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Background VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a genetic disorder characterized by bone marrow failure and systemic inflammation, putting patients at risk for infections. This study comprehensively examines the prevalence of opportunistic infections in patients with VEXAS, evaluating their impact on clinical outcomes and potential preventive measures. Methods Patients with confirmed VEXAS were included. Survival analysis and logistic regression were used to identify associations between opportunistic infections and mortality. Infection rates (IRs) for Pneumocystis jirovecii pneumonia (PJP) and alphaherpesviruses were calculated over a prospective 8-month observation period in relationship to prophylaxis. Results Of 94 patients with VEXAS, 6% developed PJP; 15% had alphaherpesvirus reactivation, with varicella zoster virus (VZV) being the most common herpesvirus; and 10% contracted a nontuberculous mycobacterial (NTM) infection. Risk of death was significantly increased per month following a diagnosis of PJP (hazard ratio [HR], 72.41 [95% confidence interval {CI}, 13.67–533.70]) or NTM (HR, 29.09 [95% CI, 9.51–88.79]). Increased odds for death were also observed in patients with a history of herpes simplex virus (HSV) reactivation (odds ratio [OR], 12.10 [95% CI, 1.29–114.80]) but not in patients with VZV (OR, 0.89 [95% CI,.30–2.59]). Prophylaxis for PJP (IR, 0.001 vs 0 per person-day, P <.01) and VZV (IR, 0.006 vs 0 per person-day, P =.04) markedly decreased infection rates with a number needed to treat of 4 and 7, respectively. Conclusions Opportunistic infections are common in patients with VEXAS. Patients who develop PJP, HSV, or NTM are at increased risk for death. Prophylaxis against PJP and VZV is highly effective. [ABSTRACT FROM AUTHOR]

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic vasculitis syndrome caused by autosomal‐recessive loss‐of‐function mutations in the ADA2 gene (previously known as CECR1). Vasculitis, vasculopathy, and inflammation are dominant clinical features of this disease; the spectrum of manifestations includes immunodeficiency and lymphoproliferation as well as hematologic manifestations. ADA2 is primarily secreted by stimulated monocytes and macrophages. Aberrant monocyte differentiation to macrophages and neutrophils are important in the pathogenesis of DADA2, but little is known about T lymphocytes in this disease. We performed combined single‐cell RNA sequencing and single‐cell TCR sequencing in order to profile T cell repertoires in 10 patients with DADA2. Although there were no significant alterations of T cell subsets, we observed activation of both CD8+ and CD4+ T cells. There was no clonal expansion of T cells: most TCRs were expressed at basal levels in patients and healthy donors. TCR usage was private to individual patients and not disease specific, indicating as unlikely a common pathogenic background or predisposition to a common pathogen. We recognized activation of IFN pathways as a signature of T cells and STAT1 as a hub gene in the gene network of T cell activation and cytotoxicity. Overall, T cells in DADA2 patients showed distinct cell–cell interactions with monocytes, as compared with healthy donors, and many of these ligand–receptor interactions likely drove up‐regulation of STAT1 in both T cells and other immune cells in patients. Our analysis reveals previously undercharacterized cell characteristics in DADA2. [ABSTRACT FROM AUTHOR]

Deficiency of adenosine deaminase 2 (DADA2) is a rare autosomal recessive disease caused by loss‐of‐function variants in the ADA2 gene. DADA2 typically presents in childhood and is characterized by vasculopathy, stroke, inflammation, immunodeficiency, as well as hematologic manifestations. ADA2 protein is predominantly present in stimulated monocytes, dendritic cells, and macrophages. To elucidate molecular mechanisms in DADA2, CD14+ monocytes from 14 patients and 6 healthy donors were analyzed using single‐cell RNA sequencing (scRNA‐seq). Monocytes were purified by positive selection based on CD14 expression. Subpopulations were imputed from their transcriptomes. Based on scRNA‐seq, monocytes could be classified as classical, intermediate, and nonclassical. Further, we used gene pathway analytics to interpret patterns of up‐ and down‐regulated gene transcription. In DADA2, the frequency of nonclassical monocytes was higher compared with that of healthy donors, and M1 macrophage markers were up‐regulated in patients. By comparing gene expression of each monocyte subtype between patients and healthy donors, we identified upregulated immune response pathways, including IFNα/β and IFNγ signaling, in all monocyte subtypes. Distinctively, the TNFR2 noncanonical NF‐κB pathway was up‐regulated only in nonclassical monocytes. Patients' plasma showed increased IFNγ and TNFα levels. Our results suggest that elevated IFNγ activates cell signaling, leading to differentiation into M1 macrophages from monocytes and release of TNFα. Immune responses and more general response to stimuli pathways were up‐regulated in DADA2 monocytes, and protein synthesis pathways were down‐regulated, perhaps as stress responses. Our identification of novel aberrant immune pathways has implications for therapeutic approaches in DADA2 (registered at clinicaltrials.gov NCT00071045). [ABSTRACT FROM AUTHOR]

The role of mammalian target of rapamycin and its suppressor sirolimus in the regulation of hematopoietic stem and progenitor cells (HSPCs) is controversial. We show here that sirolimus enhanced regeneration of HSPCs in mice exposed to sublethal total body irradiation (TBI) and other regenerative stressors. Sorted Lin−CD150+ bone marrow cells from sirolimus‐treated TBI mice had increased expression of c‐Kit and other hematopoietic genes. HSPCs from sirolimus‐treated TBI mice were functionally competent when tested by competitive engraftment in vivo. Postradiation regeneration of HSPCs in mice treated with sirolimus was accompanied by decreased γ‐H2AX levels detected by flow cytometry and increased expression of DNA repair genes by quantitative polymerase chain reaction. Reduction of cell death and DNA damage post‐radiation by sirolimus was associated with enhanced clearance of cellular reactive oxygen species (ROS) in HSPCs. Increased HSPC recovery with sirolimus was also observed in mice injected with hematoxic agents, busulfan and 5‐fluorouracil. In contrast, sirolimus showed no effect on HSPCs in normal mice at steady state, but stimulated HSPC expansion in mice carrying the Wv mutation at the c‐Kit locus. In human to mouse xenotransplantation, sirolimus enhanced engraftment of irradiated human CD34+ cells. In summary, our results are consistent with sirolimus' acceleration of HSPC recovery in response to hematopoietic stress, associated with reduced DNA damage and ROS. Sirolimus might have clinical application for the treatment and prevention of hematopoietic injury. [ABSTRACT FROM AUTHOR]

Objectives: To determine fluorescently labeled aerolysin (FLAER) binding and glycophosphatidylinositol-anchored protein expression in bone marrow (BM) cells of healthy volunteers and patients with paroxysmal nocturnal hemoglobinuria (PNH) detected in peripheral blood (PB); compare PNH clone size in BM and PB; and detect PNH in BM by commonly used antibodies.Methods: Flow cytometry analysis of FLAER binding to leukocytes and expression of CD55/CD59 in erythrocytes. Analysis of CD16 in neutrophils and CD14 in monocytes in BM.Results: FLAER binds to all normal BM leukocytes, and binding increases with cell maturation. In PNH, lymphocytic clones are consistently smaller than clones of other BM cells. PNH clones are detectable in mature BM leukocytes with high specificity and sensitivity using common antibodies.Conclusions: PNH clone sizes measured in mature BM leukocytes and in PB are comparable, making BM suitable for PNH assessment. We further demonstrate that commonly used reagents (not FLAER or CD55/CD59) can reliably identify abnormalities of BM neutrophils and monocytes consistent with PNH cells. [ABSTRACT FROM AUTHOR]

Viruses with single-stranded (ss) DNA genomes infect hosts in all three domains of life and include many medically, ecologically, and economically important pathogens. Recently, a new group of ssDNA viruses with chimeric genomes ha sbeen discovered through viral metagenomics. These chimeric viruses combine capsid protein genes and replicative protein genes that, respectively, appear to have been inherited from viruses with positive-strand RNA genomes, such as tombusviruses, and ssDNA genomes, such as circoviruses, nanoviruses or geminiviruses. Here, we describe the genome sequence of a new representative of this virus group and reveal an additional layer of chimerism among ssDNA viruses. We show that not only do these viruses encompass genes for capsid proteins and replicative proteins that have distinct evolutionary histories, but also the replicative genes themselves are chimeras of functional domains inheritedfrom viruses of different families. Our results underscore the importance of horizontal gene transfer in the evolution of ssDNA viruses and the role of genetic recombination in the emergence of novel virus groups. [ABSTRACT FROM AUTHOR]

Survival in aplastic anemia has markedly improved in recent decades. In multivariate analysis, the introduction of newer antifungal agents and a decrease in fungal infections were independent predictors for survival in the months following immunosuppression among patients with persistent neutropenia.Background. Persistent neutropenia associated with severe aplastic anemia (SAA) is an important risk factor for development of life-threatening infections. Earlier studies underscored the high mortality associated with invasive fungal infections (IFIs) in SAA. However, little is known about the current patterns of infections and the impact of advances in anti-infective therapy on survival in SAA.Methods. We reviewed the records of 174 patients with SAA admitted to the Hematology Branch at NHLBI from 1989 to 2008 who were unresponsive to initial immunosuppressive therapy (IST) at 6 months. Three patient groups determined by IST protocol and time interval were compared: group 1 (43 patients; December 1989–October 1996), group 2 (51 patients; November 1996–October 2002), and group 3 (80 patients; November 2002–April 2008). Outcome variables included infections, patterns of resistance, survival, and infection-related mortality.Results. During the past 2 decades, infection-related mortality decreased from 37% in group 1 to 11% in group 3 (P<.001), and the frequency of IFIs decreased from 49% in group 1 to 8% in group 3 (P<.001). Overall 5-year survival for all patients (n = 420) increased from 64% in group 1 to 79% in group 3 (P<.001). Among non-responders (n = 174), it increased from 23% in group 1 to 57% in group 3 (P<.001). In multivariate analysis, younger age, absolute neutrophil count >200 cells/μL before IST, absence of IFIs, and use of voriconazole were independently predictive of survival.Conclusion. During the past 2 decades, there has been a significant decrease in IFIs, infection-related mortality, and overall mortality in patients with SAA unresponsive to initial IST. [ABSTRACT FROM AUTHOR]

We applied a single-cell method to detect mitochondrial DNA (mtDNA) mutations to evaluate the reconstitution of hematopoietic stem cells (HSCs) and committed progenitor cells after nonmyeloablative allogeneic stem cell transplantation in humans. In a total of 1,958 single CD34+ cells from six human leukocyte antigen-matched sibling donor and recipient pairs, individual CD34+ clones were recognized based on the observed donor- or recipient-specific mtDNA sequence somatic alteration. There was no overall reduction of mtDNA heterogeneity among CD34+ cells from the recipient after transplantation. Samples collected from two donors over time showed the persistence of certain CD34+ clones marked by specific mutations. Our results demonstrate the feasibility of distinguishing donor and recipient individual CD34+ clones based on mtDNA mutations during engraftment. HSCs were not limited in number, and similar mtDNA heterogeneity levels suggested representation of the total stem cell compartment during rapid hematopoietic reconstitution in the recipient. [ABSTRACT FROM AUTHOR]

For the production of dengue-vaccine candidates, empty capsids, or virus-like particles (VLPs), of parvovirus B19 that carry dengue 2-specific epitopes were employed as antigen carriers. Two epitopes (comprising amino acids 352-368 and 386-397) of domain BIII of the envelope glycoprotein were chosen to produce recombinant B19 VLPs for immunization of BALB/c mice. Serum samples from immunized mice revealed that recombinant B19 VLPs elicited strong humoral immune responses. In summary, this B19 VLP-vaccine platform produced high (⩾2.0 × 105) anti-dengue 2 titers and robust (⩽1:120) 50%-plaque-reduction neutralization test (PRNT50) titers, which effectively neutralized live dengue 2 virus in PRNT50 assays. [ABSTRACT FROM AUTHOR]

Discusses the findings of an investigation regarding SEN virus infection in patients with cryptogenic acute liver failure, hepatitis-associated aplastic anemia, or acute and chronic non-A-E hepatitis. Use of polymerase chain reaction amplification to detect SENV variants; Prevalence of SENV among case and control subjects when controlling for geographic region; Influence of infection on disease severity.

Studies the prevalence of parvovirus B19 in liver-tissue samples from patients with fulminant hepatitis (FH) and hepatitis-associated aplastic anemia (HAA) and from control subjects. Increase in the prevalence of variant erythrovirus sequences in livers of patients with hepatitis B or C infections; Role of parvovirus B19 as possible etiological agent of FH or HAA.

A recombinant human parvovirus B19 vaccine (MEDI-491; MedImmune) composed of the VP1 and VP2 capsid proteins and formulated with MF59C.1 adjuvant was evaluated in a randomized, double-blind, phase 1 trial. Parvovirus B19-seronegative adults (n=24) received either 2.5 or 25 μg MEDI-491 at 0, 1, and 6 months. MEDI-491 was safe and immunogenic. All volunteers developed neutralizing antibody titers that peaked after the third immunization and were sustained through study day 364. [ABSTRACT FROM AUTHOR]

Develops a sensitive quantitative assay for parvovirus neutralizing capacities of immune sera obtained from individuals infected with B19 using a novel reverse transcriptase-polymerase chain reaction- (RT-PCR) based system. Reliability of the RT-PCR neutralization test; Relationship between adjuvant and anti-virus-like particle response; Common features of sera with high neutralizing capacity.

GB virus C or hepatitis G virus (GBV-C/HGV), a novel Flavivirus, is detected in 1.5% of US blood donors. The prevalence is higher in multiply transfused patients and in persons with liver disease. Because of the increased incidence of hepatitis in Asia, sera from healthy Vietnamese were tested for the presence of GBV-CIHGV RNA by the reverse transcription polymerase chain reaction. Viral RNA was detected in 5.7% of those tested; 6 of 81 volunteer blood donors had positive samples as did 5 of 97 army recruits and 2 of 50 postpartum women. When the 188-bp product from 6 subjects was sequenced, there was 75%–85% homology at the nucleotide level compared with published sequences, indicating a high degree of genotypic variation, even within a putatively well-conserved region of the viral genome. Viremia with this non-cell-associated novel virus appears to be common among normal persons in Vietnam. [ABSTRACT FROM PUBLISHER]

Recombinant baculoviruses were used to produce human B19 parvovirus empty capsids composed of only VP2 and VP2 capsids containing 4%,25%,35%, or 41% VP1 protein. Immunogenicity of the purified capsids, formulated with or without adjuvant, was evaluated in mice, guinea pigs, and rabbits. Sera were analyzed for total anti-B19 parvovirus antibodies, antibodies specific to the region unique to the VP1 capsid protein, and virus neutralizing antibodies. A relationship was observed between the development of antibodies specific to sequences unique to the VPl protein and virus neutralization. The polypeptide composition of the empty capsid immunogens appeared to be important for elicitation ofpotent virus neutralizing activity. VP2 capsid immunogens devoid of VP1 protein, or consisting of only 4% VP1, the composition of naturally occurring virions, were generally poor at eliciting high levels of virus neutralizing activity. Capsids consisting of ⩾25% VP1 protein efficiently and consistently provoked vigorous B19 virus neutralizing responses. Recombinant empty capsids enriched for the VPl protein should serve as the basis for a human B19 parvovirus vaccine. [ABSTRACT FROM PUBLISHER]

In 1984, simultaneous outbreaks of aplastic crisis and erythema infectiosum occurred in northeastern Ohio. Sera were analyzed from 26 patients with aplastic crisis: 24 had IgM specific for parvovirus B19, five had Bl9-like particles by electron microscopy, and 13 had DNA from B19; no sera from 33 controls had evidence of recent infection with B19 (P < .0001). DNA from B19was also detected in specimens of throat gargle and urine from two patients with aplastic crisis. Sera from 36 of 51 children with erythema infectiosum had Bl9-specific IgM, compared with serum from one of 42 susceptible controls (P < .0001). DNA from B19 was detected in sera from only two of 51 patients who had erythema infectiosum. The secondary attack rates among susceptible contacts decreased with age (overall total, 49.6%). Differential rates of asymptomatic infection were observed among black (68.8%) and white (20.0%) household members (P = .003). These were the first identified simultaneous outbreaks of aplastic crisis and erythema infectiosum. Their occurrence provided an opportunity to study the epidemiology and spectrum of B19infection with geographically and temporally matched comparison groups; our results support the hypothesis that infection with parvovirus causes these two clinical entities. [ABSTRACT FROM PUBLISHER]

Examines the rate of the flavivirus GB virus C/hepatitis G virus (GBV-C/HGV) infection in American children and young adults in the United States. Detection of the flavivirus GBV-C/HGV in blood donors; Presence of neutralizing antibody to the envelope protein in donors; Prevalence of GBV-C/HGV infection among American children and young adults even in the absence of blood transfusion.