Previous studies reported associations of IFITM3 SNP rs12252 with severe influenza, but evidence of association and the mechanism of risk remains controversial. We prioritized SNPs in IFITM3 based on putative biological function and identified rs34481144 in the 5′ UTR. We found evidence of a novel association of rs34481144 with severe influenza in three influenza-infected cohorts characterized by different levels of influenza illness severity. We determined the role of rs34481144 as an expression quantitative trait loci (eQTL) for IFITM3, with the risk allele associated with lower mRNA expression. The risk allele was found to have decreased IRF3 binding and increased CTCF binding in promoter-binding assays, and risk allele carriage diminished transcriptional correlations among neighboring genes, indicative of CTCF boundary activity. Furthermore, the risk allele disrupts a CpG site that undergoes differential methylation in CD8 T-cell subsets. Carriers of the risk allele had reduced CD8 T-cells in their airways during natural influenza infection, consistent with IFITM3 promoting airway CD8 T-cell accumulation, indicating that a critical function for IFITM3 may be to promote immune cell persistence at mucosal sites. Our study identifies a new regulator of IFITM3 expression that associates with CD8 T-cell levels in the airways and a spectrum of clinical outcomes.

Rationale: Children are an at-risk population for developing complications following influenza infection, but immunologic correlates of disease severity are not understood. We hypothesized that innate cellular immune responses at the site of infection would correlate with disease outcome.Objectives: To test the immunologic basis of severe illness during natural influenza virus infection of children and adults at the site of infection.Methods: An observational cohort study with longitudinal sampling of peripheral and mucosal sites in 84 naturally influenza-infected individuals, including infants. Cellular responses, viral loads, and cytokines were quantified from nasal lavages and blood, and correlated to clinical severity. Measurements and Main Results:We show for the first time that although viral loads in children and adults were similar, innate responses in the airways were stronger in children and varied considerably between plasma and site of infection. Adjusting for age and viral load, an innate immune profile characterized by increased nasal lavage monocyte chemotactic protein-3, IFN-a2, and plasma IL-10 levels at enrollment predicted progression to severe disease. Increased plasma IL-10, monocyte chemotactic protein-3, and IL-6 levels predicted hospitalization. This inflammatory cytokine production correlated significantly with monocyte localization from the blood to the site of infection, with conventional monocytes positively correlating with inflammation. Increased frequencies of CD14 lo monocytes were in the airways of participants with lower inflammatory cytokine levels.Conclusions: An innate profile was identified that correlated with disease progression independent of viral dynamics and age. The airways and blood displayed dramatically different immune profiles emphasizing the importance of cellular migration and localized immune phenotypes.

The COVID-19 pandemic is one of the most serious global challenges to delivering affordable and equitable treatment to children with cancer we have witnessed in the last few decades.

During the SARS-CoV-2 pandemic, multiple variants with differing amounts of escape from pre-existing immunity have emerged, causing concerns about continued protection. Here, we use antigenic cartography to quantify and visualize the antigenic relationships among 16 SARS-CoV-2 variants titrated against serum samples taken post-vaccination and post-infection with seven different variants. We find major antigenic differences caused by substitutions at positions 417, 452, 484, and possibly 501. B.1.1.529 (Omicron) showed the highest escape from all sera tested. Visualization of serological responses as antibody landscapes shows how reactivity clusters in different regions of antigenic space. We find changes in immunodominance of different spike regions depending on the variant an individual was exposed to, with implications for variant risk assessment and vaccine strain selection.

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Background Previous studies have shown that children and adolescents with COVID-19 generally have mild disease. Children and adolescents with cancer, however, can have severe disease when infected with respiratory viruses. In this study, we aimed to understand the clinical course and outcomes of SARS-CoV-2 infection in children and adolescents with cancer. Methods We did a cohort study with data from 131 institutions in 45 countries. We created the Global Registry of COVID-19 in Childhood Cancer to capture de-identified data pertaining to laboratory-confirmed SARS-CoV-2 infections in children and adolescents (<19 years) with cancer or having received a haematopoietic stem-cell transplantation. There were no centre-specific exclusion criteria. The registry was disseminated through professional networks through email and conferences and health-care providers were invited to submit all qualifying cases. Data for demographics, oncological diagnosis, clinical course, and cancer therapy details were collected. Primary outcomes were disease severity and modification to cancer-directed therapy. The registry remains open to data collection. Findings Of 1520 submitted episodes, 1500 patients were included in the study between April 15, 2020, and Feb 1, 2021. 1319 patients had complete 30-day follow-up. 259 (19•9%) of 1301 patients had a severe or critical infection, and 50 (3•8%) of 1319 died with the cause attributed to COVID-19 infection. Modifications to cancer-directed therapy occurred in 609 (55•8%) of 1092 patients receiving active oncological treatment. Multivariable analysis revealed several factors associated with severe or critical illness, including World Bank low-income or lower-middle-income (odds ratio [OR] 5•8 [95% CI 3•8-8•8]; p<0•0001) and upper-middle-income (1•6 [1•2-2•2]; p=0•0024) country status; age 15-18 years (1•6 [1•1-2•2]; p=0•013); absolute lymphocyte count of 300 or less cells per mm³ (2•5 [1•8-3•4]; p<0•0001), absolute neutrophil count of 500 or less cells per mm³ (1•8 [1•3-2•4]; p=0•0001), and intensive treatment (1•8 [1•3-2•3]; p=0•0005). Factors associated with treatment modification included upper-middle-income country status (OR 0•5 [95% CI 0•3-0•7]; p=0•0004), primary diagnosis of other haematological malignancies (0•5 [0•3-0•8]; p=0•0088), the presence of one of more COVID-19 symptoms at the time of presentation (1•8 [1•3-2•4]; p=0•0002), and the presence of one or more comorbidities (1•6 [1•1-2•3]; p=0•020).Interpretation In this global cohort of children and adolescents with cancer and COVID-19, severe and critical illness occurred in one fifth of patients and deaths occurred in a higher proportion than is reported in the literature in the general paediatric population. Additionally, we found that variables associated with treatment modification were not the same as those associated with greater disease severity. These data could inform clinical practice guidelines and raise awareness globally that children and adolescents with cancer are at high-risk of developing severe COVID-19 illn...

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Experimental and computational evidence suggests that HLAs preferentially bind conserved regions of viral proteins, a concept we term "targeting efficiency," and that this preference may provide improved clearance of infection in several viral systems. To test this hypothesis, T-cell responses to A/H1N1 (2009) were measured from peripheral blood mononuclear cells obtained from a household cohort study performed during the 2009-2010 influenza season. We found that HLA targeting efficiency scores significantly correlated with IFN-γ enzyme-linked immunosorbent spot responses (P = 0.042, multiple regression). A further population-based analysis found that the carriage frequencies of the alleles with the lowest targeting efficiencies, A*24, were associated with pH1N1 mortality (r = 0.37, P = 0.031) and are common in certain indigenous populations in which increased pH1N1 morbidity has been reported. HLA efficiency scores and HLA use are associated with CD8 T-cell magnitude in humans after influenza infection. The computational tools used in this study may be useful predictors of potential morbidity and identify immunologic differences of new variant influenza strains more accurately than evolutionary sequence comparisons. Population-based studies of the relative frequency of these alleles in severe vs. mild influenza cases might advance clinical practices for severe H1N1 infections among genetically susceptible populations.MHC | HLA association | T-cell epitope | Native American