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Mutations and the glycosylation of epitopes can convert immunogenic epitopes into non-immunogenic ones via natural selection or evolutionary pressure, thereby decreasing their sensitivity to neutralizing antibodies. Based on Thomas Francis's theory, memory B and T cells induced during primary infections or vaccination will freeze the new mutated epitopes specific to naïve B and T cells from the repertoire. On this basis, some researchers argue that the current vaccines derived from the previous strains of the SARS-CoV-2 virus do not increase immunity and may also prevent the immune response against new epitopes. However, evidence shows that even if the binding affinity is reduced, the previous antibodies or T cell receptors (TCRs) can still bind to this new epitope of the Beta, Gamma, and Delta variant if their concentration is high enough (from a booster injection) and neutralize the virus. This paper presents some convincing immunological reasons that may challenge this theory and argue for the continuation of universal vaccination to prevent further mutations of the SARS-CoV-2 virus. Simultaneously, the information presented can be used to develop vaccines that target novel epitopes or create new recombinant drugs that do not lose their effectiveness when the virus mutates. [ABSTRACT FROM AUTHOR]

Granuloma is a crucial pathological feature of tuberculosis (TB). The relationship between CD4+ T cells in both peripheral blood and granulomatous tissue, and the integrity of granulomas in Human Immunodeficiency Virus (HIV)–MTB co-infection, remains unexplored. This study collected biopsy specimens from 102 TB patients (53 with HIV-MTB co-infection and 49 only with TB). Hematoxylin and eosin (HE) staining and immunohistochemical staining were performed, followed by microscopic examination of the integrity of tuberculous granulomas. Through statistical analysis of peripheral blood CD4+ T cell counts, tissue CD4+ T cell proportion, and the integrity of granulomas, it was observed that HIV infection leads to poor formation of tuberculous granulomas. Peripheral blood CD4+ T cell counts were positively correlated with granuloma integrity, and there was a similar positive correlation between tissue CD4+ T cell proportions and granuloma integrity. Additionally, a positive correlation was found between peripheral blood CD4+ T cell counts and the proportion of CD4+ T cells in granuloma tissues. Therefore, HIV infection could impact the morphology and structure of tuberculous granulomas, with a reduced proportion of both peripheral blood and tissue CD4+ T lymphocytes. [ABSTRACT FROM AUTHOR]

Humans continue to be at risk from the Zika virus. Although there have been significant research advancements regarding Zika, the absence of a vaccine or approved treatment poses further challenges for healthcare providers. In this study, we developed a microparticulate Zika vaccine using an inactivated whole Zika virus as the antigen that can be administered pain-free via intranasal (IN) immunization. These microparticles (MP) were formulated using a double emulsion method developed by our lab. We explored a prime dose and two-booster-dose vaccination strategy using MPL-A® and Alhydrogel® as adjuvants to further stimulate the immune response. MPL-A® induces a Th1-mediated immune response and Alhydrogel® (alum) induces a Th2-mediated immune response. There was a high recovery yield of MPs, less than 5 µm in size, and particle charge of −19.42 ± 0.66 mV. IN immunization of Zika MP vaccine and the adjuvanted Zika MP vaccine showed a robust humoral response as indicated by several antibodies (IgA, IgM, and IgG) and several IgG subtypes (IgG1, IgG2a, and IgG3). Vaccine MP elicited a balance Th1- and Th2-mediated immune response. Immune organs, such as the spleen and lymph nodes, exhibited a significant increase in CD4+ helper and CD8+ cytotoxic T-cell cellular response in both vaccine groups. Zika MP vaccine and adjuvanted Zika MP vaccine displayed a robust memory response (CD27 and CD45R) in the spleen and lymph nodes. Adjuvanted vaccine-induced higher Zika-specific intracellular cytokines than the unadjuvanted vaccine. Our results suggest that more than one dose or multiple doses may be necessary to achieve necessary immunological responses. Compared to unvaccinated mice, the Zika vaccine MP and adjuvanted MP vaccine when administered via intranasal route demonstrated robust humoral, cellular, and memory responses. In this pre-clinical study, we established a pain-free microparticulate Zika vaccine that produced a significant immune response when administered intranasally. [ABSTRACT FROM AUTHOR]

Gliomas account for approximately 75–80% of all malignant primary tumors in the central nervous system (CNS), with glioblastoma multiforme (GBM) considered the deadliest. Despite aggressive treatment involving a combination of chemotherapy, radiotherapy, and surgical intervention, patients with GBM have limited survival rates of 2 to 5 years, accompanied by a significant decline in their quality of life. In recent years, novel management strategies have emerged, such as immunotherapy, which includes the development of vaccines or T cells with chimeric antigen receptors, and oncolytic virotherapy (OVT), wherein wild type (WT) or genetically modified viruses are utilized to selectively lyse tumor cells. In vitro and in vivo studies have shown that the Zika virus (ZIKV) can infect glioma cells and induce a robust oncolytic activity. Consequently, interest in exploring this virus as a potential oncolytic virus (OV) for high-grade gliomas has surged. Given that ZIKV actively circulates in Colombia, evaluating its neurotropic and oncolytic capabilities holds considerable national and international importance, as it may emerge as an alternative for treating highly complex gliomas. Therefore, this literature review outlines the generalities of GBM, the factors determining ZIKV's specific tropism for nervous tissue, and its oncolytic capacity. Additionally, we briefly present the progress in preclinical studies supporting the use of ZIKV as an OVT for gliomas. [ABSTRACT FROM AUTHOR]

The ability of recombinant, SARS-CoV-2 Spike (S) protein to modulate the production of two COVID-19 relevant, pro-inflammatory cytokines (IL-6 and IFN-γ) in PBMC cultures of healthy, pre-COVID-19 subjects was investigated. We observed that cytokine production was largely and diversely modulated by the S protein depending on antigen or mitogen stimulation, as well as on the protein source, insect (S-in) or human (S-hu) cells. While both proteins co-stimulated cytokine production by polyclonally CD3-activated T cells, PBMC activation by the mitogenic lectin Concanavalin A (Con A) was up-modulated by S-hu protein and down-modulated by S-in protein. These modulatory effects were likely mediated by the S glycans, as demonstrated by direct Con A-S binding experiments and use of yeast mannan as Con A binder. While being ineffective in modulating memory antigenic T cell responses, the S proteins and mannan were able to induce IL-6 production in unstimulated PBMC cultures and upregulate the expression of the mannose receptor (CD206), a marker of anti-inflammatory M2 macrophage. Our data point to a relevant role of N-glycans, particularly N-mannosidic chains, decorating the S protein in the immunomodulatory effects here reported. These novel biological activities of the S glycan ectodomain may add to the comprehension of COVID-19 pathology and immunity to SARS-CoV-2. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 Omicron sub-variants BA.2.86 and JN.1 contain multiple mutations in the spike protein that were not present in previous variants of concern and Omicron sub-variants. Preliminary research suggests that these variants reduce the neutralizing capability of antibodies induced by vaccines, which is particularly significant for JN.1. This raises concern as many widely deployed COVID-19 vaccines are based on the spike protein of the ancestral Wuhan strain of SARS-CoV-2. While T cell responses have been shown to be robust against previous SARS-CoV-2 variants, less is known about the impact of mutations in BA.2.86 and JN.1 on T cell responses. We evaluate the effect of mutations specific to BA.2.86 and JN.1 on experimentally determined T cell epitopes derived from the spike protein of the ancestral Wuhan strain and the spike protein of the XBB.1.5 strain that has been recommended as a booster vaccine. Our data suggest that BA.2.86 and JN.1 affect numerous T cell epitopes in spike compared to previous variants; however, the widespread loss of T cell recognition against these variants is unlikely. [ABSTRACT FROM AUTHOR]

Infection at barrier sites, e.g., skin, activates local immune defenses that limit pathogen spread, while preserving tissue integrity. Phenotypically distinct γδ T cell populations reside in skin, where they shape immunity to cutaneous infection prior to onset of an adaptive immune response by conventional αβ CD4+ (TCD4+) and CD8+ (TCD8+) T cells. To examine the mechanisms used by γδ T cells to control cutaneous virus replication and tissue pathology, we examined γδ T cells after infection with vaccinia virus (VACV). Resident γδ T cells expanded and combined with recruited γδ T cells to control pathology after VACV infection. However, γδ T cells did not play a role in control of local virus replication or blockade of systemic virus spread. We identified a unique wound healing signature that has features common to, but also features that antagonize, the sterile cutaneous wound healing response. Tissue repair generally occurs after clearance of a pathogen, but viral wound healing started prior to the peak of virus replication in the skin. γδ T cells contributed to wound healing through induction of multiple cytokines/growth factors required for efficient wound closure. Therefore, γδ T cells modulate the wound healing response following cutaneous virus infection, maintaining skin barrier function to prevent secondary bacterial infection. [ABSTRACT FROM AUTHOR]

CD8+ T cells are critical to the adaptive immune response against viral pathogens. However, overwhelming antigen exposure can result in their exhaustion, characterised by reduced effector function, failure to clear virus, and the upregulation of inhibitory receptors, including programmed cell death 1 (PD-1). However, exhausted T cell responses can be "re-invigorated" by inhibiting PD-1 or the primary ligand of PD-1: PD-L1. Further, the absence of the type I interferon receptor IFNAR1 also results in T cell exhaustion and virus persistence in lymphocytic choriomeningitis virus Armstrong (LCMV-Arm)-infected mice. In this study, utilizing single- and double-knockout mice, we aimed to determine whether ablation of PD-1 could restore T cell functionality in the absence of IFNAR1 signalling in LCMV-Arm-infected mice. Surprisingly, this did not re-invigorate the T cell response and instead, it converted chronic LCMV-Arm infection into a lethal disease characterized by severe lung inflammation with an infiltration of neutrophils and T cells. Depletion of CD8+ T cells, but not neutrophils, rescued mice from lethal disease, demonstrating that IFNAR1 is required to prevent T cell exhaustion and virus persistence in LCMV-Arm infection, and in the absence of IFNAR1, PD-L1 is required for survival. This reveals an important interplay between IFNAR1 and PD-L1 with implications for therapeutics targeting these pathways. [ABSTRACT FROM AUTHOR]

HIV-1 latency remains a barrier to a functional cure because of the ability of virtually silent yet inducible proviruses within reservoir cells to transcriptionally reactivate upon cell stimulation. HIV-1 reactivation occurs through the sequential action of host transcription factors (TFs) during the "host phase" and the viral TF Tat during the "viral phase", which together facilitate the positive feedback loop required for exponential transcription, replication, and pathogenesis. The sequential action of these TFs poses a challenge to precisely delineate the contributions of the host and viral phases of the transcriptional program to guide future mechanistic and therapeutic studies. To address this limitation, we devised a genome engineering approach to mutate tat and create a genetically matched pair of Jurkat T cell clones harboring HIV-1 at the same integration site with and without Tat expression. By comparing the transcriptional profile of both clones, the transition point between the host and viral phases was defined, providing a system that enables the temporal mechanistic interrogation of HIV-1 transcription prior to and after Tat synthesis. Importantly, this CRISPR method is broadly applicable to knockout individual viral proteins or genomic regulatory elements to delineate their contributions to various aspects of the viral life cycle and ultimately may facilitate therapeutic approaches in our race towards achieving a functional cure. [ABSTRACT FROM AUTHOR]

This review summarizes current advances in the role of transcriptional stochasticity in HIV-1 latency, which were possible in a large part due to the development of single-cell approaches. HIV-1 transcription proceeds in bursts of RNA production, which stem from the stochastic switching of the viral promoter between ON and OFF states. This switching is caused by random binding dynamics of transcription factors and nucleosomes to the viral promoter and occurs at several time scales from minutes to hours. Transcriptional bursts are mainly controlled by the core transcription factors TBP, SP1 and NF-κb, the chromatin status of the viral promoter and RNA polymerase II pausing. In particular, spontaneous variability in the promoter chromatin creates heterogeneity in the response to activators such as TNF-α, which is then amplified by the Tat feedback loop to generate high and low viral transcriptional states. This phenomenon is likely at the basis of the partial and stochastic response of latent T cells from HIV-1 patients to latency-reversing agents, which is a barrier for the development of shock-and-kill strategies of viral eradication. A detailed understanding of the transcriptional stochasticity of HIV-1 and the possibility to precisely model this phenomenon will be important assets to develop more effective therapeutic strategies. [ABSTRACT FROM AUTHOR]

Cytotoxic T lymphocytes (CTLs) are important in controlling some viral infections, and therapies involving the transfer of large numbers of cancer-specific CTLs have been successfully used to treat several types of cancers in humans. While the molecular mechanisms of how CTLs kill their targets are relatively well understood, we still lack a solid quantitative understanding of the kinetics and efficiency by which CTLs kill their targets in vivo. Collagen–fibrin-gel-based assays provide a tissue-like environment for the migration of CTLs, making them an attractive system to study T cell cytotoxicity in in vivo-like conditions. Budhu.et al. systematically varied the number of peptide (SIINFEKL)-pulsed B16 melanoma cells and SIINFEKL-specific CTLs (OT-1) and measured the remaining targets at different times after target and CTL co-inoculation into collagen–fibrin gels. The authors proposed that their data were consistent with a simple model in which tumors grow exponentially and are killed by CTLs at a per capita rate proportional to the CTL density in the gel. By fitting several alternative mathematical models to these data, we found that this simple "exponential-growth-mass-action-killing" model did not precisely describe the data. However, determining the best-fit model proved difficult because the best-performing model was dependent on the specific dataset chosen for the analysis. When considering all data that include biologically realistic CTL concentrations ( E ≤ 10 7 cell / mL ), the model in which tumors grow exponentially and CTLs suppress tumor's growth non-lytically and kill tumors according to the mass–action law (SiGMA model) fit the data with the best quality. A novel power analysis suggested that longer experiments (∼3–4 days) with four measurements of B16 tumor cell concentrations for a range of CTL concentrations would best allow discriminating between alternative models. Taken together, our results suggested that the interactions between tumors and CTLs in collagen–fibrin gels are more complex than a simple exponential-growth-mass–action killing model and provide support for the hypothesis that CTLs' impact on tumors may go beyond direct cytotoxicity. [ABSTRACT FROM AUTHOR]

Objective: The kinetics of immune responses to various SARS-CoV-2 vaccines in cancer patients were investigated. Methods: In total, 57 cancer patients who received BNT162b2-RNA or BBIBP-CorV vaccines were enrolled. Cellular and humoral immunity were assessed at three-time points, before the first vaccine dose and 14–21 days after the first and second doses. Chemiluminescent microparticle immunoassay was used to evaluate SARS-CoV-2 anti-spike IgG response, and QuantiFERON® SARS-CoV-2 kit assessed T-cell response. Results: Data showed that cancer patients' CD4+ and CD8+ T cell-median IFN-γ secretion of SARS-CoV-2 antigens increased after the first and second vaccine doses (p = 0.027 and p = 0.042). BNT162b2 vaccinees had significantly higher IFN-γ levels to CD4+ and CD8+ T cell epitopes than BBIBP-CorV vaccinees (p = 0.028). There was a positive correlation between IgG antibody titer and T cell response regardless of vaccine type (p < 0.05). Conclusions: This study is one of the first to investigate cellular and humoral immune responses to SARS-CoV-2 immunization in cancer patients on active therapy after each vaccine dose. COVID-19 immunizations helped cancer patients develop an effective immune response. Understanding the cellular and humoral immune response to COVID-19 in cancer patients undergoing active treatment is necessary to improve vaccines and avoid future SARS pandemics. [ABSTRACT FROM AUTHOR]

Despite the availability on the market of different anti-SARS-CoV-2 vaccines, there are still unanswered questions on whether they can stimulate long-lasting protection. A deep understanding of adaptive immune response to SARS-CoV-2 is important for optimizing both vaccine development and pandemic control measures. Among cytokines secreted by lymphocytes in response to viral infection, IFN-γ plays a pivotal role both in innate and adaptive immunity. In this study, we report on 28 naïve-to-SARS-Cov-2-infection and unvaccinated subjects, having reported a close and prolonged contact with COVID-19-positive patients. Samples were tested for defective genetic variants in interferon pathway genes by whole exome sequencing and anti-IFN autoantibodies production was investigated. Subject T-cells were cultured and infected with pseudotype particles bearing the S proteins and in parallel stimulated with two S-peptides designed on the RBD region of the spike protein. Our results showed that one of these peptides, RBD 484–508, induces a significant increase in IFN-γ gene expression and protein production in T-cells, comparable to those obtained in cells infected by SARS-CoV-2 pseudovirus. This work deepens our understanding of immune response and highlights the selected peptide as a reasonable approach to induce broad, potent, and variant concern-independent T-cell responses. [ABSTRACT FROM AUTHOR]

Brazil is one of the countries that experienced an epidemic of microcephaly and other congenital manifestations related to maternal Zika virus infection which can result in Congenital Zika Syndrome (CZS). Since the Zika virus can modulate the immune system, studying mothers' and children's immune profiles become essential to better understanding CZS development. Therefore, we investigated the lymphocyte population profile of children who developed CZS and their mothers' immune response in this study. The study groups were formed from the Plaque Reduction Neutralization Test (PRNT) (CZS+ group) result. To evaluate the lymphocyte population profile, we performed phenotyping of peripheral lymphocytes and quantification of serum cytokine levels. The immunophenotyping and cytokine profile was correlated between CSZ+ children and their mothers. Both groups exhibited increased interleukin-17 levels and a reduction in the subpopulation of CD4+ T lymphocytes. In contrast, the maternal group showed a reduction in the population of B lymphocytes. Thus, the development of CZS is related to the presence of an inflammatory immune profile in children and their mothers characterized by Th17 activation. [ABSTRACT FROM AUTHOR]

Kidney transplanted recipients (KTR) are at high risk of severe SARS-CoV-2 infection due to immunosuppressive therapy. Although several studies reported antibody production in KTR after vaccination, data related to immunity to the Omicron (B.1.1.529) variant are sparse. Herein, we analyzed anti-SARS-CoV-2 immune response in seven KTR and eight healthy controls after the second and third dose of the mRNA vaccine (BNT162b2). A significant increase in neutralizing antibody (nAb) titers were detected against pseudoviruses expressing the Wuhan-Hu-1 spike (S) protein after the third dose in both groups, although nAbs in KTR were lower than controls. nAbs against pseudoviruses expressing the Omicron S protein were low in both groups, with no increase after the 3rd dose in KTR. Reactivity of CD4+ T cells after boosting was observed when cells were challenged with Wuhan-Hu-1 S peptides, while Omicron S peptides were less effective in both groups. IFN-γ production was detected in KTR in response to ancestral S peptides, confirming antigen-specific T cell activation. Our study demonstrates that the 3rd mRNA dose induces T cell response against Wuhan-Hu-1 spike peptides in KTR, and an increment in the humoral immunity. Instead, humoral and cellular immunity to Omicron variant immunogenic peptides were low in both KTR and healthy vaccinated subjects. [ABSTRACT FROM AUTHOR]

Background: COVID-19 pathophysiology and the predictive factors involved are not fully understood, but lymphocytes dysregulation appears to play a role. This paper aims to evaluate lymphocyte subsets in the pathophysiology of COVID-19 and as predictive factors for severe disease. Patient and methods: A prospective cohort study of patients with SARS-CoV-2 bilateral pneumonia recruited at hospital admission. Demographics, medical history, and data regarding SARS-CoV-2 infection were recorded. Patients systematically underwent complete laboratory tests, including parameters related to COVID-19 as well as lymphocyte subsets study at the time of admission. Severe disease criteria were established at admission, and patients were classified on remote follow-up according to disease evolution. Linear regression models were used to assess associations with disease evolution, and Receiver Operating Characteristic (ROC) and the corresponding Area Under the Curve (AUC) were used to evaluate predictive values. Results: Patients with critical COVID-19 showed a decrease in CD3+CD4+ T cells count compared to non-critical (278 (485 IQR) vs. 545 (322 IQR)), a decrease in median CD4+/CD8+ ratio (1.7, (1.7 IQR) vs. 3.1 (2.4 IQR)), and a decrease in median CD4+MFI (21,820 (4491 IQR) vs. 26,259 (3256 IQR)), which persisted after adjustment. CD3+CD8+ T cells count had a high correlation with time to hospital discharge (PC = −0.700 (−0.931, −0.066)). ROC curves for predictive value showed lymphocyte subsets achieving the best performances, specifically CD3+CD4+ T cells (AUC = 0.756), CD4+/CD8+ ratio (AUC = 0.767), and CD4+MFI (AUC = 0.848). Conclusions: A predictive value and treatment considerations for lymphocyte subsets are suggested, especially for CD3CD4+ T cells. Lymphocyte subsets determination at hospital admission is recommended. [ABSTRACT FROM AUTHOR]

In this review, the interaction between conventional T cells and T cells for haematopoietic reconstitution, and the role of T cells for the control of CMV/EBV reactivation as well as for the control of tumour relapse are discussed. In SARS-CoV-2 infections [[2]], single-cell transcriptome analysis was used to correlate markers of activation, differentiation and tissue residence with the T cell receptor characteristics of T cell subsets. T cells are members of "unconventional" T cells that combine the properties of adaptive T lymphocytes and innate cells such as NK cells. [Extracted from the article]

Objectives: The objective of this prospective study was to investigate the role of adaptive immunity in response to SARS-CoV-2 vaccines. Design and Methods: A cohort of 677 vaccinated individuals participated in a comprehensive survey of their vaccination status and associated side effects, and donated blood to evaluate their adaptive immune responses by neutralizing antibody (NAb) and T cell responses. The cohort then completed a follow-up survey to investigate the occurrence of breakthrough infections. Results: NAb levels were the highest in participants vaccinated with Moderna, followed by Pfizer and Johnson & Johnson. NAb levels decreased with time after vaccination with Pfizer and Johnson & Johnson. T cell responses showed no significant difference among the different vaccines and remained stable up to 10 months after the study period for all vaccine types. In multivariate analyses, NAb responses (<95 U/mL) predicted breakthrough infection, whereas previous infection, the type of vaccine, and T cell responses did not. T cell responses to viral epitopes (<0.120 IU/mL) showed a significant association with the self-reported severity of COVID-19 disease. Conclusion: This study provides evidence that NAb responses to SARS-CoV-2 vaccination correlate with protection against infection, whereas the T cell memory responses may contribute to protection against severe disease but not against infection. [ABSTRACT FROM AUTHOR]

People living with HIV (PLWH) may be at risk for poor immunogenicity to certain vaccines, including the ability to develop immunological memory. Here, we assessed T-cell immunogenicity following three SARS-CoV-2 vaccine doses in PLWH versus uninfected controls. Blood was collected from 38 PLWH on antiretroviral therapy and 24 age-matched HIV-negative controls, pre-vaccination and after 1st/2nd/3rd dose of SARS-CoV-2 vaccines, without prior SARS-CoV-2 infection. Flow cytometry was used to assess ex vivo T-cell immunophenotypes and intracellular Tumor necrosis factor (TNF)-α/interferon(IFN)-γ/interleukin(IL)-2 following SARS-CoV-2-Spike-peptide stimulation. Comparisons were made using Wilcoxon signed-rank test for paired variables and Mann–Whitney for unpaired. In PLWH, Spike-specific CD4 T-cell frequencies plateaued post-2nd dose, with no significant differences in polyfunctional SARS-CoV-2-specific T-cell proportions between PLWH and uninfected controls post-3rd dose. PLWH had higher frequencies of TNFα+CD4 T-cells and lower frequencies of IFNγ+CD8 T-cells than seronegative participants post-3rd dose. Regardless of HIV status, an increase in naive, regulatory, and PD1+ T-cell frequencies was observed post-3rd dose. In summary, two doses of SARS-CoV-2 vaccine induced a robust T-cell immune response in PLWH, which was maintained after the 3rd dose, with no significant differences in polyfunctional SARS-CoV-2-specific T-cell proportions between PLWH and uninfected controls post-3rd dose. [ABSTRACT FROM AUTHOR]

A mathematical model of the human immunodeficiency virus Type 1 (HIV-1) life cycle in CD4 T cells was constructed and calibrated. It describes the activation of the intracellular Type I interferon (IFN-I) response and the IFN-induced suppression of viral replication. The model includes viral replication inhibition by interferon-induced antiviral factors and their inactivation by the viral proteins Vpu and Vif. Both deterministic and stochastic model formulations are presented. The stochastic model was used to predict efficiency of IFN-I-induced suppression of viral replication in different initial conditions for autocrine and paracrine effects. The probability of virion excretion for various MOIs and various amounts of IFN-I was evaluated and the statistical properties of the heterogeneity of HIV-1 and IFN-I production characterised. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 Omicron (B.1.1.529) lineages rapidly became dominant in various countries reflecting its enhanced transmissibility and ability to escape neutralizing antibodies. Although T cells induced by ancestral SARS-CoV-2-based vaccines also recognize Omicron variants, we showed in our previous study that there was a marked loss of T cell cross-reactivity to spike epitopes harboring Omicron BA.1 mutations. The emerging BA.4/BA.5 subvariants carry other spike mutations than the BA.1 variant. The present study aims to investigate the impact of BA.4/BA.5 spike mutations on T cell cross-reactivity at the epitope level. Here, we focused on universal T-helper epitopes predicted to be presented by multiple common HLA class II molecules for broad population coverage. Fifteen universal T-helper epitopes of ancestral spike, which contain mutations in the Omicron BA.4/BA.5 variants, were identified utilizing a bioinformatic tool. T cells isolated from 10 subjects, who were recently vaccinated with mRNA-based BNT162b2, were tested for functional cross-reactivity between epitopes of ancestral SARS-CoV-2 spike and the Omicron BA.4/BA.5 spike counterparts. Reduced T cell cross-reactivity in one or more vaccinees was observed against 87% of the tested 15 non-conserved CD4+ T cell epitopes. These results should be considered for vaccine boosting strategies to protect against Omicron BA.4/BA.5 and future SARS-CoV-2 variants. [ABSTRACT FROM AUTHOR]

(1) Background: Tropical spastic paraparesis (TSP/HAM) associated with the T cell lymphotropic virus in type I humans (HTLV-1) is a slow, chronic, and progressive disease that causes balance changes. TSP/HAM diagnosis can be classified as probable, possible, and definite. We compared the static balance control of HTLV-1-infected patients with different TSP/HAM diagnosis. (2) Methods: Our sample consisted of 13 participants infected with HTLV-1 and 16 healthy participants. The center of pressure was recorded using a force platform with open and closed eyes. We divided the recordings into three intervals, period T1 (corresponds to the first 10 s); period T2 (from 10 to 45 s); period T3 (from 45 to 55 s). (3) Results: Eight participants infected with HTLV-1 were classified as probable TSP/HAM and five participants infected with HTLV-1 were classified as definite TSP/HAM. There was a significant increase in postural instability in patients with definite PET/MAH considering the structural and global variables of body sway compared to the control and the probable TSP/HAM. (4) Conclusions: We concluded that the severity of balance is directly related to the degree of signs and symptoms of TSP/HAM. [ABSTRACT FROM AUTHOR]

Reports on T-cell cross-reactivity against SARS-CoV-2 epitopes in unexposed individuals have been linked with prior exposure to the human common cold coronaviruses (HCCCs). Several studies suggested that cross-reactive T-cells response to live attenuated vaccines (LAVs) such as BCG (Bacillus Calmette–Guérin), OPV (Oral Polio Vaccine), and MMR (measles, mumps, and rubella) can limit the development and severity of COVID-19. This study aims to identify potential cross-reactivity between SARS-CoV-2, HCCCs, and LAVs in the context of T-cell epitopes peptides presented by HLA (Human Leukocyte Antigen) alleles of the Indonesian population. SARS-CoV-2 derived T-cell epitopes were predicted using immunoinformatics tools and assessed for their conservancy, variability, and population coverage. Two fully conserved epitopes with 100% similarity and nine heterologous epitopes with identical T-cell receptor (TCR) contact residues were identified from the ORF1ab fragment of SARS-CoV-2 and all HCCCs. Cross-reactive epitopes from various proteins of SARS-CoV-2 and LAVs were also identified (15 epitopes from BCG, 7 epitopes from MMR, but none from OPV). A majority of the identified epitopes were observed to belong to ORF1ab, further suggesting the vital role of ORF1ab in the coronaviruses family and suggesting it as a candidate for a potential universal coronavirus vaccine that protects against severe disease by inducing cell mediated immunity. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate CD4/CD8 dynamics in patients on dolutegravir (DTG)-based two-drug regimens (2DRs) and compare them with DTG-containing triple-drug regimens (3DRs). A prospective observational study was performed in the context of the SCOLTA cohort. Experienced PWH with HIV-RNA < 50 copies/mL were included if they were on the DTG-2DR, the DTG + tenofovir/emtricitabine (TDF/FTC) regimen, the DTG + tenofovir alafenamide (TAF)/FTC regimen, or the DTG + abacavir/lamivudine (ABC/3TC) regimen; they were followed-up for at least one year. A total of 533 PWH were enrolled, 120 in the DTG + 3TC group, 38 in the DTG + protease inhibitors (PI) group, 67 in the DTG + rilpivirine (RPV) group, 49 in the DTG + TDF/FTC group, 27 in the DTG + TAF/FTC group, and 232 in the DTG + ABC/3TC group. After one year, the CD4/CD8 ratio significantly increased in the PWH treated with DTG + 3TC (+0.08 ± 0.26), DTG + TDF/FTC (+0.1 ± 0.19), and DTG + ABC/3TC (+0.08 ± 0.25). At two years, the CD4/CD8 increase was confirmed for PWH on DTG + TDF/FTC (+0.16 ± 0.28) and DTG + ABC/3TC (+0.1 ± 0.3). In the SCOLTA cohort, PWH on 2DRs experienced a CD4/CD8 increase only in the DTG + 3TC group. Controlled studies with longer follow-up will clarify the long-term immunological and clinical impacts of DTG-2DR. [ABSTRACT FROM AUTHOR]

(1) Background: HIV-1 sub-subtype A1 is common in parts of Africa, Russia, former Soviet Union countries, and Eastern Europe. In Pakistan, sub-subtype A1 is the predominant HIV-1 subtype. Preliminary evidence suggests that distinct strains of HIV-1 sub-subtype A1 are circulating in Pakistan; however, an in-depth molecular phylogenetic characterization of HIV-1 sub-subtype A1 strains in Pakistan have not been presented. We performed a detailed characterization of the HIV-1 sub-subtype A1 epidemic in Pakistan using state-of-the-art molecular epidemiology and phylodynamics. (2) Methods: A total of 143 HIV-1 sub-subtype A1 gag sequences, including 61 sequences generated specifically for this study from PLHIVs part of our cohort, representing all sub-subtype A1 gag sequences from Pakistan, were analyzed. Maximum-likelihood phylogenetic cluster analysis was used to determine the relationship between Pakistani sub-subtype A1 strains and pandemic sub-subtype A1 strains. Furthermore, we used signature variation, charge distribution, selection pressures, and epitope prediction analyses to characterize variations unique to Pakistani HIV-1 strains and establish the association between signature variations and Gag epitope profile. (3) Results: The HIV-1 sub-subtype A1 sequences from Pakistan formed three main clusters: two that clustered with Kenyan sequences (7 and 10 sequences, respectively) and one that formed a Pakistan-specific cluster of 123 sequences that were much less related to other sub-subtype A1 sequences available in the database. The sequences in the Pakistan-specific cluster and the Kenyan reference strains exhibited several signature variations, especially at amino acid positions 312, 319, 331, 372, 373, 383, and 402. Structural protein modeling suggested that amino acid changes in these positions result in alterations of the Gag protein structure as well as in Gag-specific T-cell epitopes. (4) Conclusions: Our results suggest that the majority of the Pakistan HIV-1 sub-subtype A1 strains were unique to Pakistan and with a specific mutation pattern in Gag. [ABSTRACT FROM AUTHOR]

Solid organ transplant recipients (SOTRs) show higher rates of COVID-19 breakthrough infection than the general population, and nowadays, vaccination is the key preventative strategy. Nonetheless, SOTRs show lower vaccine efficacy for the prevention of severe COVID-19. Moreover, the emergence of new SARS-CoV-2 variants of concern has highlighted the need to improve vaccine-induced immune responses by the administration of repeated booster doses. In this study, we analyzed the humoral and cellular responses in a cohort of 25 SOTRs, including 15 never-infected SOTRs who received the fourth dose of the mRNA vaccine and 10 SOTRs who contracted SARS-CoV-2 infection after the third dose. We analyzed the serum IgG and IgA levels through CLIA or ELISA, respectively, and the Spike-specific T cells by ELISpot assay. We report a significant increase in anti-Spike IgG and no differences in IgA secretion in both groups of patients before and after the booster dose or the natural infection. Still, we show higher IgA levels in recovered SOTRs compared to the fourth dose recipients. Conversely, we show the maintenance of a positive Spike-specific T-cell response in SOTRs who received the fourth dose, which, instead, was significantly increased in SOTRs who contracted the infection. Our results suggest that the booster, either through the fourth dose or natural infection, in vulnerable poor responder SOTRs, improves both humoral and cellular-specific immune responses against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

The importance of the bursa of Fabricius (BF) for the pathogenesis of Marek's disease (MD) has been studied since the late 1960's. In this review, the results of these studies are analyzed in the context of the developing knowledge of the immune system of chickens and the pathogenesis of MD from 1968 to 2022. Based on the available techniques to interfere with the development of the BF, three distinct periods are identified and discussed. During the initial period between 1968 and 1977, the use of neonatal bursectomy, chemical methods and irradiation were the main tools to interfere with the B lymphocyte development. The application of these techniques resulted in contradictory results from no effects to an increase or decrease in MD incidence. Starting in the late 1970's, the use of bursectomy in 18-day-old embryos led to the development of the "Cornell model" for the pathogenesis of MD, in which the infection of B lymphocytes is an important first step in MD virus (MDV) replication causing the activation of thymus-derived lymphocytes (T cells). Following this model, these activated T cells, but not resting T cells, are susceptible to MDV infection and subsequent transformation. Finally, B-cell knockout chickens lacking the J gene segment of the IgY heavy chain gene were used to further define the role of the BF in the pathogenesis of MD. [ABSTRACT FROM AUTHOR]

Varicella–zoster virus (VZV) is the causative agent of varicella and herpes zoster (HZ) and can pose a significant challenge to human health globally. The initial VZV infection—more common in children—causes a self-limiting chicken pox. However, in later life, the latent VZV can become reactivated in these patients, causing HZ and postherpetic neuralgia (PHN), a serious and painful complication. VZV glycoprotein E (gE) has been developed into a licensed subunit vaccine against HZ (Shingrix). However, its efficacy relies on the concomitant delivery of a robust adjuvant (AS01B). Here, we sought to create a new immunogen for vaccine design by displaying the VZV–gE on the baculovirus surface (Bac–gE). Correct localization and display of gE on the engineered baculovirus was verified by flow cytometry and immune electron microscopy. We show that Bac–gE provides excellent antigenicity against VZV and induces not only stronger gE-specific CD4+ and CD8+ T cell responses but also higher levels of VZV–specific neutralizing antibodies as compared with other vaccine strategies in mice. Collectively, we show that the baculovirus display of VZV–gE confers ideal humoral and cellular immune responses required for HZ vaccine development, paving the way for a baculovirus-based vaccine design. [ABSTRACT FROM AUTHOR]

Nucleus accumbens-associated protein 1 (NAC1) is a transcription co-factor that has been shown to possess multiple roles in stem cell and cancer biology. However, little is known about its roles in regulation of the immune system. In the current study, we observed that expression of NAC1 impacted the survival of CD8+ T cells in vitro. NAC1−/− CD8+ T cells displayed lower metabolism, including reduced glycolysis and oxidative phosphorylation. In vivo, compared with wild-type (WT) mice, NAC1−/− mice produced a lower response to vaccinia virus (VACV) infection, and viral antigen (Ag)-specific CD8+ T cells decreased more slowly. Additionally, we observed that the NAC1−/− mice demonstrated a stronger memory formation of viral Ag-specific CD8+ T cells post-viral infection. Mechanically, we identified that compared with WT CD8+ T cells, the Interferon Regulatory Factor 4 (IRF4), a key transcription factor in T cell development, was highly expressed in NAC1−/− CD8+ T cells, insinuating that IRF4 could be a critical regulatory target of NAC1 in the memory formation of CD8+ T cells. Our results indicate that NAC1 restrains the memory formation of CD8+ T cells by modulating IRF4, and targeting NAC1 may be exploited as a new approach to boosting CD8+ T cell memory. [ABSTRACT FROM AUTHOR]

Omicron BA.1 variant can readily infect people with vaccine-induced or naturally acquired SARS-CoV-2 immunity facilitated by escape from neutralizing antibodies. In contrast, T-cell reactivity against the Omicron BA.1 variant seems relatively well preserved. Here, we studied the preexisting T cells elicited by either vaccination with the mRNA-based BNT162b2 vaccine or by natural infection with ancestral SARS-CoV-2 for their cross-reactive potential to 20 selected CD4+ T-cell epitopes of spike-protein-harboring Omicron BA.1 mutations. Although the overall memory CD4+ T-cell responses primed by the ancestral spike protein was still preserved generally, we show here that there is also a clear loss of memory CD4+ T-cell cross-reactivity to immunodominant epitopes across the spike protein due to Omicron BA.1 mutations. Complete or partial loss of preexisting T-cell responsiveness was observed against 60% of 20 nonconserved CD4+ T-cell epitopes predicted to be presented by a broad set of common HLA class II alleles. Monitoring such mutations in circulating strains helps predict which virus variants may escape previously induced cellular immunity and could be of concern. [ABSTRACT FROM AUTHOR]

Although surgical resection is available as a potentially curative therapy for hepatocellular carcinoma (HCC), high recurrence of HCC after surgery remains a serious obstacle for long-term patient survival. Therefore, the discovery of valuable prognostic biomarkers for HCC recurrence is urgently needed. Pre-S2 mutant is a mutant form of hepatitis B virus (HBV) large surface protein which is expressed from the HBV surface gene harboring deletion mutations spanning the pre-S2 gene segment. Pre-S2 mutant-positive HCC patients have been regarded as a high-risk population of HCC recurrence after resection surgery and display increased immune checkpoint programmed death ligand 1 (PD-L1) expression and pro-tumor regulatory T cells (Tregs) infiltration in tumor tissues. In this study, the association of higher levels of PD-L1 expression and Tregs infiltration in tumor tissues with post-operative HCC recurrence in pre-S2 mutant-positive HCC patients was evaluated. We found that patients with pre-S2 mutant in combination with higher levels of PD-L1 expression and Tregs infiltration in tumor tissues were independently associated with a higher risk of HCC recurrence (hazard ratio, 4.109; p value = 0.0011) and poorer recurrence-free survival (median, 8.2 versus 18.0 months; p value = 0.0004) than those of patients with either one or two of these three biomarkers. Furthermore, a combination of pre-S2 mutant, intra-tumoral PD-L1 expression, and tumor-infiltrating Tregs exhibited superior performance in identifying patients at a higher risk of HCC recurrence (area under the receiver operating characteristic curve, 0.8400). Collectively, this study suggests that higher levels of PD-L1 expression and Tregs infiltration in tumor tissues predicted a higher risk of HCC recurrence in pre-S2 mutant-positive HCC patients after curative surgical resection. [ABSTRACT FROM AUTHOR]

(1) Background: As the pandemic months progress, more and more evidence shows that the placenta acts as a "barrier" to SARS-CoV-2, although rare cases of vertical transmission have been described. (2) Methods: In an attempt to investigate whether the symptoms' severity was related to different placental histological characteristics and the immune microenvironment, we subdivided 29 placentas from 29 mothers positive for SARS-CoV-2 into two groups, depending on the symptomatology (moderate/severe vs. asymptomatic/mild), performing immunohistochemical investigations for CD4 + and CD8 + T lymphocytes, as well as for CD68 + macrophage. We also evaluated the immuno-expression of the ACE2 receptor at the placental level. These two groups were compared to a control group of 28 placentas from 28 SARS-CoV-2-negative healthy mothers. (3) Results: The symptoms (likely to be related to viremia) were statistically significantly correlated (p < 0.05) with histopathological changes, such as maternal malperfusion, decidual arteriopathy, blood vessel thrombus of fetal relevance. Furthermore, the immuno-expression of ACE2 was significantly lower in SARS-CoV-2-positive groups vs. control group (p = 0.001). (4) Conclusions: There is still much to study and discover regarding the relationship between SARS-CoV-2 and histological changes in placentas and how the latter might contribute to various neonatal clinical outcomes, such as prematurity. [ABSTRACT FROM AUTHOR]

Here, we longitudinally assessed the ex vivo frequency and phenotype of SARS-CoV-2 membrane protein (aa145–164) epitope-specific CD4+ T-cells of an anti-CD20-treated patient with prolonged viral positivity in direct comparison to an immunocompetent patient through an MHC class II DRB1*11:01 Tetramer analysis. We detected a high and stable SARS-CoV-2 membrane-specific CD4+ T-cell response in both patients, with higher frequencies of virus-specific CD4+ T-cells in the B-cell-depleted patient. However, we found an altered virus-specific CD4+ T-cell memory phenotype in the B-cell-depleted patient that was skewed towards late differentiated memory T-cells, as well as reduced frequencies of SARS-CoV-2-specific CD4+ T-cells with CD45RA− CXCR5+ PD-1+ circulating T follicular helper cell (cTFH) phenotype. Furthermore, we observed a delayed contraction of CD127− virus-specific effector cells. The expression of the co-inhibitory receptors TIGIT and LAG-3 fluctuated on the virus-specific CD4+ T-cells of the patient, but were associated with the inflammation markers IL-6 and CRP. Our findings indicate that, despite B-cell depletion and a lack of B-cell—T-cell interaction, a robust virus-specific CD4+ T-cell response can be primed that helps to control the viral replication, but which is not sufficient to fully abrogate the infection. [ABSTRACT FROM AUTHOR]

New emerging viruses belonging to the Coronaviridae, Flaviviridae, and Filoviridae families are serious threats to public health and represent a global concern. The surveillance to monitor the emergence of new viruses and their transmission is an important target for public health authorities. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is an excellent example of a pathogen able to cause a pandemic. In a few months, SARS-CoV-2 has spread globally from China, and it has become a world health problem. Gammadelta (γδ) T cell are sentinels of innate immunity and are able to protect the host from viral infections. They enrich many tissues, such as the skin, intestines, and lungs where they can sense and fight the microbes, thus contributing to the protective immune response. γδ T cells perform their direct antiviral activity by cytolytic and non-cytolytic mechanisms against a wide range of viruses, and they are able to orchestrate the cellular interplay between innate and acquired immunity. For their pleiotropic features, γδ T cells have been proposed as a target for immunotherapies in both cancer and viral infections. In this review, we analyzed the role of γδ T cells in emerging viral infections to define the profile of the response and to better depict their role in the host protection. [ABSTRACT FROM AUTHOR]

HLA-B*57:01 is an HLA allelic variant associated with positive outcomes during viral infections through interactions with T cells and NK cells, but severe disease in persons treated with the anti-HIV-1 drug abacavir. The role of HLA-B*57:01 in the context of HSV infection is unknown. We identified an HLA-B*57:01-restricted CD8 T-cell epitope in the ICP22 (US1) protein of HSV-2. CD8 T cells reactive to the HSV-2 ICP22 epitope recognized the orthologous HSV-1 peptide, but not closely related peptides in human IFNL2 or IFNL3. Abacavir did not alter the CD8 T-cell recognition of the HSV or self-derived peptides. Unexpectedly, a tetramer of HSV-2 ICP22 epitope (228–236) and HLA-B*57:01 bound both CD8 T cells and NK cells. Tetramer specificity for KIR3DL1 was confirmed using KIR3DL1 overexpression on non-human primate cells lacking human KIR and studies with blocking anti-KIR3DL1 antibody. Interaction with KIR3DL1 was generalizable to donors lacking the HLA-B*57:01 genotype or HSV seropositivity. These findings suggest a mechanism for the recognition of HSV infection by NK cells or KIR-expressing T cells via KIR3DL1. [ABSTRACT FROM AUTHOR]

Pulmonary microbial invasion frequently occurs during AIDS progression in HIV patients. Inflammatory cytokines and other immunoregulatory factors play important roles in this process. We previously established an AIDS model of SIVmac239 infection in northern pig-tailed macaques (NPMs), which were divided into rapid progressor (RP) and slow progressor (SP) groups according to their AIDS progression rates. In this study, we performed 16S rDNA and transcriptome sequencing of the lungs to reveal the molecular mechanism underlying the difference in progression rate between the RPs and SPs. We found that microbial invasion in the RP group was distinct from that in the SP group, showing marker flora of the Family XI, Enterococcus and Ezakiella, and more Lactobacilli. Through pulmonary transcriptome analysis, we found that the transcription factor ZNF683 had higher expression in the SP group than in the RP group. In subsequent functional experiments, we found that ZNF683 increased the proliferation and IFNγ secretion ability of CD8+ T cells, thus decreasing SIV or HIV replication, which may be related to AIDS progression in SIVmac239-infected NPMs. This study helps elucidate the various complexities of disease progression in HIV-1-infected individuals. [ABSTRACT FROM AUTHOR]

T cells infected with human T-cell leukemia virus type 1 (HTLV-1) acquire various abnormalities during a long latent period and transform into highly malignant adult T-cell leukemia-lymphoma (ATL) cells. This can be described as "clonal evolution", in which a single clone evolves into ATL cells after overcoming various selective pressures in the body of the infected individuals. Many studies have shown that the genome and epigenome contain a variety of abnormalities, which are reflected in gene expression patterns and define the characteristics of the disease. The latest research findings suggest that epigenomic disorders are thought to begin forming early in infection and evolve into ATL through further changes and accentuation as they progress. Genomic abnormalities profoundly affect clonal dominance and tumor cell characteristics in later events. ATL harbors both genomic and epigenomic abnormalities, and an accurate understanding of these can be expected to provide therapeutic opportunities. [ABSTRACT FROM AUTHOR]

It has been proposed that blood coagulation factors, principally factor X (FX), enhance the uptake of human adenovirus type 5 (Ad5) into cultured epithelial cells by bridging the viral hexon capsid protein and cell-surface heparan sulphate proteoglycans (HSPGs). We studied the effects of FX on Ad transduction of lymphoid cell lines (NK92MI, a natural killer cell line; Daudi, a B-cell line and Jurkat, a T-cell line) as well as primary peripheral blood lymphocytes (PBL) and HeLa epithelial cells using either replication-deficient Ad5, or a derivative in which the Ad5 fiber was replaced with that of another Ad type, Ad35, termed Ad5F35. PBL and NK92MI were resistant to Ad5 transduction. Transduction of Jurkat and Daudi cells by Ad5 was reduced by FX but without discernible effects on cell-surface Ad5 binding. FX reduced virus binding and transduction of all lymphoid cell lines by Ad5F35, as well as transduction of the T- and Natural Killer (NK)-cell populations of PBL. Flow cytometry analysis showed that all lymphoid cell lines were negative for HSPG components, in contrast to HeLa cells. FX reduced transduction of an HSPG-negative mutant Chinese hamster ovary cell line (CHOpgsA745) by Ad5 and Ad5F35, with Ad5F35 binding also being reduced by FX. These results point to fiber-dependent differences (Ad5 versus Ad35 fiber) in Ad binding to and transduction of human lymphoid and epithelial cells in the presence of FX. [ABSTRACT FROM AUTHOR]

The exposure to CCR5 (CC chemokine receptor 5) specific natural antibodies in vitro produces a Class B β-arrestin2-dependent CCR5 retention with the aid of ERK1, due to the formation of a CCR5 signalosome, which remains stable for at least 48 h. Considering that β-arrestins and MAPKs are receptive to environmental signals, their signal complexes could be one of the key junction for GPCRs internalization related signal transduction. Here, we demonstrate that, in T cells, the phosphorylation status of either CCR5 receptor or ERK1 protein is necessary to drive the internalized receptor into the early endosomes, forming the CCR5 signalosome. In particular, our data show that β-arrestin2/ERK1 complex is a relevant transducer in the CCR5 signaling pathway. Understanding the mechanism of CCR5 regulation is essential for many inflammatory disorders, tumorigenesis and viral infection such as HIV. [ABSTRACT FROM AUTHOR]

Chemokine receptor type 6 (CCR6)+CD4+ T cells are preferentially infected and depleted during HIV disease progression, but are preserved in non-progressors. CCR6 is expressed on a heterogeneous population of memory CD4+ T cells that are critical to mucosal immunity. Preferential infection of these cells is associated, in part, with high surface expression of CCR5, CXCR4, and α4β7. In addition, CCR6+CD4+ T cells harbor elevated levels of integrated viral DNA and high levels of proliferation markers. We have previously shown that the CCR6 ligands MIP-3 and human beta defensins inhibit HIV replication. The inhibition required CCR6 and the induction of APOBEC3G. Here, we further characterize the induction of apolipoprotein B mRNA editing enzyme (APOBEC3G) by human beta defensin 2. Human beta defensin 2 rapidly induces transcriptional induction of APOBEC3G that involves extracellular signal-regulated kinases 1/2 (ERK1/2) activation and the transcription factors NFATc2, NFATc1, and IRF4. We demonstrate that human beta defensin 2 selectively protects primary CCR6+CD4+ T cells infected with HIV-1. The selective protection of CCR6+CD4+ T cell subsets may be critical in maintaining mucosal immune function and preventing disease progression. [ABSTRACT FROM AUTHOR]

Human T-cell leukemia virus type-1 (HTLV-1) is a tumorigenic retrovirus responsible for development of adult T-cell leukemia/lymphoma (ATLL). This disease manifests after a long clinical latency period of up to 2-3 decades. Two viral gene products, Tax and HBZ, have transforming properties and play a role in the pathogenic process. Genetic and epigenetic cellular changes also occur in HTLV-1-infected cells, which contribute to transformation and disease development. However, the role of cellular factors in transformation is not completely understood. Herein, we examined the role of protein arginine methyltransferase 5 (PRMT5) on HTLV-1-mediated cellular transformation and viral gene expression. We found PRMT5 expression was upregulated during HTLV-1-mediated T-cell transformation, as well as in established lymphocytic leukemia/lymphoma cell lines and ATLL patient PBMCs. shRNA-mediated reduction in PRMT5 protein levels or its inhibition by a small molecule inhibitor (PRMT5i) in HTLV-1-infected lymphocytes resulted in increased viral gene expression and decreased cellular proliferation. PRMT5i also had selective toxicity in HTLV-1-transformed T-cells. Finally, we demonstrated that PRMT5 and the HTLV-1 p30 protein had an additive inhibitory effect on HTLV-1 gene expression. Our study provides evidence for PRMT5 as a host cell factor important in HTLV-1-mediated T-cell transformation, and a potential target for ATLL treatment. [ABSTRACT FROM AUTHOR]

Oncolytic viruses represent a diverse class of replication competent viruses that curtail tumor growth. These viruses, through their natural ability or through genetic modifications, can selectively replicate within tumor cells and induce cell death while leaving normal cells intact. Apart from the direct oncolytic activity, these viruses mediate tumor cell death via the induction of innate and adaptive immune responses. The field of oncolytic viruses has seen substantial advancement with the progression of numerous oncolytic viruses in various phases of clinical trials. Tumors employ a plethora of mechanisms to establish growth and subsequently metastasize. These include evasion of immune surveillance by inducing up-regulation of checkpoint proteins which function to abrogate T cell effector functions. Currently, antibodies blocking checkpoint proteins such as anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) and anti-programmed cell death-1 (PD-1) have been approved to treat cancer and shown to impart durable clinical responses. These antibodies typically need pre-existing active immune tumor microenvironment to establish durable clinical outcomes and not every patient responds to these therapies. This review provides an overview of published pre-clinical studies demonstrating superior therapeutic efficacy of combining oncolytic viruses with checkpoint blockade compared to monotherapies. These studies provide compelling evidence that oncolytic therapy can be potentiated by coupling it with checkpoint therapies. [ABSTRACT FROM AUTHOR]

In April 2013, human infections with a novel avian influenza (H7N9) virus emerged in China. It has caused serious concerns for public health throughout the world. However, there is presently no effective treatment, and an A (H7N9) H7 subtype influenza vaccine is not available. Vaccination with virus-like particles (VLPs) has showed considerable promise for many other subtype influenza viruses. To produce H7N9 VLPs, full length, unmodified hemagglutinin (HA), neuraminidase (NA), and matrix1 (M1) genes from the A/Wuxi/1/2013(H7N9) were cloned into a pCDNA5.1 FRT vector. By co-transfection, VLPs containing HA, NA, and M1 were secreted by 293T cells. VLPs were purified by ultracentrifugation and injected into mice by the intramuscular route. In animal experiments, humoral and cellular immunoresponse were all triggered by H7N9 VLPs. High levels of specific antibodies and the isotypes of IgG were detected by ELISA. Anamnestic cellular immune responses were examined by detecting specific cytotoxic T cell for IFN-γ production in ELISPOT assay. The hemagglutination-inhibition (HAI) against the homologous virus was more than 1:64, and cross-reactive HAI titers against the heterologous virus (H1N1 and H3N2) were more than 1:16. Moreover, VLPs immunized mice showed a rapid increase of neutralizing antibodies, with neutralizing antibody titers more than 1:8, which increased four-fold against PBS immunized mice in week four. By week six, the mice had high neutralization ability against the given strain and held a potent homologous virus neutralizing capacity. Thus, VLPs represent a potential strategy for the development of a safe and effective vaccine against novel avian influenza (H7N9) virus. [ABSTRACT FROM AUTHOR]

We developed an innovative strategy to induce a cytotoxic T cell (CTL) immune response against protein antigens of choice. It relies on the production of exosomes, i.e., nanovesicles spontaneously released by all cell types. We engineered the upload of huge amounts of protein antigens upon fusion with an anchoring protein (i.e., HIV-1 Nefmut), which is an inactive protein incorporating in exosomes at high levels also when fused with foreign proteins. We compared the immunogenicity of engineered exosomes uploading human papillomavirus (HPV)-E7 with that of lentiviral virus-like particles (VLPs) incorporating equivalent amounts of the same antigen. These exosomes, whose limiting membrane was decorated with VSV-G, i.e., an envelope protein inducing pH-dependent endosomal fusion, proved to be as immunogenic as the cognate VLPs. It is noteworthy that the immunogenicity of the engineered exosomes remained unaltered in the absence of VSV-G. Most important, we provide evidence that the inoculation in mouse of exosomes uploading HPV-E7 induces production of anti-HPV E7 CTLs, blocks the growth of syngeneic tumor cells inoculated after immunization, and controls the development of tumor cells inoculated before the exosome challenge. These results represent the proof-of-concept about both feasibility and efficacy of the Nefmut-based exosome platform for the induction of CD8+ T cell immunity. [ABSTRACT FROM AUTHOR]

CD4+ T cells are principal targets for human immunodeficiency virus type 1 (HIV-1) infection. CD4+ T cell subsets are heterogeneous cell populations, divided by functional and phenotypic differences into naïve and memory T cells. The memory CD4+ T cells are further segregated into central, effector and transitional memory cell subsets by functional, phenotypic and homeostatic characteristics. Defining the distribution of HIV-1 infection in different T cell subsets is important, as this can play a role in determining the size and composition of the viral reservoir. Both central memory and transitional memory CD4+ T cells have been described as long-lived viral reservoirs for HIV. Recently, the newly described stem memory T cell subset has also been implicated as a long-lived HIV reservoir. Using green fluorescent protein (GFP) reporter strains of HIV-1 and multi parameter flow cytometry, we developed an assay to simultaneously quantify the susceptibility of stem memory (TSCM), central memory, effector memory, transitional memory and naïve CD4+ T cell subsets, to HIV-1 infection in vitro. We show that TSCM are susceptible to infection with laboratory adapted and clinical HIV-1 strains. Our system facilitates the quantitation of HIV-1 infection in alternative T cell subsets by CCR5- and CXCR4-using viruses across different HIV-1 subtypes, and will be useful for studies of HIV-1 pathogenesis and viral reservoirs. [ABSTRACT FROM AUTHOR]

After integration to the human genome as a provirus, human T-cell leukemia virus type 1 (HTLV-1) utilizes host T cell gene expression machinery for viral replication. The viral RNA-binding protein, Rex, is known to transport unspliced/incompletely spliced viral mRNAs encoding viral structural proteins out of the nucleus to enhance virus particle formation. However, the detailed mechanism of how Rex avoids extra splicing of unspliced/incompletely spliced viral mRNAs and stabilizes them for effective translation is still unclear. To elucidate the underlying molecular mechanism of Rex function, we comprehensively analyzed the changes in gene expression and splicing patterns in Rex-overexpressing T cells. In addition, we identified 81 human proteins interacting with Rex, involved in transcription, splicing, translation, and mRNA quality control. In particular, Rex interacts with NONO and SFPQ, which play important roles in the regulation of transcription and splicing. Accordingly, expression profiles and splicing patterns of a wide variety of genes are significantly changed in Rex-expressing T cells. Especially, the level of vPD-L1 mRNA that lacks the part of exon 4, thus encodes soluble PD-L1 was significantly increased in Rex-expressing cells. Overall, by integrated analysis of these three datasets, we showed for the first time that Rex intervenes the host gene expression machinery throughout the pathway, probably to escort viral unstable mRNAs from transcription (start) to translation (end). Upon exerting its function, Rex may alter the expression level and splicing patterns of various genes, thus influencing the phenotype of the host cell. [ABSTRACT FROM AUTHOR]

The human retrovirus human T-cell leukemia virus type I (HTLV-1) infects human T cells by vertical transmission from mother to child through breast milk or horizontal transmission through blood transfusion or sexual contact. Approximately 5% of infected individuals develop adult T-cell leukemia/lymphoma (ATL) with a poor prognosis, while 95% of infected individuals remain asymptomatic for the rest of their lives, during which time the infected cells maintain a stable immortalized latent state in the body. It is not known why such a long latent state is maintained. We hypothesize that the role of functional proteins of HTLV-1 during early infection influences the phenotype of infected cells in latency. In eukaryotic cells, a mRNA quality control mechanism called nonsense-mediated mRNA decay (NMD) functions not only to eliminate abnormal mRNAs with nonsense codons but also to target virus-derived RNAs. We have reported that HTLV-1 genomic RNA is a potential target of NMD, and that Rex suppresses NMD and stabilizes viral RNA against it. In this study, we aimed to elucidate the molecular mechanism of NMD suppression by Rex using various Rex mutant proteins. We found that region X (aa20–57) of Rex, the function of which has not been clarified, is required for NMD repression. We showed that Rex binds to Upf1, which is the host key regulator to detect abnormal mRNA and initiate NMD, through this region. Rex also interacts with SMG5 and SMG7, which play essential roles for the completion of the NMD pathway. Moreover, Rex selectively binds to Upf3B, which is involved in the normal NMD complex, and replaces it with a less active form, Upf3A, to reduce NMD activity. These results revealed that Rex invades the NMD cascade from its initiation to completion and suppresses host NMD activity to protect the viral genomic mRNA. [ABSTRACT FROM AUTHOR]

SARS-CoV-2-specific CD8+ T cell immunity is expected to counteract viral variants in both efficient and durable ways. We recently described a way to induce a potent SARS-CoV-2 CD8+ T immune response through the generation of engineered extracellular vesicles (EVs) emerging from muscle cells. This method relies on intramuscular injection of DNA vectors expressing different SARS-CoV-2 antigens fused at their N-terminus with the Nefmut protein, i.e., a very efficient EV-anchoring protein. However, quality, tissue distribution, and efficacy of these SARS-CoV-2-specific CD8+ T cells remained uninvestigated. To fill the gaps, antigen-specific CD8+ T lymphocytes induced by the immunization through the Nefmut-based method were characterized in terms of their polyfunctionality and localization at lung airways, i.e., the primary targets of SARS-CoV-2 infection. We found that injection of vectors expressing Nefmut/S1 and Nefmut/N generated polyfunctional CD8+ T lymphocytes in both spleens and bronchoalveolar lavage fluids (BALFs). When immunized mice were infected with 4.4 lethal doses of 50% of SARS-CoV-2, all S1-immunized mice succumbed, whereas those developing the highest percentages of N-specific CD8+ T lymphocytes resisted the lethal challenge. We also provide evidence that the N-specific immunization coupled with the development of antigen-specific CD8+ T-resident memory cells in lungs, supporting the idea that the Nefmut-based immunization can confer a long-lasting, lung-specific immune memory. In view of the limitations of current anti-SARS-CoV-2 vaccines in terms of antibody waning and efficiency against variants, our CD8+ T cell-based platform could be considered for a new combination prophylactic strategy. [ABSTRACT FROM AUTHOR]

High levels of T helper 17 cell (Th17)-related cytokines have been shown in acute Zika virus (ZIKV) infection. We hypothesized that the high levels of Th17-related cytokines, associated with a regulatory environment during pregnancy, create a favorable milieu for the differentiation of CD4+Th17 cells. We present data from a cross-sectional study on mothers who confirmed ZIKV infection by qRT-PCR and their children. We also recruited non-pregnant women infected with ZIKV in the same period. ZIKV infection occurred between 2015 and 2017. We collected samples for this study between 2018 and 2019, years after the initial infection. We highlight that, after in vitro stimulation with ZIKV CD4 megapool (ZIKV MP), we found a lower frequency of IL-17-producing CD4+ T cells (Th17), especially in the mothers, confirmed by the decrease in IL-17 production in the supernatant. However, a higher frequency of CD4+ IL-17+ IFN-γ+ T cells (Th1Th17) responding to the ZIKV MP was observed in the cells of the mothers and children but not in those of the non-pregnant women. Our data indicate that the priming of CD4 T cells of the Th1Th17 phenotype occurred preferentially in the mothers who gave birth to children with CZS and in the children. [ABSTRACT FROM AUTHOR]

Due to their ability to trigger strong immune responses, adenoviruses (HAdVs) in general and the serotype5 (HAdV-5) in particular are amongst the most popular viral vectors in research and clinical application. However, efficient transduction using HAdV-5 is predominantly achieved in coxsackie and adenovirus receptor (CAR)-positive cells. In the present study, we used the transduction enhancer LentiBOOST® comprising the polycationic Polybrene to overcome these limitations. Using LentiBOOST®/Polybrene, we yielded transduction rates higher than 50% in murine bone marrow-derived dendritic cells (BMDCs), while maintaining their cytokine expression profile and their capability to induce T-cell proliferation. In human dendritic cells (DCs), we increased the transduction rate from 22% in immature (i)DCs or 43% in mature (m)DCs to more than 80%, without inducing cytotoxicity. While expression of specific maturation markers was slightly upregulated using LentiBOOST®/Polybrene on iDCs, no effect on mDC phenotype or function was observed. Moreover, we achieved efficient HAdV5 transduction also in human monocytes and were able to subsequently differentiate them into proper iDCs and functional mDCs. In summary, we introduce LentiBOOST® comprising Polybrene as a highly potent adenoviral transduction agent for new in-vitro applications in a set of different immune cells in both mice and humans. [ABSTRACT FROM AUTHOR]