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George M. Carlone - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of P1-deficient isogenic mutant of Haemophilus influenzae biogroup aegyptius associated with Brazilian Purpuric Fever.
    Microbial pathogenesis, 2000
    Co-Authors: Lynn M. Segada, George M. Carlone, Linda L. Gheesling, Alan J. Lesse
    Abstract:

    Haemophilus influenzae biogroup aegyptius (formerly H. aegyptius) is the etiologic agent of Brazilian Purpuric Fever (BPF). A surface-exposed epitope on the outer membrane protein P1 is present on most strains of H. influenzae biogroup aegyptius associated with BPF but is absent in almost all non-disease associated strains. The role of the outer membrane protein P1 in the pathogenesis of this disease was evaluated by utilizing an isogenic P1-deficient mutant. We compared the ability of the wild type and P1 isogenic mutant to grow under various conditions. The P1-deficient strain grew at a similar rate to the wild type in both complex and chemically defined medium. The P1-deficient mutant also had a similar growth rate to the wild type under anaerobic conditions. Anaerobic growth, however, resulted in up-regulation of the P1 protein in the wild type strain. Three assays were used to examine the pathophysiologic role of the P1 protein in BPF: 1) serum resistance; 2) sustained bacteremia in the infant rat model; and 3) the human microvascular endothelial cell (HMEC) cytotoxicity assay. Both the mutant and wild-type strains were resistant to killing in 95% normal human serum. The P1-deficient strain was also as virulent as the wild type in both the infant rat model of bacteremia and in the HMEC-1 tissue culture model. These results demonstrate that serum resistance, sustained bacteremia in the infant rat, and cytotoxicity of HMEC cells occur in the absence of P1. The P1 protein is not essential for the pathogenic potential identified by these assays. However, these results demonstrate that an anaerobic environment is a potent physiologic regulator of P1 protein expression. The impact of anaerobiosis on protein expression and pathogenesis will require further investigations.

  • Febre purpúrica brasileira, virulência em modelo animal do Haemophilus Aegyptius (H. influenzae biogrupo aegyptius)
    Revista do Instituto de Medicina Tropical de Sao Paulo, 1993
    Co-Authors: M. C. C. Brandileone, V. S. D. Vieira, M. L. C. Tondella, Rosemeire Cobo Zanella, L. Gheesling, George M. Carlone
    Abstract:

    Brazilian Purpuric Fever (BPF) is caused by invasive strains of Haemophilus aegyptius (H.influenzae biogroup aegyptius, Hae). These strains were differentiated from Hae strains associated only with conjunctivitis (non-invasive Hae strains) through specific molecular markers. Complement-depleted infant rat model was used to study the invasive and non-invasive Hae strains to compare their virulence potential. Inoculating 105 bacteria in the rats, the invasive strains caused 80 to 100% bacteremia and the intensity of bacteremia was 102,5±0,49 to > 104,69 cfu/ml of blood. Using the same infectious dose, the non-invasive strains did not cause frequent bacteremia (0 to 50%) and the intensity was 0 to 103,69±0,53 cfu/ml of blood. The infectious doses able to cause 50% of bacteremia in the rats (BD 50%) varied from 107,3 bacteria for non-invasive strains. Passive immunization using antisera to invasive strains protected rats against bacteremia caused by homologous strains, but not by heterologous strain. By comparing the bacteremia caused by Hae and bacteremia caused by H. influenzae b (Eagan strain, Hib), it was demonstrated that Hib had higher virulence potential. This animal model was useful to clarify the virulence potential of invasive Hae strains.

  • Stable, conserved outer membrane epitope of strains of Haemophilus influenzae biogroup aegyptius associated with Brazilian Purpuric Fever.
    Infection and immunity, 1992
    Co-Authors: Alan J. Lesse, Linda L. Gheesling, Sheila D. Myers, William E. Bittner, George M. Carlone
    Abstract:

    Brazilian Purpuric Fever is a rapidly fatal childhood disease associated with a clonal strain of Haemophilus influenzae biogroup aegyptius. We describe a conserved, surface-exposed epitope present on 95% of H. influenzae biogroup aegyptius isolates that are associated with Brazilian Purpuric Fever. This epitope, defined by reaction with the monoclonal antibody 8G3, is on or associated with the 48-kDa heat-modifiable P1 protein. The epitope is absent on strains of H. influenzae biogroup aegyptius that are not associated with Brazilian Purpuric Fever but is present on one strain of H. influenzae biotype II. None of 81 other Haemophilus strains tested reacted with 8G3. The sensitivity and specificity of the 8G3 monoclonal antibody in detecting Brazilian case-clone strains of H. influenzae biogroup aegyptius associated with Brazilian Purpuric Fever are 95 and 99%, respectively. Immunoelectron microscopy revealed that the epitope is surface exposed, and N-terminal amino acid sequencing of an 8G3-reactive P1 protein from a strain of H. influenzae biogroup aegyptius showed 100% correlation with the published N-terminal amino acid sequence of a P1 protein of H. influenzae type b. The virulence of the organism in an infant rat model of bacteremia was not dependent on the expression of this epitope.

  • Stable, Conserved Outer Membrane Epitope of Strains of Haemophilus influenzae Biogroup aegyptius Associated with Brazilian Purpuric Fever
    1991
    Co-Authors: Alan J. Lesse, Linda L. Gheesling, William E. Bitfner, Sheila D. Myers, George M. Carlone
    Abstract:

    Brazilian Purpuric Fever is a rapidly fatal childhood disease associated with a clonal strain of Haemophilus influenzae biogroup aegyptius. We describe a conserved, surface-exposed epitope present on 95 % of H. influenzae biogroup aegyptius isolates that are associated with Brazilian Purpuric Fever. This epitope, defined by reaction with the monoclonal antibody 8G3, is on or associated with the 48-kDa heat-modifiable P1 protein. The epitope is absent on strains of H. influenzae biogroup aegyptius that are not associated with Brazilian Purpuric Fever but is present on one strain of H. influenzae biotype II. None of 81 other Haemophilus strains tested reacted with 8G3. The sensitivity and specificity of the 8G3 monoclonal antibody in detecting Brazilian case-clone strains ofH. influenzae biogroup aegyptius associated with Brazilian Purpuric Fever are 95 and 99%o, respectively. Immunoelectron microscopy revealed that the epitope is surface exposed, and N-terminal amino acid sequencing of an 8G3-reactive P1 protein from a strain ofH. influenzae biogroup aegyptius showed 100%v correlation with the published N-terminal amino acid sequence of a P1 protein of H. influenzae type b. The virulence of the organism in an infant rat model of bacteremia was not dependent on the expression of this epitope. Brazilian Purpuric Fever (BPF) is a newly described fatal pediatric disease first recognized in Promissao, Sao Paul

Alan J. Lesse - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of P1-deficient isogenic mutant of Haemophilus influenzae biogroup aegyptius associated with Brazilian Purpuric Fever.
    Microbial pathogenesis, 2000
    Co-Authors: Lynn M. Segada, George M. Carlone, Linda L. Gheesling, Alan J. Lesse
    Abstract:

    Haemophilus influenzae biogroup aegyptius (formerly H. aegyptius) is the etiologic agent of Brazilian Purpuric Fever (BPF). A surface-exposed epitope on the outer membrane protein P1 is present on most strains of H. influenzae biogroup aegyptius associated with BPF but is absent in almost all non-disease associated strains. The role of the outer membrane protein P1 in the pathogenesis of this disease was evaluated by utilizing an isogenic P1-deficient mutant. We compared the ability of the wild type and P1 isogenic mutant to grow under various conditions. The P1-deficient strain grew at a similar rate to the wild type in both complex and chemically defined medium. The P1-deficient mutant also had a similar growth rate to the wild type under anaerobic conditions. Anaerobic growth, however, resulted in up-regulation of the P1 protein in the wild type strain. Three assays were used to examine the pathophysiologic role of the P1 protein in BPF: 1) serum resistance; 2) sustained bacteremia in the infant rat model; and 3) the human microvascular endothelial cell (HMEC) cytotoxicity assay. Both the mutant and wild-type strains were resistant to killing in 95% normal human serum. The P1-deficient strain was also as virulent as the wild type in both the infant rat model of bacteremia and in the HMEC-1 tissue culture model. These results demonstrate that serum resistance, sustained bacteremia in the infant rat, and cytotoxicity of HMEC cells occur in the absence of P1. The P1 protein is not essential for the pathogenic potential identified by these assays. However, these results demonstrate that an anaerobic environment is a potent physiologic regulator of P1 protein expression. The impact of anaerobiosis on protein expression and pathogenesis will require further investigations.

  • Creation of an isogenic P1-deficient mutant of Haemophilus influenzae biogroup aegyptius.
    Gene, 1997
    Co-Authors: Lynn M. Segada, Alan J. Lesse
    Abstract:

    Abstract Haemophilus influenzae biogroup aegyptius, the causative agent of Brazilian Purpuric Fever (BPF), expresses a heat-modifiable 48 kDa outer membrane protein, P1, which is conserved in most Brazilian case-clone isolates. To study the role of P1 in pathogenesis of BPF we constructed via homologous recombination an isogenic P1-deficient mutant of H. influenzae biogroup aegyptius. The procedure involved a modification of Hererot's method for development of competence. Modifications included variations in the growth conditions, use of cAMP, specific charcteristics of the donor DNA, and antibiotic selection. P1-deficient mutants were confirmed by SDS–PAGE, loss of reactivity with a specific monoclonal antibody on Western blot, restriction analysis and Southern blot. Our results establish the first successful transformation of homologous DNA into H. influenzae biogroup aegyptius.

  • DNA sequence analysis and restriction fragment length polymorphisms of the P1 gene of Haemophilus influenzae biogroup aegyptius associated with Brazilian Purpuric Fever.
    Infection and immunity, 1996
    Co-Authors: Robyn B. Reed, Sheila D. Myers, Jeff B. Frost, Kristy Kort, Alan J. Lesse
    Abstract:

    Brazilian Purpuric Fever (BPF) is a fulminant pediatric disease caused by specific strains of Haemophilus influenzae biogroup aegyptius. A conserved epitope on the P1 protein of strains of H. influenzae biogroup aegyptius is seen on most virulent isolates. The P1 protein from a Brazilian case-clone strain of H. influenzae biogroup aegyptius was analyzed by cloning and sequencing the gene. Three major variable regions are present within the P1 gene of the BPF clone in an architecture similar to that of the previously sequenced P1 genes from H. influenzae. The DNA sequence data of the P1 gene provided information for restriction fragment length polymorphism analyses among strains of H. influenzae biogroup aegyptius. Using PCR for amplification of the P1 gene, we found that AlwI restriction of this gene allowed for a highly accurate segregation of virulent strains of H. influenzae biogroup aegyptius associated with BPF. The strong association of virulent phenotypes with specific AlwI restriction patterns of the P1 gene provides a basis for the convenient and accurate identification of strains of H. influenzae biogroup aegyptius which cause BPF.

  • Expression of an immunoreactive 72 kDa protein in strains of Haemophilus influenzae biogroup aegyptius associated with Brazilian Purpuric Fever
    Microbial pathogenesis, 1993
    Co-Authors: Alan J. Lesse, William E. Bittner
    Abstract:

    Brazilian Purpuric Fever (BPF) is a newly described pediatric syndrome that results in significant morbidity and mortality. BPF is caused by specific phenotypic strains of Haemophilus influenzae biogroup aegyptius that are capable of intravascular survival. Immunoblotting of outer membrane proteins of H. influenzae biogroup aegyptius with normal human serum showed that most virulent strains of H. influenzae biogroup aegyptius associated with BPF expressed an immunologically prominent protein at 72 kDa. A corresponding protein in avirulent isolates migrated at 79 kDa. Although a minor component on SDS-PAGE analysis of the outer membrane, specific antibody against this protein is present in high concentrations in normal human serum.

  • Stable, conserved outer membrane epitope of strains of Haemophilus influenzae biogroup aegyptius associated with Brazilian Purpuric Fever.
    Infection and immunity, 1992
    Co-Authors: Alan J. Lesse, Linda L. Gheesling, Sheila D. Myers, William E. Bittner, George M. Carlone
    Abstract:

    Brazilian Purpuric Fever is a rapidly fatal childhood disease associated with a clonal strain of Haemophilus influenzae biogroup aegyptius. We describe a conserved, surface-exposed epitope present on 95% of H. influenzae biogroup aegyptius isolates that are associated with Brazilian Purpuric Fever. This epitope, defined by reaction with the monoclonal antibody 8G3, is on or associated with the 48-kDa heat-modifiable P1 protein. The epitope is absent on strains of H. influenzae biogroup aegyptius that are not associated with Brazilian Purpuric Fever but is present on one strain of H. influenzae biotype II. None of 81 other Haemophilus strains tested reacted with 8G3. The sensitivity and specificity of the 8G3 monoclonal antibody in detecting Brazilian case-clone strains of H. influenzae biogroup aegyptius associated with Brazilian Purpuric Fever are 95 and 99%, respectively. Immunoelectron microscopy revealed that the epitope is surface exposed, and N-terminal amino acid sequencing of an 8G3-reactive P1 protein from a strain of H. influenzae biogroup aegyptius showed 100% correlation with the published N-terminal amino acid sequence of a P1 protein of H. influenzae type b. The virulence of the organism in an infant rat model of bacteremia was not dependent on the expression of this epitope.

L G Rubin - One of the best experts on this subject based on the ideXlab platform.

  • Phase-Variable Expression Of The 145-Kda Surface Protein Of Brazilian Purpuric Fever Case-Clone Strains Of Haemophilus Influenzae Biogroup Aegyptius
    The Journal of infectious diseases, 1995
    Co-Authors: L G Rubin
    Abstract:

    Clonally related strains of Haemophilus influenzae biogroup aegyptius have recently been associated with Brazilian Purpuric Fever (BPF). Antibodies to a 145-kDa minor outer membrane protein (P145) are bactericidal and protect against experimental bacteremia. To determine if P145 is conserved among case-clone strains, case-clone strains were screened for P145 expression. Assays of a large number of colonies of each strain using colony immunoblot revealed colonies reactive with anti-P145 sera in all 17 case-clone strains. P145 was expressed at a low frequency (0.08%-2.2% of colonies) in 14 strains and at a high frequency (> 98%) in 3 strains. Expression of P145 by reactive colonies was confirmed by SDS-PAGE. Also, anti-P145-nonreactive variant colonies of P145-expressing strains were detected in 0.4%-1.5% of colonies. These findings indicate P145 is conserved among BPF case-clone strains and is subject to phase-variable expression.

  • Brazilian Purpuric Fever Clone of Haemophilus influenzae Biogroup aegyptius for Infant Rats
    1995
    Co-Authors: L G Rubin
    Abstract:

    for infant rats. of Haemophilus influenzae biogroup aegyptius virulence of the Brazilian Purpuric Fever clone Role of the 145-kilodalton surface protein i

  • Role of the 145-kilodalton surface protein in virulence of the Brazilian Purpuric Fever clone of Haemophilus influenzae biogroup aegyptius for infant rats.
    Infection and immunity, 1995
    Co-Authors: L G Rubin
    Abstract:

    Brazilian Purpuric Fever (BPF) is a fulminant infection associated with bacteremia with clonally related strains of Haemophilus influenzae biogroup aegyptius. Case-associated clone strains are more virulent for infant rats than are non-BPF case-associated H. influenzae biogroup aegyptius isolates. I sought to determine the possible role of P145, a 145-kDa surface protein of BPF case H. influenzae biogroup aegyptius clone isolates, in virulence. First, I compared the virulence of two case-associated clone isolates from the blood of children with BPF from Serrana, Brazil, which differed in P145 expression but were identical in all other phenotypic and genotypic characteristics studied. Twenty-four hours after intraperitoneal inoculation of infant rats, there was a significantly higher incidence (51 versus 26%; P = 0.035) and magnitude (2.9 +/- 5.8 versus 0.7 +/- 2.0 CFU/0.01 ml; P = 0.024) of bacteremia in rats inoculated with the P145-expressing strain. I next compared the virulence of a P145-expressing case-associated clone strain with two P145-nonexpressing phase variants of this strain. One variant exhibited a lower mean magnitude of bacteremia and one displayed a similar magnitude of bacteremia compared with that displayed the P145-expressing parental strain. P145-expressing revertants of the P145-nonexpressing strains exhibited the same virulence as the P145-negative variants from which they were derived. Colonies grown from blood cultures maintained the P145 phenotype of the inoculated strain. These results suggest that P145 expression does not contribute to the virulence of the BPF case clone strain for infant rats following intraperitoneal inoculation.

M. L. C. Tondella - One of the best experts on this subject based on the ideXlab platform.

  • Brazilian Purpuric Fever Caused By Haemophilus influenzae Biogroup Aegyptius Strains Lacking The 3031 Plasmid
    The Journal of infectious diseases, 1995
    Co-Authors: M. L. C. Tondella, Frederick D. Quinn, Bradley A. Perkins
    Abstract:

    Brazilian Purpuric Fever (BPF) is a life-threatening pediatric infection caused by Haemophilus influenzae biogroup aegyptius (Hae), an organism formerly associated with only self-limited purulent conjunctivitis. Strains of Hae causing BPF have a 24-MDa plasmid with a specific AccI restriction pattern designated 3031. This plasmid was thought to code for a virulence factor because it had been detected only among Hae strains isolated from BPF cases or their contacts. From 3 typical BPF cases recently identified in Sao Paulo State, sterile-site Hae isolates were obtained; these isolates were similar to earlier BPF-associated Hae except they did not possess a 3031 plasmid. HindIII restricted chromosomal DNA from these strains was probed with purified 3031 plasmid DNA under high-stringency conditions. There was no evidence that 3031 plasmid DNA had become chromosomally integrated. It appears that the 3031 plasmid does not code for BPF-specific virulence factors.

  • isolation of haemophilus aegyptius associated with Brazilian Purpuric Fever of chloropidae diptera of the genera hippelates and liohippelates
    Revista Do Instituto De Medicina Tropical De Sao Paulo, 1994
    Co-Authors: M. L. C. Tondella, M. C. C. Brandileone, V. S. D. Vieira, Kinue Irino, C H Paganelli, I M Bortolotto, O A Takano, Mezzacapa B Neto, Bradley A. Perkins
    Abstract:

    The recognition of the Brazilian Purpuric Fever (BPF) in 1984 led to a number of studies which showed a relation between this disease and conjunctivitis caused by Haemophilus aegyptius. The increase in cases of conjunctivitis in children associated with higher population density of eye gnats (Chloropidae: Hippelates) has been reported since last century. This phenomenon is related to the attraction that those flies show for the eyes, secretions and wounds, from where they feed on. Although there are evidences on the role of these flies in the mechanical transmission of seasonal bacterial conjunctivitis, the isolation of Haemophilus aegyptius from them in their natural habitat had not been demonstrated yet. In this study Haemophilus aegyptius associated to BPF was isolated from two pools of chloropids collected around the eyes of children with conjuntivitis which were identified as Liohippelates peruanus (Becker) and a new species Hippelates neoproboscideus.

  • Isolamento de Haemophiliis aegyptius associado à Febre Purpúrica Brasileira, de cloropídeos (Diptera) dos gêneros Hippelates e Liohippelates Isolation of Haemophilus aegyptius associated to Brazilian Purpuric Fever from Hippelates and Liohippelates f
    Universidade de São Paulo, 1994
    Co-Authors: M. L. C. Tondella, K. Irino, M. C. C. Brandileone, V. S. D. Vieira, C H Paganelli, I M Bortolotto, O A Takano, Mezzacapa B Neto, B. A. Perkins
    Abstract:

    O reconhecimento da Febre Purpúrica Brasileira (FPB), em 1984, originou uma série de estudos que revelaram uma correlação desta doença com conjuntivites causadas por Haemophiliis aegyptius. A associação do aumento de conjuntivites em crianças e a maior densidade populacional de cloropídeos do gênero Hippelates já havia sido verificada desde o século passado. Este fenômeno está relacionado ao tropismo que estes insetos apresentam pelos olhos, secreções e feridas de onde se alimentam. Embora haja evidências do papel destes cloropídeos na transmissão mecânica de conjuntivites bacterianas, o isolamento de Haemophilus aegyptius a partir dos mesmos, no seu habitat natural, ainda não havia sido verificado. No presente trabalho obtivemos o isolamento de cepas invasivas de Haemophilus aegyptius, associadas à FPB, de duas coleções de cloropídeos, classificados como Liohippelates peruanus e uma espécie nova, Hippelates neoproboscideus, coletados ao redor dos olhos de crianças com conjuntivite.The recognition of the Brazilian Purpuric Fever (BPF) in 1984 led to a number of studies which showed a relation between this disease and conjunctivitis caused by Haemophilus aegyptius. The increase in cases of conjunctivitis in children associated with higher population density of eye gnats (Chloropidae: Hippelates) has been reported since last century. This phenomenon is related to the attraction that those flies show for the eyes, secretions and wounds, from where they feed on. Although there are evidences on the role of these flies in the mechanical transmission of seasonal bacterial conjunctivitis, the isolation of Haemophilus aegyptius from them in their natural habitat had not been demonstrated yet. In this study Haemophilus aegyptius associated to BPF was isolated from two pools of chloropids collected around the eyes of children with conjuntivitis which were identified as Liohippelates peruanus (Becker) and a new species Hippelates neoproboscideus

  • Isolation of Haemophilus aegyptius associated with Brazilian Purpuric Fever, of Chloropidae (Diptera) of the genera Hippelates and Liohippelates
    Revista do Instituto de Medicina Tropical de Sao Paulo, 1994
    Co-Authors: M. L. C. Tondella, M. C. C. Brandileone, V. S. D. Vieira, Kinue Irino, C H Paganelli, I M Bortolotto, O A Takano, B Mezzacapa Neto, Bradley A. Perkins
    Abstract:

    O reconhecimento da Febre Purpurica Brasileira (FPB), em 1984, originou uma serie de estudos que revelaram uma correlacao desta doenca com conjuntivites causadas por Haemophiliis aegyptius. A associacao do aumento de conjuntivites em criancas e a maior densidade populacional de cloropideos do genero Hippelates ja havia sido verificada desde o seculo passado. Este fenomeno esta relacionado ao tropismo que estes insetos apresentam pelos olhos, secrecoes e feridas de onde se alimentam. Embora haja evidencias do papel destes cloropideos na transmissao mecânica de conjuntivites bacterianas, o isolamento de Haemophilus aegyptius a partir dos mesmos, no seu habitat natural, ainda nao havia sido verificado. No presente trabalho obtivemos o isolamento de cepas invasivas de Haemophilus aegyptius, associadas a FPB, de duas colecoes de cloropideos, classificados como Liohippelates peruanus e uma especie nova, Hippelates neoproboscideus, coletados ao redor dos olhos de criancas com conjuntivite.

  • Febre purpúrica brasileira, virulência em modelo animal do Haemophilus Aegyptius (H. influenzae biogrupo aegyptius)
    Revista do Instituto de Medicina Tropical de Sao Paulo, 1993
    Co-Authors: M. C. C. Brandileone, V. S. D. Vieira, M. L. C. Tondella, Rosemeire Cobo Zanella, L. Gheesling, George M. Carlone
    Abstract:

    Brazilian Purpuric Fever (BPF) is caused by invasive strains of Haemophilus aegyptius (H.influenzae biogroup aegyptius, Hae). These strains were differentiated from Hae strains associated only with conjunctivitis (non-invasive Hae strains) through specific molecular markers. Complement-depleted infant rat model was used to study the invasive and non-invasive Hae strains to compare their virulence potential. Inoculating 105 bacteria in the rats, the invasive strains caused 80 to 100% bacteremia and the intensity of bacteremia was 102,5±0,49 to > 104,69 cfu/ml of blood. Using the same infectious dose, the non-invasive strains did not cause frequent bacteremia (0 to 50%) and the intensity was 0 to 103,69±0,53 cfu/ml of blood. The infectious doses able to cause 50% of bacteremia in the rats (BD 50%) varied from 107,3 bacteria for non-invasive strains. Passive immunization using antisera to invasive strains protected rats against bacteremia caused by homologous strains, but not by heterologous strain. By comparing the bacteremia caused by Hae and bacteremia caused by H. influenzae b (Eagan strain, Hib), it was demonstrated that Hib had higher virulence potential. This animal model was useful to clarify the virulence potential of invasive Hae strains.

Luis A. Actis - One of the best experts on this subject based on the ideXlab platform.

  • 0 1999 The Pathological Society of Great Britain and Ireland BACTERIAL PATH OG EN I CITY
    2013
    Co-Authors: Laura M. Smoot, E. C. Bell, J. H. Crosa, Luis A. Actis
    Abstract:

    Fur and iron transport proteins in the Brazilian Purpuric Fever clone of Haemophilus influenzae biogroup aegyptiu

  • Characterization of the IgA1 protease from the Brazilian Purpuric Fever strain F3031 of Haemophilus influenzae biogroup aegyptius
    FEMS microbiology letters, 2005
    Co-Authors: Glen Mcgillivary, Laura M. Smoot, Luis A. Actis
    Abstract:

    Brazilian Purpuric Fever is a severe vascular disease caused by an invasive clone of Haemophilus influenzae biogroup aegyptius, which normally causes self-limiting eye infections. A previous genome subtraction procedure resulted in the isolation of a DNA fragment, which encodes a putative IgA1 protease, specific to the F3031 Brazilian Purpuric Fever type strain. Cloning and sequencing of the entire F3031 iga1 gene showed that the subtracted DNA fragment encompasses the iga1 region encoding the active site and the cleavage specificity determinant of the protein, which are different from the cognate regions of the proteases produced by other H. influenzae strains. Western and IgA cleavage assays together with clustering analysis showed that the F3031 IgA1 protease is most similar to the type 2 proteases produced by H. influenzae type c and e strains. Analysis of the promoter region of the F3031 iga1 gene revealed the presence of Fur binding sites. However, real-time PCR analysis and transcriptional fusion assays showed that the expression of iga1 is not regulated by iron or hemin under the conditions tested.

  • Cloning and Sequencing of a Genomic Island Found in the Brazilian Purpuric Fever Clone of Haemophilus influenzae Biogroup Aegyptius
    Infection and immunity, 2005
    Co-Authors: Glen Mcgillivary, Andrew P. Tomaras, Eric R. Rhodes, Luis A. Actis
    Abstract:

    A genomic island was identified in the Haemophilus influenzae biogroup aegyptius Brazilian Purpuric Fever (BPF) strain F3031. This island, which was also found in other BPF isolates, could not be detected in non-BPF biogroup aegyptius strains or in nontypeable or typeable H. influenzae strains, with the exception of a region present in the type b Eagan strain. This 34,378-bp island is inserted, in reference to H. influenzae Rd KW20, within a choline transport gene and contains a mosaic structure of Mu-like prophage genes, several hypothetical genes, and genes potentially encoding an Erwinia carotovora carotovoricin Er-like bacteriocin. The product of the tail fiber ORF in the bacteriocin-like region shows a hybrid structure where the C terminus is similar to an H. influenzae phage HP1 tail protein implicating this open reading frame in altering host specificity for a putative bacteriocin. Significant synteny is seen in the entire genomic island with genomic regions from Salmonella enterica subsp. enterica serovar Typhi CT18, Photorhabdus luminescens subsp. laumondii TT01, Chromobacterium violaceum, and to a lesser extent Haemophilus ducreyi 35000HP. In a previous work, we isolated several BPF-specific DNA fragments through a genome subtraction procedure, and we have found that a majority of these fragments map to this locus. In addition, several subtracted fragments generated from an independent laboratory by using different but related strains also map to this island. These findings underscore the importance of this BPF-specific chromosomal region in explaining some of the genomic differences between highly invasive BPF strains and non-BPF isolates of biogroup aegyptius.

  • Genomic Analysis of the F3031 Brazilian Purpuric Fever Clone of Haemophilus influenzae Biogroup Aegyptius by PCR-Based Subtractive Hybridization
    Infection and immunity, 2002
    Co-Authors: Laura M. Smoot, Glen Mcgillivary, Deanna D. H. Franke, Luis A. Actis
    Abstract:

    PCR-based subtractive genome hybridization produced clones harboring inserts present in Brazilian Purpuric Fever (BPF) prototype strain F3031 but absent in noninvasive Haemophilus influenzae biogroup aegyptius isolate F1947. Some of these inserts have no matches in the GenBank database, while others are similar to genes encoding either known or hypothetical proteins. One insert represents a 2.3-kb locus with similarity to a Thermotoga maritima hypothetical protein, while another is part of a 7.6-kb locus that contains predicted genes encoding hypothetical, phage-related, and carotovoricin Er-like proteins. The presence of DNA related to these loci is variable among BPF isolates and nontypeable H. influenzae strains, while neither of them was detected in strains of types a to f. The data indicate that BPF-causing strain F3031 harbors unique chromosomal regions, most of which appear to be acquired from unrelated microbial sources.

  • Fur and iron transport proteins in the Brazilian Purpuric Fever clone of Haemophilus influenzae biogroup aegyptius.
    Journal of medical microbiology, 1999
    Co-Authors: Laura M. Smoot, E. C. Bell, J. H. Crosa, Luis A. Actis
    Abstract:

    The Brazilian Purpuric Fever (BPF) clone of Haemophilus influenzae biogroup aegyptius causes a fatal septicaemic disease, resembling fulminant meningococcal sepsis, in children. When isolate F3031 was grown under iron-limiting conditions, the presence of several iron-regulated proteins of 38-110 kDa was revealed by electrophoretic analysis and a Fur homologue was shown by immunoblotting. Dot-blot assays and immunoblotting indicated that BPF cells bound human transferrin and contained transferrin-binding proteins in the outer membrane. However, the binding activity and the biosynthesis of these proteins were detected even under iron-rich conditions. Immunoblot analysis demonstrated the presence of a periplasmic protein related to the ferric iron-binding protein A (FbpA), the major iron-binding protein described in Neisseria spp. However, the FbpA homologue in strain F3031 was constitutively expressed and was smaller than the periplasmic protein detected in H. influenzae type b strain Eagan. The periplasm of strain F3031 also contained a protein related to the Streptococcus parasanguis FimA protein which recently has been shown to be involved in iron acquisition in Yersinia pestis. Although the Eagan and F3031 FimA homologues had a similar mol. wt, of 31 kDa, the expression of the BPF fimA-like gene was not regulated by the iron concentration of the culture medium.