Fatal Lymphoproliferative Disease in Two Siblings Lacking Functional FAAP24.

Hereditary defects in several genes have been shown to disturb the normal immune response to EBV and to give rise to severe EBV-induced lymphoproliferation in the recent years. Nevertheless, in many patients, the molecular basis of fatal EBV infection still remains unclear. The Fanconi anemia-associated protein 24 (FAAP24) plays a dual role in DNA repair. By association with FANCM as component of the FA core complex, it recruits the FA core complex to damaged DNA. Additionally, FAAP24 has been shown to evoke ATR-mediated checkpoint responses independently of the FA core complex. By whole exome sequencing, we identified a homozygous missense mutation in the FAAP24 gene (cC635T, pT212M) in two siblings of a consanguineous Turkish family who died from an EBV-associated lymphoproliferative disease after infection with a variant EBV strain, expressing a previously unknown EBNA2 allele.In order to analyze the functionality of the variant FAAP24 allele, we used herpes virus saimiri-transformed patient T cells to test endogenous cellular FAAP24 functions that are known to be important in DNA damage control. We saw an impaired FANCD2 monoubiquitination as well as delayed checkpoint responses, especially affecting CHK1 phosphorylation in patient samples in comparison to healthy controls. The phenotype of this FAAP24 mutation might have been further accelerated by an EBV strain that harbors an EBNA2 allele with enhanced activities compared to the prototype laboratory strain B95.8. This is the first report of an FAAP24 loss of function mutation found in human patients with EBV-associated lymphoproliferation.

Prolonged detection of human bocavirus DNA in nasopharyngeal aspirates of children with respiratory tract disease.

Increasing evidence suggests that the recently identified human bocavirus (hBoV) is a cause of acute respiratory illness. However, the duration of hBoV shedding from the respiratory tract as demonstrated by positive hBoV polymerase chain reaction is unclear. We describe the virologic and clinical characteristics of 6 immunocompetent children with hBoV persistence in the respiratory tract for up to 4.5 months.

Detection of WU polyomavirus DNA by real-time PCR in nasopharyngeal aspirates, serum, and stool samples.

BACKGROUND: The human WU polyomavirus (WUPyV) has been recently described as a novel virus in respiratory tract samples. OBJECTIVE: To investigate the viral load of WUPyV in nasopharyngeal aspirates (NPAs), stool, and serum samples of pediatric patients with acute respiratory tract diseases. STUDY DESIGN: We established a real-time PCR for WUPyV DNA and tested NPA obtained between 2002 and 2007 from pediatric in-patients with acute respiratory tract diseases. In addition, 14 stool and 14 serum samples of children with WUPyV DNA positive NPA were analysed. RESULTS: WUPyV DNA was found in 5.2% of 1232 NPA. The median viral load in the NPA was 950 copies/ml (maximum 3.4 x 10(10) copies/ml). The WUPyV load in NPA was neither associated with the coinfection status nor with the clinical diagnoses. WUPyV DNA was found in 3 of 14 serum samples and in 2 of 14 stool samples. The WUPyV load in NPA tended to be higher in viremic children. CONCLUSION: WUPyV DNA was found in NPA, serum, and stool of hospitalised children with acute respiratory tract diseases. Further studies are necessary to determine whether WUPyV is a human pathogen.

Viral exanthems in childhood. Part 3: Parainfectious exanthems and those associated with virus-drug interactions.

Viruses cause not only direct infectious exanthems, but also parainfectious exanthems, which provoke skin alterations via interactions with the immune system. These distinct exanthems, for instance Gianotti-Crosti syndrome and pityriasis lichenoides group, do not reflect a specific pathogen but can occur in the course of many viral infections. In addition, some exanthems result from the interaction between viruses and drugs.

Viral exanthems in childhood--infectious (direct) exanthems. Part 2: Other viral exanthems.

The group of the non-classic infectious exanthems are mostly maculopapular or vesicular. The latter changes are typical for infections with varicella-zoster virus and Coxsackie viruses. Congenital cytomegalovirus infections are characterized by petechiae and purpura, while the papular-purpuric gloves and socks syndrome is usually associated with parvovirus B19. Aside from these, the non-classic infectious exanthems diseases include nonspecific exanthems coupled with respiratory and enteric infections.

Viral exanthems in childhood--infectious (direct) exanthems. Part 1: Classic exanthems.

Exanthems during childhood occur quite often and are mostly harmless in nature. Among different trigger factors, viruses are of prime importance. Viral exanthems may manifest as a macular, maculopapular, papular, urticarial or vesicular rash. Exanthems with other causes (bacterial toxins, drugs, autoimmune diseases) as well as those with unclear etiology such as unilateral lat-erothoracic exanthem or Kawasaki disease must be differentiated from viral exanthems. This review focuses on the classic viral exanthems.

Abscess-forming lymphadenopathy and osteomyelitis in children with Bartonella henselae infection.

Bartonella henselae is the agent of cat-scratch disease (CSD), a chronic lymphadenopathy among children and adolescents. A systemic infection is very rare and most of these cases are found in patients with immunodeficiency. Here, cases involving four children of 6-12 years of age are reported. Three of the children had an abscess-forming lymphadenopathy and surrounding myositis in the clavicular region of the upper arm. The diagnosis was made serologically and, in one case, using eubacterial universal PCR. One child was treated with erythromycin for 10 days, the second received cefotaxime and flucloxacillin for 14 days and the third child was not treated with antibiotics. The fourth child had a different course: a significantly elevated signal intensity affecting the complete humerus was found in magnetic resonance imaging, consistent with osteomyelitis. A lymph node abscess was also found in the axilla. Diagnosis was established by indirect fluorescence assay and lymph node biopsy. Antibiotic therapy using clarithromycin, clindamycin and rifampicin was gradually successful. Immunodeficiency was excluded. All described lesions healed without residues. In immunocompetent patients, infection affects skin and draining lymph nodes; however, prolonged fever of unknown origin as in the fourth patient indicated a systemic complication of CSD.

Varicella-related deaths in children and adolescents--Germany 2003-2004.

AIM: Although varicella is acknowledged as a rare cause of death in children, there are few comprehensive data with respect to the clinical course leading to death. METHODS: A nationwide, active surveillance was carried out in Germany for children up to age 17 years who were admitted to a paediatric hospital for varicella or associated complications, including deaths. RESULTS: A total of 10 children with varicella-associated death were reported over period of 2 years, yielding a mortality rate of 0.4/1 000 000 children per year. Three deaths occurred in children diagnosed with acute lymphocytic leukaemia and disseminated varicella, two shortly after diagnosis of leukaemia and therefore not preventable, and one during remission with an untypical presentation. Two children died with a congenital varicella syndrome. There was no death in children with neonatal varicella. Four other cases were related to varicella pneumonia or septicaemia and one to myocarditis. CONCLUSION: In a population with no general varicella vaccination programme, varicella accounted for a small but not negligible risk for death in immunocompetent and immunocompromised children. Together these data point to the importance of a thoroughly implemented, general varicella vaccination programme.

Real-time PCR for diagnosis of human bocavirus infections and phylogenetic analysis.

The human bocavirus (hBoV) was first described in 2005 in respiratory tract samples. The clinical relevance of hBoV is still unclear. The aim of our study was to establish a real-time PCR assay for the detection and quantification of hBoV DNA, to apply the real-time assay for the analysis of stool and serum samples for the presence of hBoV DNA, and to perform a phylogenetic analysis of the hBoV positive samples. A total of 834 nasopharyngeal aspirates (NPA), 10 serum samples, and 31 stool samples of children with acute respiratory diseases were retrospectively tested. For phylogenetic analysis, 968 bp of the VP2 gene were sequenced from 69 hBoV-positive NPA samples. The qualitative results of the real-time hBoV PCR were in good agreement with a conventional hBoV PCR. We found that 12% of the NPA were positive for hBoV DNA. The median viral load in the NPA was 4.9 x 10(3) copies/ml (range, 2.7 x 10 degrees to 1.5 x 10(11) copies/ml). There was no difference of the hBoV load in NPA between children with or without known coinfection, but the load was significantly higher in children with bronchitis than in children with the diagnosis of febrile seizures. hBoV DNA was found in 1 of 10 serum samples and in 14 of 31 stool samples. hBoV sequence identity was >99% in the VP2 region. In conclusion, hBoV DNA can be found in NPA samples at very high titers. In addition to being found in the respiratory tract, hBoV was found in stool samples. The clinical relevance of these findings remains to be determined.

Safety, reactogenicity, and immunogenicity of live attenuated varicella vaccine in children between 1 and 9 years of age with atopic dermatitis.

INTRODUCTION: Infection with varicella-zoster virus (VZV) is known to facilitate secondary bacterial infection, which is cause for particular concern in children with atopic dermatitis. This 2-year study assessed the safety, reactogenicity, and immunogenicity of a live attenuated Oka strain varicella vaccine (Varilrix, GlaxoSmithKline Biologicals) in 160 children aged 1-9 years with atopic dermatitis randomized to vaccination at the start of either the 1st or 2nd study year (VAR-1Y and VAR-2Y, respectively). Mean SCORing Atopic Dermatitis (SCORAD) scores at baseline were 19.3+/-11.1 and 26.0+/-10.4 in the two groups, respectively. RESULTS: Varicella vaccination did not adversely affect the severity of atopic dermatitis, with analysis of variance (ANOVA) confirming equivalence for the change in SCORAD index from baseline to week 8 between vaccinated and unvaccinated subjects. Within-group comparison of post-vaccination changes in SCORAD index from baseline to week 8 and month 12 in the VAR-2Y group showed a greater reduction in mean SCORAD scores following vaccination in year 2 than in year 1 when subjects were unvaccinated. Overall, SCORAD indices fell by approximately 10 points in both study groups over the 2 years of follow-up. Varicella vaccination was well tolerated, with no children withdrawn due to adverse events. Injection site redness was the most frequent solicited adverse event, occurring in 17.1% of subjects. Seroconversion rates were 94.3% at week 8 and 88.9% at month 12. In all, 43.6% of vaccinees reported at least one varicella contact during the course of the study. However, none developed varicella infection after vaccination over the 2 years of follow-up. CONCLUSION: In summary, vaccination with a live attenuated varicella vaccine appears safe and effective in children with atopic dermatitis.

Frequent detection of bocavirus DNA in German children with respiratory tract infections.

BACKGROUND: In a substantial proportion of respiratory tract diseases of suspected infectious origin, the etiology is unknown. Some of these cases may be caused by the recently described human bocavirus (hBoV). The aim of this study was to investigate the frequency and the potential clinical relevance of hBoV in pediatric patients. METHODS: We tested 835 nasopharyngeal aspirates (NPA) obtained between 2002 and 2005 from pediatric in-patients with acute respiratory tract diseases at the University of Würzburg, Germany, for the presence of hBoV DNA. The specificity of positive PCR reactions was confirmed by sequencing. RESULTS: HBoV DNA was found in 87 (10.3 %) of the NPAs. The median age of the infants and children with hBoV infection was 1.8 years (mean age 2.0 years; range 18 days - 8 years). Infections with hBoV were found year-round, though most occurred in the winter months. Coinfections were found in 34 (39.1 %) of the hBoV positive samples. RSV, influenza A, and adenoviruses were most frequently detected as coinfecting agents. Sequence determination of the PCR products in the NP-1 region revealed high identity (99 %) between the nucleotide sequences obtained in different years and in comparison to the Swedish viruses ST1 and ST2. An association of hBoV with a distinct respiratory tract manifestation was not apparent. CONCLUSION: HBoV is frequently found in NPAs of hospitalized infants and children with acute respiratory tract diseases. Proving the clinical relevance of hBoV is challenging, because application of some of Koch's revised postulates is not possible. Because of the high rate of coinfections with hBoV and other respiratory tract pathogens, an association between hBoV and respiratory tract diseases remains unproven.

Bruton's tyrosine kinase is activated upon CD40 stimulation in human B lymphocytes.

Bruton's tyrosine kinase (Btk) is known to be involved in a broad array of signal transduction pathways necessary for the proliferation, survival and development of B cells. Mutations in the Btk gene are causually linked to the development of X-linked agammaglobulinemia (XLA) in humans. We show here, that CD40 ligation leads to tyrosine phosphorylation of Btk in the human immature B cell line MHH-PREB-1. Even though the CD40-mediated tyrosine phosphorylation of Btk is less efficient than that mediated through the B cell receptor, CD40 stimulation results in a marked and continous activation of Btk in MHH-PREB-1 cells and, to a lesser extent, in a transient Btk activation in Daudi cells. Furthermore, in Daudi cells we observed that tyrosine phosphorylation and activation of Btk is correlated with its translocation from the cytosolic to the membraneous fraction. These data suggest that, in addition to the BCR, CD40 is a surface receptor through which the activity of Btk can be stimulated in human B cells.

Unimpaired activation of c-Jun NH2-terminal kinase (JNK) 1 upon CD40 stimulation in B cells of patients with X-linked agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is caused by mutations in the gene encoding the cytoplasmic Bruton's tyrosine kinase (Btk). Btk has been shown to play an essential role in the development of B1 (CD5+) and conventional circulating mature B cells (B2) in mouse and man. It has been shown in earlier studies that Btk is involved in both the BCR- and CD40-mediated signaling pathways. In this study, we analyzed the responsiveness of Epstein-Barr virus (EBV) transformed B cells from nine XLA patients to CD40 stimulation, particularly the CD40 induced activation of c-Jun N-terminal kinase (JNK). In eight XLA patients the JNK activation was unimpaired and in one case INK could not be activated by anti-CD40 stimulation. Btk protein expression was detectable by Western blotting in six cases, in one case Btk expression was drastically reduced, and in three cases no Btk expression could be observed. Btk kinase activity was found in three cases and it was reduced in one and not detectable in five cases. Furthermore, in one female patient with an agammaglobulinemia, Btk expression and function as well as JNK activation by CD40 stimulation was unimpaired. Our findings demonstrate that INK activation via the CD40 signaling pathway is intact in EBV-transformed B cells of most if not all XLA patients, independent of the mutation and its effect on Btk expression and kinase activity. We suggest that Btk is not necessary for the activation of INK upon CD40 stimulation, at least in the B cell subpopulation we had studied. We cannot exclude that these B cells belong to a "leaky" B-cell subpopulation in which the CD40 signaling pathway has become independent of Btk function.