Tracing the Genetic Evolution of Canine Parvovirus Type 2 (CPV-2) in Thailand.

Canine parvovirus type 2 (CPV-2) is responsible for hemorrhagic gastroenteritis in dogs worldwide. High genomic substitution rates in CPV-2 contribute to the progressive emergence of novel variants with increased ability to evade the host immune response. Three studies have analyzed the genomic mutations of CPV-2 variants in Thailand. These investigations were independently conducted at different timepoints. Thus, a retrospective integrated analysis of CPV-2 genomic mutations has not been fully performed. Our study aimed at evaluating the evolutionary changes in CPV-2 in Thailand from 2003 to 2019. Two hundred and sixty-eight Thai CPV-2 nucleotide sequences were used for multiple amino acid sequence alignment and phylogenetic analyses. From 2003 to 2010, CPV-2a and -2b were the only variants detected. CPV-2c, emerged in 2014, replacing CPV-2a and -2b, and has become a major variant in 2019. Phylogenetic analysis revealed that the proposed mutation pattern of VP2 amino acid residues could help distinguish Thai CPV-2 variants. This comprehensive examination provides insight into the genomic evolution of CPV-2 in Thailand since its first reporting in 2003, which may facilitate the surveillance of the potential genetic alteration of emergent CPV-2 variants.

Absence of Grail promotes CD8+ T cell anti-tumour activity.

T-cell tolerance is a major obstacle to successful cancer immunotherapy; thus, developing strategies to break immune tolerance is a high priority. Here we show that expression of the E3 ubiquitin ligase Grail is upregulated in CD8+ T cells that have infiltrated into transplanted lymphoma tumours, and Grail deficiency confers long-term tumour control. Importantly, therapeutic transfer of Grail-deficient CD8+ T cells is sufficient to repress established tumours. Mechanistically, loss of Grail enhances anti-tumour reactivity and functionality of CD8+ T cells. In addition, Grail-deficient CD8+ T cells have increased IL-21 receptor (IL-21R) expression and hyperresponsiveness to IL-21 signalling as Grail promotes IL-21R ubiquitination and degradation. Moreover, CD8+ T cells isolated from lymphoma patients express higher levels of Grail and lower levels of IL-21R, compared with CD8+ T cells from normal donors. Our data demonstrate that Grail is a crucial factor controlling CD8+ T-cell function and is a potential target to improve cytotoxic T-cell activity.Grail is an E3 ubiquitin ligase that inhibits T-cell receptor signalling in CD4+ T cells. Here the authors show Grail also limits IL-21 receptor expression and function in CD8+ T cells, is overactive in these cells in patients with lymphoma, and promotes tumour development in a lymphoma transplant mouse model.

Multifaceted Role of BTLA in the Control of CD8+ T-cell Fate after Antigen Encounter.

Purpose: Adoptive T-cell therapy using autologous tumor-infiltrating lymphocytes (TIL) has shown an overall clinical response rate 40%-50% in metastatic melanoma patients. BTLA (B-and-T lymphocyte associated) expression on transferred CD8+ TILs was associated with better clinical outcome. The suppressive function of the ITIM and ITSM motifs of BTLA is well described. Here, we sought to determine the functional characteristics of the CD8+BTLA+TIL subset and define the contribution of the Grb2 motif of BTLA in T-cell costimulation.Experimental Design: We determined the functional role and downstream signal of BTLA in both human CD8+ TILs and mouse CD8+ T cells. Functional assays were used including single-cell analysis, reverse-phase protein array (RPPA), antigen-specific vaccination models with adoptively transferred TCR-transgenic T cells as well as patient-derived xenograft (PDX) model using immunodeficient NOD-scid IL2Rgammanull (NSG) tumor-bearing mice treated with autologous TILs.Results: CD8+BTLA- TILs could not control tumor growth in vivo as well as their BTLA+ counterpart and antigen-specific CD8+BTLA- T cells had impaired recall response to a vaccine. However, CD8+BTLA+ TILs displayed improved survival following the killing of a tumor target and heightened "serial killing" capacity. Using mutants of BTLA signaling motifs, we uncovered a costimulatory function mediated by Grb2 through enhancing the secretion of IL-2 and the activation of Src after TCR stimulation.Conclusions: Our data portrays BTLA as a molecule with the singular ability to provide both costimulatory and coinhibitory signals to activated CD8+ T cells, resulting in extended survival, improved tumor control, and the development of a functional recall response. Clin Cancer Res; 23(20); 6151-64. ©2017 AACR.

PD-L1 expression and prognostic impact in glioblastoma.

BACKGROUND: Therapeutic targeting of the immune checkpoints cytotoxic T-lymphocyte-associated molecule-4 (CTLA-4) and PD-1/PD-L1 has demonstrated tumor regression in clinical trials, and phase 2 trials are ongoing in glioblastoma (GBM). Previous reports have suggested that responses are more frequent in patients with tumors that express PD-L1; however, this has been disputed. At issue is the validation of PD-L1 biomarker assays and prognostic impact. METHODS: Using immunohistochemical analysis, we measured the incidence of PD-L1 expression in 94 patients with GBM. We categorized our results according to the total number of PD-L1-expressing cells within the GBMs and then validated this finding in ex vivo GBM flow cytometry with further analysis of the T cell populations. We then evaluated the association between PD-L1 expression and median survival time using the protein expression datasets and mRNA from The Cancer Genome Atlas. RESULTS: The median percentage of PD-L1-expressing cells in GBM by cell surface staining is 2.77% (range: 0%-86.6%; n = 92), which is similar to the percentage found by ex vivo flow cytometry. The majority of GBM patients (61%) had tumors with at least 1% or more PD-L1-positive cells, and 38% had at least 5% or greater PD-L1 expression. PD-L1 is commonly expressed on the GBM-infiltrating T cells. Expression of both PD-L1 and PD-1 are negative prognosticators for GBM outcome. CONCLUSIONS: The incidence of PD-L1 expression in GBM patients is frequent but is confined to a minority subpopulation, similar to other malignancies that have been profiled for PD-L1 expression. Higher expression of PD-L1 is correlated with worse outcome.

BTLA marks a less-differentiated tumor-infiltrating lymphocyte subset in melanoma with enhanced survival properties.

In a recent adoptive cell therapy (ACT) clinical trial using autologous tumor-infiltrating lymphocytes (TILs) in patients with metastatic melanoma, we found an association between CD8+ T cells expressing the inhibitory receptor B- and T-lymphocyte attenuator (BTLA) and clinical response. Here, we further characterized this CD8+BTLA+ TIL subset and their CD8+BTLA- counterparts. We found that the CD8+ BTLA+ TILs had an increased response to IL-2, were less-differentiated effector-memory (TEM) cells, and persisted longer in vivo after infusion. In contrast, CD8+BTLA- TILs failed to proliferate and expressed genes associated with T-cell deletion/tolerance. Paradoxically, activation of BTLA signaling by its ligand, herpes virus entry mediator (HVEM), inhibited T-cell division and cytokine production, but also activated the Akt/PKB pathway thus protecting CD8+BTLA+ TILs from apoptosis. Our results point to a new role of BTLA as a useful T-cell differentiation marker in ACT and a dual signaling molecule that curtails T-cell activation while also conferring a survival advantage for CD8+ T cells. These attributes may explain our previous observation that BTLA expression on CD8+ TILs correlates with clinical response to adoptive T-cell therapy in metastatic melanoma.

Tumor-infiltrating lymphocyte therapy for melanoma: rationale and issues for further clinical development.

Cancer immunotherapy has become an important area for the future development of cancer therapy; this includes T-cell-based therapies that involve adoptive transfer of autologous T cells derived from the tumors or peripheral blood of cancer patients, vaccines, oncolytic virus therapy, and immunomodulatory antibodies and ligands. Here, we summarize the current approaches and clinical data in the field of adoptive T-cell transfer therapy using tumor-infiltrating lymphocytes (TILs) for metastatic melanoma. We also discuss current knowledge on the mechanism of transferred TILs in mediating tumor regression and the growing need for and recent advances in the identification of predictive biomarkers to better select patients for TIL therapy. The current technical limitations of current TIL expansion methods for out-scaling are discussed as well as how these are being addressed in order to further "industrialize" this form of cell therapy. Lastly, how TIL adoptive transfer can be incorporated into the current melanoma treatment continuum, especially as combination therapy with other immunomodulators and targeted drugs, is discussed.

Viral FLICE inhibitory protein of rhesus monkey rhadinovirus inhibits apoptosis by enhancing autophagosome formation.

Rhesus monkey rhadinovirus (RRV) is a gamma-2 herpesvirus closely related to human herpesvirus 8 (HHV8). RRV encodes viral FLICE inhibitory protein (vFLIP), which has death effector domains. Little is known about RRV vFLIP. This study intended to examine its function in apoptosis. Here we found that RRV vFLIP inhibits apoptosis induced by tumor necrosis factor-α (TNF-α) and cycloheximide. In HeLa cells with vFLIP expression, the cleavage of poly [ADP-ribose] polymerase 1 (PARP-1) and activities of caspase 3, 7, and 9 were much lower than those in controls. Cell viability of HeLa cells with vFLIP expression was significantly higher than control cells after apoptosis induction. However, RRV vFLIP appears unable to induce NF-κB signaling when tested in NF-κB reporter assay. RRV vFLIP was able to enhance cell survival under starved conditions or apoptosis induction. At early time points after apoptosis induction, autophagosome formation was enhanced and LC3-II level was elevated in cells with vFLIP and, when autophagy was blocked with chemical inhibitors, these cells underwent apoptosis. Moreover, RRV latent infection of BJAB B-lymphoblastoid cells protects the cells against apoptosis by enhancing autophagy to maintain cell survival. Knockdown of vFLIP expression in the RRV-infected BJAB cells with siRNA abolished the protection against apoptosis. These results indicate that vFLIP protects cells against apoptosis by enhancing autophagosome formation to extend cell survival. The finding of vFLIP's inhibition of apoptosis via the autophagy pathway provides insights of vFLIP in RRV pathogenesis.

Porcine reproductive and respiratory syndrome virus inhibits type I interferon signaling by blocking STAT1/STAT2 nuclear translocation.

Type I interferons (IFNs) IFN-α/ß play an important role in innate immunity against viral infections by inducing antiviral responses. Porcine reproductive and respiratory syndrome virus (PRRSV) inhibits the synthesis of type I IFNs. However, whether PRRSV can inhibit IFN signaling is less well understood. In the present study, we found that PRRSV interferes with the IFN signaling pathway. The transcript levels of IFN-stimulated genes ISG15 and ISG56 and protein level of signal transducer and activator of transcription 2 (STAT2) in PRRSV VR2385-infected MARC-145 cells were significantly lower than those in mock-infected cells after IFN-α treatment. IFN-induced phosphorylation of both STAT1 and STAT2 and their heterodimer formation in the PRRSV-infected cells were not affected. However, the majority of the STAT1/STAT2/IRF9 (IFN regulatory factor 9) heterotrimers remained in the cytoplasm of PRRSV-infected cells, which indicates that the nuclear translocation of the heterotrimers was blocked. Overexpression of NSP1ß of PRRSV VR2385 inhibited expression of ISG15 and ISG56 and blocked nuclear translocation of STAT1, which suggests that NSP1ß might be the viral protein responsible for the inhibition of IFN signaling. PRRSV infection in primary porcine pulmonary alveolar macrophages (PAMs) also inhibited IFN-α-stimulated expression of the ISGs and the STAT2 protein. In contrast, a licensed low-virulence vaccine strain, Ingelvac PRRS modified live virus (MLV), activated expression of IFN-inducible genes, including those of chemokines and antiviral proteins, in PAMs without the addition of external IFN and had no detectable effect on IFN signaling. These findings suggest that PRRSV interferes with the activation and signaling pathway of type I IFNs by blocking ISG factor 3 (ISGF3) nuclear translocation.