immunosuppressed Mice Demonstrating Disseminated Infection with Multi-organ Involvement Including Orchitis Effectively Treated by Recombinant Type I Interferons

EBioMedicine, 2016

Disseminated or fatal Zika virus (ZIKV) infections were reported in immunosuppressed patients. Ex... more Disseminated or fatal Zika virus (ZIKV) infections were reported in immunosuppressed patients. Existing interferon-signaling/receptor-deficient mouse models may not be suitable for evaluating treatment effects of recombinant interferons. We developed a novel mouse model for ZIKV infection by immunosuppressing BALB/c mice with dexamethasone. Dexamethasone-immunosuppressed male mice (6-8weeks) developed disseminated infection as evidenced by the detection of ZIKV-NS1 protein expression and high viral loads in multiple organs. They had ≥10% weight loss and high clinical scores soon after dexamethasone withdrawal (10dpi), which warranted euthanasia at 12dpi. Viral loads in blood and most tissues at 5dpi were significantly higher than those at 12dpi (P<0.05). Histological examination revealed prominent inflammatory infiltrates in multiple organs, and CD45+ and CD8+ inflammatory cells were seen in the testis. These findings suggested that clinical deterioration occurred during viral cl...

Research paper thumbnail of Differential cell line susceptibility to the emerging Zika virus: implications for disease pathogenesis, non-vector-borne human transmission and animal reservoirs

Emerging microbes & infections, Jan 24, 2016

Zika virus (ZIKV) is unique among human-pathogenic flaviviruses by its association with congenita... more Zika virus (ZIKV) is unique among human-pathogenic flaviviruses by its association with congenital anomalies and trans-placental and sexual human-to-human transmission. Although the pathogenesis of ZIKV-associated neurological complications has been reported in recent studies, key questions on the pathogenesis of the other clinical manifestations, non-vector-borne transmission and potential animal reservoirs of ZIKV remain unanswered. We systematically characterized the differential cell line susceptibility of 18 human and 15 nonhuman cell lines to two ZIKV isolates (human and primate) and dengue virus type 2 (DENV-2). Productive ZIKV replication (⩾2 log increase in viral load, ZIKV nonstructural protein-1 (NS1) protein expression and cytopathic effects (CPE)) was found in the placental (JEG-3), neuronal (SF268), muscle (RD), retinal (ARPE19), pulmonary (Hep-2 and HFL), colonic (Caco-2),and hepatic (Huh-7) cell lines. These findings helped to explain the trans-placental transmission...

Research paper thumbnail of A novel peptide with potent and broad-spectrum antiviral activities against multiple respiratory viruses

Scientific reports, Jan 25, 2016

A safe, potent and broad-spectrum antiviral is urgently needed to combat emerging respiratory vir... more A safe, potent and broad-spectrum antiviral is urgently needed to combat emerging respiratory viruses. In light of the broad antiviral activity of β-defensins, we tested the antiviral activity of 11 peptides derived from mouse β-defensin-4 and found that a short peptide, P9, exhibited potent and broad-spectrum antiviral effects against multiple respiratory viruses in vitro and in vivo, including influenza A virus H1N1, H3N2, H5N1, H7N7, H7N9, SARS-CoV and MERS-CoV. The antiviral activity of P9 was attributed to its high-affinity binding to viral glycoproteins, as well as the abundance of basic amino acids in its composition. After binding viral particles through viral surface glycoproteins, P9 entered into cells together with the viruses via endocytosis and prevented endosomal acidification, which blocked membrane fusion and subsequent viral RNA release. This study has paved the avenue for developing new prophylactic and therapeutic agents with broad-spectrum antiviral activities.

Research paper thumbnail of An H5N1-based matrix protein 2 ectodomain tetrameric peptide vaccine provides cross-protection against lethal infection with H7N9 influenza virus

Emerging Microbes & Infections, 2015

In March 2013, a patient infected with a novel avian influenza A H7N9 virus was reported in China... more In March 2013, a patient infected with a novel avian influenza A H7N9 virus was reported in China. Since then, there have been 458 confirmed infection cases and 177 deaths. The virus contains several human-adapted markers, indicating that H7N9 has pandemic potential. The outbreak of this new influenza virus highlighted the need for the development of universal influenza vaccines. Previously, we demonstrated that a tetrameric peptide vaccine based on the matrix protein 2 ectodomain (M2e) of the H5N1 virus (H5N1-M2e) could protect mice from lethal infection with different clades of H5N1 and 2009 pandemic H1N1 influenza viruses. In this study, we investigated the cross-protection of H5N1-M2e against lethal infection with the new H7N9 virus. Although five amino acid differences existed at positions 13, 14, 18, 20, and 21 between M2e of H5N1 and H7N9, H5N1-M2e vaccination with either Freund's adjuvant or the Sigma adjuvant system (SAS) induced a high level of anti-M2e antibody, which cross-reacted with H7N9-M2e peptide. A mouse-adapted H7N9 strain, A/Anhui/01/2013m, was used for lethal challenge in animal experiments. H5N1-M2e vaccination provided potent cross-protection against lethal challenge of the H7N9 virus. Reduced viral replication and histopathological damage of mouse lungs were also observed in the vaccinated mice. Our results suggest that the tetrameric H5N1-M2e peptide vaccine could protect against different subtypes of influenza virus infections. Therefore, this vaccine may be an ideal candidate for developing a universal vaccine to prevent the reemergence of avian influenza A H7N9 virus and the emergence of potential novel reassortants of influenza virus.

Research paper thumbnail of A critical role of IL-17 in modulating the B-cell response during H5N1 influenza virus infection

Cellular & Molecular …, 2011

Cellular and Molecular Immunology aims to report the dynamic progress being made in China and abr... more Cellular and Molecular Immunology aims to report the dynamic progress being made in China and abroad in immunological research, and welcomes high-quality Research Articles, Reviews and Brief Reports across a broad range of topics including, but not limited to, clinical immunology ...

Research paper thumbnail of A 219-mer CHO-Expressing Receptor-Binding Domain of SARS-CoV S Protein Induces Potent Immune Responses and Protective Immunity

Viral …, 2010

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