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RHOH, an atypical small GTPase predominantly expressed in hematopoietic cells, plays a vital role in immune function. A deficiency in RHOH has been linked to epidermodysplasia verruciformis, lung disease, Burkitt lymphoma and T cell defects. Here, we report a novel germline homozygous RHOH c.245G > A (p.Cys82Tyr) variant in a 21-year-old male suffering from recurrent, invasive, opportunistic infections affecting the lungs, eyes, and brain. His sister also succumbed to a lung infection during early adulthood. The patient exhibited a persistent decrease in CD4 + T, B, and NK cell counts, and hypoimmunoglobulinemia. The patient's T cell showed impaired activation upon in vitro TCR stimulation. In Jurkat T cells transduced with RHOH C82Y , a similar reduction in activation marker CD69 up-regulation was observed. Furthermore, the C82Y variant showed reduced RHOH protein expression and impaired interaction with the TCR signaling molecule ZAP70. Together, these data suggest that the newly identified autosomal-recessive RHOH variant is associated with T cell dysfunction and recurrent opportunistic infections, functioning as a hypomorph by disrupting ZAP70-mediated TCR signaling., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Serratia marcescens is an emerging opportunistic pathogen with high genetic diversity. This article describes the microbiological characteristics of isolates and the risk factors for infections caused by carbapenem-resistant S. marcescens. A retrospective study of patients colonized (n=43) and infected (n=20) with carbapenem-resistant S. marcescens over a 3-year period was conducted. Polymerase chain reaction for carbapenemase genes and molecular typing of all available strains was performed. Forty-two isolates were analysed, including three environmental samples identified during an outbreak. Thirty-five carbapenem-resistant S. marcescens carried bla KPC-2 , one isolate was bla NDM -positive and four isolates carried bla OXA-101 . The genomes were grouped into three clusters with 100% bootstrap; three patterns of mutations on ompC and ompF were found. The strains carried virulence genes related to invasion and haemolysis, and the environmental strains presented fewer mutations on the virulence genes than the clinical strains. Multi-variate analysis showed that previous use of polymyxin (P=0.008) was an independent risk factor for carbapenem-resistant S. marcescens infection. This study highlighted that bla KPC-2 in association with ompC or ompF mutation was the most common mechanism of resistance in the study hospital, and that previous use of polymyxin was an independent risk factor for carbapenem-resistant S. marcescens. There was a predominant clone, including the environmental isolates, suggesting that cross-transmission was involved in the dissemination of this pathogen., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Infections are the major cause of morbidity and mortality in patients with primary immunodeficiency disease (PID). Timely and accurate microbiological diagnosis is particularly important in these patients. Metagenomic next-generation sequencing (mNGS) has been used for pathogen detection recently. However, few reports describe the use of mNGS for pathogen identification in patients with PID., Objective: To evaluate the utility of mNGS for detecting pathogens in patients with PID, and to compare it with conventional microbiological tests (CMT)., Methods: This single center retrospective study investigated the diagnostic performance of mNGS for pathogens detection in PID patients and compared it with CMT. Sixteen PID patients with suspected infection were enrolled, and medical records were analyzed to extract detailed clinical characteristics such as gene variation, immune status, microbial distribution, time-consuming of mNGS and CMT, treatment, and outcomes., Results: mNGS identified pathogenic microbe in 93.75% samples, compared to 31.25% for culture and 68.75% for conventional methods, and detected an extra 18 pathogenic microorganisms including rare opportunistic pathogens and Mycobacterium tuberculosis . Pathogen identification by mNGS required 48 hours, compared with bacterial culture for 3-7 days and even longer for fungus and Mycobacterium tuberculosis culture., Conclusions: mNGS has marked advantages over conventional methods for pathogenic diagnosis, particularly opportunistic pathogens and mixed infections, in patients with PID. This method might enable clinicians to make more timely and targeted therapeutic decisions, thereby improving the prognosis of these patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Tang, Zhang, Luo, Zhou, Zhang, Tang, Zhao and An.)

The opportunistic pathogen Pseudomonas aeruginosa is responsible for much of the morbidity and mortality associated with cystic fibrosis (CF), a condition that predisposes patients to chronic lung infections. P. aeruginosa lung infections are difficult to treat because P. aeruginosa adapts to the CF lung, can develop multidrug resistance, and can form biofilms. Despite the clinical significance of P. aeruginosa , modeling P. aeruginosa infections in CF has been challenging. Here, we characterize Scnn1b -transgenic (Tg) BALB/c mice as P. aeruginosa lung infection models. Scnn1b -Tg mice overexpress the epithelial Na + channel (ENaC) in their lungs, driving increased sodium absorption that causes lung pathology similar to CF. We intranasally infected Scnn1b -Tg mice and wild-type littermates with the laboratory P. aeruginosa strain PAO1 and CF clinical isolates and then assessed differences in bacterial clearance, cytokine responses, and histological features up to 12 days postinfection. Scnn1b -Tg mice carried higher bacterial burdens when infected with biofilm-grown rather than planktonic PAO1; Scnn1b -Tg mice also cleared infections more slowly than their wild-type littermates. Infection with PAO1 elicited significant increases in proinflammatory and Th17-linked cytokines on day 3. Scnn1b -Tg mice infected with nonmucoid early CF isolates maintained bacterial burdens and mounted immune responses similar to those of PAO1-infected Scnn1b -Tg mice. In contrast, Scnn1b -Tg mice infected with a mucoid CF isolate carried high bacterial burdens, produced significantly more interleukin 1β (IL-1β), IL-13, IL-17, IL-22, and KC, and showed severe immune cell infiltration into the bronchioles. Taken together, these results show the promise of Scnn1b -Tg mice as models of early P. aeruginosa colonization in the CF lung., (Copyright © 2020 American Society for Microbiology.)

The application of CLSI and EUCAST guidelines led to many discrepancies. Various doubts have already appeared in preliminary stages of microbiological diagnostics of Haemophilus spp. A total of 87 H. parainfluenzae isolates were obtained from throat or nasopharyngeal swabs from adults 18 to 70 years old, both healthy volunteers and patients with chronic diseases between 2013 to 2015 in eastern Poland. Haemophilus spp. were identified by colony morphology, Gram-staining, API NH and MALDI-TOF MS technique. Both susceptibility to various antimicrobials and phenotypes of Haemophilus spp. resistance to beta-lactams were determined. Statistically significant association between applied guidelines and drug resistance patterns were observed to as follows: ampicillin, cefuroxime, cefotaxime, amoxicillin-clavulanate, azithromycin, tetracycline and trimethoprim-sulfamethoxazole. Resistance phenotypes according to CLSI vs. EUCAST were as follows: 3.4% vs. 8.0% for BLNAR and 6.9% vs. 19.5% for BLPACR isolates. In conclusion, this is the first study that reports comparative analysis of drug susceptibility interpretation using CLSI and EUCAST of haemophili rods from human respiratory microbiota in Poland. In case of susceptible, increased exposure (formerly intermediate) category of susceptibility within H. parainfluenzae isolates we have observed EUCAST as more restrictive than CLSI. Moreover, BLNAI and BLPAI phenotype isolates have been observed, as well as BLPBR using only CLSI or EUCAST guidelines, respectively.

Deficiencies in T regulatory (Treg) and Th17 cells attenuate peripheral tolerance and the IL-17 family of cytokines, contributing to autoimmune disorders and opportunistic (fungal) infections, respectively. Because of limited blood samples from patients with primary immunodeficiency diseases (PIDs), a positive correlation/linear relationship between Treg and Th17 cells and their respective expressions of transcription factors forkhead box P3 (FOXP3) and retinoic acid-related orphan receptor γ (RORγt) by real-time PCR (RT-PCR) amplification, was used to predict the percentages of Treg and Th17 cells in peripheral blood. Compared to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression, the percentages of Treg and Th17 cells were calculated as the linear relationship to the 2 -ΔCT value (cycle threshold). Among 91 PIDs patients, 68 and 78 had predicted Treg and Th17 percentages below 5% of the normal ranges (0.859 and 0.734%, respectively), which expanded different categories beyond obvious T cell deficiency. Notably, FOXP3 was undetectable in one patient (CVID), RORγt was undetectable in six patients (one CVID, one CID, two neutropenia, one WAS, and one CMC), and both were undetectable in four patients (two SCID, one STAT1, and one periodic fever). In contrast, two patients with auto-IFNγ antibodies had increased susceptibility to intracellular mycobacterial infections, interrupted Th1 development and subsequent elevation in the Th17 cells. Both predicted Treg and Th17 percentages in the PIDs patients were more independent of age (months) than in the controls. The predicted Th17/Treg ratio in the PIDs patients, overall, was lower than that in the healthy controls (0.79 ± 0.075 vs. 1.16 ± 0.208; p = 0.038). In conclusion, lower predicted Treg and Th17 cell populations calculated by RT-PCR-amplified FOXP3 and RORγt in PIDs patients at diagnosis can explain the higher potential phenotypes of autoimmune disorders and opportunistic infections, although effective interventions in the early stage might have prevented such phenotypic development and caused a statistical bias in the comparisons., (Copyright © 2020 Lee, Huang, Lin, Yeh, Chen, Ou, Yao, Jaing, Shih and Wu.)

Both the herpes zoster virus and suid herpesvirus type 1 (SuHV-1) belong to the Varicellovirus genus of the α-herpesviridae subfamily. They may cause opportunistic infections especially in patients with kidney diseases, varying from latent illness to overt lethality. Under these circumstances, impaired renal function is both the culprit for and victim of the infection. However, fulminant eruption of severe skin herpes zoster in lupus nephritis (LN) patients under prolonged immunosuppressive therapy is rare and even more rarely seen is the SuHV-1 encephalitis in human. Facing the evolution of these rare infections, we hence chose to review the clinical pathogenicity of these two viruses which were cognate in origin but distinct in virulence. As such, we began with the first of the two above viral diseases and proceeded with peculiar renal involvement, unique clinical symptoms and pertinent lethal risk. Of importance, LN was used to exemplify the reciprocally detrimental interactions between impaired renal function and suppressed immune response. Then in a manner similar to the gradient overlay, SuHV-1 encephalitis was discussed focusing on its neurotropic features, specific MRI findings and exclusive test of high throughput sequencing. Our report highlighted novel presentations of the Varicellovirus genus infection by providing a productive multidisciplinary communication with pointed disclosure of the renal involvement. It may therefore be of great medical relevance and educational value for clinicians, especially the unseasoned ones, to foresee and manage similar cases in susceptible patients., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Patients with acute myeloid leukemia frequently present translocations of MLL gene. Rearrangements of MLL protein (MLL-r) in complexes that contain the histone methyltransferase DOT1L are common, which elicit abnormal methylation of lysine 79 of histone H3 at MLL target genes. Phase 1 clinical studies with pinometostat (EPZ-5676), an inhibitor of DOT1L activity, demonstrated the therapeutic potential for targeting DOT1L in MLL-r leukemia patients. We previously reported that down-regulation of DOT1L increases influenza and vesicular stomatitis virus replication and decreases the antiviral response. Here we show that DOT1L inhibition also reduces Sendai virus-induced innate response and its overexpression decreases influenza virus multiplication, reinforcing the notion of DOT1L controlling viral replication. Accordingly, genes involved in the host innate response against pathogens (RUBICON, TRIM25, BCL3) are deregulated in human lung epithelial cells treated with pinometostat. Concomitantly, deregulation of some of these genes together with that of the MicroRNA let-7B, may account for the beneficial effects of pinometostat treatment in patients with MLL-r involving DOT1L. These results support a possible increased vulnerability to infection in MLL-r leukemia patients undergoing pinometostat treatment. Close follow up of infection should be considered in pinometostat therapy to reduce some severe side effects during the treatment.

Schizophyllum commune is a well-known mushroom forming fungi which is an edible one due to its nutritive value. It exhibits a special wood degrading mechanism to grow in decay matters by releasing a series of enzymes. These enzymes might make them an opportunistic pathogen which has been reported to infect various animals and human beings too. Although these fungi were identified as human and animal pathogens, their mechanisms of pathogenesis and the key virulence factors involved in disease establishment are not known. In this study, we reported this fungal infection in freshwater fish for the first time and its morphological features. Further, we employed RNA-seq technique to identify the major virulence factors involved in the pathogenesis in fish and the network of interaction between the identified virulence factors were analysed. Also, we confirmed the virulence roles of this fungus during infection by qRT-PCR analysis. This study emphasizes the virulence nature of the common mushroom forming food fungus and the involvement of enzymes such as phosphoinositide phospholipase C, hexosaminidase and few toxins such as pesticidal and insecticidal crystal proteins which opened a new avenue in the virulence nature of edible mushrooms.

Here, we describe the creation of three integration vectors, pPEPX, pPEPY and pPEPZ, for use with the opportunistic human pathogen Streptococcus pneumoniae . The constructed vectors, named PEP for Pneumococcal Engineering Platform (PEP), employ an IPTG-inducible promoter and BglBrick and BglFusion compatible multiple cloning sites allowing for fast and interchangeable cloning. PEP plasmids replicate in Escherichia coli and harbor integration sites that have homology in a large set of pneumococcal strains, including recent clinical isolates. In addition, several options of antibiotic resistance markers are available, even allowing for selection in multidrug resistant clinical isolates. The transformation efficiency of these PEP vectors as well as their ability to be expressed simultaneously was tested. Two of the three PEP vectors share homology of the integration regions with over half of the S. pneumoniae genomes examined. Transformation efficiency varied among PEP vectors based on the length of the homology regions, but all were highly transformable and can be integrated simultaneously in strain D39V. Vectors used for pneumococcal cloning are an important tool for researchers for a wide range of uses. The PEP vectors described are of particular use because they have been designed to allow for easy transfer of genes between vectors as well as integrating into transcriptionally silent areas of the chromosome. In addition, we demonstrate the successful production of several new spectrally distinct fluorescent proteins (mTurquoise2, mNeonGreen and mScarlet-I) from the PEP vectors. The PEP vectors and newly described fluorescent proteins will expand the genetic toolbox for pneumococcal researchers and aid future discoveries., Competing Interests: The authors declare no conflict of interest.

Recent discoveries in innate immunity together with improvements in the analysis of the human genome have led to the identification of factors that make certain individuals more susceptible to infections than other. We know understand why herpes simplex virus I, a virus with a minor burden in most individuals, is responsible for devastating encephalitis in children unable to detect primo-infection of neural cells. A growing number of patients are treated with immunosuppressive drugs in the field of oncology, organ transplantation and immunology. In such patients, opportunistic infections such invasive aspergillosis are clearly associated with genetic polymorphisms. Medical immune suppression represents a possible model for personalized approaches, in which infections could be prevented by individualized prophylactic strategies based on genetic testing., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Streptococcus pneumoniae is an opportunistic human pathogen that typically colonizes the nasopharyngeal passage and causes lethal disease in other host niches, such as the lung or the meninges. The expression and regulation of pneumococcal genes at different life-cycle stages, such as commensal or pathogenic, are not entirely understood. To chart the transcriptional responses of S. pneumoniae, we used RNA-seq to quantify the relative abundance of the transcriptome under 22 different infection-relevant conditions. The data demonstrated a high level of dynamic expression and, strikingly, all annotated pneumococcal genomic features were expressed in at least one of the studied conditions. By computing the correlation values of every pair of genes across all studied conditions, we created a co-expression matrix that provides valuable information on both operon structure and regulatory processes. The co-expression data are highly consistent with well-characterized operons and regulons, such as the PyrR, ComE and ComX regulons, and have allowed us to identify a new member of the competence regulon. Lastly, we created an interactive data center named PneumoExpress (https://veeninglab.com/pneumoexpress) that enables users to access the expression data as well as the co-expression matrix in an intuitive and efficient manner, providing a valuable resource to the pneumococcal research community.

Purpose of Review: Many genetic conditions predispose affected individuals to opportunistic infections. A number of immunodeficiency diseases, including genetic defects termed Mendelian susceptibility to mycobacterial disease (MSMD), permit infection from many different strains of mycobacteria that would otherwise not cause disease. These include tuberculous and nontuberculous mycobacteria, and bacille Calmette-Guérin vaccine (BCG). Patients may present with infections from other organisms that depend on macrophage function for containment. Defects in multiple genes in the IL-12 and NFKB signaling pathways can cause the MSMD phenotype, some of which include IL12RB1, IL12B, IKBKG, ISG15, IFNGR1, IFNGR2, CYBB, TYK2, IRF8, and STAT1., Recent Findings: Multiple autosomal recessive and dominant, and 2 X-linked recessive gene defects resulting in the MSMD phenotype have been reported, and others await discovery. This review presents the known gene defects and describes clinical findings that result from the mutations. If MSMD is suspected, a careful clinical history and examination and basic immunodeficiency screening tests will narrow the differential diagnosis. A specific diagnosis requires more sophisticated laboratory investigation. Genetic testing permits a definitive diagnosis, permitting genetic counseling. Mild cases respond well to appropriate antibiotic therapy, whereas severe disease may require hematopoietic stem cell transplantation.

Background: The diagnosis of granulomatous amoebic encephalitis is challenging for clinicians because it is a rare and lethal disease. Previous reports have indicated that Acanthamoeba with some specific genotypes tend to cause the majority of human infections. We report a case of granulomatous amoebic encephalitis caused by Acanthamoeba spp. with genotype T18 in an immunodeficient patient in Japan after allogenic bone marrow transplantation, along with the morphological characteristics and genetic analysis., Case Presentation: A 52-year old man, who had undergone allogenic bone marrow transplantation, suffered from rapid-growing brain masses in addition to pneumonia and died within 1 month from the onset of the symptoms including fever, headache and disorientation. Infection with Acanthamoeba in the brain and lung was confirmed by histological evaluation; immunohistochemical staining and polymerase chain reaction analysis using autopsy samples also indicated the growth of Acanthamoeba in the brain. Gene sequence analysis indicated that this is the second documented case of infection with Acanthamoeba spp. with genotype T18 in a human host. Postmortem retrospective evaluation of cerebrospinal fluid sample in our case, as well as literature review, indicated that some cases of granulomatous amoebic encephalitis caused by Acanthamoeba may be diagnosable by cerebrospinal fluid examination., Conclusion: This case indicates that Acanthamoeba spp. with genotype T18 can also be an important opportunistic pathogen. For pathologists as well as physicians, increased awareness of granulomatous amoebic encephalitis is important for improving the poor prognosis along with the attempt to early diagnosis with cerebrospinal fluid.

Background: Primary immunodeficiency disorders (PID) include a wide spectrum of inherited disorders characterised by functional abnormalities of one or more components of the immune system. Recent updates from the genomic data have contributed significantly to its better understanding with identification of new entities. Diagnosis is always challenging due to their variable clinical presentation. With the evolution of molecular diagnosis, many of these children are being diagnosed early and offered appropriate therapy. However, in developing countries, early diagnosis is still not being made: as a result these patients succumb to their disease. Autopsy data on PID is notably lacking in the literature with histopathological evaluation of PID being limited to rare case reports., Objective: To analyse the clinical, immunologic (including mutational) and morphologic features at autopsy in 10 proven and suspected cases of primary immunodeficiency disorders diagnosed at our Institute over the past decade., Methods: Study includes a detailed clinico-pathological analysis of 10 proven and suspected cases of primary immunodeficiency disorders., Results: A varied spectrum of infectious and non-infectious complications were identified in these cases of which fungal infections were found to be more frequent compared with viral or bacterial infections. Rare and novel morphological findings, like granulomatous involvement of the heart in a patient with chronic granulomatous disease, systemic amyloidosis in a teenage girl with X-linked agammaglobulinemia, are highlighted which is distinctly lacking in the literature., Conclusions: The present study is perhaps the first autopsy series on PID. Even in the molecular era, such analysis is still important, as correlation of pathological features with clinical symptoms provides clues for a timely diagnosis and appropriate therapeutic intervention., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Staphylococcus xylosus is a commensal bacterium found on the skin and mucosal surfaces of SPF mice. S. xylosus is rarely pathogenic, most often causing skin lesions and dermatitis in immunocompromised mice, particularly those with impaired NADPH oxidase function. Here we report spontaneous infection with S. xylosus in Rag1-/-Tpl2-/- mice. Infection was characterized by the presence of alopecia, crusts, and scaly skin. S. xylosus was detected in the feces, skin, lymph nodes, and lungs of Rag1-/-Tpl2-/- mice and led to mortality or euthanasia due to humane endpoints. C57BL/6 mice were culture-positive for S. xylosus on the skin, and Rag1-/- and Tpl2-/- mice were culture-positive on the skin and occasionally in the feces. However, S. xylosus did not cause clinical symptoms in C57BL/6, Rag1-/-, or Tpl2-/- mice. Compared with those in Rag1-/- mice, relative concentrations of circulating monocytes, but not neutrophils or lymphocytes, were increased in Rag1-/-Tpl2-/- mice, consistent with their increased incidence of clinical symptoms. Overall, this case study suggests a novel role for Tpl2 in T-cell-independent host resistance to the otherwise commensal organism S. xylosus.

Background: Opportunistic chlamydia screening of <25 year-olds was nationally-implemented in England in 2008 but its impact on chlamydia transmission is poorly understood. We undertook a population-based seroprevalence study to explore the impact of screening on cumulative incidence of chlamydia, as measured by C.trachomatis-specific antibody., Methods: Anonymised sera from participants in the nationally-representative Health Surveys for England (HSE) were tested for C.trachomatis antibodies using two novel Pgp3 enzyme-linked immunosorbent assays (ELISAs) as a marker of past infection. Determinants of being seropositive were explored using logistic regression among 16-44 year-old women and men in 2010 and 2012 (years when sexual behaviour questions were included in the survey) (n = 1,402 women; 1,119 men). Seroprevalence trends among 16-24 year-old women (n = 3,361) were investigated over ten time points from 1994-2012., Results: In HSE2010/2012, Pgp3 seroprevalence among 16-44 year-olds was 24.4% (95%CI 22.0-27.1) in women and 13.9% (11.8-16.2) in men. Seroprevalence increased with age (up to 33.5% [27.5-40.2] in 30-34 year-old women, 18.7% [13.4-25.6] in 35-39 year-old men); years since first sex; number of lifetime sexual partners; and younger age at first sex. 76.7% of seropositive 16-24 year-olds had never been diagnosed with chlamydia. Among 16-24 year-old women, a non-significant decline in seroprevalence was observed from 2008-2012 (prevalence ratio per year: 0.94 [0.84-1.05])., Conclusion: Our application of Pgp3 ELISAs demonstrates a high lifetime risk of chlamydia infection among women and a large proportion of undiagnosed infections. A decrease in age-specific cumulative incidence following national implementation of opportunistic chlamydia screening has not yet been demonstrated. We propose these assays be used to assess impact of chlamydia control programmes., Competing Interests: SCW, AN and GM are employed by Public Health England. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

GATA2 deficiency is a genetic disorder caused by inherited or sporadic haploinsufficient mutations in the GATA2 gene. Patients have abnormalities in hematopoiesis, lymphangiogenesis and immunity; encompassing a broad range of clinical syndromes, mainly characterized by monocytopenia, B and NK cell cytopenia, severe or recurrent infections, and a high risk of developing myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). We report a case of an Argentinean woman who presented with multiple opportunistic infections as her first manifestation of GATA2 deficiency., (Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Malnutrition is commonly associated with increased infectious disease susceptibility and severity. Whereas malnutrition might enhance the incidence of disease as well as its severity, active infection can in turn exacerbate malnutrition. Therefore, in a malnourished individual suffering from a severe infection, it is not possible to determine the contribution of the pre-existing malnutrition and/or the infection itself to increased disease severity. In the current study we focussed on two groups of malnourished, but otherwise healthy individuals: moderately malnourished (BMI: 18.4-16.5) and severely malnourished (BMI <16.5) and compared several immune parameters with those of individuals with a normal BMI (≥18.5). Our results show a similar haematological profile in all three groups, as well as a similar ratio of CD4+ and CD8+ T cells. We found significant correlations between low BMI and increased levels of T helper (Th) 1 (Interferon (IFN)-γ, (interleukin (IL)-2, IL-12), Th2 (IL-4, IL-5, IL-13), as well as IL-10, IL-33 and tumor necrosis factor-α, but not IL-8 or C reactive protein. The activities of arginase, an enzyme associated with immunosuppression, were similar in plasma, peripheral blood mononuclear cells (PBMC) and neutrophils from all groups and no differences in the expression levels of CD3ζ, a marker of T cell activation, were observed in CD4+ and CD8+T cells. Furthermore, whereas the capacity of neutrophils from the malnourished groups to phagocytose particles was not impaired, their capacity to produce reactive oxygen species was impaired. Finally we evaluated the frequency of a subpopulation of low-density neutrophils and show that they are significantly increased in the malnourished individuals. These differences were more pronounced in the severely malnourished group. In summary, our results show that even in the absence of apparent infections, healthy malnourished individuals display dysfunctional immune responses that might contribute to increased susceptibility and severity to infectious diseases., Competing Interests: The authors have declared that no competing interests exist.

Staphylococcus aureus and Pseudomonas aeruginosa are foregroundpathogens of bacteriemia and sepsis. They produce large spectrum of such factors of pathogenicity permitting them to proliferate and survive in bloodstream as hydrolytic enzymes, adenosine diphosphate-ribosylarginine toxins, plasmocoagulase, etc. The occurrence of alteration of growth and expression of virulence factors of S. aureus and P. aeruginosa at fermentation in LB-broth depending on iron concentration was demonstrated previously. The conditions in vivo significantly differ the laboratory conditions. The activity of growth and expression of pathogenicity factors of S. aureus and P. aeruginosa at fermentation in blood serum of donors with different alternative of iron homeostasis was analyzed. The study established expression of genes of hemolytic phospholipase C (plcH), alginate (algD), exotoxin A (exoA) for P. aeruginosa and genes of protein A (spA), virulence global regulator (RNAIII) for S. aureus. The iron-deficient serum and serum with normal iron homeostasis decreased activity of growth of S. aureus and P. aeruginosa. The growth rate and expression level of all analyzed genes turned out higher at fermentation of S. aureus and P. aeruginosa in serums containing excess of iron (more than 30 mkM). The fermentation of P. aeruginosa in iron-deficient serum resulted in decreasing of expression level of genes plcH, algD, exoA. The expression of RNA III and spaA S.aureus in iron-deficient serum increased towards normal content of iron in blood. The example of S. aureus and P. aeruginosa demonstrated that expression of many virulence factors of opportunistic microorganisms depends on iron homeostasis of host organism. The survival and proliferation of microorganisms in blood depend on both immune status of host organism and biological characteristics of pathogen.

Purpose: X-linked agammagobulinemia (XLA) is a primary immunodeficiency caused by Bruton's tyrosine kinase (BTK) gene defect. XLA patients have absent or reduced number of peripheral B cells and a profound deficiency in all immunoglobulin isotypes. This multicenter study reports the clinical, immunological and molecular features of Bruton's disease in 40 North African male patients., Methods: Fifty male out of 63 (male and female) patients diagnosed with serum agammaglobulinemia and non detectable to less than 2% peripheral B cells were enrolled. The search for BTK gene mutations was performed for all of them by genomic DNA amplification and Sanger sequencing., Results: We identified 33 different mutations in the BTK gene in 40 patients including 12 missense mutations, 6 nonsense mutations, 6 splice-site mutations, 5 frameshift, 2 large deletions, one complex mutation and one in-frame deletion. Seventeen of these mutations are novel. This large series shows a lower frequency of XLA among male patients from North Africa with agammaglobulinemia and absent to low B cells compared with other international studies (63.5% vs. 85%). No strong evidence for genotype-phenotype correlation was observed., Conclusions: This study adds to other reports from highly consanguineous North African populations, showing lower frequency of X-linked forms as compared to AR forms of the same primary immunodeficiency. Furthermore, a large number of novel BTK mutations were identified and could further help identify carriers for genetic counseling.

Purpose: Complete interferon-γ receptor 1 (IFN-γR1) deficiency is a primary immunodeficiency causing predisposition to severe infection due to intracellular pathogens. Only 36 cases have been reported worldwide. The purpose of this article is to describe a large novel deletion found in 3 related cases, which resulted in the complete removal of the IFNGR1 gene., Methods: Whole blood from three patients was stimulated with lipopolysaccharide (LPS) and IFN-γ to determine production of tumor necrosis factor (TNF), interleukin-12 p40 (IL-12p40) and IL-10. Expression of IFN-γR1 on the cell membrane of patients' monocytes was assessed using flow cytometry. IFNGR1 transcript was analyzed in RNA and the gene and adjacent regions were analyzed in DNA. Finally, IL22RA2 transcript levels were analyzed in whole blood cells and dendritic cells., Results: There was no expression of the IFN-γR1 on the monocytes. Consistent with this finding, there was no IFN-γ response in the whole blood assay as measured by effect on LPS-induced IL-12p40, TNF and IL-10 production. A 119.227 nt homozygous deletion on chromosome 6q23.3 was identified, removing the IFNGR1 gene completely and ending 117 nt upstream of the transcription start of the IL22RA2 gene. Transcript levels of IL22RA2 were similar in patient and control., Conclusions: We identified the first large genomic deletion of IFNGR1 causing complete IFN-γR1 deficiency. Despite the deletion ending very close to the IL22RA2 gene, it does not appear to affect IL22RA2 transcription and, therefore, may not have any additional clinical consequence.

Endoglin is an auxiliary receptor for members of the TGF-β superfamily and plays an important role in the homeostasis of the vessel wall. Mutations in endoglin gene (ENG) or in the closely related TGF-β receptor type I ACVRL1/ALK1 are responsible for a rare dominant vascular dysplasia, the Hereditary Hemorrhagic Telangiectasia (HHT), or Rendu-Osler-Weber syndrome. Endoglin is also expressed in human macrophages, but its role in macrophage function remains unknown. In this work, we show that endoglin expression is triggered during the monocyte-macrophage differentiation process, both in vitro and during the in vivo differentiation of blood monocytes recruited to foci of inflammation in wild-type C57BL/6 mice. To analyze the role of endoglin in macrophages in vivo, an endoglin myeloid lineage specific knock-out mouse line (Eng(fl/fl)LysMCre) was generated. These mice show a predisposition to develop spontaneous infections by opportunistic bacteria. Eng(fl/fl)LysMCre mice also display increased survival following LPS-induced peritonitis, suggesting a delayed immune response. Phagocytic activity is impaired in peritoneal macrophages, altering one of the main functions of macrophages which contributes to the initiation of the immune response. We also observed altered expression of TGF-β1 target genes in endoglin deficient peritoneal macrophages. Overall, the altered immune activity of endoglin deficient macrophages could help to explain the higher rate of infectious diseases seen in HHT1 patients.

Opportunistic fungal infections are an increasing threat for global health, and for immunocompromised patients in particular. These infections are characterized by interaction between fungal pathogen and host cells. The exact mechanisms and the attendant variability in host and fungal pathogen interaction remain to be fully elucidated. The field of systems biology aims to characterize a biological system, and utilize this knowledge to predict the system's response to stimuli such as fungal exposures. A multi-omics approach, for example, combining data from genomics, proteomics, metabolomics, would allow a more comprehensive and pan-optic "two systems" biology of both the host and the fungal pathogen. In this review and literature analysis, we present highly specialized and nascent methods for analysis of multiple -omes of biological systems, in addition to emerging single-molecule visualization techniques that may assist in determining biological relevance of multi-omics data. We provide an overview of computational methods for modeling of gene regulatory networks, including some that have been applied towards the study of an interacting host and pathogen. In sum, comprehensive characterizations of host-fungal pathogen systems are now possible, and utilization of these cutting-edge multi-omics strategies may yield advances in better understanding of both host biology and fungal pathogens at a systems scale.

Background: Natural genetic variation ultimately arises from the process of mutation. Knowledge of how the raw material for evolution is produced is necessary for a full understanding of several fundamental evolutionary concepts. We performed a mutation accumulation experiment with wild-type and mismatch-repair deficient, mutator lines of the pathogenic bacterium Pseudomonas aeruginosa, and used whole-genome sequencing to reveal the genome-wide rate, spectrum, distribution, leading/lagging bias, and context-dependency of spontaneous mutations., Results: Wild-type base-pair mutation and indel rates were ~10(-10) and ~10(-11) per nucleotide per generation, respectively, and deficiencies in the mismatch-repair system caused rates to increase by over two orders of magnitude. A universal bias towards AT was observed in wild-type lines, but was reversed in mutator lines to a bias towards GC. Biases for which types of mutations occurred during replication of the leading versus lagging strand were detected reciprocally in both replichores. The distribution of mutations along the chromosome was non-random, with peaks near the terminus of replication and at positions intermediate to the replication origin and terminus. A similar distribution bias was observed along the chromosome in natural populations of P. aeruginosa. Site-specific mutation rates were higher when the focal nucleotide was immediately flanked by C:G pairings., Conclusions: Whole-genome sequencing of mutation accumulation lines allowed the comprehensive identification of mutations and revealed what factors of molecular and genomic architecture affect the mutational process. Our study provides a more complete view of how several mechanisms of mutation, mutation repair, and bias act simultaneously to produce the raw material for evolution.

Candida metapsilosis is a rarely-isolated, opportunistic pathogen that belongs to a clade of pathogenic yeasts known as the C. parapsilosis sensu lato species complex. To gain insight into the recent evolution of C. metapsilosis and the genetic basis of its virulence, we sequenced the genome of 11 clinical isolates from various locations, which we compared to each other and to the available genomes of the two remaining members of the complex: C. orthopsilosis and C. parapsilosis. Unexpectedly, we found compelling genomic evidence that C. metapsilosis is a highly heterozygous hybrid species, with all sequenced clinical strains resulting from the same past hybridization event involving two parental lineages that were approximately 4.5% divergent in sequence. This result indicates that the parental species are non-pathogenic, but that hybridization between them formed a new opportunistic pathogen, C. metapsilosis, that has achieved a worldwide distribution. We show that these hybrids are diploid and we identified strains carrying loci for both alternative mating types, which supports mating as the initial mechanism for hybrid formation. We trace the aftermath of this hybridization at the genomic level, and reconstruct the evolutionary relationships among the different strains. Recombination and introgression -resulting in loss of heterozygosis- between the two subgenomes have been rampant, and includes the partial overwriting of the MTLa mating locus in all strains. Collectively, our results shed light on the recent genomic evolution within the C. parapsilosis sensu lato complex, and argue for a re-definition of species within this clade, with at least five distinct homozygous lineages, some of which having the ability to form hybrids.

The impact of particular microbes on genetically engineered mice depends on the genotype and the environment. Infections resulting in clinical disease have an obvious impact on animal welfare and experimentation. In this study, we investigated the bacterial and fungal aetiology of spontaneous clinical disease of infectious origin among the genetically engineered mice from our institution in relation to their genotype. A total of 63 mice belonging to 33 different mice strains, from severe immunodeficient to wild-type, were found to display infections as the primary cause leading to their euthanasia. The necropsies revealed abscesses localized subcutaneously as well as in the kidney, preputial glands, seminal vesicles, in the uterus, umbilicus or in the lung. In addition, pneumonia, endometritis and septicaemia cases were recorded. Escherichia coli was involved in 21 of 44 (47.72%) of the lesions of bacterial origin, whereas [Pasteurella] pneumotropica was isolated from 19 of 44 (43.18%) cases. The infections with the two agents mentioned above included three cases of mixed infection with both pathogens. Staphylococcus aureus was considered responsible for five of 44 (11.36%) cases whereas Enterobacter cloacae was found to cause lesions in two of 44 (4.54%) mice. Overall, 16 of the 44 (36.36%) cases of bacterial aetiology affected genetically engineered mice without any explicit immunodeficiency or wild-type strains. The remaining 19 cases of interstitial pneumonia were caused by Pneumocystis murina. In conclusion, the susceptibility of genetically modified mice to opportunistic infections has to be regarded with precaution, regardless of the type of genetic modification performed. Beside the classical opportunists, such as [Pasteurella] pneumotropica and Staphylococcus aureus, Escherichia coli should as well be closely monitored to evaluate whether it represents an emerging pathogen in the laboratory mouse.

Pneumocystis pneumonia is a severe opportunistic infection in immunocompromised patients caused by the unusual fungus Pneumocystis jirovecii. Transmission is airborne, with both immunocompromised and immunocompetent individuals acting as a reservoir for the fungus. Numerous reports of outbreaks in renal transplant units demonstrate the need for valid genotyping methods to detect transmission of a given genotype. Here, we developed a short tandem repeat (STR)-based molecular typing method for P. jirovecii. We analyzed the P. jirovecii genome and selected six genomic STR markers located on different contigs of the genome. We then tested these markers in 106 P. jirovecii PCR-positive respiratory samples collected between October 2010 and November 2013 from 91 patients with various underlying medical conditions. Unique (one allele per marker) and multiple (more than one allele per marker) genotypes were observed in 34 (32%) and 72 (68%) samples, respectively. A genotype could be assigned to 55 samples (54 patients) and 61 different genotypes were identified in total with a discriminatory power of 0.992. Analysis of the allelic distribution of the six markers and minimum spanning tree analysis of the 61 genotypes identified a specific genotype (Gt21) in our hospital, which may have been transmitted between 10 patients including six renal transplant recipients. Our STR-based molecular typing method is a quick, cheap and reliable approach to genotype Pneumocystis jirovecii in hospital settings and is sensitive enough to detect minor genotypes, thus enabling the study of the transmission and pathophysiology of Pneumocystis pneumonia.

We have previously demonstrated an impact of the BRAF inhibitor vemurafenib on patient lymphocyte counts. In the current study, the extent to which concomitant use of corticosteroids in BRAF inhibitor treated patients affects lymphocyte counts and predisposes to infection was investigated. A cohort of 102 patients receiving either the selective BRAF inhibitor vemurafenib or dabrafenib was analyzed. The amount of patients receiving either medication with or without systemic corticosteroids (dexamethasone) was determined and lymphocyte counts before and under therapy assessed. Additionally, the number and severity of infections occurring in these groups was analyzed. Vemurafenib treatment led to a considerable decrease in lymphocyte cell counts, with 62.3% of patients having lymphopenia. Dabrafenib treated patients only rarely demonstrated lymphopenia (12.5%). Dexamethasone co-administration further diminished lymphocyte counts. Lymphopenias were observed in 84.6% of patients receiving vemurafenib and dexamethasone. In our cohort, infections were noted in 9 patients, 4 of these were severe and 2 eventually fatal. All 9 cases with infections demonstrated lymphopenia, 8 of these had received dexamethasone and 7 of these a therapy with vemurafenib. Our findings demonstrate a significant lymphopenia in patients treated with the BRAF inhibitor vemurafenib, which is further augmented by dexamethasone and predisposes to infection. If validated in other studies, risk of infection should be considered when applying corticosteroids in combination with BRAF inhibitors, in particular vemurafenib.

Candida albicans is part of the normal commensal microbiota of mucosal surfaces in a large percentage of the human population. However, perturbations of the host's immune response or bacterial microbiota have been shown to predispose individuals to the development of opportunistic Candida infections. It was recently discovered that a defect in the chemokine receptor CX3CR1 increases susceptibility of mice and humans to systemic candidiasis. However, whether CX3CR1 confers protection against mucosal C. albicans infection has not been investigated. Using two different mouse models, we found that Cx3cr1 is dispensable for the induction of interleukin 17A (IL-17A), IL-22, and IL-23 in the tongue after infection, as well as for the clearance of mucosal candidiasis from the tongue or lower gastrointestinal (GI) tract colonization. Furthermore, the dysfunctional human CX3CR1 allele CX3CR1-M280 was not associated with development of recurrent vulvovaginal candidiasis (RVVC) in women. Taken together, these data indicate that CX3CR1 is not essential for protection of the host against mucosal candidiasis, underscoring the dependence on different mammalian immune factors for control of mucosal versus systemic Candida infections., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Sex chromosome aneuploidies range in incidence from rather common to exceedingly rare and have a variable phenotype. We report 2 patients with sex chromosome aneuploidies who developed severe aplastic anemia requiring treatment. The first patient had tetrasomy X (48,XXXX) and presented at 9 years of age, and the second patient had trisomy X (47,XXX) and presented at 5 years of age. Although aplastic anemia has been associated with other chromosomal abnormalities, sex chromosome abnormalities have not been traditionally considered a risk factor for this condition. A review of the literature reveals that at least one other patient with a sex chromosome aneuploidy (45,X) has suffered from aplastic anemia and that other autosomal chromosomal anomalies have been described. Despite the uncommon nature of each condition, it is possible that the apparent association is coincidental. A better understanding of the genetic causes of aplastic anemia remains important., (© 2015 S. Karger AG, Basel.)

The bacterium Pseudomonas aeruginosa is a significant cause of acute nosocomial infections as well as chronic respiratory infections in patients with cystic fibrosis (CF). Recent reports of the intercontinental spread of a CF-specific epidemic strain, combined with high intrinsic levels of antibiotic resistance, have made this opportunistic pathogen an important public health concern. Strain-specific differences correlate with variation in clinical outcomes of infected CF patients, increasing the urgency to understand the evolutionary origin of genetic factors conferring important phenotypes that enable infection, virulence, or resistance. Here, we describe the genome-wide patterns of homologous and nonhomologous recombination in P. aeruginosa, and the extent to which the genomes are affected by these diversity-generating processes. Based on whole-genome sequence data from 32 clinical isolates of P. aeruginosa, we examined the rate and distribution of recombination along the genome, and its effect on the reconstruction of phylogenetic relationships. Multiple lines of evidence suggested that recombination was common and usually involves short stretches of DNA (200-300 bp). Although mutation was the main source of nucleotide diversity, the import of polymorphisms by homologous recombination contributed nearly as much. We also identified the genomic regions with frequent recombination, and the specific sequences of recombinant origin within epidemic strains. The functional characteristics of the genes contained therein were examined for potential associations with a pathogenic lifestyle or adaptation to the CF lung environment. A common link between many of the high-recombination genes was their functional affiliation with the cell wall, suggesting that the products of recombination may be maintained by selection for variation in cell-surface molecules that allows for evasion of the host immune system., (© The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Current knowledge on the human pathophysiology of fungal infections highlights the crucial role of genetic pitfalls in specific immunity pathways that determine, together with other risk factors, the predisposition to and clinical outcome of fungal disease. In several studies, associations between gene polymorphisms and genetic errors have been implicated in an immunodeficiency phenotype and an increased incidence of opportunistic fungal diseases. The major challenge is to fully understand the complex interactions between genetic variations and multiple factors, and their relative contributions to the final clinical fungal disease phenotype. The aim of this review is to present updated knowledge on immunity genetics and susceptibility to medically relevant fungal diseases, such as those caused by Candida, Aspergillus, and certain other more rare fungi., (© 2014 The Authors Clinical Microbiology and Infection © 2014 European Society of Clinical Microbiology and Infectious Diseases.)

Osteopetrosis, lymphedema, hypohidrotic ectodermal dysplasia, and immunodeficiency (OL-HED-ID) is a rare X-linked disorder with only three reported prior cases in the English-language literature. We describe a case of OL-HED-ID in a male infant who initially presented with congenital lymphedema, leukocytosis, and thrombocytopenia of unknown etiology at 7 days of age. He subsequently developed gram-negative sepsis and multiple opportunistic infections including high-level cytomegalovirus viremia and Pneumocystis jiroveci pneumonia. The infant was noted to have mildly xerotic skin, fine sparse hair, and periorbital wrinkling, all features suggestive of ectodermal dysplasia. Skeletal imaging showed findings consistent with osteopetrosis, and immunologic investigation revealed hypogammaglobulinemia and mixed T- and B-cell dysfunction. Genetic testing revealed a novel mutation in the nuclear factor kappa beta (NF-KB) essential modulator (NEMO) gene, confirming the diagnosis of OL-HED-ID. Mutations in the NEMO gene have been reported in association with hypohidrotic ectodermal dysplasia with immunodeficiency (HED-ID), OL-HED-ID, and incontinentia pigmenti. In this case, we report a novel mutation in the NEMO gene associated with OL-HED-ID. This article highlights the dermatologic manifestations of a rare disorder, OL-HED-ID, and underscores the importance of early recognition and prompt intervention to prevent life-threatening infections., (© 2013 Wiley Periodicals, Inc.)

Susceptibility to invasive pneumococcal disease (IPD) correlates with age, younger children being the group with the highest burden of disease. The relevance of the innate immune response and particularly the role of mannose-binding lectin (MBL) in combating IPD is not well known. This is a 2-year prospective study (February 2011 to March 2013) including patients with IPD who attended two hospitals from Catalonia, Spain. Variables including attack rate of pneumococcal serotype (high or low invasive potential serotypes) and genotypes associated with low serum MBL levels were recorded. One hundred and forty-seven patients were included in the study. One hundred and two (69.4%) patients were children or adolescents <18 years and 45 (30.6%) were adults. Overall, low-MBL genotypes (O/O; XA/O) were detected in 23 (15.6%) patients. Children <2 years showed a higher frequency of low-MBL genotypes compared with other patients (31.0% vs. 11.9%; p = 0.031). Further sub-analysis revealed a higher proportion of low-MBL genotypes in children <2 years with IPD caused by opportunistic or low-attack-rate serotypes when compared with older patients (46.2% vs. 13.2%; p = 0.02). However, no statistically significant differences between the two groups were observed when including patients infected with invasive or high-attack-rate serotypes (18.8% vs. 10.0%; p = 0.59). Our data suggest that young children with a genetically determined low-MBL production are at a higher risk of developing IPD, particularly that caused by opportunistic or low-attack-rate pneumococcal serotypes., (© 2014 The Authors Clinical Microbiology and Infection © 2014 European Society of Clinical Microbiology and Infectious Diseases.)

Opportunistic infections caused by Pseudomonas aeruginosa can be acute or chronic. While acute infections often spread rapidly and can cause tissue damage and sepsis with high mortality rates, chronic infections can persist for weeks, months, or years in the face of intensive clinical intervention. Remarkably, this diverse infectious capability is not accompanied by extensive variation in genomic content, suggesting that the genetic capacity to be an acute or a chronic pathogen is present in most P. aeruginosa strains. To investigate the genetic requirements for acute and chronic pathogenesis in P. aeruginosa infections, we combined high-throughput sequencing-mediated transcriptome profiling (RNA-seq) and genome-wide insertion mutant fitness profiling (Tn-seq) to characterize gene expression and fitness determinants in murine models of burn and non-diabetic chronic wound infection. Generally we discovered that expression of a gene in vivo is not correlated with its importance for fitness, with the exception of metabolic genes. By combining metabolic models generated from in vivo gene expression data with mutant fitness profiles, we determined the nutritional requirements for colonization and persistence in these infections. Specifically, we found that long-chain fatty acids represent a major carbon source in both chronic and acute wounds, and P. aeruginosa must biosynthesize purines, several amino acids, and most cofactors during infection. In addition, we determined that P. aeruginosa requires chemotactic flagellar motility for fitness and virulence in acute burn wound infections, but not in non-diabetic chronic wound infections. Our results provide novel insight into the genetic requirements for acute and chronic P. aeruginosa wound infections and demonstrate the power of using both gene expression and fitness profiling for probing bacterial virulence.

The immunoglobulin class switch recombination deficiency or hyper-IgM syndrome is characterized by normal or elevated serum IgM and low serum levels of other immunoglobulins. Since the first reported patient with hyper-IgM, more than 200 patients with this phenotype resulted from CD40 ligand deficiency have been reported. However, in addition to this common finding, they presented with different manifestations like opportunistic infections, autoimmunity and malignancies each of them are worth a detailed look. In this review, we will focus on different underlying mechanisms of these presentations to review what we have learned from our patients. In the end, we will discuss different treatment options available for these patients using this knowledge.

Pneumocystosis is a common opportunistic infection in immunocompromised patients, especially in AIDS patients. The diagnosis of this pneumonia has presented several difficulties due to the low sensitivity of conventional staining methods and the absence of culture system for Pneumocystis. The molecular biology techniques, especially the PCR, have improved the detection of DNA of this fungus in invasive and noninvasive samples, and in the environment which highlighted human transmission and the existence of environmental source of Pneumocystis. In addition, various molecular biology techniques were used for typing of Pneumocystis strains, especially P. jirovecii, which is characterized by a significant genetic biodiversity. Finally, the widespread use of cotrimoxazole for the treatment and prophylaxis of pneumocystosis has raised questions about possible resistance to sulfa drugs in P. jirovecii., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

In children with primary immunodeficiencies, the onset of symptoms precedes the diagnosis and the initiation of appropriate treatment by months or years. This delay in diagnosis is due to the fact that while these disorders are rare, some of the infections seen in immunodeficient patients are common. Defective antibody production represents the largest group among these disorders, with otitis, sinusitis and pneumonia as the most frequent initial manifestation. We performed a prospective study of humoral immunity in children hospitalized due to community-acquired pneumonia in tertiary care hospital. Out of 254 patients (131 boys, 123 girls, median age 4.5 years) recruited over 3 years, we found 2 boys (age 11 and 21 months) lacking serum immunoglobulins and circulating B cells. Subsequent genetic analysis confirmed diagnosis of X-linked agammaglobulinemia. Despite their immunodeficiency, the pneumonia was uncomplicated in both patients and did not call for immunological evaluation. However, the immunoglobulin screening at admission allowed for an early diagnosis of the immunodeficiency and timely initiation of immunoglobulin substitution, the key prerequisite for a favorable course of the disease.Simple and inexpensive immuno-globulin measurement during the manage-ment of hospitalized children with community-acquired pneumonia may help in early identification of patients with compromised humoral immunity and prevent serious complications., (© Georg Thieme Verlag KG Stuttgart · New York.)

Objectives: Cornelia de Lange syndrome (CdLS) is a genetic syndrome with multisystem abnormalities. Infections are a significant cause of morbidity and mortality. The goals of our study were to identify the frequency and types of infections in CdLS and to determine if underlying immunodeficiency contributes to the clinical spectrum of this syndrome., Methods: We assessed infectious histories in 45 patients with CdLS and evaluated conventional immunologic screening tests in 27 patients. Among these 27 subjects, additional phenotypic enumeration of T-cell subsets, expression of activation markers in T cells, and production of cytokines in response to T-cell stimulants were studied in 12 CdLS subjects compared with 12 normal case control subjects., Results: Recurrent infections were reported at high frequency in CdLS patients and included chronic ear infections (53%), chronic viral respiratory infections (46%), pneumonia (42%), sinus infections (33%), oral candidiasis (13%), sepsis (6%), and bacterial skin infections (4%). Full immune evaluation in 27 subjects led to identification of 9 cases of antibody deficiency syndrome in patients with severe forms of CdLS. Subjects with CdLS had decreased percentages of T regulatory cells and T follicular helper cells compared with normal control subjects (P < .05)., Conclusions: This study identified for the first time a high frequency of antibody deficiency in CdLS subjects, indicating a critical need for screening and management of immunodeficiency in CdLS patients with a history of well-documented severe or recurrent infections. Furthermore, our results indicate that impaired T-cell populations may be associated with antibody deficiency in CdLS.

The structural diversity of basic replicons and repB gene of the IncP-7 plasmids' collection was firstly assessed on the basis of PCR, restriction analysis and partial sequencing. It has been revealed that DNA fragment containing gene for UvrD-like helicase RepB is a part of all known P-7 replicons, but often serves as hot place for diverse IS-elements invasion. The first system of P-7 plasmids' classification has been worked out on the basis of determined repA-oriV-par WABC nucleotide divergency. Most degradation plasmids established to be belonging to large beta-subgroup, streptomycin resistance plasmid Rms148 (IncP-7 archetype)--to alpha-subgroup, carbazole degradation plasmid pCAR1 and NAH/SAL-plasmids from pY-line (Yamal oil deposits)--to gamma-subgroup and CAP-plasmid pBS270 with potentially reduced P-7 replicon--to delta-subgroup. It has been observed that the type of IncP-7 basic replicon molecular organization does not correlate with fixed phenotypic character in most cases, that is plasmids encoding different phenotypic markers could be members of the same P-7 subgroup.

Folate and vitamin B(12) metabolism are essential for de novo purine synthesis, and several defects in these pathways have been associated with immunodeficiency. Here we describe the occurrence of severe combined immunodeficiency (SCID) with megaloblastic anemia, leukopenia, atypical hemolytic uremic syndrome, and neurologic abnormalities in which hydroxocobalamin and folate therapy provided partial immune reconstitution. Whole exome sequencing identified compound heterozygous mutations in the MTHFD1 gene, which encodes a trifunctional protein essential for processing of single-carbon folate derivatives. We now report the immunologic details of this novel genetic cause of SCID and the response to targeted metabolic supplementation therapies. This finding expands the known metabolic causes of SCID and presents an important diagnostic consideration given the positive impact of therapy.