Project description:Memory B cells represent one of the pillar of humoral protection and are found in the circulation and secondary lymphoid organs several decades after initial pathogen or vaccine encounter. The exact cellular and biological mechanisms allowing long-term survival of quiescent cells in such a fluctuating microenvironment remain poorly understood. Assessing the true longevity of human memory B cells against common pathogens is, in most settings, hindered by the possibility for any given individual to re-encounter them during his lifetime. Smallpox, officially declared eradicated in 1980 (Fenner WHO 1988), represents one notable exception. Alongside smallpox eradication, anti-smallpox vaccination, based on the live Vaccinia virus, was progressively discontinued during the 1970s. As such, any detectable anti-vaccinia memory B cell in an individual post 2010 would likely have been generated more than 40 years ago, without any re-stimulation with the immunizing antigen during that timeframe. Anti-vaccinia antibodies serum titers remain stable in human for more than 80 years after first vaccination (Amanna NEJM 2007, PMID: 17989383), with several identified immunodominant epitopes including the envelope glycoprotein B5R (Lantto J Virol 2011, PMID: 21147924). Anti-vaccinia memory B cells have similarly been followed longitudinally in the blood for up to 65 years post vaccination (Amanna NEJM 2007, PMID: 17989383 ; Crotty JI 2003, PMID : 14607890) and, following a contraction phase taking place in the first couple of years after immunization, reach a remarkably stable plateau that last for decades at around 0.1% of total circulating IgG+ memory B cells. Functional analysis of such long-lived memory B cells, however, is still lacking. As a proxy to study long-lived memory B cells, IgG+ switched memory B cells specific for the immunodominant Vaccinia antigen B5R (B5R+ IgG+ memory B cells) were sorted and analyzed by scRNAseq from the spleen of six organ donors, collected between 2015 and 2018. For all donors, B5R+ IgG+ memory B cells were sorted alongside total IgG+ memory B cells (live IgD-CD27+IgG+CD20+CD3-CD14-CD16-) and naïve B cells (live IgD+CD27-CD38-CD24-CD20+CD3-CD14-CD16-). Single-cell mRNA sequencing was performed according to an adapted version of the SORT-seq protocol (Muraro et al., 2016, PMID: 27693023), with cDNA libraries generation, sequencing and reads alignment performed at Single Cell Discoveries (Utrecht, Netherlands).

Project description:The objective of this study is to: 1) Characterize the immune responsiveness to administration of non-live vaccines in three cohorts of healthy adult subjects through the analysis of blood leukocytes transcriptional profiles. 2) Validate whole blood transcriptional profiles generated from standard 3mL blood draws versus 200uL blood draws obtained by finger stick. 3) Discover potential biomarkers for immune-responsiveness to non-live vaccines. A total of 621 blood samples were collected either by venipuncture (387) or finger prick (234) from four groups of healthy adults receiving either, 2009/10 seasonal influenza or 23-valent pneumococcal vaccine or placebo (saline) injections. Subjects were recruited in 3 cohorts with 4-7 individuals per group; cohort 3 was recruited for validation of the systemic day 1 immune signature in response to seasonal influenza and pneumococcal vaccination. From each subject, peripheral blood was drawn into Tempus tubes (Applied Biosystems) or obtained by finger prick into micro capillaries and then transferred into tempus reagent to lyse blood cells and stabilize RNA before storing at -80ºC until mRNA extraction. The training set for transcriptional profiling of blood obtained by venipuncture was performed in cohort 1 which included 6 healthy adult individuals receiving seasonal influenza vaccine, 6 healthy adult individuals receiving pneumococcal vaccine, and 6 healthy adult individuals receiving placebo (saline injections). The test set for transcriptional profiling of blood obtained by venipuncture was performed in cohort 2 which included 6 healthy adult individuals receiving seasonal influenza vaccine, 6 healthy adult individuals receiving pneumococcal vaccine, and 6 healthy adult individuals receiving placebo (saline injections). The validation set for confirming systemic day 1 transcriptome immune signature in response to seasonal influenza and pneumococcal vaccination was performed in cohort 3 which included 6 healthy adult individuals receiving seasonal influenza vaccine and 4 healthy adult individuals receiving pneumococcal vaccine. The training set for transcriptional profiling of blood obtained by finger prick was performed in cohort 2 and the test set in cohort 1.

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Antibody profiling of smallpox vaccinees with/without a 'take' using custom vaccinia virus proteome microarrays

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