This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The mechanistic understandings derived from these data are likely to provide a unique handle for ... more The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens.
Over the past two years, scientific research has moved at an unprecedented rate in response to th... more Over the past two years, scientific research has moved at an unprecedented rate in response to the COVID-19 pandemic. The rapid development of effective vaccines and therapeutics would not have been possible without extensive background knowledge on coronaviruses developed over decades by researchers, including Kathryn (Kay) Holmes. Kay’s research team discovered the first coronavirus receptors for mouse hepatitis virus and human coronavirus 229E and contributed a wealth of information on coronaviral spike glycoproteins and receptor interactions that are critical determinants of host and tissue specificity. She collaborated with several research laboratories to contribute knowledge in additional areas, including coronaviral pathogenesis, epidemiology, and evolution. Throughout her career, Kay was an extremely dedicated and thoughtful mentor to numerous graduate students and post-doctoral fellows. This article provides a review of her contributions to the coronavirus field and her ex...
The mechanistic understandings derived from these data are likely to provide a unique handle for ... more The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens.
Nuclear magnetic resonance spectroscopy is a powerful tool to study structural and functional pro... more Nuclear magnetic resonance spectroscopy is a powerful tool to study structural and functional properties of proteins, provided that they can be enriched in stable isotopes such as (15)N, (13)C and (2)H. This is usually easy and inexpensive when the proteins are expressed in Escherichiacoli, but many eukaryotic (human in particular) proteins cannot be produced this way. An alternative is to express them in insect cells. Labeled insect cell growth media are commercially available but at prohibitive prices, limiting the NMR studies to only a subset of biologically important proteins. Non-commercial solutions from academic institutions have been proposed, but none of them is really satisfying. We have developed a (15)N-labeling procedure based on the use of a commercial medium depleted of all amino acids and supplemented with a (15)N-labeled yeast autolysate for a total cost about five times lower than that of the currently available solutions. We have applied our procedure to the produ...
Severe acute respiratory syndrome (SARS) is a disease characterized by diffuse alveolar damage. W... more Severe acute respiratory syndrome (SARS) is a disease characterized by diffuse alveolar damage. We isolated human alveolar type II cells and maintained them in a highly differentiated state. Type II cell cultures supported SARS-CoV replication as evidenced by RT-PCR detection of viral subgenomic RNA and an increase in virus titer. Virus titers were maximal by 24 h and peaked at approximately 10 5 pfu/mL. Two cell types within the cultures were infected. One cell type was type II cells, which were positive for SPA , SP-C, cytokeratin, a type II cell-specific monoclonal antibody, and Ep-CAM. The other cell type was composed of spindle-shaped cells that were positive for vimentin and collagen III and likely fibroblasts. Viral replication was not detected in type I-like cells or macrophages. Hence, differentiated adult human alveolar type II cells were infectible but alveolar type I-like cells and alveolar macrophages did not support productive infection.
Proceedings of the National Academy of Sciences, 2004
Angiotensin-converting enzyme 2 (ACE2) is a receptor for SARS-CoV, the novel coronavirus that cau... more Angiotensin-converting enzyme 2 (ACE2) is a receptor for SARS-CoV, the novel coronavirus that causes severe acute respiratory syndrome [Li, W. Moore, M. J., Vasilieva, N., Sui, J., Wong, S. K., Berne, M. A., Somasundaran, M., Sullivan, J. L., Luzuriaga, K., Greenough, T. C.,et al.(2003)Nature426, 450–454]. We have identified a different human cellular glycoprotein that can serve as an alternative receptor for SARS-CoV. A human lung cDNA library in vesicular stomatitis virus G pseudotyped retrovirus was transduced into Chinese hamster ovary cells, and the cells were sorted for binding of soluble SARS-CoV spike (S) glycoproteins, S590and S1180. Clones of transduced cells that bound SARS-CoV S glycoprotein were inoculated with SARS-CoV, and increases in subgenomic viral RNA from 1–16 h or more were detected by multiplex RT-PCR in four cloned cell lines. Sequencing of the human lung cDNA inserts showed that each of the cloned cell lines contained cDNA that encoded human CD209L, a C-type...
The role of covalent modifications of the Ebola virus glycoprotein (GP) and the significance of t... more The role of covalent modifications of the Ebola virus glycoprotein (GP) and the significance of the sequence identity between filovirus and avian retrovirus GPs were investigated through biochemical and functional analyses of mutant GPs. The expression and processing of mutant GPs with altered N-linked glycosylation, substitutions for conserved cysteine residues, or a deletion in the region of O-linked glycosylation were analyzed, and virus entry capacities were assayed through the use of pseudotyped retroviruses. Cys-53 was the only GP 1 (∼130 kDa) cysteine residue whose replacement resulted in the efficient secretion of GP 1 , and it is therefore proposed that it participates in the formation of the only disulfide bond linking GP 1 to GP 2 (∼24 kDa). We propose a complete cystine bridge map for the filovirus GPs based upon our analysis of mutant Ebola virus GPs. The effect of replacement of the conserved cysteines in the membrane-spanning region of GP 2 was found to depend on the ...
ABSTRACTThe severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein (S) is a ... more ABSTRACTThe severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein (S) is a class I viral fusion protein that binds to its receptor glycoprotein, human angiotensin converting enzyme 2 (hACE2), and mediates virus entry and cell-cell fusion. The juxtamembrane domain (JMD) of S is an aromatic amino acid-rich region proximal to the transmembrane domain that is highly conserved in all coronaviruses. Alanine substitutions for one or two of the six aromatic residues in the JMD did not alter the surface expression of the SARS-CoV S proteins with a deletion of the C-terminal 19 amino acids (S Δ19) or reduce binding to soluble human ACE2 (hACE2). However, hACE2-dependent entry of trypsin-treated retrovirus pseudotyped viruses expressing JMD mutant S Δ19 proteins was greatly reduced. Single alanine substitutions for aromatic residues reduced entry to 10 to 60% of the wild-type level. The greatest reduction was caused by residues nearest the transmembrane domain. Four doubl...
The practical application of gene therapy as a treatment for cystic fibrosis is limited by poor g... more The practical application of gene therapy as a treatment for cystic fibrosis is limited by poor gene transfer efficiency with vectors applied to the apical surface of airway epithelia. Recently, folate receptor alpha (FRα), a glycosylphosphatidylinositol-linked surface protein, was reported to be a cellular receptor for the filoviruses. We found that polarized human airway epithelia expressed abundant FRα on their apical surface. In an attempt to target these apical receptors, we pseudotyped feline immunodeficiency virus (FIV)-based vectors by using envelope glycoproteins (GPs) from the filoviruses Marburg virus and Ebola virus. Importantly, primary cultures of well-differentiated human airway epithelia were transduced when filovirus GP-pseudotyped FIV was applied to the apical surface. Furthermore, by deleting a heavily O-glycosylated extracellular domain of the Ebola GP, we improved the titer of concentrated vector severalfold. To investigate the folate receptor dependence of gene...
The Spike (S) glycoprotein of coronaviruses (CoV) mediates viral entry into host cells. It contai... more The Spike (S) glycoprotein of coronaviruses (CoV) mediates viral entry into host cells. It contains two hydrophobic heptad repeat (HR) regions, denoted HRN and HRC, which oligomerize the S glycoprotein into a trimer in the native state and when activated collapse into a six-helix bundle structure driving fusion of the host and viral membranes. Previous studies have shown that peptides of the HR regions can inhibit viral infectivity. These studies imply that the HR regions are accessible and that agents which can interact with them may prevent viral entry. In the present study, we have investigated an approach to generate antibodies that speciWcally recognize the HRN and HRC regions of the SARS-CoV spike (S) glycoprotein in order to evaluate whether these antibodies can inhibit viral infectivity and thus neutralize the SARS-CoV. In this regard, we incorporated HRN and HRC coiled-coil surface residues into a de novo designed two-stranded-helical coiled-coil template for generating conformation-speciWc antibodies that recognize-helices in proteins (
Severe acute respiratory syndrome (SARS) is an infectious disease caused by a novel coronavirus t... more Severe acute respiratory syndrome (SARS) is an infectious disease caused by a novel coronavirus that cost nearly 800 lives. While there have been no recent outbreaks of the disease, the threat remains as SARS coronavirus (SARS‐CoV) like strains still exist in animal reservoirs. Therefore, the development of a vaccine against SARS is in grave need. Here, we have designed and produced a prototypic SARS vaccine: a self‐assembling polypeptide nanoparticle that repetitively displays a SARS B‐cell epitope from the C‐terminal heptad repeat of the virus’ spike protein. Biophysical analyses with circular dichroism, transmission electron microscopy and dynamic light scattering confirmed the computational design showing α‐helcial nanoparticles with sizes of about 25 nm. Immunization experiments with no adjuvants were performed with BALB/c mice. An investigation of the binding properties of the elicited antibodies showed that they were highly conformation specific for the coiled‐coil epitope be...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The mechanistic understandings derived from these data are likely to provide a unique handle for ... more The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens.
Over the past two years, scientific research has moved at an unprecedented rate in response to th... more Over the past two years, scientific research has moved at an unprecedented rate in response to the COVID-19 pandemic. The rapid development of effective vaccines and therapeutics would not have been possible without extensive background knowledge on coronaviruses developed over decades by researchers, including Kathryn (Kay) Holmes. Kay’s research team discovered the first coronavirus receptors for mouse hepatitis virus and human coronavirus 229E and contributed a wealth of information on coronaviral spike glycoproteins and receptor interactions that are critical determinants of host and tissue specificity. She collaborated with several research laboratories to contribute knowledge in additional areas, including coronaviral pathogenesis, epidemiology, and evolution. Throughout her career, Kay was an extremely dedicated and thoughtful mentor to numerous graduate students and post-doctoral fellows. This article provides a review of her contributions to the coronavirus field and her ex...
The mechanistic understandings derived from these data are likely to provide a unique handle for ... more The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens.
Nuclear magnetic resonance spectroscopy is a powerful tool to study structural and functional pro... more Nuclear magnetic resonance spectroscopy is a powerful tool to study structural and functional properties of proteins, provided that they can be enriched in stable isotopes such as (15)N, (13)C and (2)H. This is usually easy and inexpensive when the proteins are expressed in Escherichiacoli, but many eukaryotic (human in particular) proteins cannot be produced this way. An alternative is to express them in insect cells. Labeled insect cell growth media are commercially available but at prohibitive prices, limiting the NMR studies to only a subset of biologically important proteins. Non-commercial solutions from academic institutions have been proposed, but none of them is really satisfying. We have developed a (15)N-labeling procedure based on the use of a commercial medium depleted of all amino acids and supplemented with a (15)N-labeled yeast autolysate for a total cost about five times lower than that of the currently available solutions. We have applied our procedure to the produ...
Severe acute respiratory syndrome (SARS) is a disease characterized by diffuse alveolar damage. W... more Severe acute respiratory syndrome (SARS) is a disease characterized by diffuse alveolar damage. We isolated human alveolar type II cells and maintained them in a highly differentiated state. Type II cell cultures supported SARS-CoV replication as evidenced by RT-PCR detection of viral subgenomic RNA and an increase in virus titer. Virus titers were maximal by 24 h and peaked at approximately 10 5 pfu/mL. Two cell types within the cultures were infected. One cell type was type II cells, which were positive for SPA , SP-C, cytokeratin, a type II cell-specific monoclonal antibody, and Ep-CAM. The other cell type was composed of spindle-shaped cells that were positive for vimentin and collagen III and likely fibroblasts. Viral replication was not detected in type I-like cells or macrophages. Hence, differentiated adult human alveolar type II cells were infectible but alveolar type I-like cells and alveolar macrophages did not support productive infection.
Proceedings of the National Academy of Sciences, 2004
Angiotensin-converting enzyme 2 (ACE2) is a receptor for SARS-CoV, the novel coronavirus that cau... more Angiotensin-converting enzyme 2 (ACE2) is a receptor for SARS-CoV, the novel coronavirus that causes severe acute respiratory syndrome [Li, W. Moore, M. J., Vasilieva, N., Sui, J., Wong, S. K., Berne, M. A., Somasundaran, M., Sullivan, J. L., Luzuriaga, K., Greenough, T. C.,et al.(2003)Nature426, 450–454]. We have identified a different human cellular glycoprotein that can serve as an alternative receptor for SARS-CoV. A human lung cDNA library in vesicular stomatitis virus G pseudotyped retrovirus was transduced into Chinese hamster ovary cells, and the cells were sorted for binding of soluble SARS-CoV spike (S) glycoproteins, S590and S1180. Clones of transduced cells that bound SARS-CoV S glycoprotein were inoculated with SARS-CoV, and increases in subgenomic viral RNA from 1–16 h or more were detected by multiplex RT-PCR in four cloned cell lines. Sequencing of the human lung cDNA inserts showed that each of the cloned cell lines contained cDNA that encoded human CD209L, a C-type...
The role of covalent modifications of the Ebola virus glycoprotein (GP) and the significance of t... more The role of covalent modifications of the Ebola virus glycoprotein (GP) and the significance of the sequence identity between filovirus and avian retrovirus GPs were investigated through biochemical and functional analyses of mutant GPs. The expression and processing of mutant GPs with altered N-linked glycosylation, substitutions for conserved cysteine residues, or a deletion in the region of O-linked glycosylation were analyzed, and virus entry capacities were assayed through the use of pseudotyped retroviruses. Cys-53 was the only GP 1 (∼130 kDa) cysteine residue whose replacement resulted in the efficient secretion of GP 1 , and it is therefore proposed that it participates in the formation of the only disulfide bond linking GP 1 to GP 2 (∼24 kDa). We propose a complete cystine bridge map for the filovirus GPs based upon our analysis of mutant Ebola virus GPs. The effect of replacement of the conserved cysteines in the membrane-spanning region of GP 2 was found to depend on the ...
ABSTRACTThe severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein (S) is a ... more ABSTRACTThe severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein (S) is a class I viral fusion protein that binds to its receptor glycoprotein, human angiotensin converting enzyme 2 (hACE2), and mediates virus entry and cell-cell fusion. The juxtamembrane domain (JMD) of S is an aromatic amino acid-rich region proximal to the transmembrane domain that is highly conserved in all coronaviruses. Alanine substitutions for one or two of the six aromatic residues in the JMD did not alter the surface expression of the SARS-CoV S proteins with a deletion of the C-terminal 19 amino acids (S Δ19) or reduce binding to soluble human ACE2 (hACE2). However, hACE2-dependent entry of trypsin-treated retrovirus pseudotyped viruses expressing JMD mutant S Δ19 proteins was greatly reduced. Single alanine substitutions for aromatic residues reduced entry to 10 to 60% of the wild-type level. The greatest reduction was caused by residues nearest the transmembrane domain. Four doubl...
The practical application of gene therapy as a treatment for cystic fibrosis is limited by poor g... more The practical application of gene therapy as a treatment for cystic fibrosis is limited by poor gene transfer efficiency with vectors applied to the apical surface of airway epithelia. Recently, folate receptor alpha (FRα), a glycosylphosphatidylinositol-linked surface protein, was reported to be a cellular receptor for the filoviruses. We found that polarized human airway epithelia expressed abundant FRα on their apical surface. In an attempt to target these apical receptors, we pseudotyped feline immunodeficiency virus (FIV)-based vectors by using envelope glycoproteins (GPs) from the filoviruses Marburg virus and Ebola virus. Importantly, primary cultures of well-differentiated human airway epithelia were transduced when filovirus GP-pseudotyped FIV was applied to the apical surface. Furthermore, by deleting a heavily O-glycosylated extracellular domain of the Ebola GP, we improved the titer of concentrated vector severalfold. To investigate the folate receptor dependence of gene...
The Spike (S) glycoprotein of coronaviruses (CoV) mediates viral entry into host cells. It contai... more The Spike (S) glycoprotein of coronaviruses (CoV) mediates viral entry into host cells. It contains two hydrophobic heptad repeat (HR) regions, denoted HRN and HRC, which oligomerize the S glycoprotein into a trimer in the native state and when activated collapse into a six-helix bundle structure driving fusion of the host and viral membranes. Previous studies have shown that peptides of the HR regions can inhibit viral infectivity. These studies imply that the HR regions are accessible and that agents which can interact with them may prevent viral entry. In the present study, we have investigated an approach to generate antibodies that speciWcally recognize the HRN and HRC regions of the SARS-CoV spike (S) glycoprotein in order to evaluate whether these antibodies can inhibit viral infectivity and thus neutralize the SARS-CoV. In this regard, we incorporated HRN and HRC coiled-coil surface residues into a de novo designed two-stranded-helical coiled-coil template for generating conformation-speciWc antibodies that recognize-helices in proteins (
Severe acute respiratory syndrome (SARS) is an infectious disease caused by a novel coronavirus t... more Severe acute respiratory syndrome (SARS) is an infectious disease caused by a novel coronavirus that cost nearly 800 lives. While there have been no recent outbreaks of the disease, the threat remains as SARS coronavirus (SARS‐CoV) like strains still exist in animal reservoirs. Therefore, the development of a vaccine against SARS is in grave need. Here, we have designed and produced a prototypic SARS vaccine: a self‐assembling polypeptide nanoparticle that repetitively displays a SARS B‐cell epitope from the C‐terminal heptad repeat of the virus’ spike protein. Biophysical analyses with circular dichroism, transmission electron microscopy and dynamic light scattering confirmed the computational design showing α‐helcial nanoparticles with sizes of about 25 nm. Immunization experiments with no adjuvants were performed with BALB/c mice. An investigation of the binding properties of the elicited antibodies showed that they were highly conformation specific for the coiled‐coil epitope be...
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