Infectious Diseases Institute Research Articles

TGF-β promotes the resolution of acute hepatitis B virus infection

Abstract An estimated 296 million people live with a chronic hepatitis B virus (HBV) infection, resulting in approximately 800,000 annual deaths. Thus, despite the availability of an effective vaccine, HBV remains a global health concern. Most children and a fraction of adults infected with HBV develop a persistent liver infection that yields lifelong complications. It is believed that the immune tolerogenic environment of the liver and the dysfunction of T and B cells contribute to HBV persistence in these individuals. Here, an adeno-associated virus (AAV)-based mouse model of HBV infection was utilized to investigate the underlying mechanisms of immune dysfunction that impede viral clearance. HBV infection was initiated in mice by AAV-HBV transduction, and TGF-β was depleted to determine the role of this cytokine in HBV persistence. As TGF-β is often associated with negative regulation of the immune response, we hypothesized that its inhibition might improve HBV-specific T and B cell responses. However, the lack of TGF-β resulted in impaired HBV surface antigen (HBsAg) clearance and diminished anti-HBsAg antibody levels, revealing a positive role for TGF-β in the antibody response to HBV. This effect of TGF-β on the antibody response to HBsAg was unique to AAV-HBV transduction, as a similar increase in anti-HBsAg was not observed by TGF-β depletion following infection with recombinant vesicular stomatitis virus expressing HBsAg. We also observed differences in B cell activation marker expression during HBsAg clearance in mice transduced with AAV-HBV and depleted of TGF-β. Together, these findings highlight the impact of TGF-β on the B cell response to HBV and have begun to define a unique role for this cytokine in promoting HBV clearance. Supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under award number R01AI148354. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Safety and Efficacy of Combination SARS-CoV-2 Neutralizing Monoclonal Antibodies Amubarvimab Plus Romlusevimab in Nonhospitalized Patients With COVID-19.

Development of safe and effective SARS-CoV-2 therapeutics is a high priority. Amubarvimab and romlusevimab are noncompeting anti-SARS-CoV-2 monoclonal antibodies with an extended half-life. To assess the safety and efficacy of amubarvimab plus romlusevimab. Randomized, placebo-controlled, phase 2 and 3 platform trial. (ClinicalTrials.gov: NCT04518410). Nonhospitalized patients with COVID-19 in the United States, Brazil, South Africa, Mexico, Argentina, and the Philippines. Adults within 10 days onset of symptomatic SARS-CoV-2 infection who are at high risk for clinical progression. Combination of monoclonal antibodies amubarvimab plus romlusevimab or placebo. Nasopharyngeal and anterior nasal swabs for SARS-CoV-2, COVID-19 symptoms, safety, and progression to hospitalization or death. Eight-hundred and seven participants who initiated the study intervention were included in the phase 3 analysis. Median age was 49 years (quartiles, 39 to 58); 51% were female, 18% were Black, and 50% were Hispanic or Latino. Median time from symptom onset at study entry was 6 days (quartiles, 4 to 7). Hospitalizations and/or death occurred in 9 (2.3%) participants in the amubarvimab plus romlusevimab group compared with 44 (10.7%) in the placebo group, with an estimated 79% reduction in events (P<0.001). This reduction was similar between participants with 5 or less and more than 5 days of symptoms at study entry. Grade 3 or higher treatment-emergent adverse events through day 28 were seen less frequently among participants randomly assigned to amubarvimab plus romlusevimab (7.3%) than placebo (16.1%) (P<0.001), with no severe infusion reactions or drug-related serious adverse events. The study population was mostly unvaccinated against COVID-19 and enrolled before the spread of Omicron variants and subvariants. Amubarvimab plus romlusevimab was safe and significantly reduced the risk for hospitalization and/or death among nonhospitalized adults with mild to moderate SARS-CoV-2 infection at high risk for progression to severe disease. National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

GATA1 controls numbers of hematopoietic progenitors and their response to autoimmune neuroinflammation

Abstract GATA-binding factor 1 (GATA1) is a transcription factor that governs the development and function of multiple hematopoietic cell lineages. GATA1 is expressed in hematopoietic stem and progenitor cells (HSPCs) and is essential for erythroid lineage commitment; however, whether it plays a role in hematopoietic stem cell (HSC) biology and the development of myeloid cells, and what that role might be, remains unclear. We initially set out to test the role of eosinophils in experimental autoimmune encephalomyelitis (EAE), a model of central nervous system autoimmunity, using mice lacking a double GATA-site (ΔdblGATA), which lacks eosinophils due to the deletion of the dblGATA enhancer to Gata1, which alters its expression. ΔdblGATA mice were resistant to EAE, but not because of a lack of eosinophils, suggesting that these mice have an additional defect. ΔdblGATA mice with EAE had fewer inflammatory myeloid cells than the control mice, suggesting that resistance to EAE is caused by a defect in myeloid cells. Naïve ΔdblGATA mice also showed reduced frequency of CD11b +myeloid cells in the blood, indicating a defect in myeloid cell production. Examination of HSPCs revealed fewer HSCs and myeloid cell progenitors in the ΔdblGATA bone marrow (BM), and competitive BM chimera experiments showed a reduced capacity of the ΔdblGATA BM to reconstitute immune cells, suggesting that reduced numbers of ΔdblGATA HSPCs cause a functional deficit during inflammation. Taken together, our data show that GATA1 regulates the number of HSPCs and that reduced GATA1 expression due to dblGATA deletion results in a diminished immune response following the inflammatory challenge. This work was supported by a grant from the National Institute of Allergy and Infectious Diseases, National Institutes of Health (T32 training grant T32AI134646).

Restoring T cell function to promote resolution of chronic HBV infection

Abstract An estimated 296 million people worldwide suffer from chronic hepatitis B virus (HBV) infection, with 1.5 million new infections occurring each year despite the availability of an effective vaccine. Chronic HBV infection persists in a dysfunctional immune environment, manifested by an ineffective T cell response to the virus. Patient HBV-specific CD8 +T cells have diminished proliferative capacity and cytokine production, and they exhibit increased and sustained expression of inhibitory immune checkpoint receptors. In mice with persistent HBV replication, reduction of viral antigens can be achieved by therapeutic immunization with alphavirus- and vesiculovirus-based vaccine platforms expressing HBV antigens. However, blocking PD-1 and CTLA-4 signaling may further enhance antiviral effector T cell function and therapeutic efficacy. Using a mouse model of HBV replication in which mice are transduced with adeno-associated virus encoding the HBV genome (AAV-HBV), we investigated the role of these inhibitory receptors in the T cell response to HBV. Antibody-mediated blockade of either PD-1 or CTLA-4 independently in AAV-HBV mice did not promote viral clearance. Likewise, PD-1 and CTLA-4 inhibition combined with therapeutic immunization with VSV expressing an HBV antigen did not improve anti-HBV T cell responses or virus clearance in high-antigen mice with persistent viral replication. However, in mice with lower initial antigen loads, blockade of these receptors along with VSV therapeutic immunization resulted in an enhanced decrease of circulating HBV antigen. These results suggest new methodologies for improving HBV-specific immune responses to promote a functional cure of the infection. Supported by the National Institute of Allergy and Infectious Diseases and the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under award numbers R01AI148354 and R44DK113858. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Host-targeted self-attenuated influenza virus as an effective nasal spray vaccine in aged population

Abstract The elderly are at high risk for influenza infection and its complication. However, current inactivated influenza vaccines are often modestly immunogenic and show low protective immunity in the elderly, due to immunosenescence. New approaches are urgently needed for developing effective vaccines against influenza for the elderly. In current study, we have constructed new recombinant influenza viruses, named host-targeted self-attenuated influenza viruses (SAIVs), which can express functional mammalian species-specific artificial microRNAs (amiRNAs). The expression of these amiRNAs can inhibit expression of some host factors critical for influenza replication, and therefore the resultant recombinant influenza viruses are replication restricted and attenuated in the host cells. One of these SAIVs, which can express an amiRNA that inhibits expression of the host cellular Cdc2-like kinase 1 (CLK1), was produced in embryonic chicken eggs and evaluated in an aged mouse model of influenza infection. It elicited robust antibody and T cell responses against influenza virus and demonstrated significantly protective efficacy against lethal infection with wild type influenza virus H1N1 PR8 after single dose of intranasal vaccination. Our research finding provided a proof of concept that the new host targeted self-attenuated influenza virus can be further used as an effective vaccine against influenza in aged population. Supported by a research grant from National Institute of Allergy and Infectious Diseases (AI133207).

Age-associated variations in anti-spike antibody responses in mild SARS-CoV-2 disease.

Abstract Background: SARS-CoV-2 most severely affects older age groups, while children experience minimal disease. We measured elements of adaptive immunity in children and adults with SARS-CoV-2 to define the age-dependent viral and host response. Methods: Participants were enrolled in the Epidemiology, Immunology, and Clinical Characteristics of Emerging Infectious Diseases with Pandemic Potential (EPICC) study. Eligibility required that individuals present with COVID-19-like symptoms between March 2020 to March 2022. Magnitude of viral RNA was determined by quantitative PCR. SARS-CoV-2-specific antibodies were measured from blood with multiplex microsphere immunoassays. Results: Serologic responses against the spike protein were measured at early and convalescent time points and compared by age, predominant infecting SARS-CoV-2 variant, and vaccination status. In those with mild disease, the seropositivity rates did not differ based on age. The magnitude of the anti-spike IgG response differed by age at early time points. Only the oldest age group differed at convalescent time points. Conclusions: The serologic response to SAR-CoV-2 differs with age, implicating host immunity in pathogenesis. Improved understanding of the host immune response has the potential to optimize vaccine design. Disclaimer:The views expressed are those of the authors and do not reflect the official policy of the Department of the Army, Department of the Navy, the Department of the Air Force, the Department of Defense or the U.S. Government and the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF). The investigators have adhered to the policies for protection of human subjects as prescribed in 45 CFR 46. This work was supported by the Defense Health Program (grant number HU00012020067) and the National Institute of Allergy and Infectious Diseases (grant number HU00011920111).

Genome engineering of HMC-1.2 cells renders a human mast cell line with a single KIT mutation: an improved preclinical model for mastocytosis research

Abstract The HMC-1.2 human mast cell (huMC) line is often employed in the study of attributes of neoplastic huMCs as found in patients with mastocytosis and their sensitivity to interventional drugs in vitro and in vivo. HMC-1.2 cells express constitutively active KIT, an essential growth factor receptor for huMC survival and function, due to the presence of two oncogenic mutations (D816V and V560G). However, systemic mastocytosis is commonly associated with a single D816V-KIT mutation. The functional consequences of the coexisting KIT mutations in HMC-1.2 cells are unknown. We used CRISPR/Cas9 engineering to reverse the V560G mutation in HMC-1.2 cells, resulting in a subline (HMC-1.3) with a single monoallelic D816V-KIT variant. Transcriptome analyses predicted reduced activity in pathways involved in survival, cell-to-cell adhesion, and neoplasia in HMC-1.3 compared to HMC-1.2 cells. Consistently, subcutaneous inoculation of HMC-1.3 into mice produced significantly smaller tumors than HMC-1.2 cells, and in colony assays, HMC-1.3 formed less numerous and smaller colonies than HMC-1.2 cells. However, in liquid culture conditions, the growth of HMC-1.2 and HMC-1.3 cells was comparable. Phosphorylation levels of ERK1/2, AKT and STAT5 were also similar between HMC-1.2 and HMC-1.3 cells. However, HMC-1.3 cells were more susceptible to KIT, JAK2, and BCL2 inhibitors than HMC-1.2. Our study reveals that the additional V560G-KIT oncogenic variant modifies transcriptional programs induced by D816V-KIT, confers a survival advantage, alters sensitivity to interventional drugs, and increases neoplasia, suggesting that huMCs with a single D816V-KIT (HMC-1.3) variant may represent an improved preclinical model for mastocytosis. This work was supported by the Division of Intramural Research of the National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID).

Pre-existing T cell immune response specific to computationally optimized broadly reactive hemagglutinin antigens (COBRA-HA) in influenza vaccinees

Abstract The biggest challenge in developing a universal influenza vaccine is the extensive antigenic drift. In contrast to humoral immunity, cell-mediated immunity is more cross-reactive and can protect against various subtypes and drift variants. Our research group has described computationally optimized broadly reactive antigens (COBRA) to develop HA-based broadly protective influenza vaccine. However, studies that characterize the potential of COBRA-HA to elicit a functional T-cell response have yet to be developed. Cross-reactive response to conserved T cell epitopes from previous exposure can provide an efficient heterologous immunity. Thus, we aim to immune profile the pre-existing and cross-reactive COBRA-HA T cell response at the functionality and epitope conservation level to identify potential targets to be included in universal flu vaccine design. To achieve this goal, 50 donors who received the seasonal influenza vaccine (Fluzone, Sanofi) for two consecutive seasons were HLA typed, and the epitopes of COBRA-HA vaccine candidates Y2 (H1) and NG2 (H3) were predicted using IEDB software. Using the high dimensional flow cytometry, eight peptides for Y2 and 15 for NG2 were combined in pools to determine the phenotypes and cytokine secretion. We found that the vaccination induced a cross-reactive COBRA HA-specific CD4+ and CD8+ T cell response independent of antibody titers. Next, we will evaluate the Th helper subsets (Th1/Th2/Th17/cTfh) and the breadth of immune response by deconvoluting the pools in IFNγ Fluospot assay. Nonetheless, the next generation of the universal influenza vaccine recalled a functional CD4+ pre-existing response, demonstrating the potential efficacy of COBRA-HA in clinical trials. National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Department of Health and Human Services contract 75N93019C00052 (TMR).

TNF receptors orchestrate differential neutrophil responses critical to immunity against Staphylococcus aureusskin infection

Abstract As the leading cause of skin and soft tissue infections, Staphylococcus aureus is a major health burden and a continued threat to human health due to the emergence of antibiotic-resistance. Through this current study, we aimed to better characterize the protective immune mechanisms against S. aureus skin infection to identify novel targets for the development of host-directed immunotherapeutics as alternatives to antibiotics. Tumor necrosis factor (TNF) is a master regulatory cytokine whose inhibition is associated with the increased risk of S. aureus skin colonization and infection in humans. Despite the clinical implications, the contribution of TNF and its cognate receptors, TNFR1 and TNFR2, to immunity against S. aureus skin infection is unclear. Utilizing an in vivo mouse model of S. aureus intradermal infection, we determined that immune cell-derived TNF engages with both TNFR1 and TNFR2 to promote protection against S. aureus in the skin. Neutrophil-intrinsic TNFR1 and TNFR2 signaling directed differential antimicrobial mechanisms against S. aureus skin infections. Mechanistically, TNFR1 mediated neutrophil recruitment to the skin, whereas TNFR2 directed neutrophil activation (e.g.-NOX2 activation, ROS production, and PAD4-dependent neutrophil extracellular trap (NET) formation) and prevented systemic dissemination of skin infection. Collectively, our findings revealed non-redundant functions and cellular mechanisms mediated by TNFR1 and TNFR2 in neutrophils for immunity against S. aureus. This study was funded in part by grants R01AR073665 (NKA), R01AR069502 (NKA), R01AI111205 (NKA), and R01AI146177 (NKA) and from the United States National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and National Institute of Allergy and Infectious Diseases (NIAID).

Defining the Role of HDAC3 Deacetylation and Decrotonylation in T Cells

Abstract Histone acetyltransferases (HATs) and histone deacetylases (HDACs) facilitate addition or removal of various acyl groups from lysine residues, including acetylation (K Ac) and crotonylation (K Cr). Recently, mutations in p300 and CBP were identified that abrogate their function as an acetyltransferase but not the ability to mediate crotonylation. These mutants can activate transcription independent of their ability to acetylate histones, demonstrating that crotonylation can also lead to transcriptional activation. The Class I deacetylases HDAC1, HDAC2, and HDAC3 have been shown to have both decrotonylase and deacetylase activity, but the relative importance of each function in T cells is not known. Genetic knockout of HDAC3 using CD2 icre mice results in a severe block in T cell development and spontaneous development of severe colitis. Examination of HDAC3 cKO mice has shown an aberrant ratio of Treg:Th 17cells within the gut, driving inflammation and loss of mucosal barrier integrity. Our lab has also determined that HDAC3 is required for at least three aspects of T cell development: CD4 +CD8 +(DP) cell survival, positive selection, and CD4 +lineage development. Recently, a mutation was identified in either HDAC1 or HDAC3 that eradicated deacetylase activity but retained decrotonylase activity (“VRPP”). Through this mutation we were able to generate a novel mouse model with Cre-mediated deletion of endogenous HDAC3 and linked re-expression of HDAC3 VRPP. Strikingly, this mouse does not develop colitis, although T cell development is still impaired. Thus, HDAC3 decrotonylase activity alone is sufficient to impede the IBD phenotype. Support by grants from National Institute of Allergy and Infectious Diseases (R01 AI150100)

CD4+ T cells show a cytolytic phenotype functions in human visceral leishmaniasis

Abstract Control of Visceral leishmaniasis (VL), a parasitic disease caused by L. donovani, requires robust CD4 +T cells response to control the parasite replication by IFN-γ production and activation of macrophages. Our recent study on transcriptional signature of CD4 +T cell isolated from peripheral blood of active VL patients showed enhanced expression of genes related to cytotoxicity. In present study, we investigated expression of these cytotoxic molecules including granzyme B (GZMB), Granulysin, Perforin and NKG7 on different CD4 +T cell subsets to establish the role of GZMB in regulating CD4 +T cells functional capacity. PBMCs cells were isolated from active and post treated VL patients and endemic controls, and flow cytometry was performed. LAMP assay (CD107b expression) was performed to study the degranulation capacity of CD4 +T cells. Whole blood assay followed by ELISA was performed to measure antigen specific cytokine / GZMB production by CD4 +T cells. We found that activated and degranulating CD4 +T cells (CD38 +CD107 +) had higher expression of GZMB, Granulysin, perforin and NKG-7. Similarly, GZMB level in plasma and antigen stimulated whole blood culture supernatant were significantly elevated in active VL patient compared to post treatment and EC. There was no change is IFN-γ secretion when whole blood culture was stimulated with soluble leishmania antigen in presence of Con-A but a significant decline in IL-6 production was observed. In summary, VL CD4 +T cells show a cytolytic phenotype and further investigations are required to understand their differentiation and function, particularly for promoting anti-parasitic immunity for host protection and effective intervention or therapy. Extramural Program of the National Institute of Allergy and Infectious Diseases, National Institutes of Health (TMRC grant number U19AI074321)

Cell-specific P2RX7 promotes the longevity of lung tissue-resident helper CD4 T cells in response to influenza infection

Abstract Development of universal influenza (flu) vaccines requires better knowledge of lung-resident immune responses. That includes flu-specific CD4 T cells, which establish long-term lung residency and induce a diversified local protective response to subsequent infection. Tissue-resident helper (Trh) cells are a subset of lung-resident CD4 T cells that share phenotypic and functional features with follicular helper cells (Tfh). Trh cells serve to amplify lung-resident immune responses, and express high levels of the extracellular ATP (eATP) sensor P2RX7. Considering that eATP levels in the lung increase in response to flu infection, we used T cell-specific P2RX7-knockout (KO) mice to test the role of P2RX7 for CD4 T cell responses to flu. During acute phase of infection, we found that P2RX7 promotes the accumulation of flu-specific CD4 T cells inside the lung tissue. Moreover, P2RX7 promoted this establishment via induction of CXCR3 upregulation. Despite no specific defects in the Trh pool at the acute phase, T cell-specific P2RX7-KO led to a progressive decay of Trh cells. Consequently, lungs of T cell-P2RX7-KO mice had reduced lung B cell responses. Our single-cell RNAseq of lung flu-specific CD4 T cells showed reduced expression of cell survival and mitochondrial genes in P2RX7-KO Trh cells. Our findings suggest that lung eATP sensing by CD4 T cells induces lung-resident CD4 T cell accumulation in response to flu, impacting the survival of specific lung CD4 T cell subsets. National Institute of Allergy and Infectious Diseases (NIAID) (H.BdS.: R00 AI139381, R01 AI170649).

Cost-effectiveness of point-of-care versus centralised, laboratory-based nucleic acid testing for diagnosis of HIV in infants: a systematic review of modelling studies

Point-of-care (POC) nucleic acid testing for diagnosis of HIV in infants facilitates earlier initiation of antiretroviral therapy (ART) than with centralised (standard-of-care, SOC) testing, but can be more expensive. We evaluated cost-effectiveness data from mathematical models comparing POC with SOC to provide global policy guidance. In this systematic review of modelling studies, we searched PubMed, MEDLINE, Embase, the National Health Service Economic Evaluation Database, Econlit, and conference abstracts, combining terms for "HIV" + "infant"/"early infant diagnosis" + "point-of-care" + "cost-effectiveness" + "mathematical models", without restrictions from database inception to July 15, 2022. We selected reports of mathematical cost-effectiveness models comparing POC with SOC for HIV diagnosis in infants younger than 18 months. Titles and abstracts were independently reviewed, with full-text review for qualifying articles. We extracted data on health and economic outcomes and incremental cost-effectiveness ratios (ICERs) for narrative synthesis. The primary outcomes of interest were ICERs (comparing POC with SOC) for ART initiation and survival of children living with HIV. Our search identified 75 records through database search. 13 duplicates were excluded, leaving 62 non-duplicate articles. 57 records were excluded and five were reviewed in full text. One article was excluded as it was not a modelling study, and four qualifying studies were included in the review. These four reports were from two mathematical models from two independent modelling groups. Two reports used the Johns Hopkins model to compare POC with SOC for repeat early infant diagnosis testing in the first 6 months in sub-Saharan Africa (first report, simulation of 25 000 children) and Zambia (second report, simulation of 7500 children). In the base scenario, POC versus SOC increased probability of ART initiation within 60 days of testing from 19% to 82% (ICER per additional ART initiation range US$430-1097; 9-month cost horizon) in the first report; and from 28% to 81% in the second ($23-1609, 5-year cost horizon). Two reports compared POC with SOC for testing at 6 weeks in Zimbabwe using the Cost-Effectiveness of Preventing AIDS Complications-Paediatric model (simulation of 30 million children; lifetime horizon). POC increased life expectancy and was considered cost-effective compared with SOC (ICER $711-850 per year of life saved in HIV-exposed children). Results were robust throughout sensitivity and scenario analyses. In most scenarios, platform cost-sharing (co-use with other programmes) resulted in POC being cost-saving compared with SOC. Four reports from two different models suggest that POC is a cost-effective and potentially cost-saving strategy for upscaling of early infant testing compared with SOC. Bill & Melinda Gates Foundation, Unitaid, National Institute of Allergy and Infectious Diseases, National Institute of Child Health and Human Development, WHO, and Massachusetts General Hospital Research Scholars.

New syndromic combined immunodeficiency with severe neurodevelopmental defects caused by biallelic null variants in the PPM1D gene

PPM1D (protein phosphatase Mn2+/Mg2+-dependent 1D) is a phosphatase that targets proteins related to the DNA damage repair system. C-terminal variants in PPM1D have been associated with: i) malignancy as somatic variants; and ii) Jansen-de-Vries (JdV) syndrome as germline heterozygous variants. JdV syndrome curses with moderate neurodevelopmental alterations and behavioral problems, such as autistic spectrum disorders (ASD), without reports of immunodeficiency.We describe two siblings (9 and 11 years old) born to consanguineous parents with progressive B and NK cell lymphopenia, agammaglobulinemia, non-ulcerative colitis and severe neurodevelopmental defects including microcephaly, severe encephalopathy, profound cognitive deficiency, and refractory epilepsy. Exome analysis revealed a homozygous N-terminal truncating variant in PPM1D (p.Thr174fs*6) in the two siblings inherited from their healthy heterozygous parents. The siblings’ clinical phenotype was markedly more severe than in the reported JdV patients, suggesting a different mechanism of action. To test this, we included a pediatric patient with classical JdV syndrome carrying an heterozygous PPM1D variant (p. Ser403fs*30). Using primary cells and exogenous overexpression we showed that mutation p.T174fs*6 abrogated protein expression by increased proteasome degradation, leading to no protein expression in a homozygous patient and a reduction in a haplosufficient parent. In contrast, the JdV variant (p.Ser403fs*30) led to accumulation of the truncated protein with conserved phosphatase activity, resulting in a previously undescribed gain-of-function (GOF) mechanism.We also demonstrated that chemical inhibition of WT-PPM1D in-vitro dramatically decreased B cell viability. This data, similar to the reported B cell deficiency in PPM1D-KO mice, helps to address the humoral deficiency in the patients, while not observed in the heterozygous parents nor JdV patient. To further explore NK cell deficiency, we will evaluate PPM1D-KO mice. We have generated EBV-B cell-derived iPSCs from PPM1D-null, PPM1D-haplosufficient an GOF-JdV individuals, to generate artificial cerebral organoids that will allow us to explore PPM1D gene-dosage effect in neurodevelopment and its potential manipulation.Here we report a novel biallelic PPM1D-null deficiency impairing B cell development. Besides, PPM1D dysregulation either by no protein expression or GOF appears to cause neurodevelopment abnormalities. Future studies will help to understand pathophysiology of PPM1D and better targeted clinical management.PPM1D research interest group:JF Quesada1, Mercè Bolasell2, Julie E. Niemela3, Jennifer L. Stoddard3, Agustin Gil Silva3, Brigette Boast3, José R Regueiro4, Pierre Martine5, David Lopez Perez5, Ettore Appella5, Laia Alsina6,7,8, Harry L Malech9, Hye Sun Kuehn3, Sergio D. Rosenzweig31. Department of Genetics, Hospital Universitario 12 de Octubre, Madrid, Spain.2. Department of Genetic and Molecular Medicine IPER, Institut de Recerca, Hospital Sant Joan de Déu Barcelona, Barcelona, Spain.3. Immunology Service, Department of Laboratory Medicine, Clinical Center, NIH, Bethesda, Maryland, USA4. Department of Immunology, Complutense University School of Medicine and Hospital 12 de Octubre Health Research Insitute, Madrid, Spain5. Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892.6. Clinical Immunology and Primary Immunodeficiencies Unit. Allergy and Clinical Immunology Department. Hospital Sant Joan de Déu. Barcelona, Spain.7. Clinical Immunology Unit. Hospital Sant Joan de Déu-Hospital Clinic. Barcelona, Spain.8. Study Group for Immune Dysfunction Diseases in Children (GEMDIP). Institut de Recerca Sant Joan de Déu. Barcelona, Spain.9. Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD.

Fishing for novel dengue broadly neutralizing antibodies

Abstract Due to a patent filing, the content of this abstract is not available to be shared at this time. The abstract will be shared at the poster session. This work was supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health.

US National Institutes of Health Prioritization of SARS-CoV-2 Variants.

Since late 2020, SARS-CoV-2 variants have regularly emerged with competitive and phenotypic differences from previously circulating strains, sometimes with the potential to escape from immunity produced by prior exposure and infection. The Early Detection group is one of the constituent groups of the US National Institutes of Health National Institute of Allergy and Infectious Diseases SARS-CoV-2 Assessment of Viral Evolution program. The group uses bioinformatic methods to monitor the emergence, spread, and potential phenotypic properties of emerging and circulating strains to identify the most relevant variants for experimental groups within the program to phenotypically characterize. Since April 2021, the group has prioritized variants monthly. Prioritization successes include rapidly identifying most major variants of SARS-CoV-2 and providing experimental groups within the National Institutes of Health program easy access to regularly updated information on the recent evolution and epidemiology of SARS-CoV-2 that can be used to guide phenotypic investigations.

The majority of circulating human B cells belong to a naïve anergic B cell subset distinguished by expression of CD73

Abstract In humans, it is estimated that ~40% of peripheral blood (PB) naïve (CD19 +CD27 −CD45RB MEM−CD38 −) B cells are in a state of anergy defined as IgD +IgM low. Presumably these anergic B cells express only weakly autoreactive B cell receptors (BCR) that allowed them to escape elimination by central tolerance mechanisms in the bone marrow, but were sufficient to induce anergy in the periphery. Although the ultimate fate of these B cells is not known, it is hypothesized that anergic B cells undergo a process of redemption in which they are activated and somatically hypermutate away from self, allowing them to be recruited into foreign antigen-specific responses. To better characterize human anergic B cells, we utilized a panel of 18 antibodies specific for B cell surface markers and BCR isotypes, which allowed identification of the known human B cell subsets by flow cytometry. We determined that ~50% of B cells were contained in the naïve compartment, of which ~60% were anergic (IgD +IgM low) cells distinguished by the expression of CD73. In contrast, CD11c +CD27 −B cells (termed ABCs) and CD45RB +CD27 −MBCs comprised only 0.6% and 7.0% of circulating anergic B cells, respectively. Using 9G4 to identify inherently autoreactive B cells expressing germline VH4–34, we found that the majority of 9G4 +cells were naïve anergic B cells that express CD73. Thus, in humans the CD73 +naïve compartment appears to be the major reservoir of anergic B cells, possibly for redemption and participation in immune responses to pathogens. Studies are underway to define the responses of these B cells in health and disease. This work was supported by the Intramural Research Program of the US National Institutes of Health, National Institute of Allergy and Infectious Diseases, and National Institute of Arthritis and Musculoskeletal and Skin Diseases.

Evaluation of cutaneous immune response in a controlled human in vivo model of mosquito bites

Abstract Mosquito-borne viruses are a growing global threat. Initial viral inoculation occurs in the skin via the mosquito ‘bite’, eliciting immune responses that shape the establishment of infection and pathogenesis. Here we assess the cutaneous innate and adaptive immune responses to controlled Aedes aegypti feedings in humans living in Aedes-endemic areas. In this single-arm, cross- sectional interventional study (trial registration #NCT04350905), we enroll 30 healthy adult participants aged 18 to 45 years of age from Cambodia between October 2020 and January 2021. We perform 3-mm skin biopsies at baseline as well as 30 min, 4 h, and 48 h after a controlled feeding by uninfected Aedes aegypti mosquitos. The primary endpoints are measurement of changes in early and late innate responses in bitten vs unbitten skin by gene expression profiling, immunophenotyping, and cytokine profiling. The results reveal induction of neutrophil degranulation and recruitment of skin-resident den- dritic cells and M2 macrophages. As the immune reaction progresses T cell priming and regulatory pathways are upregulated along with a shift to Th2-driven responses and CD8+ T cell activation. Stimulation of participants’ bitten skin cells with Aedes aegypti salivary gland extract results in reduced pro-inflammatory cytokine production. These results identify key immune genes, cell types, and pathways in the human response to mosquito bites and can be leveraged to inform and develop novel therapeutics and vector- targeted vaccine candidates to interfere with vector-mediated disease. Division of Intramural Research at National Institute of Allergy and Infectious Diseases at the National Institutes of Health #1ZIAAI001066-12: J.M., F.O.; Howard Hughes Medical Institute-Wellcome #208710/Z/17/Z: T.C.; French National Research Agency #ANR-17-CE15-00029: D.M.; Calmette-Yersin PhD Scholarship: D.G.

Spleen tyrosine kinase inhibition restores neutrophil homeostasis in COVID-19

Abstract Spleen tyrosine kinase (SYK) is a novel therapeutic target that inhibits neutrophil and macrophage activation in coronavirus disease 2019 (COVID-19). Fostamatinib, a SYK inhibitor, was studied in a phase 2 placebo-controlled randomized clinical trial and was associated with improvements in many secondary end points related to efficacy. Here, we used a multiomic approach to evaluate cellular and soluble immune mediator responses of patients enrolled in this trial. We demonstrated that SYK inhibition was associated with reduced neutrophil activation, increased circulation of mature neutrophils (CD10+CD33−), and decreased circulation of low-density granulocytes (LDG) and polymorphonuclear myeloid-derived suppressor cells (HLA-DR–CD33+CD11b−). Additionally, LDG transcriptional profiles were distinct in COVID-19 compared to during autoimmune conditions. Together, these data suggest that SYK inhibition may mitigate proinflammatory neutrophil cellular and soluble mediator responses thought to contribute to immunopathogenesis of severe COVID-19. This work has been funded in part by the Intramural Research Program of the NIH Clinical Center (NIHCC) including a Research Award for Staff Clinicians (FY2020/FY2021), NHLBI, National Institute of Allergy and Infectious Diseases (NIAID), and National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAIMS)

Indirect IgG ELISA and serotype-specific neutralizing antibody titers are associated with protection against dengue in children in Cebu, Philippines

Abstract Standard measures of dengue virus (DENV) antibodies have not been established as protective against dengue. We assess whether an indirect dengue IgG ELISA (PanBio; Brisbane, QLD, Australia) and serotype-specific neutralizing antibody titers measured by a two-dilution focus reduction neutralization test (FRNT) are associated with protection against dengue. Healthy children (n = 1,214) aged 9–14 years in Cebu, Philippines were enrolled in a prospective population-based cohort study in May – June 2017 and were tested for dengue when they reported a febrile illness through March 2020. Serum samples were collected at enrollment, and all were tested by ELISA. FRNTs were performed using the WHO DENV1–4 reference strains on a random subset to quantify serotype-specific neutralizing antibodies (nAbs). Inverse probability weighting was used to adjust for subset size. The odds of dengue as predicted by antibody measures were assessed by logistic regressions and adjusted for age, gender, and residential site. Dengue naïve children were used as the reference group in all models. The probability of dengue was 9.2% (95% CI: 4.5 – 17.9) for the naïve group, 9.5% (4.8 – 17.8) for those with ELISA &amp;lt; 2, but 4.5% (2.8 – 7.2) for those with ELISA &amp;gt;= 2 (p=0.04). The probability was even lower at 1.4% (0.6 – 3.1) for those with the highest DENV1–4 geometric mean titers (GMT, p = 0.0001). Pre-vaccine nAbs to DENV2 and DENV3 were protective against a homotypic dengue case (DENV2: OR 0.28, 95% CI 0.12 to 0.65; DENV3: OR 0.27, 95% CI 0.13 to 0.57), but not heterotypic dengue. We show a commercial ELISA and serotype-specific nAbs are associated with the probability of dengue, providing useful assays for use in population and vaccine trials. This work was supported by the Philippine Department of Health, the Intramural Research Program of the National Institute of Allergy and Infectious Diseases (NIAID), and NIH Extramural Grant: P01AI106695.