evaluation-zika-virus-specific-t-cell-responses-immunoprivileged

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1<sup>-/-</sup> Mice

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and ...

stability-structure-bat-major-histocompatibility-complex-class-i-with

Stability and Structure of Bat Major Histocompatibility Complex Class I with Heterologous &beta;<sub>2</sub>-Microglobulin

The major histocompatibility complex (MHC) plays a pivotal role in antigen peptide presentation and T cell immune responses against infectious disease and ...

Wenzhou Medical University

Chinese Center For Disease Control And Prevention

Chinese Academy of Sciences

University of Macau

Structural basis of anti-PD-L1 monoclonal antibody avelumab for tumor therapy.

Antibody-based PD-1/PD-L1 blockade therapies have taken center stage in immunotherapies for cancer, with multiple clinical successes. PD-1 signaling plays pivotal roles in tumor-driven T-cell dysfunction. In contrast to prior approaches to generate or boost tumor-specific T-cell responses, antibody-based PD-1/PD-L1 blockade targets tumor-induced T-cell defects and restores pre-existing T-cell function to modulate antitumor immunity. In this review, the fundamental knowledge on the expression regulations and inhibitory functions of PD-1 and the present understanding of antibody-based PD-1/PD-L1 blockade therapies are briefly summarized. We then focus on the recent breakthrough work concerning the structural basis of the PD-1/PD-Ls interaction and how therapeutic antibodies, pembrolizumab targeting PD-1 and avelumab targeting PD-L1, compete with the binding of PD-1/PD-L1 to interrupt the PD-1/PD-L1 interaction. We believe that this structural information will benefit the design and improvement of therapeutic antibodies targeting PD-1 signaling.

Crystal clear: visualizing the intervention mechanism of the PD-1/PD-L1 interaction by two cancer therapeutic monoclonal antibodies.

Over 12 years have elapsed since severe acute respiratory syndrome (SARS) triggered the first global alert for coronavirus infections. Virus transmission in humans was quickly halted by public health measures and human infections of SARS coronavirus (SARS-CoV) have not been observed since. However, other coronaviruses still pose a continuous threat to human health, as exemplified by the recent emergence of Middle East respiratory syndrome (MERS) in humans. The work on SARS-CoV widens our knowledge on the epidemiology, pathophysiology and immunology of coronaviruses and may shed light on MERS coronavirus (MERS-CoV). It has been confirmed that T-cell immunity plays an important role in recovery from SARS-CoV infection. Herein, we summarize T-cell immunological studies of SARS-CoV and discuss the potential cross-reactivity of the SARS-CoV-specific immunity against MERS-CoV, which may provide useful recommendations for the development of broad-spectrum vaccines against coronavirus infections.

T-cell immunity of SARS-CoV: Implications for vaccine development against MERS-CoV.

The coordinated recognition of virus-derived T cell epitopes and MHC molecules by T cells plays a pivotal role in cellular immunity-mediated virus clearance. It has been demonstrated that the conformation of MHC class I (MHC I) molecules can be adjusted by the presented peptide, which impacts T cell activation. However, it is still largely unknown whether the conformational shift of MHC I influences the protective effect of virus-specific T cells. In this study, utilizing the Middle East respiratory syndrome coronavirus-infected mouse model, we observed that through the unusual secondary anchor Ile5, a CD8 T cell epitope drove the conformational fit of Trp on the α1 helix of murine MHC I H-2K In vitro renaturation and circular dichroism assays indicated that this shift of the structure did not influence the peptide/MHC I binding affinity. Nevertheless, the T cell recognition and the protective effect of the peptide diminished when we made an Ile to Ala mutation at position 5 of the original peptide. The molecular bases of the concordant recognition of T cell epitopes and host MHC-dependent protection were demonstrated through both crystal structure determination and tetramer staining using the peptide-MHC complex. Our results indicate a coordinated MHC I/peptide interaction mechanism and provide a beneficial reference for T cell-oriented vaccine development against emerging viruses such as Middle East respiratory syndrome coronavirus.

Protective T Cell Responses Featured by Concordant Recognition of Middle East Respiratory Syndrome Coronavirus-Derived CD8+ T Cell Epitopes and Host MHC.

Distinct PD-L1 binding characteristics of therapeutic monoclonal antibody durvalumab.

Against a backdrop of seasonal influenza virus epidemics, emerging avian influenza viruses (AIVs) occasionally jump from birds to humans, posing a public health risk, especially with the recent sharp increase in H7N9 infections. Evaluations of cross-reactive T-cell immunity to seasonal influenza viruses and human-infecting AIVs have been reported previously. However, the roles of influenza A virus-derived epitopes in the cross-reactive T-cell responses and heterosubtypic protections are not well understood; understanding those roles is important for preventing and controlling new emerging AIVs. Here, among the members of a healthy population presumed to have previously been infected by pandemic H1N1 (pH1N1), we found that pH1N1-specific T cells showed cross- but biased reactivity to human-infecting AIVs, i.e., H5N1, H6N1, H7N9, and H9N2, which correlates with distinct protections. Through a T-cell epitope-based phylogenetic analysis, the cellular immunogenic clustering expanded the relevant conclusions to a broader range of virus strains. We defined the potential key conserved epitopes required for cross-protection and revealed the molecular basis for the immunogenic variations. Our study elucidated an overall profile of cross-reactivity to AIVs and provided useful recommendations for broad-spectrum vaccine development. We revealed preexisting but biased T-cell reactivity of pH1N1 influenza virus to human-infecting AIVs, which provided distinct protections. The cross-reactive T-cell recognition had a regular pattern that depended on the T-cell epitope matrix revealed via bioinformatics analysis. Our study elucidated an overall profile of cross-reactivity to AIVs and provided useful recommendations for broad-spectrum vaccine development.

Heterosubtypic Protections against Human-Infecting Avian Influenza Viruses Correlate to Biased Cross-T-Cell Responses.

Human leukocyte antigen (HLA) alleles have a high degree of polymorphism, which determines their peptide-binding motifs and subsequent T-cell receptor recognition. The simplest way to understand the cross-presentation of peptides by different alleles is to classify these alleles into supertypes. A1 and A3 HLA supertypes are widely distributed in humans. However, direct structural and functional evidence for peptide presentation features of key alleles (e.g., HLA-A30:01 and -A30:03) are lacking. Herein, the molecular basis of peptide presentation of HLA-A30:01 and -A30:03 was demonstrated by crystal structure determination and thermostability measurements of complexes with T-cell epitopes from influenza virus (NP44), human immunodeficiency virus (RT313), and  (MTB). When binding to the HIV peptide, RT313, the PΩ-Lys anchoring modes of HLA-A30:01, and -A30:03 were similar to those of HLA-A11:01 in the A3 supertype. However, HLA-A30:03, but not -A30:01, also showed binding with the HLA01:01-favored peptide, NP44, but with a specific structural conformation. Thus, different from our previous understanding, HLA-A30:01 and -A30:03 have specific peptide-binding characteristics that may lead to their distinct supertype-featured binding peptide motifs. Moreover, we also found that residue 77 in the F pocket was one of the key residues for the divergent peptide presentation characteristics of HLA-A30:01 and -A30:03. Interchanging residue 77 between HLA-A30:01 and HLA-A30:03 switched their presented peptide profiles. Our results provide important recommendations for screening virus and tumor-specific peptides among the population with prevalent HLA supertypes for vaccine development and immune interventions.

Divergent Peptide Presentations of HLA-A30 Alleles Revealed by Structures With Pathogen Peptides.

Bats harbor many zoonotic viruses, including highly pathogenic viruses of humans and other mammals, but they are typically asymptomatic in bats. To further understand the antiviral immunity of bats, we screened and identified a series of bat major histocompatibility complex (MHC) I Ptal-N*01:01-binding peptides derived from four different bat-borne viruses, i.e., Hendra virus (HeV), Ebola virus (EBOV), Middle East respiratory syndrome coronavirus (MERS-CoV), and H17N10 influenza-like virus. The structures of Ptal-N*01:01 display unusual peptide presentation features in that the bat-specific 3-amino acid (aa) insertion enables the tight "surface anchoring" of the P1-Asp in pocket A of bat MHC I. As the classical primary anchoring positions, the B and F pockets of Ptal-N*01:01 also show unconventional conformations, which contribute to unusual peptide motifs and distinct peptide presentation. Notably, the features of bat MHC I may be shared by MHC I from various marsupials. Our study sheds light on bat adaptive immunity and may benefit future vaccine development against bat-borne viruses of high impact on humans.

Peptide presentation by bat MHC class I provides new insight into the antiviral immunity of bats.

Rabbits are pivotal domestic animals for both the economy and as an animal model for human diseases. A large number of rabbits have been infected by rabbit hemorrhagic disease virus (RHDV) in natural and artificial pandemics in the past. Differences in presentation of antigenic peptides by polymorphic major histocompatibility complex (MHC) molecules to T-cell receptors (TCR) on T lymphocytes are associated with viral clearance in mammals. Here, we screened and identified a series of peptides derived from RHDV binding to the rabbit MHC class I molecule, RLA-A1. The small, hydrophobic B and F pockets of RLA-A1 capture a peptide motif analogous to that recognized by human class I molecule HLA-A*0201, with more restricted aliphatic anchors at P2 and PΩ positions. Moreover, the rabbit molecule is characterized by an uncommon residue combination of Gly53, Val55, and Glu56, making the 3 helix and the loop between the 3 and α1 helices closer to the α2 helix. A wider A pocket in RLA-A1 can induce a special conformation of the P1 anchor and may play a pivotal role in peptide assembly and TCR recognition. Our study broadens the knowledge of T-cell immunity in domestic animals and also provides useful insights for vaccine development to prevent infectious diseases in rabbits. We screened rabbit MHC class I RLA-A1-restricted peptides from the capsid protein VP60 of rabbit hemorrhagic disease virus (RHDV) and determined the structures of RLA-A1 complexed with three peptides, VP60-1, VP60-2, and VP60-10. From the structures, we found that the peptide binding motifs of RLA-A1 are extremely constraining. Thus, there is a generally restricted peptide selection for RLA-A1 compared to that for human HLA-A*0201. In addition, uncommon residues Gly53, Val55, and Glu56 of RLA-A1 are located between the 3 helix and α1 helix, which makes the steric position of the 3 helix in RLA-A1 much closer to the α2 helix than that found in other mammalian MHC class I molecules. This special conformation between the 3 helix and α1 helix plays a pivotal role in rabbit MHC class I assembly. Our results provide new insights into MHC class I molecule assembly and peptide presentation of domestic mammals. Furthermore, these data also broaden our knowledge on T-cell immunity in rabbits and may also provide useful information for vaccine development to prevent infectious diseases in rabbits.

Strict Assembly Restriction of Peptides from Rabbit Hemorrhagic Disease Virus Presented by Rabbit Major Histocompatibility Complex Class I Molecule RLA-A1.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the recent pandemic COVID-19, is reported to have originated from bats, with its intermediate host unknown to date. Here, we screened 26 animal counterparts of the human ACE2 (hACE2), the receptor for SARS-CoV-2 and SARS-CoV, and found that the ACE2s from various species, including pets, domestic animals and multiple wild animals, could bind to SARS-CoV-2 receptor binding domain (RBD) and facilitate the transduction of SARS-CoV-2 pseudovirus. Comparing to SARS-CoV-2, SARS-CoV seems to have a slightly wider range in choosing its receptor. We further resolved the cryo-electron microscopy (cryo-EM) structure of the cat ACE2 (cACE2) in complex with the SARS-CoV-2 RBD at a resolution of 3 Å, revealing similar binding mode as hACE2 to the SARS-CoV-2 RBD. These results shed light on pursuing the intermediate host of SARS-CoV-2 and highlight the necessity of monitoring susceptible hosts to prevent further outbreaks.

Broad host range of SARS-CoV-2 and the molecular basis for SARS-CoV-2 binding to cat ACE2.

PD-1 is a highly glycosylated inhibitory receptor expressed mainly on T cells. Targeting of PD-1 with monoclonal antibodies (MAbs) to block the interaction with its ligand PD-L1 has been successful for the treatment of multiple tumors. However, polymorphisms at N-glycosylation sites of PD-1 exist in the human population that might affect antibody binding, and dysregulated glycosylation has been observed in the tumor microenvironment. Here, we demonstrate varied N-glycan composition in PD-1, and show that the binding affinity of camrelizumab, a recently approved PD-1-specific MAb, to non-glycosylated PD-1 proteins from E. coli is substantially decreased compared with glycosylated PD-1. The structure of the camrelizumab/PD-1 complex reveals that camrelizumab mainly utilizes its heavy chain to bind to PD-1, while the light chain sterically inhibits the binding of PD-L1 to PD-1. Glycosylation of asparagine 58 (N58) promotes the interaction with camrelizumab, while the efficiency of camrelizumab to inhibit the binding of PD-L1 is substantially reduced for glycosylation-deficient PD-1. These results increase our understanding of how glycosylation affects the activity of PD-1-specific MAbs during immune checkpoint therapy.

N-glycosylation of PD-1 promotes binding of camrelizumab.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a major threat to global health. Although varied SARS-CoV-2-related coronaviruses have been isolated from bats and SARS-CoV-2 may infect bat, the structural basis for SARS-CoV-2 to utilize the human receptor counterpart bat angiotensin-converting enzyme 2 (bACE2) for virus infection remains less understood. Here, we report that the SARS-CoV-2 spike protein receptor binding domain (RBD) could bind to bACE2 from  (bACE2-Rm) with substantially lower affinity compared with that to the human ACE2 (hACE2), and its infectivity to host cells expressing bACE2-Rm was confirmed with pseudotyped SARS-CoV-2 virus and SARS-CoV-2 wild virus. The structure of the SARS-CoV-2 RBD with the bACE2-Rm complex was determined, revealing a binding mode similar to that of hACE2. The analysis of binding details between SARS-CoV-2 RBD and bACE2-Rm revealed that the interacting network involving Y41 and E42 of bACE2-Rm showed substantial differences with that to hACE2. Bats have extensive species diversity and the residues for RBD binding in bACE2 receptor varied substantially among different bat species. Notably, the Y41H mutant, which exists in many bats, attenuates the binding capacity of bACE2-Rm, indicating the central roles of Y41 in the interaction network. These findings would benefit our understanding of the potential infection of SARS-CoV-2 in varied species of bats.

ArticleTotal : 2	Year
Publication title Cited by 5	2018
Publication title Cited by 1	2021

Article	Year
Structural basis of anti-PD-L1 monoclonal antibody avelumab for tumor therapy. Cell research\| PubMed ID: 27573173	2017
Crystal clear: visualizing the intervention mechanism of the PD-1/PD-L1 interaction by two cancer therapeutic monoclonal antibodies. Protein & cell\| PubMed ID: 27815822	2016
T-cell immunity of SARS-CoV: Implications for vaccine development against MERS-CoV. Antiviral research\| PubMed ID: 27840203	2017
Protective T Cell Responses Featured by Concordant Recognition of Middle East Respiratory Syndrome Coronavirus-Derived CD8+ T Cell Epitopes and Host MHC. Journal of immunology (Baltimore, Md. : 1950)\| PubMed ID: 27903740	2017
Distinct PD-L1 binding characteristics of therapeutic monoclonal antibody durvalumab. Protein & cell\| PubMed ID: 28488247	2018
Heterosubtypic Protections against Human-Infecting Avian Influenza Viruses Correlate to Biased Cross-T-Cell Responses. mBio\| PubMed ID: 30087171	2018
Divergent Peptide Presentations of HLA-A30 Alleles Revealed by Structures With Pathogen Peptides. Frontiers in immunology\| PubMed ID: 31396224	2019
Peptide presentation by bat MHC class I provides new insight into the antiviral immunity of bats. PLoS biology\| PubMed ID: 31498797	2019
Strict Assembly Restriction of Peptides from Rabbit Hemorrhagic Disease Virus Presented by Rabbit Major Histocompatibility Complex Class I Molecule RLA-A1. Journal of virology\| PubMed ID: 32522857	2020
Broad host range of SARS-CoV-2 and the molecular basis for SARS-CoV-2 binding to cat ACE2. Cell discovery\| PubMed ID: 33020722	2020
N-glycosylation of PD-1 promotes binding of camrelizumab. EMBO reports\| PubMed ID: 33063473	2020
Cross-species recognition of SARS-CoV-2 to bat ACE2. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 33335073	2021

Kefang Liu

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