We report a Human Immune System (HIS)-humanized mouse model ("DRAGA": HLA-A2.HLA-DR4.Rag1KO.IL-2 RγcKO.NOD) for COVID-19 research. DRAGA mice express transgenically HLA-class I and class-II molecules in the mouse thymus to promote human T cell development and human B cell Ig-class switching. When infused with human hematopoietic stem cells from cord blood reconstitute a functional human immune system, as well as human epi/endothelial cells in lung and upper respiratory airways expressing the human ACE2 receptor for SARS-CoV-2. The DRAGA mice were able to sustain SARS-CoV-2 infection for at least 25 days. Infected mice showed replicating virus in the lungs, deteriorating clinical condition, and human-like lung immunopathology including human lymphocyte infiltrates, microthrombi and pulmonary sequelae. Among the intra-alveolar and peri-bronchiolar lymphocyte infiltrates, human lung-resident (CD103+) CD8+ and CD4+ T cells were sequestered in epithelial (CD326+) lung niches and secreted granzyme B and perforin, suggesting anti-viral cytotoxic activity. Infected mice also mounted human IgG antibody responses to SARS-CoV-2 viral proteins. Hence, HIS-DRAGA mice showed unique advantages as a surrogate in vivo human model for studying SARS-CoV-2 immunopathological mechanisms and testing the safety and efficacy of candidate vaccines and therapeutics.

The ongoing COVID-19 pandemic calls for more effective diagnostic tools. T cell response assessment serves as an independent indicator of prior COVID-19 exposure while also contributing to a more comprehensive characterization of SARS-CoV-2 immunity. In this study, we systematically assessed the immunogenicity of 118 epitopes with immune cells collected from multiple cohorts of vaccinated, convalescent, healthy unexposed, and SARS-CoV-2-exposed donors. We identified 75 immunogenic epitopes, 24 of which were immunodominant. We further confirmed HLA restriction for 49 epitopes and described association with more than 1 HLA allele for 14 of these. Exclusion of 2 cross-reactive epitopes that generated a response in prepandemic samples left us with a 73-epitope set that offered excellent diagnostic specificity without losing sensitivity compared with full-length antigens, and this evoked a robust cross-reactive response. We subsequently incorporated this set of epitopes into an in vitro diagnostic Corona-T-test, which achieved a diagnostic accuracy of 95% in a clinical trial. In a cohort of asymptomatic seronegative individuals with a history of prolonged SARS-CoV-2 exposure, we observed a complete absence of T cell response to our epitope panel. In combination with strong reactivity to full-length antigens, this suggests that a cross-reactive response might protect these individuals.

The mean age of lung transplant recipients has significantly increased in recent decades. Elderly recipients have a higher risk of developing herpes zoster (HZ), and they have in general a worse response to vaccination than younger persons do. We investigated the relationship between the humoral and cellular immune response to a live-attenuated HZ vaccine (Zostavax®, Merck Sharp and Dohme) and the frequencies of T and B cell subsets, especially aged cell subsets (CD28-T cells and age associated B cells, ABCs). In total, 37 patients awaiting lung transplantation received one dose of Zostavax®, and peripheral blood was collected before and within 6 months after vaccination. We observed a robust immune response after vaccination. The frequencies of CD28-T cells before vaccination had no impact on the subsequent immune response to HZ vaccination. However, a higher frequency of ABCs before vaccination correlated with a lower immune response especially regarding the cellular immune response. Cytomegalovirus seropositivity was associated with increased frequencies of CD28-T cells but not with frequencies of ABCs in the patients. In conclusion, increased levels of ABCs might disturb the cellular immune response to HZ vaccination, which could lower the efficacy of such vaccination in elderly transplant recipients.

HIV-1 broadly neutralizing antibodies (bnAbs) are difficult to induce with vaccines but are generated in ∼50% of HIV-1-infected individuals. Understanding the molecular mechanisms of host control of bnAb induction is critical to vaccine design. Here, we performed a transcriptome analysis of blood mononuclear cells from 47 HIV-1-infected individuals who made bnAbs and 46 HIV-1-infected individuals who did not and identified in bnAb individuals upregulation of RAB11FIP5, encoding a Rab effector protein associated with recycling endosomes. Natural killer (NK) cells had the highest differential expression of RAB11FIP5, which was associated with greater dysregulation of NK cell subsets in bnAb subjects. NK cells from bnAb individuals had a more adaptive/dysfunctional phenotype and exhibited impaired degranulation and cytokine production that correlated with RAB11FIP5 transcript levels. Moreover, RAB11FIP5 overexpression modulated the function of NK cells. These data suggest that NK cells and Rab11 recycling endosomal transport are involved in regulation of HIV-1 bnAb development.Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

INTRODUCTION    Interleukin 27 (IL‑27) is a cytokine secreted mostly by antigen‑presenting cells. It is important for the immune polarization of T helper‑1 (Th1) cells, and its role in interstitial lung diseases (ILDs) and lung cancer has been investigated. OBJECTIVES    We assessed IL‑27 expression in the lower airways of patients with selected ILDs and early‑stage non-small cell lung cancer (NSCLC). PATIENTS AND METHODS    IL‑27 concentrations were examined by an enzyme‑linked immunosorbent assay in bronchoalveolar lavage (BAL) fluid supernatants collected from patients with pulmonary sarcoidosis (PS; n = 30), extrinsic allergic alveolitis (EAA; n = 14), idiopathic pulmonary fibrosis (IPF; n = 12), nonspecific interstitial pneumonia (NSIP; n = 14), and NSCLC stages I to IIa (n = 16) with peripheral localization, and in controls (n = 14). The major lymphocyte subsets in BAL fluid were phenotyped, and intracellular IL‑27 expression was evaluated by flow cytometry.  RESULTS    IL‑27 concentrations in BAL fluid supernatants were significantly increased in Th1‑mediated conditions such as EAA and PS, but not in IPF or NSIP. The highest IL‑27 levels (median [SEM], 16.9 [17.5] pg/ml) were reported for NCSLC, and the lowest-for controls (median [SEM], 0.4 [0.2] pg/ml). IL‑27 was undetectable in corticosteroid‑treated patients with PS. Both CD4+ and CD8+ lymphocytes were positive for IL‑27; they were a possible local source of IL‑27 because the cytokine levels were positivelysignificantly correlated with the total number of lymphocytes, including CD4+ cells. CONCLUSIONS    Our results support the Th1‑linked activity of IL‑27in ILDs. Early‑stageNSCLC is characterizedby high IL‑27expression in the lower airways. IL‑27 is produced by a high percentage of CD4+ and CD8+ cells in BAL fluid, both in patients and controls.