Lethbridge and the Trans-Canada Airway

Permission granted by Editor of Alberta History to include an e-version of article in the University of Lethbridge Institutional Repository.For the first nine years of transcontinental airline service, 1939-1948, Lethbridge was western Canada's principal airline hub. The city was ideally situated to fulfill this function due to its location on the southerly route of the Trans-Canada Airway and the limited operational ceiling of the unpressurized Lockeed aircraft then in use.N

Molecular characterisation of CD4+ T cell responses to tumour antigens

Background – Colorectal cancer (CRC) is the second most common cause of cancer death. CD4+ T cells play an important role in anti-tumour immunity by promoting immune processes that can mediate tumour inhibition. CD4+ immunity to tumours, however, is not able to prevent tumour outgrowth. It is hypothesised that tumour outgrowth can occur due to weak recognition of tumour-derived epitopes by tumour-reactive T cell receptors (TCRs) and due to negative reg-ulation by inhibitory T cell molecules. In this study, CD4+ T cell responses to the oncofoetal antigen 5T4 are studied at the molecular level. The function of the co-inhibitory molecule LAG-3 is described biophysically and monoclonal antibodies which recognise LAG-3 were devel-oped. Results – Three 5T4-reactive CD4+ T cell clones were shown to recognise 5T4-derived pep-tides restricted to HLA-DR1. Each clone was sensitive to antigen and produced TH1 cytokines despite exhibiting weak recognition of cognate antigen. Subsequently, the structural character-istics of a 5T4-derived peptide epitope was described through x-ray crystallography which revealed insights into MHC-II presentation of peptides. Cell expressed LAG-3 was shown to interact with MHC-II at the cell surface and was characterised at the protein level using surface plasmon resonance (SPR) where LAG-3 bound MHC-II via an intermediate affinity interaction. Thirdly, through the immunisation of mice, anti-LAG-3 antibodies were cloned and character-ised in terms of their specificity and function. Conclusions – These studies demonstrate how tumour-specific CD4+ T cells can produce immune-stimulatory molecules in vitro yet exhibit weak engagement of cognate antigen. It is shown that peptide flanking residues of HLA-DR1 presented epitopes can contribute to peptide anchoring as well as form structural features that may influence TCR binding. It is shown that LAG-3 binds MHC-II at higher affinity than CD4 with implications in its inhibitory function. Finally, specific antibodies that bind LAG-3 have been characterised with potential for thera-peutic development

The Development of Canada's Competency Profile for Professional Geoscientists at Entry-to-Practice

Competency-based assessment approaches to professional registration reflect the move by professions, both in Canada and around the world, away from traditional credentials-based assessments centred on a combination of academic achievements and supervised practice time. Entry to practice competencies are the abilities required to enable effective and safe entry-level practice in a profession.   In 2012, Geoscientists Canada received funding from the Government of Canada’s Foreign Credentials Recognition Program. A central component of the funding involved the development of a competency profile to assist in assessment for licensing in the geoscience profession. Work concluded with the approval of the Competency Profile for Professional Geoscientists at Entry to Practice by Geoscientists Canada in November 2014.   The Competency Profile comprises concise statements in plain language, setting out the skills and abilities that are required to be able to work as a geoscientist, in an effective and safe manner, independent of direct supervision. It covers competencies common to all geoscientists; competencies for the primary subdisciplines of geoscience (geology, environmental geoscience and geophysics); and a generic set of high level competences that can apply in any specific work context in geoscience.   The paper is in two parts. Part 1 puts the concept of competencies in context and describes the approach taken to develop the profile, including: input from Subject Matter Experts (practising geoscientists representing a diverse sampling of the profession); extensive national consultation and refinement; and a validation procedure, including a survey of practising Canadian geoscientists. Part 2 introduces the profile, explains its structure, and provides examples of some of the competencies. The full competency profile can be obtained from the Geoscientists Canada website www.geoscientistscanada.ca.  Future work will identify specific indicators of proficiency related to each competency and suggest appropriate methodologies to assess such competencies. It will also involve mapping the profile to the existing Canadian reference standard, Geoscience Knowledge and Experience Requirements for Professional Registration in Canada.RÉSUMÉLes approches d'évaluation basées sur les compétences en vue de l'inscription professionnelle reflètent l'abandon par les professions, tant au Canada que partout dans le monde, des évaluations classiques basées sur les titres de compétences et axées sur une combinaison de réalisations académiques et de temps de pratique supervisée. Les compétences au niveau débutant sont les capacités requises pour une pratique efficace et en toute sécurité audit niveau dans une profession.   En 2012, Géoscientifiques Canada a reçu un financement du Programme de reconnaissance des titres de compétences étrangers du gouvernement du Canada. Une composante centrale du financement incluait l’élaboration d'un profil des compétences pour faciliter l'évaluation de la délivrance de permis dans la profession de géoscience. Ce travail a été conclu en novembre 2014 avec l'approbation par Géoscientifiques Canada du Profil des compétences pour les géoscientifiques professionnels au niveau débutant.   Le profil des compétences comprend des déclarations concises dans un langage clair, définissant les compétences et les capacités requises pour exercer efficacement, en toute sécurité et indépendamment de toute supervision directe, en tant que géoscientifique. Il couvre les compétences communes à tous les géoscientifiques; les compétences pour les sous-disciplines primaires de la géoscience (géologie, géoscience environnementale et géophysique); et un ensemble générique de compétences de haut niveau pouvant s'appliquer dans tout contexte de travail spécifique en géoscience.   Le document comporte deux parties. La 1ère partie met en contexte le concept de compétences et décrit l'approche adoptée pour élaborer le profil, y compris : les contributions d'experts dans le domaine (géoscientifiques professionnels représentant un échantillonnage diversifié de la profession); de vastes consultations et perfectionnements à l'échelle nationale; et une procédure de validation, incluant une enquête auprès des géoscientifiques professionnels canadiens. La 2ème partie présente le profil, explique sa structure et fournit des exemples pour certaines des compétences. Le profil des compétences complet est disponible sur le site web de Géoscientifiques Canada www.geoscientistscanada.ca.   Les travaux futurs identifieront des indicateurs spécifiques d’aptitude liés à chaque compétence et suggèreront des méthodologies appropriées pour leur évaluation. Ils comprendront également la mise en correspondance du profil avec la norme de référence canadienne existante et les exigences en matière de Connaissances et expérience des géosciences requises pour l'inscription à titre professionnel au Canada.

Structure of the murine CD94 – NKG2A receptor in complex with Qa‐1b presenting an MHC‐I leader peptide

The heterodimeric natural killer cells antigen CD94 (CD94)–NKG2‐A/NKG2‐B type II integral membrane protein (NKG2A) receptor family expressed on human and mouse natural killer (NK) cells monitors global major histocompatibility complex (MHC) class I cell surface expression levels through binding to MHC class Ia‐derived leader sequence peptides presented by HLA class I histocompatibility antigen, alpha chain E (HLA‐E; in humans) or H‐2 class I histocompatibility antigen, D‐37 (Qa‐1b; in mice). Although the molecular basis underpinning human CD94–NKG2A recognition of HLA‐E is known, the equivalent interaction in the murine setting is not. By determining the high‐resolution crystal structure of murine CD94–NKG2A in complex with Qa‐1b presenting the Qa‐1 determinant modifier peptide (QDM), we resolved the mode of binding. Compared to the human homologue, the murine CD94–NKG2A–Qa‐1b–QDM displayed alterations in the distribution of interactions across CD94 and NKG2A subunits that coincide with differences in electrostatic complementarity of the ternary complex and the lack of cross‐species reactivity. Nevertheless, we show that Qa‐1b could be modified through W65R + N73I mutations to mimic HLA‐E, facilitating binding with both human and murine CD94–NKG2A. These data underscore human and murine CD94–NKG2A cross‐species heterogeneity and provide a foundation for humanising Qa‐1b in immune system models

Structural definition of HLA class II-presented SARS-CoV-2 epitopes reveals a mechanism to escape pre-existing CD4+ T cell immunity

CD4+ T cells recognize a broad range of peptide epitopes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which contribute to immune memory and limit COVID-19 disease. We demonstrate that the immunogenicity of SARS-CoV-2 peptides, in the context of the model allotype HLA-DR1, does not correlate with their binding affinity to the HLA heterodimer. Analyzing six epitopes, some with very low binding affinity, we solve X-ray crystallographic structures of each bound to HLA-DR1. Further structural definitions reveal the precise molecular impact of viral variant mutations on epitope presentation. Omicron escaped ancestral SARS-CoV-2 immunity to two epitopes through two distinct mechanisms: (1) mutations to TCR-facing epitope positions and (2) a mechanism whereby a single amino acid substitution caused a register shift within the HLA binding groove, completely altering the peptide-HLA structure. This HLA-II-specific paradigm of immune escape highlights how CD4+ T cell memory is finely poised at the level of peptide-HLA-II presentation

Seven mysteries of LAG-3: a multi-faceted immune receptor of increasing complexity

Despite three decades of research to its name and increasing interest in immunotherapies that target it, LAG-3 remains an elusive co-inhibitory receptor in comparison to the well-established PD-1 and CTLA-4. As such, LAG-3 targeting therapies have yet to achieve the clinical success of therapies targeting other checkpoints. This could, in part, be attributed to the many unanswered questions that remain regarding LAG-3 biology. Of these, we address: (i) the function of the many LAG-3-ligand interactions, (ii) the hurdles that remain to acquire a high-resolution structure of LAG-3, (iii) the under-studied LAG-3 signal transduction mechanism, (iv) the elusive soluble form of LAG-3, (v) the implications of the lack of (significant) phenotype of LAG-3 knockout mice, (vi) the reports of LAG-3 expression on the epithelium, and (vii) the conflicting reports of LAG-3 expression (and potential contributions to pathology) in the brain. These mysteries which surround LAG-3 highlight how the ever-evolving study of its biology continues to reveal ever-increasing complexity in its role as an immune receptor. Importantly, answering the questions which shroud LAG-3 in mystery will allow the maximum therapeutic benefit of LAG-3 targeting immunotherapies in cancer, autoimmunity and beyond

In silico and structural analyses demonstrate that intrinsic protein motions guide T cell receptor complementarity determining region loop flexibility

T-cell immunity is controlled by T cell receptor (TCR) binding to peptide major histocompatibility complexes (pMHCs). The nature of the interaction between these two proteins has been the subject of many investigations because of its central role in immunity against pathogens, cancer, in autoimmunity, and during organ transplant rejection. Crystal structures comparing unbound and pMHC-bound TCRs have revealed flexibility at the interaction interface, particularly from the perspective of the TCR. However, crystal structures represent only a snapshot of protein conformation that could be influenced through biologically irrelevant crystal lattice contacts and other factors. Here, we solved the structures of three unbound TCRs from multiple crystals. Superposition of identical TCR structures from different crystals revealed some conformation differences of up to 5 Å in individual complementarity determining region (CDR) loops that are similar to those that have previously been attributed to antigen engagement. We then used a combination of rigidity analysis and simulations of protein motion to reveal the theoretical potential of TCR CDR loop flexibility in unbound state. These simulations of protein motion support the notion that crystal structures may only offer an artifactual indication of TCR flexibility, influenced by crystallization conditions and crystal packing that is inconsistent with the theoretical potential of intrinsic TCR motions

Molecular characterization of HLA class II binding to the LAG-3 T cell co-inhibitory receptor

Immune checkpoint inhibitors (antibodies that block the T cell co-inhibitory receptors PD-1/PD-L1 or CTLA-4) have revolutionized the treatment of some forms of cancer. Importantly, combination approaches using drugs that target both pathways have been shown to boost the efficacy of such treatments. Subsequently, several other T cell inhibitory receptors have been identified for the development of novel immune checkpoint inhibitors. Included in this list is the co-inhibitory receptor lymphocyte activation gene-3 (LAG-3), which is upregulated on T cells extracted from tumor sites that have suppressive or exhausted phenotypes. However, the molecular rules that govern the function of LAG-3 are still not understood. Using surface plasmon resonance combined with a novel bead-based assay (AlphaScreenTM), we demonstrate that LAG-3 can directly and specifically interact with intact human leukocyte antigen class II (HLA-II) heterodimers. Unlike the homologue CD4, which has an immeasurably weak affinity using these biophysical approaches, LAG3 binds with low micromolar affinity. We further validated the interaction at the cell surface by staining LAG-3+ cells with pHLA-II-multimers. These data provide new insights into the mechanism by which LAG-3 initiates T cell inhibitio