The early cellular signatures of protective immunity induced by live viral vaccination

Abstract

Here, we have used primary vaccination of healthy donors with attenuated live yellow fever virus 17D (YFV-17D) as a model to study the generation of protective immunity. In short intervals after vaccination, we analyzed the induction of YFV-17D specific T-and B-cell immunity, bystander activation, dendritic cell subsets, changes in serum cytokine levels, and YFV-17D-specific antibodies. We show activation of innate immunity and a concomitant decline of numbers of peripheral blood T and B cells. An early peak of antigen-specific T cells at day 2, followed by mobilization of innate immune cells, preceded the development of maximal adaptive immunity against YFV-17D at day 14 after vaccination. Interestingly, potent adaptive immunity as measured by high titers of neutralizing YFV-17D-specific antibodies, correlated with early activation and recruitment of YFV-17D-specific CD4 + T cells and higher levels of sIL-6R. Thus our data might provide new insights into the interplay of innate and adaptive immunity for the induction of protective immunity. Keywords: Immune responses r Protective immunity r T cells r Vaccination r Yellow fever virus Supporting Information available online IntroductionVaccines were introduced into modern medicine about 300 years ago and are now administered to millions of people every year, conferring efficient protection against a variety of toxins as well as bacterial and viral diseases. However, the complex interplay of innate and adaptive immune cells, particularly in the first few Correspondence: Dr. Siegfried Kohler e-mail: siegfried.kohler@charite.de days after vaccination, leading to protective immunity after challenge with an innocuous agent is still incompletely understood. Yet this information might be crucial to developing new vaccines or improving current vaccinations with respect to efficiency, especially in risk groups and prevention of side effects.In order to assess early events in the course of a defined protective immune response, we studied vaccination of healthy * These authors contributed equally to this work. Eur. J. Immunol. 2012. 42: 2363-2373 humans with the 17D yellow fever virus vaccine (YFV-17D 5] and efficiently induce DC maturation, characterized by upregulation of CD86, CD80, MHC class II, and CD40. Barba-Spaeth et al. detected YFV-17D-dependent infection of human DCs irrespective of their maturation state but no infection of monocytes [6]. In vivo, the activation of B-and T cells has been shown to occur between day 4 and day 15 in YFV-17D vaccinated subjects, characterized by the expression of phenotypic markers such as CD69 or IL-10-R on CD8 + T and B cells and HLA-DR on CD4 + T cells [7]. A persistent, broadly reactive CD4 + T-cell response with a mixed TH1/TH2 phenotype was observed [8]. The maximal expansion of CD8 + T cells was detectable at day 30 with 0.5 to 17% of CD8 + T cells recognized by tetramers, yet activation determined by expression of HLA-DR + , CD38 + , KI-67 high , and BCL-2 low , among YFV-17D-specific CD8 + T cells was already detected at ...

The yellow fever 17D virus as a platform for new live attenuated vaccines

“…After this period of time, the gradual differentiation of these effector cells into memory cells starts. These observations were further confirmed in a complete study of activation and differentiation kinetics of various cell types of both the innate and adaptive immune systems implicated in the immune response to YF17D 25 . A more detailed phenotypic analysis provided further evidence for YF17D-driven activation and differentiation of CD8 + T cells, demonstrating the functional profile alteration of these lymphocytes in composition as these cell types mature from effector to memory.…”

Low Thymic Activity and Dendritic Cell Numbers Are Associated with the Immune Response to Primary Viral Infection in Elderly Humans

“…Although we verified our assessment of vaccine-induced T cell activation by Ag-specific ex vivo stimulation, we cannot completely rule out that we measured some CD4 + and CD8 + bystander activation in our study. However, published data from others and us show that at least in young vaccinees nonrelated T cell specificities transiently increase in peripheral numbers but do not show signs of activation (15,16). Importantly, we can rule out for our study that reactive T cell counts simply reflect the total cell counts, because underlying total leukocyte counts were not affected by age.…”

“…After 5 min of incubation, 1 ml L/D Red (Invitrogen) was supplemented to each sample. After incubation with surface Abs, cells were fixed and permeabilized with FOXP3 Fixation/Permeabilization Kit (eBioscience) according to manufacturer's protocol and stained intracellularly with anti-Helios (22F6; Biolegend), anti-FOXP3 (259D/C7), anti-Ki-67 (B56), and anti-CD3 (UCHT1; all BD Biosciences (15,(26)(27)(28)(29). At all other days activated cells do not necessarily represent YF-specific T cells but rather, for example, steady-state turnover.…”

“…But whether such age-related qualitative and quantitative cellular alterations affect a primary immune response has not yet been demonstrated directly in humans. We approached this issue using yellow fever (YF) vaccination fever as a model for a primary infection in humans (15,16). The vaccine contains the live-attenuated YF virus 17D (YFV-17D) strain, which is able to infect human cells productively (17), causing a full acute immune response (18).…”

Absolute counting of neutrophils in whole blood using flow cytometry

“…However, there is a current need for a simple, single-platform FCM-based method to obtain ANC from mouse blood in the research laboratory. The Trucount tube system has been adapted to enumerate mouse erythrocytes (14), dendritic cells and lymphocytes (15) but to the best of our knowledge no assay combining counting and classification has been designed for mouse ANC. Volumetric FCM is popular in resource poor settings, as a tool to diagnose HIV infections in human (16,17).…”