Single-cell analysis of memory B cells from top neutralizers reveals multiple sites of vulnerability within HCMV Trimer and Pentamer.

Human cytomegalovirus (HCMV) can cause severe diseases in fetuses, newborns, and immunocompromised individuals. Currently, no vaccines are approved, and treatment options are limited. Here, we analyzed the human B cell response of four HCMV top neutralizers from a cohort of 9,000 individuals. By single-cell analyses of memory B cells targeting the pentameric and trimeric HCMV surface complexes, we identified vulnerable sites on the shared gH/gL subunits as well as complex-specific subunits UL128/130/131A and gO. Using high-resolution cryogenic electron microscopy, we revealed the structural basis of the neutralization mechanisms of antibodies targeting various binding sites. Moreover, we identified highly potent antibodies that neutralized a broad spectrum of HCMV strains, including primary clinical isolates, that outperform known antibodies used in clinical trials. Our study provides a deep understanding of the mechanisms of HCMV neutralization and identifies promising antibody candidates to prevent and treat HCMV infection.

Neurological Manifestations of COVID-19 Feature T Cell Exhaustion and Dedifferentiated Monocytes in Cerebrospinal Fluid.

Patients suffering from Coronavirus disease 2019 (COVID-19) can develop neurological sequelae, such as headache and neuroinflammatory or cerebrovascular disease. These conditions-termed here as Neuro-COVID-are more frequent in patients with severe COVID-19. To understand the etiology of these neurological sequelae, we utilized single-cell sequencing and examined the immune cell profiles from the cerebrospinal fluid (CSF) of Neuro-COVID patients compared with patients with non-inflammatory and autoimmune neurological diseases or with viral encephalitis. The CSF of Neuro-COVID patients exhibited an expansion of dedifferentiated monocytes and of exhausted CD4+ T cells. Neuro-COVID CSF leukocytes featured an enriched interferon signature; however, this was less pronounced than in viral encephalitis. Repertoire analysis revealed broad clonal T cell expansion and curtailed interferon response in severe compared with mild Neuro-COVID patients. Collectively, our findings document the CSF immune compartment in Neuro-COVID patients and suggest compromised antiviral responses in this setting.

Influenza virus infection enhances tumour-specific CD8+ T-cell immunity, facilitating tumour control.

Influenza A virus (IAV) can cause severe respiratory infection leading to significant global morbidity and mortality through seasonal epidemics. Likewise, the constantly increasing number of cancer diseases is a growing problem. Nevertheless, the understanding of the mutual interactions of the immune responses between cancer and infection is still very vague. Therefore, it is important to understand the immunological cross talk between cancer and IAV infection. In several preclinical mouse models of cancer, including melanoma and colorectal cancer, we observed that IAV infection in the lung significantly decreased the tumour burden. Concomitantly, tumour-specific CD8+ T-cells are strongly activated upon infection, both in the tumour tissue and in the lung. CD8+ T-cell depletion during infection reverses the reduced tumour growth. Interestingly, IAV infection orchestrated the migration of tumour-specific CD8+ T-cells from the tumour into the infected lung. Blocking the migration of CD8+ T-cells prevented the anti-tumoural effect. Thus, our findings show that viral respiratory infection has significant impact on the anti-tumour CD8+ T-cell response, which will significantly improve our understanding of the immunological cross talk between cancer and infection.

The interferon-regulated host factor hnRNPA0 modulates HIV-1 production by interference with LTR activity, mRNA trafficking, and programmed ribosomal frameshifting.

The interplay between host factors and viral components impacts viral replication efficiency profoundly. Members of the cellular heterogeneous nuclear ribonucleoprotein family (hnRNPs) have been extensively studied as HIV-1 host dependency factors, but whether they play a role in innate immunity is currently unknown. This study aimed to identify hnRNPA0 as a type I interferon (IFN)-repressed host factor in HIV-1-infected cells. Knockdown of hnRNPA0, a situation that mirrors conditions under IFN stimulation, increased LTR activity, export of unspliced HIV-1 mRNA, viral particle production, and thus, increased infectivity. Conversely, hnRNPA0 overexpression primarily reduced plasmid-driven and integrated HIV-1 long terminal repeat (LTR) activity, significantly decreasing total viral mRNA and protein levels. In addition, high levels of hnRNPA0 significantly reduced the HIV-1 programmed ribosomal frameshifting efficiency, resulting in a shift in the HIV-1 p55/p15 ratio. The HIV-1 alternative splice site usage remained largely unaffected by altered hnRNPA0 levels suggesting that the synergistic inhibition of the LTR activity and viral mRNA transcription, as well as impaired ribosomal frameshifting efficiency, are critical factors for efficient HIV-1 replication regulated by hnRNPA0. The pleiotropic dose-dependent effects under high or low hnRNPA0 levels were further confirmed in HIV-1-infected Jurkat cells. Finally, our study revealed that hnRNPA0 levels in PBMCs were lower in therapy-naive HIV-1-infected individuals compared to healthy controls. Our findings highlight a significant role for hnRNPA0 in HIV-1 replication and suggest that its IFN-I-regulated expression levels are critical for viral fitness allowing replication in an antiviral environment.IMPORTANCERNA-binding proteins, in particular, heterogeneous nuclear ribonucleoproteins (hnRNPs), have been extensively studied. Some act as host dependency factors for HIV-1 since they are involved in multiple cellular gene expression processes. Our study revealed hnRNPA0 as an IFN-regulated host factor, that is differently expressed after IFN-I treatment in HIV-1 target cells and lower expressed in therapy-naïve HIV-1-infected individuals. Our findings demonstrate the significant pleiotropic role of hnRNPA0 in viral replication: In high concentrations, hnRNPA0 limits viral replication by negatively regulating Tat-LTR transcription, retaining unspliced mRNA in the nucleus, and significantly impairing programmed ribosomal frameshifting. Low hnRNPA0 levels as observed in IFN-treated THP-1 cells, particularly facilitate HIV LTR activity and unspliced mRNA export, suggesting a role in innate immunity in favor of HIV replication. Understanding the mode of action between hnRNPA0 and HIV-1 gene expression might help to identify novel therapeutically strategies against HIV-1 and other viruses.

Immunotherapy-induced cytotoxic T follicular helper cells reduce numbers of retrovirus-infected reservoir cells in B cell follicles.

Antiretroviral therapy (ART) transformed HIV from a life-threatening disease to a chronic condition. However, eliminating the virus remains an elusive therapy goal. For several decades, Friend virus (FV) infection serves as a murine model to study retrovirus immunity. Similar to HIV, FV persists at low levels in lymph nodes B cell follicles avoiding elimination by immune cells. Such immune-privileged reservoirs exclude cytotoxic T cells from entry. However, CXCR5+ T cells are permitted to traffic through germinal centers. This marker is predominantly expressed by CD4+ follicular helper T cells (Tfh). Therefore, we explored immunotherapy to induce cytotoxic Tfh, which are rarely found under physiological conditions. The TNF receptor family member CD137 was first identified as a promising target for cancer immunotherapy. We demonstrated that FV-infected mice treatment with αCD137 antibody resulted in an induction of the cytotoxic program in Tfh. The therapy significantly increased numbers of cytotoxic Tfh within B cell follicles and contributed to viral load reduction. Moreover, αCD137 antibody combined with ART delayed virus rebound upon treatment termination without disturbing the lymph node architecture or antibody responses. Thus, αCD137 antibody therapy might be a novel strategy to target the retroviral reservoir and an interesting approach for HIV cure research.

Circulating HIV-Specific Interleukin-21(+)CD4(+) T Cells Represent Peripheral Tfh Cells with Antigen-Dependent Helper Functions.

A central effort in HIV vaccine development is to generate protective broadly neutralizing antibodies, a process dependent on T follicular helper (Tfh) cells. The feasibility of using peripheral blood counterparts of lymph node Tfh cells to assess the immune response and the influence of viral and vaccine antigens on their helper functions remain obscure. We assessed circulating HIV-specific IL-21(+)CD4(+) T cells and showed transcriptional and phenotypic similarities to lymphoid Tfh cells, and hence representing peripheral Tfh (pTfh) cells. pTfh cells were functionally active and B cell helper quality differed depending on antigen specificity. Furthermore, we found higher frequency of pTfh cells in peripheral blood mononuclear cell specimens from the ALVAC+AIDSVAX (RV144) HIV vaccine trial associated with protective antibody responses compared to the non-protective DNA+Ad5 vaccine trial. Together, we identify IL-21(+)CD4(+) T cells as pTfh cells, implicating them as key populations in the generation of vaccine-evoked antibody responses.

Differential interferon-α subtype induced immune signatures are associated with suppression of SARS-CoV-2 infection.

Type I interferons (IFN-I) exert pleiotropic biological effects during viral infections, balancing virus control versus immune-mediated pathologies, and have been successfully employed for the treatment of viral diseases. Humans express 12 IFN-alpha (α) subtypes, which activate downstream signaling cascades and result in distinct patterns of immune responses and differential antiviral responses. Inborn errors in IFN-I immunity and the presence of anti-IFN autoantibodies account for very severe courses of COVID-19; therefore, early administration of IFN-I may be protective against life-threatening disease. Here we comprehensively analyzed the antiviral activity of all IFNα subtypes against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to identify the underlying immune signatures and explore their therapeutic potential. Prophylaxis of primary human airway epithelial cells (hAEC) with different IFNα subtypes during SARS-CoV-2 infection uncovered distinct functional classes with high, intermediate, and low antiviral IFNs. In particular, IFNα5 showed superior antiviral activity against SARS-CoV-2 infection in vitro and in SARS-CoV-2-infected mice in vivo. Dose dependency studies further displayed additive effects upon coadministration with the broad antiviral drug remdesivir in cell culture. Transcriptomic analysis of IFN-treated hAEC revealed different transcriptional signatures, uncovering distinct, intersecting, and prototypical genes of individual IFNα subtypes. Global proteomic analyses systematically assessed the abundance of specific antiviral key effector molecules which are involved in IFN-I signaling pathways, negative regulation of viral processes, and immune effector processes for the potent antiviral IFNα5. Taken together, our data provide a systemic, multimodular definition of antiviral host responses mediated by defined IFN-I. This knowledge will support the development of novel therapeutic approaches against SARS-CoV-2.

UnCoVar: a reproducible and scalable workflow for transparent and robust virus variant calling and lineage assignment using SARS-CoV-2 as an example.

BACKGROUND: At a global scale, the SARS-CoV-2 virus did not remain in its initial genotype for a long period of time, with the first global reports of variants of concern (VOCs) in late 2020. Subsequently, genome sequencing has become an indispensable tool for characterizing the ongoing pandemic, particularly for typing SARS-CoV-2 samples obtained from patients or environmental surveillance. For such SARS-CoV-2 typing, various in vitro and in silico workflows exist, yet to date, no systematic cross-platform validation has been reported. RESULTS: In this work, we present the first comprehensive cross-platform evaluation and validation of in silico SARS-CoV-2 typing workflows. The evaluation relies on a dataset of 54 patient-derived samples sequenced with several different in vitro approaches on all relevant state-of-the-art sequencing platforms. Moreover, we present UnCoVar, a robust, production-grade reproducible SARS-CoV-2 typing workflow that outperforms all other tested approaches in terms of precision and recall. CONCLUSIONS: In many ways, the SARS-CoV-2 pandemic has accelerated the development of techniques and analytical approaches. We believe that this can serve as a blueprint for dealing with future pandemics. Accordingly, UnCoVar is easily generalizable towards other viral pathogens and future pandemics. The fully automated workflow assembles virus genomes from patient samples, identifies existing lineages, and provides high-resolution insights into individual mutations. UnCoVar includes extensive quality control and automatically generates interactive visual reports. UnCoVar is implemented as a Snakemake workflow. The open-source code is available under a BSD 2-clause license at github.com/IKIM-Essen/uncovar.

Monitoring of hepatitis E virus in wastewater can identify clinically relevant variants.

Hepatitis E virus (HEV) is prevalent worldwide and can cause persistent infection with severe morbidity. Antiviral treatment approaches can lead to the emergence of viral variants encoding escape mutations that may impede viral clearance. The frequency of these variants remains unknown in the human population as well as environment due to limited comprehensive data on HEV diversity. In this study, we investigated the HEV prevalence and diversity of circulating variants in environmental samples, that is, wastewater and rivers from North-Rhine Westphalia, Germany. HEV prevalence could be determined with 73% of samples tested positive for viral RNA via qRT-PCR. Using high-throughput sequencing, we were able to assess the overall genetic diversity in these samples and identified the presence of clinically relevant variants associated with drug resistance. In summary, monitoring variants from environmental samples could provide valuable insights into estimating HEV prevalence and identifying circulating variants that can impact treatment outcome.

A systematic comparison reveals dynamic differences in early adaptive immune responses of acute-resolving versus chronic HBV replication.

Chronic hepatitis B virus (HBV) infection has been characterized by lack of effective adaptive immune responses which are vital for the viral clearance. However, very little is known about the dynamics of adaptive immune responses during the early phase of chronic HBV infection especially in spleen and liver. Here, we used the hydrodynamic injection (HDI) mouse model to kinetically characterize differences in the features of adaptive immunity, including the frequencies, phenotypes and function of antigen-presenting cells and T cells in the spleen, peripheral blood mononuclear cells (PBMCs) and liver, of chronic versus acute-resolving HBV replication (AR). We found that mice with AR mice and mice with chronic HBV replication (CH) mice showed early splenomegaly accompanied by T cell expansion in spleen but not in liver after HDI. Interestingly, the early and continuous increase in HBV-specific CD8+ T cells in spleen of CH mice was comparable to that in the AR mice. However, the splenic T cells of CH mice showed no activation phenotype compared with those in AR mice. Besides, increases in activated effector CD8+ T cells in PBMCs and liver at later time points were only observed in AR mice but not CH mice. CH mice also showed insufficient expansion of dendritic cells (DCs) in spleen and increased programmed death-1 expression in DCs of the liver compared to AR mice. The adoptive transfer of total splenocytes or splenic CD8+ T cells of AR mice to CH mice demonstrated that their ability to break HBV tolerance varies at different stages of HBV clearance. Moreover, the adoptive transfer of splenocytes from AR mice induce functional activation of endogenous HBV-specific CD8+ T cells of CH mice. Our results suggest that early T cell priming and expansion initially happens in the periphery after HBV antigen exposure in acute-resolving and chronic replication. The paucity of T cell activation, and subsequent migration and liver infiltration is a key feature of the adaptive immune responses during the early phase of CH, which is probably caused by the dysfunction of DCs.

Identification of herbal teas and their compounds eliciting antiviral activity against SARS-CoV-2 in vitro.

BACKGROUND: The SARS-CoV-2/COVID-19 pandemic has inflicted medical and socioeconomic havoc, and despite the current availability of vaccines and broad implementation of vaccination programs, more easily accessible and cost-effective acute treatment options preventing morbidity and mortality are urgently needed. Herbal teas have historically and recurrently been applied as self-medication for prophylaxis, therapy, and symptom alleviation in diverse diseases, including those caused by respiratory viruses, and have provided sources of natural products as basis for the development of therapeutic agents. To identify affordable, ubiquitously available, and effective treatments, we tested herbs consumed worldwide as herbal teas regarding their antiviral activity against SARS-CoV-2. RESULTS: Aqueous infusions prepared by boiling leaves of the Lamiaceae perilla and sage elicit potent and sustained antiviral activity against SARS-CoV-2 when applied after infection as well as prior to infection of cells. The herbal infusions exerted in vitro antiviral effects comparable to interferon-ß and remdesivir but outperformed convalescent sera and interferon-α2 upon short-term treatment early after infection. Based on protein fractionation analyses, we identified caffeic acid, perilla aldehyde, and perillyl alcohol as antiviral compounds. Global mass spectrometry (MS) analyses performed comparatively in two different cell culture infection models revealed changes of the proteome upon treatment with herbal infusions and provided insights into the mode of action. As inferred by the MS data, induction of heme oxygenase 1 (HMOX-1) was confirmed as effector mechanism by the antiviral activity of the HMOX-1-inducing compounds sulforaphane and fraxetin. CONCLUSIONS: In conclusion, herbal teas based on perilla and sage exhibit antiviral activity against SARS-CoV-2 including variants of concern such as Alpha, Beta, Delta, and Omicron, and we identified HMOX-1 as potential therapeutic target. Given that perilla and sage have been suggested as treatment options for various diseases, our dataset may constitute a valuable resource also for future research beyond virology.

Generation of HBsAg-reactive T- and B-cells following HBV vaccination in serological non-responders under hemodialysis treatment.

HBV vaccination is recommend for hemodialysis patients, but only 50-60% of the patients show seroconversion. HBV vaccine-induced generation of HBV reactive T and B cells could be detected regardless of their capacity to mount a serological response, indicating that patients without seroconversion are potentially protected by their HBV-reactive T cell pool.

Prophylactic and therapeutic HBV vaccination by an HBs-expressing cytomegalovirus vector lacking an interferon antagonist in mice.

Cytomegalovirus (CMV)-based vaccines show promising effects against chronic infections in nonhuman primates. Therefore, we examined the potential of hepatitis B virus (HBV) vaccines based on mouse CMV (MCMV) vectors expressing the small HBsAg. Immunological consequences of vaccine virus attenuation were addressed by either replacing the dispensable gene m157 ("MCMV-HBsȍ) or the gene M27 ("ΔM27-HBs"), the latter encodes a potent IFN antagonist targeting the transcription factor STAT2. M27 was chosen, since human CMV encodes an analogous gene product, which also induced proteasomal STAT2 degradation by exploiting Cullin RING ubiquitin ligases. Vaccinated mice were challenged with HBV through hydrodynamic injection. MCMV-HBs and ΔM27-HBs vaccination achieved accelerated HBV clearance in serum and liver as well as robust HBV-specific CD8+ T-cell responses. When we explored the therapeutic potential of MCMV-based vaccines, especially the combination of ΔM27-HBs prime and DNA boost vaccination resulted in increased intrahepatic HBs-specific CD8+ T-cell responses and HBV clearance in persistently infected mice. Our results demonstrated that vaccines based on a replication competent MCMV attenuated through the deletion of an IFN antagonist targeting STAT2 elicit robust anti-HBV immune responses and mediate HBV clearance in mice in prophylactic and therapeutic immunization regimes.

Production of HIV-1 Env-specific antibodies mediating innate immune functions depends on cognate IL-21- secreting CD4+ T cells.

Antibodies with a functional Fc region were previously associated with protection from HIV-1 acquisition and spontaneous suppression of viral replication. Unlike broadly neutralizing antibodies, they are not restricted to neutralizing epitopes and do not require unconventional structural traits to exert their antiviral activity. They, therefore, develop earlier after infection and can be detected in the majority of cases. The conditions under which these antibodies are generated, however, remain largely unknown. Here we demonstrate that the generation of HIV-1 Env-specific antibodies facilitating Fc-dependent innate immune responses, including neutrophil phagocytosis (ADNP), complement deposition (ADCD), and NK cell activation, likely depends on help provided by CD4+ T and peripheral T follicular helper (pTfh) cells secreting IL-21. Other proteins, including CD40L, IFNγ, and IL-4/13, involved in crosstalk between B and T cells were linked to the production of antibodies with functional Fc region but only when co-expressed with IL-21. As a potential source of these antibodies, we identified a subset of Env-specific memory B cells known to be expanded in chronic HIV-1 infection. The frequency and level of Blimp-1 expression in Env-specific tissue-like memory B cells (TLM) correlated with the functional CD4+ T cell subsets associated with robust antibody-dependent innate responses. Thus, our data suggest a mechanism responsible for the generation of antibodies with functional Fc region in chronically HIV-1 infected individuals that is based on CD4+ T cell-induced activation of memory B cells.Importance To develop a vaccine or immunotherapy that would cure the HIV-1 infection it is important to identify helper T cells able to mount an efficient antibody response. Here, we demonstrate that the generation of HIV-1 Env-specific antibodies facilitating antibody-dependent innate immune responses likely depends on Env-specific IL-21-secreting CD4+ T and peripheral T follicular helper cells.

Simultaneous or Prior Activation of Intrahepatic Type I Interferon Signaling Leads to Hepatitis B Virus Persistence in a Mouse Model.

It remains controversial how interferon (IFN) response contributes to hepatitis B virus (HBV) control and pathogenesis. A previous study identified that hydrodynamic injection (HI) of type I IFN (IFN-I) inducer polyinosinic-poly(C) [poly(I·C)] leads to HBV clearance in a chronic HBV mouse model. However, recent studies have suggested that premature IFN-I activation in the liver may facilitate HBV persistence. In the present study, we investigated how the early IFN-I response induces an immunosuppressive signaling cascade and thus causes HBV persistence. We performed HI of the plasmid adeno-associated virus (pAAV)/HBV1.2 into adult BALB/c mice to establish an adult acute HBV replication model. Activation of the IFN-I signaling pathway following poly(I·C) stimulation or murine cytomegalovirus (MCMV) infection resulted in subsequent HBV persistence. HI of poly(I·C) with the pAAV/HBV1.2 plasmid resulted in not only the production of IFN-I and the anti-inflammatory cytokine interleukin-10 (IL-10) but also the expansion of intrahepatic regulatory T cells (Tregs), Kupffer cells (KCs), and myeloid-derived suppressor cells (MDSCs), all of which impaired the T cell response. However, when poly(I·C) was injected at day 14 after the HBV plasmid injection, it significantly enhanced HBV-specific T cell responses. In addition, interferon-alpha/beta receptor (IFNAR) blockade rescued T cell response by downregulating IL-10 expression and decreasing Treg and KC expansion. Consistently, Treg depletion or IL-10 blockade also controlled HBV replication. IMPORTANCE IFN-I plays a double-edged sword role during chronic HBV infection. Here, we identified that application of IFN-I at different time points causes contrast outcomes. Activation of the IFN-I pathway before HBV replication induces an immunosuppressive signaling cascade in the liver and consequently caused HBV persistence, while IFN-I activation post HBV infection enhances HBV-specific T cell responses and thus promotes HBV clearance. This result provided an important clue to the mechanism of HBV persistence in adult individuals.

Qualitative Differences Between the IFNα subtypes and IFNß Influence Chronic Mucosal HIV-1 Pathogenesis.

The Type I Interferons (IFN-Is) are innate antiviral cytokines that include 12 different IFNα subtypes and IFNß that signal through the IFN-I receptor (IFNAR), inducing hundreds of IFN-stimulated genes (ISGs) that comprise the 'interferome'. Quantitative differences in IFNAR binding correlate with antiviral activity, but whether IFN-Is exhibit qualitative differences remains controversial. Moreover, the IFN-I response is protective during acute HIV-1 infection, but likely pathogenic during the chronic stages. To gain a deeper understanding of the IFN-I response, we compared the interferomes of IFNα subtypes dominantly-expressed in HIV-1-exposed plasmacytoid dendritic cells (1, 2, 5, 8 and 14) and IFNß in the earliest cellular targets of HIV-1 infection. Primary gut CD4 T cells from 3 donors were treated for 18 hours ex vivo with individual IFN-Is normalized for IFNAR signaling strength. Of 1,969 IFN-regulated genes, 246 'core ISGs' were induced by all IFN-Is tested. However, many IFN-regulated genes were not shared between the IFNα subtypes despite similar induction of canonical antiviral ISGs such as ISG15, RSAD2 and MX1, formally demonstrating qualitative differences between the IFNα subtypes. Notably, IFNß induced a broader interferome than the individual IFNα subtypes. Since IFNß, and not IFNα, is upregulated during chronic HIV-1 infection in the gut, we compared core ISGs and IFNß-specific ISGs from colon pinch biopsies of HIV-1-uninfected (n = 13) versus age- and gender-matched, antiretroviral-therapy naïve persons with HIV-1 (PWH; n = 19). Core ISGs linked to inflammation, T cell activation and immune exhaustion were elevated in PWH, positively correlated with plasma lipopolysaccharide (LPS) levels and gut IFNß levels, and negatively correlated with gut CD4 T cell frequencies. In sharp contrast, IFNß-specific ISGs linked to protein translation and anti-inflammatory responses were significantly downregulated in PWH, negatively correlated with gut IFNß and LPS, and positively correlated with plasma IL6 and gut CD4 T cell frequencies. Our findings reveal qualitative differences in interferome induction by diverse IFN-Is and suggest potential mechanisms for how IFNß may drive HIV-1 pathogenesis in the gut.

Combination immunotherapy with anti-PD-L1 antibody and depletion of regulatory T cells during acute viral infections results in improved virus control but lethal immunopathology.

Combination immunotherapy (CIT) is currently applied as a treatment for different cancers and is proposed as a cure strategy for chronic viral infections. Whether such therapies are efficient during an acute infection remains elusive. To address this, inhibitory receptors were blocked and regulatory T cells depleted in acutely Friend retrovirus-infected mice. CIT resulted in a dramatic expansion of cytotoxic CD4+ and CD8+ T cells and a subsequent reduction in viral loads. Despite limited viral replication, mice developed fatal immunopathology after CIT. The pathology was most severe in the gastrointestinal tract and was mediated by granzyme B producing CD4+ and CD8+ T cells. A similar post-CIT pathology during acute Influenza virus infection of mice was observed, which could be prevented by vaccination. Melanoma patients who developed immune-related adverse events under immune checkpoint CIT also presented with expanded granzyme-expressing CD4+ and CD8+ T cell populations. Our data suggest that acute infections may induce immunopathology in patients treated with CIT, and that effective measures for infection prevention should be applied.

Functional Comparison of Interferon-α Subtypes Reveals Potent Hepatitis B Virus Suppression by a Concerted Action of Interferon-α and Interferon-γ Signaling.

BACKGROUND AND AIMS: Interferon (IFN)-α, composed of numerous subtypes, plays a crucial role in immune defense. As the most studied subtype, IFN-α2 has been used for treating chronic hepatitis B virus (HBV) infection, with advantages of finite treatment duration and sustained virologic response, but its efficacy remains relatively low. This study aimed to screen for IFN-α subtypes with the highest anti-HBV potency and to characterize mechanisms of IFN-α-mediated HBV restriction. APPROACH AND RESULTS: Using cell culture-based HBV infection systems and a human-liver chimeric mouse model, IFN-α subtype-mediated antiviral response and signaling activation were comprehensively analyzed. IFN-α14 was identified as the most effective subtype in suppression of HBV covalently closed circular DNA transcription and HBV e antigen/HBV surface antigen production, with median inhibitory concentration values approximately 100-fold lower than those of the conventional IFN-α2. IFN-α14 alone elicited IFN-α and IFN-γ signaling crosstalk in a manner similar to the combined use of IFN-α2 and IFN-γ, inducing multiple potent antiviral effectors, which synergistically restricted HBV replication. Guanylate binding protein 5, one of the most differentially expressed genes between IFN-α14-treated and IFN-α2-treated liver cells, was identified as an HBV restriction factor. A strong IFN-α-IFN-α receptor subunit 1 interaction determines the anti-HBV activity of IFN-α. The in vivo anti-HBV activity of IFN-α14 and treatment-related transcriptional patterns were further confirmed, and few adverse effects were observed. CONCLUSIONS: A concerted IFN-α and IFN-γ response in liver, which could be efficiently elicited by IFN-α subtype 14, is associated with potent HBV suppression. These data deepen the understanding of the divergent activities of IFN-α subtypes and the mechanism underlying the synergism between IFN-α and IFN-γ signaling, with implications for improved IFN therapy and HBV curative strategies.

Comparable Environmental Stability and Disinfection Profiles of the Currently Circulating SARS-CoV-2 Variants of Concern B.1.1.7 and B.1.351.

The emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern with increased transmission dynamics has raised questions regarding stability and disinfection of these viruses. We analyzed surface stability and disinfection of the currently circulating SARS-CoV-2 variants B.1.1.7 and B.1.351 compared to wild type. Treatment with heat, soap, and ethanol revealed similar inactivation profiles indicative of a comparable susceptibility towards disinfection. Furthermore, we observed comparable surface stability on steel, silver, copper, and face masks. Overall, our data support the application of currently recommended hygiene measures to minimize the risk of B.1.1.7 and B.1.351 transmission.

Cellular Immunity in COVID-19 Convalescents with PCR-Confirmed Infection but with Undetectable SARS-CoV-2-Specific IgG.

We investigated immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a group of convalescent, potential blood donors in Germany who had PCR-confirmed SARS-CoV-2 infection. Sixty days after onset of symptoms, 13/78 (17%) study participants had borderline or negative results to an ELISA detecting IgG against the S1 protein of SARS-CoV-2. We analyzed participants with PCR-confirmed infection who had strong antibody responses (ratio >3) as positive controls and participants without symptoms of SARS-CoV-2 infection and without household contact with infected patients as negative controls. Using interferon-γ ELISpot, we observed that 78% of PCR-positive volunteers with undetectable antibodies showed T cell immunity against SARS-CoV-2. We observed a similar frequency (80%) of T-cell immunity in convalescent donors with strong antibody responses but did not detect immunity in negative controls. We concluded that, in convalescent patients with undetectable SARS-CoV-2 IgG, immunity may be mediated through T cells.