Discovery of a Ni2+-dependent guanidine hydrolase in bacteria.

Nitrogen availability is a growth-limiting factor in many habitats1, and the global nitrogen cycle involves prokaryotes and eukaryotes competing for this precious resource. Only some bacteria and archaea can fix elementary nitrogen; all other organisms depend on the assimilation of mineral or organic nitrogen. The nitrogen-rich compound guanidine occurs widely in nature2-4, but its utilization is impeded by pronounced resonance stabilization5, and enzymes catalysing hydrolysis of free guanidine have not been identified. Here we describe the arginase family protein GdmH (Sll1077) from Synechocystis sp. PCC 6803 as a Ni2+-dependent guanidine hydrolase. GdmH is highly specific for free guanidine. Its activity depends on two accessory proteins that load Ni2+ instead of the typical Mn2+ ions into the active site. Crystal structures of GdmH show coordination of the dinuclear metal cluster in a geometry typical for arginase family enzymes and allow modelling of the bound substrate. A unique amino-terminal extension and a tryptophan residue narrow the substrate-binding pocket and identify homologous proteins in further cyanobacteria, several other bacterial taxa and heterokont algae as probable guanidine hydrolases. This broad distribution suggests notable ecological relevance of guanidine hydrolysis in aquatic habitats.

Eosinophil-selective mediators in human strongyloidiasis.

Strongyloides stercoralis infection is characterized by the production of IgE and eosinophils in peripheral blood. Experimental studies have demonstrated that eosinophils play an important role in protection against Strongyloides stercoralis, but the mechanisms regulating eosinophils are not known. In this study we have focused on analysing the molecules that selectively regulate eosinophil migration, namely eotaxin and interleukin-5 (IL-5), using an enzyme-linked immunosorbent assay in patients with strongyloidiasis. Serum expression of eotaxin and IL-5 were significantly increased in patients compared with the control group. This rise suggests that selective mediators of the eosinophil can have a role in immunity against S. stercoralis in human infection.

[Coverage of the 23-valent pneumococcal vaccine in those older than 64 years of age in the region of Castellon and Valencia, Spain]. / Cobertura de la vacuna antineumocócica 23-valente en los mayores de 64 años en el area de Castellón y Valencia.

The different serotypes of Streptococcus pneumoniae isolated from adults aged over 64 years in the Valencia and Castellon health region of Spain from June 1999 to December 2003 were analyzed. A total of 163 strains were evaluated; 58.3% were invasive, 47.24% were from respiratory source, and 4.9% were from exudates. The greatest percentage of samples was obtained from the group of patients aged 65 to 75 years (60.7%), while the lowest percentage was obtained from the group of patients aged over 85 years (10.4%). In the latter group, 53% of the strains were invasive and 29.4% were isolated from sputum. A total of 21 serotypes were identified, with the most common (> 3%) being: serotype 3 (22.1%); serotype 19 (12.9%); serotype 6 (12.3%); serotype 9 (8.6%); serotype 14 (10.4%); serotype 23 (8%); serotype 29 (3.7%); and serotype 18 (3.1%). Serotype 3 was the most common serotype found in all samples, with the exception of exudate, while serotype 23 was not isolated in blood. In this population group, the coverage of the 23-valent vaccine was 88.4%. Serotypes not included in this vaccine but isolated from invasive samples were serotypes 16, 24, 29 and 35. No changes were observed in serotype distribution over the 4-year period of the study. However, it is necessary to continue epidemiological monitoring to determine whether serotype substitution occurs.

Serotipos y sensibilidad antibiótica de Streptococcus pneumoniae en niños del área de Valencia y Castellón: estudio prospectivo multicéntrico / Serotypes and antibiotic susceptibility of Streptococcus pneumoniae in children in the health district of Valencia and Castellón, Spain: a multicenter, prospective trial

Se ha realizado un estudio para conocer los serotipos, la cobertura de la vacuna conjugada heptavalente (VCN 7-v) y la sensibilidad a los antibióticos de Streptococcus pneumoniae aislados en niños (<15 años) del área sanitaria de las provincias de Castellón y Valencia desde junio de 1999 hasta diciembre de 2002. En total se evaluaron 271 cepas, de las cuales el 15,5 por ciento fueron invasoras, el 63,5 por ciento de origen respiratorio y el 22,5 por ciento de exudados conjuntivales y óticos. El 67,2 por ciento de las cepas pertenecían a niños menores de 2 años. La distribución de los serotipos cambia ligeramente con la edad y el origen de la muestra; los más frecuentes fueron 19, 6, 23, 14, 3, 9 y 11, pero en los niños menores de 2 años el orden cambia a 19, 6, 14 y 23, 9, 11 y 3, y en las cepas invasoras es 19, 6, 14, 3 y 23. El 27,2 por ciento de las cepas fueron sensibles a los diez antibióticos probados. Frente a la penicilina, el 50,4 por ciento tuvieron sensibilidad disminuida y el 5,8 por ciento fueron altamente resistentes; el 98,3 por ciento fueron sensibles a la ampicilina y a amoxicilina-ácido clavulánico, y el 80,7 por ciento a la cefuroxima. El 52,5 por ciento fueron resistentes a la eritromicina y el 43,7 por ciento a la clindamicina. Ninguna cepa fue resistente a la rifampicina, la vancomicina, el levofloxacino ni la cefotaxima. Los serotipos más sensibles fueron el 3 y el 11, y los más resistentes el 14 (que siempre fue resistente a un antibiótico), 19, 6 y 23.Según los datos, la cobertura teórica de la VCN 7-v sería del 80,1 por ciento en los niños menores de 2 años y del 73,43 por ciento en los de 0 a 14 años (AU)

[Serotypes and antibiotic susceptibility of Streptococcus pneumoniae in children in the health district of Valencia and Castellón, Spain: a multicenter, prospective trial]. / Serotipos y sensibilidad antibiótica de Streptococcus pneumoniae en niños del área de Valencia y Castellón: estudio prospectivo multicéntrico.

A study was conducted to determine the serotypes, the coverage of the heptavalent conjugate vaccine (VCN 7-v) and the antibiotic susceptibility of Streptococcus pneumoniae in children (<15 years) in the health districts of the provinces of Castellon and Valencia, Spain, from June 1999 to December 2002. A total of 271 strains were evaluated, 15.5% of which were invasive, 63.5% were of respiratory origin and 22.5% were from conjunctival and otitic exudates; 67.2% of the strains were found in children younger than 2 years of age. The distribution of the serotypes showed slight changes according to age and the origin of the sample: the most common serotypes were 19, 6, 23, 14, 3, 9 and 11; however, in children younger than 2 years of age the order changed to 19, 6, 14 and 23, 9, 11 and 3, and in the invasive strains to 19, 6, 14, 3 and 23. A total of 27.2% of the stains were susceptible to the ten antibiotics tested. For penicillin, reduced susceptibility was found in 50.4% and high resistance in 5.8%; 98.3% were susceptible to ampicillin and amoxicillin-clavulanic acid, and 80.7% to cefuroxime; 52.5% were resistant to erythromycin and 43.7% to clindamycin. No strains were resistant to rifampicin, vancomycin, levofloxacin or cefotaxime. The most susceptible serotypes were 3 and 11, and the most resistant was 14 (which consistently showed resistance to an antibiotic), 19, 6 and 23. According to these data, the theoretical coverage of VCN 7-v would be 80.1% in children younger than 2 years and 73.43% in those aged 0-14 years.

Longitudinal analysis of human cytomegalovirus glycoprotein B (gB)-specific and neutralizing antibodies in AIDS patients either with or without cytomegalovirus end-organ disease.

Serum neutralizing and glycoprotein B (gB)-specific antibody levels were monitored prospectively in AIDS patients who either did or did not develop human cytomegalovirus (HCMV) end-organ disease, to delineate further the role of antibodies in protecting against HCMV disease. Antibody levels declined substantially (at least 4-fold) only in patients who developed HCMV disease; this decline in turn occurred concurrently with antigenemia. Nevertheless, AIDS patients who remained free of HCMV disease and did not become antigenemic during the follow-up period maintained stable levels of serum antibodies, with only minor fluctuations. The impact of HAART on the levels of functional anti-HCMV antibodies was investigated in a number of AIDS patients. Serum levels and kinetics of gB and neutralizing antibodies did not differ significantly between patients who responded biologically and virologically to therapy and those who failed to respond. In addition, CD4 + cell counts and HIV viral RNA levels did not correlate with anti-HCMV antibody titers.

Early neutralizing and glycoprotein B (gB)-specific antibody responses to human cytomegalovirus (HCMV) in immunocompetent individuals with distinct clinical presentations of primary HCMV infection.

BACKGROUND: Antibodies with functional anti-Human Cytomegalovirus (HCMV) activity are likely to be involved in preventing virus dissemination and thus may contribute to minimize the clinical manifestations of infection. OBJECTIVES: To investigate the role of humoral immunity in modulating the clinical expression of primary Human Cytomegalovirus (HCMV) infection in immunocompetent persons. STUDY DESIGN: Neutralizing (NA) and glycoprotein B (gB)-specific antibodies were quantitated in acute-phase and late-convalescence phase sera from 19 individuals who developed either HCMV mononucleosis (12) or oligosymptomatic hepatitis (seven). RESULTS: The levels of NA in sera drawn early after infection were significantly lower in the former patients than in the latter (P=0. 032). This difference was not related to either the total serum IgG levels and anti-HCMV IgGs avidity or to the presence of higher viral loads in blood, as assessed by detecting serum HCMV DNA by PCR, in patients experiencing mononucleosis. Increased NA titers were seen in all available late-convalescence sera. In these sera, median NA levels were not significantly different among the study groups. Antibodies to HCMV gB of both IgG and IgM classes were detected in all acute-phase sera analyzed. Median anti-gB IgG and IgM titers did not differ significantly between study groups. Likewise, the IgG subclass reactivity pattern against gB was found to be similar for both groups. CONCLUSIONS: The data revealed that an intense and early antibody response to gB developed in patients undergoing primary HCMV infection irrespective of the clinical manifestation of the disease. In contrast, a deficient NA response was observed in patients with HCMV mononucleosis versus that observed in patients displaying a milder form of disease-suggesting that the strength of NA response to HCMV generated early after infection might determine the severity of primary HCMV infection.

Antibody response to human cytomegalovirus (HCMV) glycoprotein B (gB) in AIDS patients with HCMV end-organ disease.

Human cytomegalovirus (HCMV)-specific antibody responses in HIV-1 infected individuals either with or without HCMV end-organ disease were examined to determine the whether development of HCMV disease was associated with a particular deficit in the antibody response. Antiwhole HCMV, anti-glycoprotein B (gB), and neutralizing antibody levels were higher in HIV-1 infected individuals than in healthy immunocompetent subjects, particularly in patients with AIDS either with or without HCMV-associated disease. Irrespective of location and spread of HCMV disease, patients who had received anti-HCMV therapy prior to sampling exhibited significantly higher anti-gB and neutralizing antibody titers than those who remained untreated. Likewise, patients with HCMV disease who were antigenemic or viremic had significantly lower anti-gB and neutralizing antibody titers than those who tested negative in either assay. Patients with untreated HCMV disease had significantly lower antibody titers than AIDS patients without disease. Analysis of the IgG subclass antibody responses to gB revealed no significant differences among HIV-1 infected individuals. These results suggest that levels of detectable anti-gB and HCMV neutralizing antibodies are inversely related to systemic viral load. Thus, antibodies with such specificities may be relevant in preventing the establishment of HCMV-associated disease or in modulating its progression.