Project description:The PI3K/Akt signaling pathway impacts various aspects of CD8 T cell homeostasis, such as effect versus memory cell differentiation, during viral infection. We used microarrays to determine which downstream molecules were affected and what other signaling pathways were interconnected with the Akt pathway by constitutive activation of Akt in LCMV-infected CD8 T cells. Splenocytes from naive P14/WT or P14/Akt mice were stained with anti-CD8 and anti-Ly5.1, and CD8 T cells were sorted using a FACSAria II instrument. Purified Ly5.1+ CD8 T cells from P14/WT or P14/Akt mice were transferred into B6 mice, which were subsequently infected with LCMV Armstrong. At day 8 post infection, splenocytes were stained with anti-CD8, anti-Ly5.1, anti-KLRG1, and anti-CD127. Following staining, short-lived effector cells (SLECs) and memory precursor effector cells (MPECs) were sorted using the FACSAria II instrument; the purity of the sorted cells was >95%. A total of 5 samples were analyzed, including WT naive, WT SLEC, WT MPEC, Akt naive and Akt SLEC.
Project description:Besides their function in recognizing cancerous and virally infected cells, natural killer (NK) cells have the potential to shape adaptive immune responses. However, the mechanisms employed by NK cells to negatively regulate virus-specific CD8 T cell responses remain to be fully defined. Using activating receptor natural cytotoxicity receptor (NCR) 1 deficient (NCR1gfp/gfp) mice, we found increased numbers of virus-specific CD8 T cells, leading to enhanced virus control during acute LCMV infection. Furthermore, virus-specific CD8 T cells were more activated in the absence of NCR1, resulting in exacerbated immunopathology, documented by weight loss, and superior virus control early during chronic LCMV infection. Transfer experiments of virus-specific CD8 T cells into NCR1 deficient hosts revealed a direct cross talk between NK and CD8 T cells. Studies on the splenic microarchitecture revealed pronounced disorganization of T cells in infected NCR1gfp/gfp mice, resulting in enhanced immunopathology and disruption of the T cell niche upon chronic LCMV infection. Our data show a novel pathway employed by NK cells to regulate antiviral CD8 T cell responses, namely direct recognition and elimination of activated CD8 T cells via NCR1 early during infection to protect the host from an overshooting T cell response.
Project description:The PI3K/Akt signaling pathway impacts various aspects of CD8 T cell homeostasis, such as effect versus memory cell differentiation, during viral infection. We used microarrays to determine which downstream molecules were affected and what other signaling pathways were interconnected with the Akt pathway by constitutive activation of Akt in LCMV-infected CD8 T cells. Overall design: Splenocytes from naive P14/WT or P14/Akt mice were stained with anti-CD8 and anti-Ly5.1, and CD8 T cells were sorted using a FACSAria II instrument. Purified Ly5.1+ CD8 T cells from P14/WT or P14/Akt mice were transferred into B6 mice, which were subsequently infected with LCMV Armstrong. At day 8 post infection, splenocytes were stained with anti-CD8, anti-Ly5.1, anti-KLRG1, and anti-CD127. Following staining, short-lived effector cells (SLECs) and memory precursor effector cells (MPECs) were sorted using the FACSAria II instrument; the purity of the sorted cells was >95%. A total of 5 samples were analyzed, including WT naive, WT SLEC, WT MPEC, Akt naive and Akt SLEC.
Project description:BACKGROUND:Lymphocytic choriomeningitis virus (LCMV) causes a variety of diseases, including asymptomatic infections, meningitis, and congenital infections in the fetus of infected mother. The development of a safe and effective vaccine against LCMV is imperative. This study aims to develop a new candidate vaccine against LCMV using a recombinant replication-incompetent rabies virus (RV) vector. METHODOLOGY/PRINCIPAL FINDINGS:In this study, we have generated a recombinant deficient RV expressing the LCMV glycoprotein precursor (GPC) (RV?P-LCMV/GPC) which is lacking the RV-P gene. RV?P-LCMV/GPC is able to propagate only in cells expressing the RV-P protein. In contrast, the LCMV-GPC can be expressed in general cells, which do not express RV-P protein. The ability of RV?P-LCMV/GPC to protect mice from LCMV infection and induce cellular immunity was assessed. Mice inoculated intraperitoneally with RV?P-LCMV/GPC showed higher survival rates (88.2%) than those inoculated with the parental recombinant RV-P gene-deficient RV (RV?P) (7.7%) following a LCMV challenge. Neutralizing antibody (NAb) against LCMV was not induced, even in the sera of surviving mice. CD8+ T-cell depletion significantly reduced the survival rates of RV?P-LCMV/GPC-inoculated mice after the LCMV challenge. These results suggest that CD8+ T cells play a major role in the observed protection against LCMV. In contrast, NAbs against RV were strongly induced in sera of mice inoculated with either RV?P-LCMV/GPC or RV?P. In safety tests, suckling mice inoculated intracerebrally with RV?P-LCMV/GPC showed no symptoms. CONCLUSIONS/SIGNIFICANCE:These results show RV?P-LCMV/GPC might be a promising candidate vaccine with dual efficacy, protecting against both RV and LCMV.
Project description:The forkhead O transcription factors (FOXO) integrate a range of extracellular signals including growth factor signaling, inflammation, oxidative stress and nutrient availability, to substantially alter the program of gene expression and modulate cell survival, cell cycle progression, and many cell-type specific responses yet to be unraveled. Naive antigen-specific CD8+ T cells undergo a rapid expansion and arming of effector function within days of pathogen exposure, but in addition, by the peak of expansion, they form precursors to memory T cells capable of self-renewal and indefinite survival. We used microarrays to determine whether FOXO1 broadly affects effector and memory differentiation, and to what extent FOXO1 determines the program of memory T cell gene expression. To obtain an unbiased analysis of genes differentially expressed in antigen-specific Foxo1-/- CD8+ T cells responding to infection, we obtained RNA and performed Affymetrix microarray analysis from KLRG1low and KLRG1high FACS-sorted congenically-marked WT and Foxo1-/- P14 cells obtained from mixed transfers, eight days post-infection with LCMV-Armstrong. We carried out gene deletion in Rosa26Cre-ERT2 Foxo1f/f (Foxo1-/-) P14 mice just prior to adoptive transfer (Kerdiles et al., 2009), and transfer equal numbers of P14 cells from the spleens of KO (Foxo1-/- P14) and WT P14 mice. Day8 post infection
Project description:During acute viral infections, naïve CD8+ T cells differentiate into effector CD8+ T cells and, after viral control, into memory CD8+ T cells. Memory CD8+ T cells are highly functional, proliferate rapidly upon reinfection and persist long-term without antigen. In contrast, during chronic infections, CD8+ T cells become “exhausted” and have poor effector function, express multiple inhibitory receptors, possess low proliferative capacity, and cannot persist without antigen. To compare the development of functional memory T cells with poorly functional exhausted T cells, we generated longitudinal transcriptional profiles for each. Naive CD44Lo CD8+ T cells were isolated and sorted from uninfected C57BL/6 mice and H2-Db GP33-specific CD8+ T cells were sorted using MHC-I tetramers at d6, 8, 15, and 30 p.i. with either LCMV Arm or LCMV clone 13. RNA from these CD8+ T cells was processed, amplified, labeled, and hybridized to Affymetrix GeneChip MoGene 1.0 st microarrays
Project description:Chromatin accessibility profiling of CD8+ T cells in chronic LCMV Clone 13 infected mice depleted of CD4+ T cells. Overall design: ATAC-seq based profiling of subsets of transferred control or Ptpn2-null P14 CD8+ T-cells from mice chronically infected with LCMV Clone 13 (day 8 post-infection).
Project description:5 distinct populations of exhausted CD8+ T cells occur in chronic LCMV Clone 13 infected mice depleted of CD4+ T cells Overall design: Single-cell RNA-sequencing based profiling of transferred control or Ptpn2-null P14 CD8+ T-cells from mice chronically infected with LCMV Clone 13 (day 30 post-infection)
Project description:In adult mice the severity of disease from viral infections is determined by the balance between the efficiency of the immune response and the magnitude of viral load. Here, the impact of this dynamic is examined in neonates. Newborns are highly susceptible to infections due to poor innate responses, lower numbers of T cells and Th2-prone immune responses. Eighty-percent of 7-day old mice, immunologically equivalent to human neonates, succumbed to extremely low doses (5 PFU) of the essentially non-lethal lymphocytic choriomeningitis virus (LCMV-Armstrong) given intraperitoneally. This increased lethality was determined to be dependent upon poor early viral control, as well as, T cells and perforin as assessed in knockout mice. By day 3, these neonatal mice had 400-fold higher viral loads as compared to adults receiving a 10,000-fold (5X104 PFU) higher dose of LCMV. The high viral load in combination with the subsequent immunological defect of partial CD8 T cell clonal exhaustion in the periphery led to viral entry and replication in the brain. Within the brain, CD8 T cells were protected from exhaustion, and thus were able to mediate lethal immunopathology. To further delineate the role of early viral control, neonatal mice were infected with Pichinde virus, a less virulent arenavirus, or LCMV was given to pups of LCMV-immune mothers. In both cases, peak viral load was at least 29-fold lower, leading to functional CD8 T cell responses and 100% survival.