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Epstein-Barr virus (EBV), a lymphomagenic human herpesvirus, colonises the host through polyclonal B cell-growth-transforming infections yet establishes persistence only in IgD+ CD27+ non-switched memory (NSM) and IgD− CD27+ switched memory (SM) B cells, not in IgD+ CD27− naïve (N) cells. How this selectivity is achieved remains poorly understood. Here we show that purified N, NSM and SM cell preparations are equally transformable in vitro to lymphoblastoid cells lines (LCLs) that, despite upregulating the activation-induced cytidine deaminase (AID) enzyme necessary for Ig isotype switching and Ig gene hypermutation, still retain the surface Ig phenotype of their parental cells. However, both N- and NSM-derived lines remain inducible to Ig isotype switching by surrogate T cell signals. More importantly, IgH gene analysis of N cell infections revealed two features quite distinct from parallel mitogen-activated cultures. Firstly, following 4 weeks of EBV-driven polyclonal proliferation, individual clonotypes then become increasingly dominant; secondly, in around 35% cases these clonotypes carry Ig gene mutations which both resemble AID products and, when analysed in prospectively-harvested cultures, appear to have arisen by sequence diversification in vitro. Thus EBV infection per se can drive at least some naïve B cells to acquire Ig memory genotypes; furthermore, such cells are often favoured during an LCL's evolution to monoclonality. Extrapolating to viral infections in vivo, these findings could help to explain how EBV-infected cells become restricted to memory B cell subsets and why EBV-driven lymphoproliferative lesions, in primary infection and/or immunocompromised settings, so frequently involve clones with memory genotypes.

Epstein-Barr virus (EBV) persists in the

In acute myeloid leukemia (AML), molecular heterogeneity across patients constitutes a major challenge for prognosis and therapy. AML with NPM1 mutation is a distinct genetic entity in the revised World Health Organization classification. However, differing patterns of co-mutation and response to therapy within this group necessitate further stratification. Here we report two distinct subtypes within NPM1 mutated AML patients, which we label as primitive and committed based on the respective presence or absence of a stem cell signature. Using gene expression (RNA-seq), epigenomic (ATAC-seq) and immunophenotyping (CyToF) analysis, we associate each subtype with specific molecular characteristics, disease differentiation state and patient survival. Using ex vivo drug sensitivity profiling, we show a differential drug response of the subtypes to specific kinase inhibitors, irrespective of the FLT3-ITD status. Differential drug responses of the primitive and committed subtype are validated in an independent AML cohort. Our results highlight heterogeneity among NPM1 mutated AML patient samples based on stemness and suggest that the addition of kinase inhibitors to the treatment of cases with the primitive signature, lacking FLT3-ITD, could have therapeutic benefit.

Background This study aimed to determine the impact of pulmonary complications on death after surgery both before and during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Methods This was a patient-level, comparative analysis of two, international prospective cohort studies: one before the pandemic (January–October 2019) and the second during the SARS-CoV-2 pandemic (local emergence of COVID-19 up to 19 April 2020). Both included patients undergoing elective resection of an intra-abdominal cancer with curative intent across five surgical oncology disciplines. Patient selection and rates of 30-day postoperative pulmonary complications were compared. The primary outcome was 30-day postoperative mortality. Mediation analysis using a natural-effects model was used to estimate the proportion of deaths during the pandemic attributable to SARS-CoV-2 infection. Results This study included 7402 patients from 50 countries; 3031 (40.9 per cent) underwent surgery before and 4371 (59.1 per cent) during the pandemic. Overall, 4.3 per cent (187 of 4371) developed postoperative SARS-CoV-2 in the pandemic cohort. The pulmonary complication rate was similar (7.1 per cent (216 of 3031) versus 6.3 per cent (274 of 4371); P = 0.158) but the mortality rate was significantly higher (0.7 per cent (20 of 3031) versus 2.0 per cent (87 of 4371); P < 0.001) among patients who had surgery during the pandemic. The adjusted odds of death were higher during than before the pandemic (odds ratio (OR) 2.72, 95 per cent c.i. 1.58 to 4.67; P < 0.001). In mediation analysis, 54.8 per cent of excess postoperative deaths during the pandemic were estimated to be attributable to SARS-CoV-2 (OR 1.73, 1.40 to 2.13; P < 0.001). Conclusion Although providers may have selected patients with a lower risk profile for surgery during the pandemic, this did not mitigate the likelihood of death through SARS-CoV-2 infection. Care providers must act urgently to protect surgical patients from SARS-CoV-2 infection.

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