Intratumoral STING agonist reverses immune evasion in PD-(L)1-refractory Merkel cell carcinoma: mechanistic insights from detailed biomarker analyses.

Background: Antibodies blocking programmed death (PD)-1 or its ligand (PD-L1) have revolutionized cancer care, but many patients do not experience durable benefits. Novel treatments to stimulate antitumor immunity are needed in the PD-(L)1 refractory setting. The stimulator of interferon genes (STING) protein, an innate sensor of cytoplasmic DNA, is a promising target with several agonists in development.

Cytomegalovirus immunity in high-risk liver transplant recipients following preemptive antiviral therapy versus prophylaxis.

CMV-specific T cells, NK cells, and neutralizing antibodies (nAbs) were assessed in a randomized trial of CMV prevention with preemptive antiviral therapy (PET) versus prophylactic antiviral therapy (PRO) in donor-seropositive/recipient-seronegative (D+R-) liver transplant recipients (LTxR) at 100 days (end of intervention) and at 6 and 12 months after transplant. The PET group had significantly increased numbers of circulating polyfunctional T cells, NK cells, and nAbs compared with the PRO group at day 100, and several CMV immune parameters remained significantly higher by 12 months after transplant. Among PET recipients, preceding CMV viremia (vs.

Tumor Regression Following Engineered Polyomavirus-Specific T Cell Therapy in Immune Checkpoint Inhibitor-Refractory Merkel Cell Carcinoma.

Although immune check-point inhibitors (CPIs) revolutionized treatment of Merkel cell carcinoma (MCC), patients with CPI-refractory MCC lack effective therapy. More than 80% of MCC express T-antigens encoded by Merkel cell polyomavirus, which is an ideal target for T-cell receptor (TCR)-based immunotherapy. However, MCC often repress HLA expression, requiring additional strategies to reverse the downregulation for allowing T cells to recognize their targets.

Treponema pallidum Periplasmic and Membrane Proteins Are Recognized by Circulating and Skin CD4+ T Cells.

Background: Histologic and serologic studies suggest the induction of local and systemic Treponema pallidum-specific CD4+ T-cell responses to T. pallidum infection. We hypothesized that T.

HSV-1 employs UL56 to antagonize expression and function of cGAMP channels.

DNA sensing is important for antiviral immunity. The DNA sensor cGAS synthesizes 2'3'-cyclic GMP-AMP (cGAMP), a second messenger that activates STING, which induces innate immunity. cGAMP not only activates STING in the cell where it is produced but cGAMP also transfers to other cells.

periplasmic and membrane proteins are recognized by circulating and skin CD4+ T cells.

Background: Histologic and serologic studies suggest the induction of local and systemic ( )-specific CD4+ T cell responses to infection. We hypothesized that -specific CD4+ T cells are detectable in blood and in the skin rash of secondary syphilis and persist in both compartments after treatment.

Methods: PBMC collected from 67 participants were screened by IFNγ ELISPOT response to sonicate.

Expansion of the HSV-2-specific T cell repertoire in skin after immunotherapeutic HSV-2 vaccine.

The skin at the site of HSV-2 reactivation is enriched for HSV-2-specific T cells. To evaluate whether an immunotherapeutic vaccine could elicit skin-based memory T cells, we studied skin biopsies and HSV-2-reactive CD4 T cells from peripheral blood mononuclear cells (PBMCs) by T cell receptor β () sequencing before and after vaccination with a replication-incompetent whole virus HSV-2 vaccine candidate (HSV529). The representation of HSV-2-reactive CD4 sequences from PBMCs in the skin repertoire increased after the first vaccine dose.

Merkel cell polyomavirus-specific and CD39CLA CD8 T cells as blood-based predictive biomarkers for PD-1 blockade in Merkel cell carcinoma.

Merkel cell carcinoma is a skin cancer often driven by Merkel cell polyomavirus (MCPyV) with high rates of response to anti-PD-1 therapy despite low mutational burden. MCPyV-specific CD8 T cells are implicated in anti-PD-1-associated immune responses and provide a means to directly study tumor-specific T cell responses to treatment. Using mass cytometry and combinatorial tetramer staining, we find that baseline frequencies of blood MCPyV-specific cells correlated with response and survival.

Circulating cancer-specific CD8 T cell frequency is associated with response to PD-1 blockade in Merkel cell carcinoma.

Understanding cancer immunobiology has been hampered by difficulty identifying cancer-specific T cells. Merkel cell polyomavirus (MCPyV) causes most Merkel cell carcinomas (MCCs). All patients with virus-driven MCC express MCPyV oncoproteins, facilitating identification of virus (cancer)-specific T cells.

Prevention of respiratory virus transmission by resident memory CD8 T cells.

An ideal vaccine both attenuates virus growth and disease in infected individuals and reduces the spread of infections in the population, thereby generating herd immunity. Although this strategy has proved successful by generating humoral immunity to measles, yellow fever and polio, many respiratory viruses evolve to evade pre-existing antibodies. One approach for improving the breadth of antiviral immunity against escape variants is through the generation of memory T cells in the respiratory tract, which are positioned to respond rapidly to respiratory virus infections.

Repeated mRNA vaccination sequentially boosts SARS-CoV-2-specific CD8 T cells in persons with previous COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hybrid immunity is more protective than vaccination or previous infection alone. To investigate the kinetics of spike-reactive T (T) cells from SARS-CoV-2 infection through messenger RNA vaccination in persons with hybrid immunity, we identified the T cell receptor (TCR) sequences of thousands of index T cells and tracked their frequency in bulk TCRβ repertoires sampled longitudinally from the peripheral blood of persons who had recovered from coronavirus disease 2019 (COVID-19). Vaccinations led to large expansions in memory T cell clonotypes, most of which were CD8 T cells, while also eliciting diverse T cell clonotypes not observed before vaccination.

Recruitment of naive CD4+ T cells by the recombinant zoster vaccine correlates with persistent immunity.

Herpes zoster (HZ) is a substantial problem for people with decreased cell-mediated immunity, including older adults. The first vaccine approved for HZ prevention, the zoster vaccine live (ZVL), which provided limited and short-lived protection, has been supplanted by the superior recombinant zoster vaccine (RZV), which provides robust and durable protection. To understand the mechanisms underlying the differential immunologic characteristics of the 2 vaccines, we used T cell receptor β chain sequencing and peptide-MHC class II tetramer staining to analyze recombinant glycoprotein E-specific (gE-specific) CD4+ T cell clonotypes in RZV and ZVL recipients.

LAMP1 targeting of the large T antigen of Merkel cell polyomavirus results in potent CD4 T cell responses and tumor inhibition.

Introduction: Most cases of Merkel cell carcinoma (MCC), a rare and highly aggressive type of neuroendocrine skin cancer, are associated with Merkel cell polyomavirus (MCPyV) infection. MCPyV integrates into the host genome, resulting in expression of oncoproteins including a truncated form of the viral large T antigen (LT) in infected cells. These oncoproteins are an attractive target for a therapeutic cancer vaccine.

Semi-infectious particles contribute substantially to influenza virus within-host dynamics when infection is dominated by spatial structure.

Influenza is an ribonucleic acid virus with a genome that comprises eight segments. Experiments show that the vast majority of virions fail to express one or more gene segments and thus cannot cause a productive infection on their own. These particles, called semi-infectious particles (SIPs), can induce virion production through complementation when multiple SIPs are present in an infected cell.

Prior Herpes Simplex Virus Infection and the Risk of Herpes Zoster.

Background: The incidence of herpes zoster (HZ) has increased in the United States concurrent with decrease in herpes simplex virus (HSV) prevalence. We hypothesized that lack of HSV-elicited cross-reactive immunity to varicella-zoster virus (VZV) results in an increased risk of HZ. Using specimens from the placebo arm of the Shingles Prevention Study, we investigated whether persons who develop HZ are less likely to have prior HSV infection than persons who do not develop HZ, and whether HZ is less severe in persons with HSV than in HSV seronegative persons.

Effect of Norovirus Inoculum Dose on Virus Kinetics, Shedding, and Symptoms.

The effect of norovirus dose on outcomes such as virus shedding and symptoms after initial infection is not well understood. We performed a secondary analysis of a human challenge study by using Bayesian mixed-effects models. As the dose increased from 4.

Varicella-zoster virus proteome-wide T-cell screening demonstrates low prevalence of virus-specific CD8 T-cells in latently infected human trigeminal ganglia.

Background: Trigeminal ganglia (TG) neurons are an important site of lifelong latent varicella-zoster virus (VZV) infection. Although VZV-specific T-cells are considered pivotal to control virus reactivation, their protective role at the site of latency remains uncharacterized.

Methods: Paired blood and TG specimens were obtained from ten latent VZV-infected adults, of which nine were co-infected with herpes simplex virus type 1 (HSV-1).

Multiple Subthreshold GPCR Signals Combined by the G-Proteins Gα and Gα Activate the Egg-Laying Muscles.

Individual neurons or muscle cells express many G-protein-coupled receptors (GPCRs) for neurotransmitters and neuropeptides, yet it remains unclear how cells integrate multiple GPCR signals that all must activate the same few G-proteins. We analyzed this issue in the egg-laying system, where multiple GPCRs on muscle cells promote contraction and egg laying. We genetically manipulated individual GPCRs and G-proteins specifically in these muscle cells within intact animals and then measured egg laying and muscle calcium activity.

Spike-specific T cells are enriched in breastmilk following SARS-CoV-2 mRNA vaccination.

Human breastmilk is rich in T cells; however, their specificity and function are largely unknown. We compared the phenotype, diversity, and antigen specificity of T cells in breastmilk and peripheral blood of lactating individuals who received SARS-CoV-2 messenger RNA (mRNA) vaccination. Relative to blood, breastmilk contained higher frequencies of T effector and central memory populations that expressed mucosal-homing markers.

NIAID workshop on T cell technologies.

On 15–16 June 2022, the National Institute of Allergy and Infectious Diseases hosted a virtual workshop on the topic of T cell technologies to discuss assays, novel technology development, bench and clinical application of those technologies, and challenges and innovations in the field.

Diminished humoral and cellular responses to SARS-CoV-2 vaccines in patients with chronic lymphocytic leukemia.

Previous studies have demonstrated low rates of seroconversion to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines in patients with chronic lymphocytic leukemia (CLL). In this national collaboration of 11 cancer centers in the United States, we aimed to further characterize and understand vaccine-induced immune responses, including T-cell responses, and the impact of CLL therapeutics (#NCT04852822). Eligible patients were enrolled in 2 cohorts (1) at the time of initial vaccination and (2) at the time of booster vaccination.

Selective retention of virus-specific tissue-resident T cells in healed skin after recovery from herpes zoster.

Herpes zoster is a localized skin infection caused by reactivation of latent varicella-zoster virus. Tissue-resident T cells likely control skin infections. Zoster provides a unique opportunity to determine if focal reinfection of human skin boosts local or disseminated antigen-specific tissue-resident T cells.