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Appropriate use and interpretation of serological tests for assessments of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure, infection and potential immunity require accurate data on assay performance. We conducted a head-to-head evaluation of ten point-of-care-style lateral flow assays (LFAs) and two laboratory-based enzyme-linked immunosorbent assays to detect anti-SARS-CoV-2 IgM and IgG antibodies in 5-d time intervals from symptom onset and studied the specificity of each assay in pre-coronavirus disease 2019 specimens. The percent of seropositive individuals increased with time, peaking in the latest time interval tested (>20 d after symptom onset). Test specificity ranged from 84.3% to 100.0% and was predominantly affected by variability in IgM results. LFA specificity could be increased by considering weak bands as negative, but this decreased detection of antibodies (sensitivity) in a subset of SARS-CoV-2 real-time PCR-positive cases. Our results underline the importance of seropositivity threshold determination and reader training for reliable LFA deployment. Although there was no standout serological assay, four tests achieved more than 80% positivity at later time points tested and more than 95% specificity.

Background:Serological tests are crucial tools for assessments of SARS-CoV-2 exposure, infection and potential immunity. Their appropriate use and interpretation require accurate assay performance data. Method:We conducted an evaluation of 10 lateral flow assays (LFAs) and two ELISAs to detect anti-SARS-CoV-2 antibodies. The specimen set comprised 128 plasma or serum samples from 79 symptomatic SARS-CoV-2 RT-PCR-positive individuals; 108 pre-COVID-19 negative controls; and 52 recent samples from individuals who underwent respiratory viral testing but were not diagnosed with Coronavirus Disease 2019 (COVID-19). Samples were blinded and LFA results were interpreted by two independent readers, using a standardized intensity scoring system. Results:Among specimens from SARS-CoV-2 RT-PCR-positive individuals, the percent seropositive increased with time interval, peaking at 81.8-100.0% in samples taken >20 days after symptom onset. Test specificity ranged from 84.3-100.0% in pre-COVID-19 specimens. Specificity was higher when weak LFA bands were considered negative, but this decreased sensitivity. IgM detection was more variable than IgG, and detection was highest when IgM and IgG results were combined. Agreement between ELISAs and LFAs ranged from 75.7-94.8%. No consistent cross-reactivity was observed. Conclusion:Our evaluation showed heterogeneous assay performance. Reader training is key to reliable LFA performance, and can be tailored for survey goals. Informed use of serology will require evaluations covering the full spectrum of SARS-CoV-2 infections, from asymptomatic and mild infection to severe disease, and later convalescence. Well-designed studies to elucidate the mechanisms and serological correlates of protective immunity will be crucial to guide rational clinical and public health policies.

Adoptive transfer of antigen-specific T cells represents a major advance in cancer immunotherapy, with robust clinical outcomes in some patients.sup.1. Both the number of transferred T cells and their differentiation state are critical determinants of effective responses.sup.2,3. T cells can be expanded with T cell receptor (TCR)-mediated stimulation and interleukin-2, but this can lead to differentiation into effector T cells.sup.4,5 and lower therapeutic efficacy.sup.6, whereas maintenance of a more stem-cell-like state before adoptive transfer is beneficial.sup.7. Here we show that H9T, an engineered interleukin-2 partial agonist, promotes the expansion of CD8.sup.+ T cells without driving terminal differentiation. H9T led to altered STAT5 signalling and mediated distinctive downstream transcriptional, epigenetic and metabolic programs. In addition, H9T treatment sustained the expression of T cell transcription factor 1 (TCF-1) and promoted mitochondrial fitness, thereby facilitating the maintenance of a stem-cell-like state. Moreover, TCR-transgenic and chimeric antigen receptor-modified CD8.sup.+ T cells that were expanded with H9T showed robust anti-tumour activity in vivo in mouse models of melanoma and acute lymphoblastic leukaemia. Thus, engineering cytokine variants with distinctive properties is a promising strategy for creating new molecules with translational potential. H9T, an engineered IL-2 partial agonist, promotes the expansion of T cells while maintaining a stem-cell-like state, leading to improved efficacy of adoptive cell therapy in mouse models of melanoma and acute lymphoblastic leukaemia., Author(s): Fei Mo [sup.1] , Zhiya Yu [sup.2] , Peng Li [sup.1] , Jangsuk Oh [sup.1] , Rosanne Spolski [sup.1] , Liang Zhao [sup.3] , Caleb R. Glassman [sup.4] , [...]

Stimulating an immune response against cancer through adoptive transfer of tumor-targeting lymphocytes has shown great promise in hematological malignancies, but clinical efficacy against many common solid epithelial cancers remains low. Targeting 'neoantigens'--the somatic mutations expressed only by tumor cells--might enable tumor destruction without causing undue damage to vital healthy tissues. Major challenges to targeting neoantigens with T cells include heterogeneity and variability in antigen processing and presentation of targets by tumors, and an incomplete understanding of which T cell qualities are essential for clinically effective therapies. Finally, the prospect of targeting somatic tumor mutations to promote T cell destruction of cancer must contend with the biology that not all tumor-expressed 'neoepitopes' actually generate neoantigens that can be functionally recognized and provoke an effective immune response. In this Review, we discuss the promise, progress and challenges for improving neoantigen-targeted T cell-based immunotherapies for cancer. This Review examines the promise, progress and challenges for developing personal T cell-based immunotherapies for cancer., Author(s): Tori N. Yamamoto [sup.1] [sup.2] [sup.3] , Rigel J. Kishton [sup.1] [sup.2] , Nicholas P. Restifo [sup.1] [sup.2] [sup.4] Author Affiliations: (1) Center for Cancer Research, National Cancer Institute [...]

Across clinical trials, T cell expansion and persistence following adoptive cell transfer (ACT) have correlated with superior patient outcomes. Herein, we undertook a pan-cancer analysis to identify actionable ligand-receptor pairs capable of compromising T cell durability following ACT. We discovered that FASLG, the gene encoding the apoptosis-inducing ligand FasL, is overexpressed within the majority of human tumor microenvironments (TMEs). Further, we uncovered that Fas, the receptor for FasL, is highly expressed on patient-derived T cells used for clinical ACT. We hypothesized that a cognate Fas-FasL interaction within the TME might limit both T cell persistence and antitumor efficacy. We discovered that genetic engineering of Fas variants impaired in the ability to bind FADD functioned as dominant negative receptors (DNRs), preventing FasL-induced apoptosis in Fas-competent T cells. T cells coengineered with a Fas DNR and either a T cell receptor or chimeric antigen receptor exhibited enhanced persistence following ACT, resulting in superior antitumor efficacy against established solid and hematologic cancers. Despite increased longevity, Fas DNR-engineered T cells did not undergo aberrant expansion or mediate autoimmunity. Thus, T cell-intrinsic disruption of Fas signaling through genetic engineering represents a potentially universal strategy to enhance ACT efficacy across a broad range of human malignancies., Introduction Adoptive cell transfer (ACT) using genetically engineered T cells has entered the standard of care for patients with refractory B cell malignancies, including pediatric acute lymphoblastic leukemia (ALL) (1) [...]

Adoptive cell transfer (ACT) of purified naive, stem cell memory, and central memory T cell subsets results in superior persistence and antitumor immunity compared with ACT of populations containing more-differentiated effector memory and effector T cells. Despite a clear advantage of the less-differentiated populations, the majority of ACT trials utilize unfractionated T cell subsets. Here, we have challenged the notion that the mere presence of less- differentiated T cells in starting populations used to generate therapeutic T cells is sufficient to convey their desirable attributes. Using both mouse and human cells, we identified a T cell-T cell interaction whereby antigen- experienced subsets directly promote the phenotypic, functional, and metabolic differentiation of naive T cells. This process led to the loss of less- differentiated T cell subsets and resulted in impaired cellular persistence and tumor regression in mouse models following ACT. The T memory-induced conversion of naive T cells was mediated by a nonapoptotic Fas signal, resulting in Akt- driven cellular differentiation. Thus, induction of Fas signaling enhanced T cell differentiation and impaired antitumor immunity, while Fas signaling blockade preserved the antitumor efficacy of naive cells within mixed populations. These findings reveal that T cell subsets can synchronize their differentiation state in a process similar to quorum sensing in unicellular organisms and suggest that disruption of this quorum-like behavior among T cells has potential to enhance T cell-based immunotherapies., Introduction Adoptive cell transfer (ACT), the ex vivo expansion and reinfusion of antigen-specific (Ag-specific) T cells, represents a potentially curative treatment for patients with advanced cancer (1-4) and viral-reactivation syndromes [...]

Herpes simplex virus type 1 (HSV-1) not only causes painful recurrent oral-labial infections, it can also cause permanent brain damage and blindness. There is currently no HSV-1 vaccine. An effective vaccine must stimu-late coordinated T cell responses, but the large size of the genome and the low frequency of HSV-1-specific T cells have hampered the search for the most effective T cell antigens for inclusion in a candidate vaccine. We have now developed what we believe to be novel methods to efficiently generate a genome-wide map of the responsiveness of HSV-1-specific T cells, and demonstrate the applicability of these methods to a second complex microbe, vaccinia virus. We used cross-presentation and CD137 activation-based FACS to enrich for polyclonal CD[8..sup.+] T effector T cells. The HSV-1 proteome was prepared in a flexible format for analyzing both CD[8.sup.+] and CD[4.sup.+] T cells from study participants. Scans with participant-specific panels of artificial APCs identi-fied an oligospecific response in each individual. Parallel CD137-based CD[4.sup.+] T cell research showed discrete oligospecific recognition of HSV-1 antigens. Unexpectedly, the two HSV-1 proteins not previously considered as vaccine candidates elicited both CD[8.sup.+] and CD[4.sup.+] T cell responses in most HSV-1-infected individuals. In this era of microbial genomics, our methods - also demonstrated in principle for vaccinia virus for both CD[8.sup.+] and CD[4.sup.+] T cells - should be broadly applicable to the selection of T cell antigens for inclusion in candidate vaccines for many pathogens., Introduction Herpes simplex virus type 1 (HSV-1) infects 60% of the US population and has a significant cumulative health care burden in addition to causing painful recurrent oral-labial infections. For [...]

Somatic gene mutations can alter the vulnerability of cancer cells to T-cell-based immunotherapies. Here we perturbed genes in human melanoma cells to mimic loss-of-function mutations involved in resistance to these therapies, by using a genome-scale CRISPRCas9 library that consisted of around 123,000 single-guide RNAs, and profiled genes whose loss in tumour cells impaired the effector function of CD8[sup.+] T cells. The genes that were most enriched in the screen have key roles in antigen presentation and interferon- signalling, and correlate with cytolytic activity in patient tumours from The Cancer Genome Atlas. Among the genes validated using different cancer cell lines and antigens, we identified multiple loss-of-function mutations in APLNR, encoding the apelin receptor, in patient tumours that were refractory to immunotherapy. We show that APLNR interacts with JAK1, modulating interferon- responses in tumours, and that its functional loss reduces the efficacy of adoptive cell transfer and checkpoint blockade immunotherapies in mouse models. Our results link the loss of essential genes for the effector function of CD8[sup.+] T cells with the resistance or non-responsiveness of cancer to immunotherapies., Author(s): Shashank J. Patel (corresponding author) [1, 2]; Neville E. Sanjana (corresponding author) [3, 4]; Rigel J. Kishton [1]; Arash Eidizadeh [1]; Suman K. Vodnala [1]; Maggie Cam [1]; Jared [...]

Adoptive transfer of antigen-specific T cells represents a major advance in cancer immunotherapy, with robust clinical outcomes in some patients1. Both the number of transferred T cells and their differentiation state are critical determinants of effective responses2,3. T cells can be expanded with T cell receptor (TCR)-mediated stimulation and interleukin-2, but this can lead to differentiation into effector T cells4,5 and lower therapeutic efficacy6, whereas maintenance of a more stem-cell-like state before adoptive transfer is beneficial7. Here we show that H9T, an engineered interleukin-2 partial agonist, promotes the expansion of CD8+ T cells without driving terminal differentiation. H9T led to altered STAT5 signalling and mediated distinctive downstream transcriptional, epigenetic and metabolic programs. In addition, H9T treatment sustained the expression of T cell transcription factor 1 (TCF-1) and promoted mitochondrial fitness, thereby facilitating the maintenance of a stem-cell-like state. Moreover, TCR-transgenic and chimeric antigen receptor-modified CD8+ T cells that were expanded with H9T showed robust anti-tumour activity in vivo in mouse models of melanoma and acute lymphoblastic leukaemia. Thus, engineering cytokine variants with distinctive properties is a promising strategy for creating new molecules with translational potential.H9T, an engineered IL-2 partial agonist, promotes the expansion of T cells while maintaining a stem-cell-like state, leading to improved efficacy of adoptive cell therapy in mouse models of melanoma and acute lymphoblastic leukaemia. [ABSTRACT FROM AUTHOR]

The adoptive transfer of donor T cells that have been genetically modified to recognize leukemia could prevent or treat leukemia relapse after allogeneic HSCT (allo-HSCT). However, adoptive therapy after allo-HSCT should be performed with T cells that have a defined endogenous TCR specificity to avoid GVHD. Ideally, T cells selected for genetic modification would also have the capacity to persist in vivo to ensure leukemia eradication. Here, we provide a strategy for deriving virus-specific T cells from CD45RA-CD62L+CD8+ central memory T (TCM) cells purified from donor blood with clinical grade reagents, and redirect their specificity to the B-cell lineage marker CD19 through lentiviral transfer of a gene encoding a CD19-chimeric Ag receptor (CAR). Virus-specific TCM were selectively transduced by exposure to the CD19 CAR lentivirus after peptide stimulation, and bi-specific cells were subsequently enriched to high purity using MHC streptamers. Activation of bi-specific T cells through the CAR or the virus-specific TCR elicited phosphorylation of downstream signaling molecules with similar kinetics, and induced comparable cytokine secretion, proliferation, and lytic activity. These studies identify a strategy for tumor-specific therapy with CAR-modified T cells after allo-HSCT, and for comparative studies of CAR and TCR signaling. [ABSTRACT FROM AUTHOR]

Herpes simplex virus type 1 (HSV-1) not only causes painful recurrent oral-labial infections, it can also cause permanent brain damage and blindness. There is currently no HSV-1 vaccine. An effective vaccine must stimulate coordinated T cell responses, but the large size of the genome and the low frequency of HSV-1-specific T cells have hampered the search for the most effective T cell antigens for inclusion in a candidate vaccine. We have now developed what we believe to be novel methods to efficiently generate a genome-wide map of the responsiveness of HSV-1-specific T cells, and demonstrate the applicability of these methods to a second complex microbe, vaccinia virus. We used cross-presentation and CD137 activation-based FACS to enrich for polyclonal CD8+ T effector T cells. The HSV-1 proteome was prepared in a flexible format for analyzing both CD8+ and CD4+ T cells from study participants. Scans with participant-specific panels of artificial APCs identified an oligospecific response in each individual. Parallel CD137-based CD4+ T cell research showed discrete oligospecific recognition of HSV-1 antigens. Unexpectedly, the two HSV-1 proteins not previously considered as vaccine candidates elicited both CD8+ and CD4+ T cell responses in most HSV-1-infected individuals. In this era of microbial genomics, our methods - also demonstrated in principle for vaccinia virus for both CD8+ and CD4+ T cells - should be broadly applicable to the selection of T cell antigens for inclusion in candidate vaccines for many pathogens. [ABSTRACT FROM AUTHOR]

Mg 2+ is required at micromolar concentrations as a cofactor for ATP, enzymatic reactions, and other biological processes. We show that decreased extracellular Mg 2+ reduced intracellular Mg 2+ levels and impaired the Ca 2+ flux, activation marker up-regulation, and proliferation after T cell receptor (TCR) stimulation. Reduced Mg 2+ specifically impairs TCR signal transduction by IL-2-inducible T cell kinase (ITK) due to a requirement for a regulatory Mg 2+ in the catalytic pocket of ITK. We also show that altered catalytic efficiency by millimolar changes in free basal Mg 2+ is an unrecognized but conserved feature of other serine/threonine and tyrosine kinases, suggesting a Mg 2+ regulatory paradigm of kinase function. Finally, a reduced serum Mg 2+ concentration in mice causes an impaired CD8 + T cell response to influenza A virus infection, reduces T cell activation, and exacerbates morbidity. Thus, Mg 2+ directly regulates the active site of specific kinases during T cell responses, and maintaining a high serum Mg 2+ concentration is important for antiviral immunity in otherwise healthy animals., (This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.)