Insertion sequence IS1016 and absence of Haemophilus capsulation genes in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius

Dobson, Simon; Kroll, J. Simon; Moxon, E. Richard

doi:10.1128/iai.60.2.618-622.1992

Cited by 23 publications

(7 citation statements)

References 20 publications

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“…HP1 is the second chromosomally integrated potentially exogenous genetic element discovered in the BPF clonal group and not present in conjunctivitis isolates. Like IS 1016 (Dobson et al ., 1992), it may contribute to the BPF phenotype through alteration in the pattern of expression of other genes, or may have imported as yet unidentified genes into the BPF chromosome. Further work will be needed for clarification, including complete sequencing of the HP1 locus in F3028.…”

Section: Discussionmentioning

confidence: 99%

“…All isolates examined have had a single multilocus enzyme electrophoresis (MLEE) type and SDS‐PAGE outer membrane protein profile and belong to one of two rDNA restriction patterns. In addition, members of the BPF clonal group possess distinct antigenic characteristics compared with non‐BPF strains and harbour at least two unique genetic elements: a ≈ 24 MDa cryptic plasmid and the H. influenzae insertion sequence IS 1016 (Brenner et al ., 1988; Musser and Selander, 1990; Dobson et al ., 1992).…”

Section: Introductionmentioning

confidence: 99%

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Identification and characterization of genomic loci unique to the Brazilian purpuric fever clonal group of H. influenzae biogroup aegyptius: functionality explored using meningococcal homology

Farrant

Langford

et al. 2003

Molecular Microbiology

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SummaryBrazilian purpuric fever (BPF) is a fulminant septicaemic infection of young children, caused by a clonal group of strains of Haemophilus influenzae biogroup aegyptius ( Hae ), an organism previously solely associated with conjunctivitis. Their special capacity to invade from the initial site of conjunctival infection is unexplained. A polymerase chain reaction (PCR)-amplified subtractive hybridization technique was used to identify genes specific to the BPF clonal group. A copy of bacteriophage HP1 and 46 further chromosomal loci were identified in the BPF but not in the conjunctivitis strain of Hae . Sixteen were characterized further, and one -encoding an analogue of the Legionella pneumophila epithelial cell entry-enhancing protein EnhC -was investigated in depth. Two genes, bpf001 and bpf002 , unique to the BPF clonal group were identified between homologues of HI1276 and HI1277 in a complex locus close to H. influenzae genetic island 1, recently identified in pathogenic H. influenzae type b. Bpf001 encodes a protein homologous to EnhC and to the previously uncharacterized product of the meningococcal gene NMB0419 . Functional studies of bpf001 proving intractable, NMB0419 was chosen as a surrogate for investigation and shown to modulate bacterial interaction with monolayers of human respiratory epithelial cells, promoting invasion, the first stage (for Hae ) in the pathogenesis of BPF.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identification and characterization of genomic loci unique to the Brazilian purpuric fever clonal group of H. influenzae biogroup aegyptius: functionality explored using meningococcal homology

Farrant

Langford

et al. 2003

Molecular Microbiology

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“…hicap implementation and validation 43 hicap uses a reference database to identify genes expected in the six cap loci (cap-a to cap-f). To this 44 end, a curated nucleotide sequence database of cap locus genes was constructed by extracting the 45 protein-coding sequences annotated from cap loci in publicly available sequences of well defined H. 46 influenzae serotypes (Table 1). Using this database, the process adopted by hicap to perform serotype 47 prediction from WGS assemblies is described in Figure 2.…”

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confidence: 99%

hicap:in silicoserotyping of theHaemophilus influenzaecapsule locus

Watts

Holt

2019

Preprint

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Haemophilus influenzae exclusively colonises the human nasopharynx and can cause a variety of respiratory infections as well as invasive diseases including meningitis and sepsis. A key virulence determinant of H. influenzae is the polysaccharide capsule of which six serotypes are known, each encoded by a distinct variation of the capsule biosynthesis locus (cap-a to cap-f). H. influenzae type b (Hib) was historically responsible for the majority of invasive H. influenzae disease and prevalence has been markedly reduced in countries that have implemented vaccination programs targeting this serotype. In the postvaccine era, non-typeable H. influenzae emerged as the most dominant group causing disease but in recent years a resurgence of encapsulated H. influenzae strains has also been observed, most notably serotype a. Given the increasing incidence of encapsulated strains and the high frequency of Hib in countries without vaccination programs, there is growing interest in genomic epidemiology of H. influenzae. Here we present hicap, a software tool for rapid in silico serotype prediction from H. influenzae genome sequences. hicap is written using Python3 and is freely available at https://github.com/scwatts/hicap under the GPL3 license. To demonstrate the utility of hicap, we used it to investigate the cap locus diversity and distribution in 691 high-quality H. influenzae genomes from GenBank. These analyses identified cap loci in 95 genomes and confirmed the general association of each serotype with a unique clonal lineage and also identified occasional recombination between lineages giving rise to hybrid cap loci (2% of encapsulated strains). 7 non-typeable H. influenzae (NTHi) [2]. 8Biosynthesis of the polysaccharide capsule is controlled by the cap loci (cap-a to cap-f), which 9 each include three contiguous but functionally distinct regions (I, II, and III) ( Figure 1). Regions I 10 and III are common to all six cap loci, and are associated with cellular transport (bex operon, region 11

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“…1). Finally, recent studies demonstrate that the BPF clone lacks any of the genes required for expression of a group II polysaccharide capsule like those found in other strains of H. influenzae (4,6). This finding makes it unlikely that enhanced virulence of the BPF clone is due to a polysaccharide capsule.…”

Section: Discussionmentioning

confidence: 89%

Role of lipooligosaccharide in virulence of the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius for infant rats

Rubin

Geme

1993

Infect Immun

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Clonally related strains of Haemophilus influenzae biogroup aegyptius have recently been associated with Brazilian purpuric fever (BPF), a fulminant, systemic disease in children. Using an infant rat bacteremia model for BPF, we found that a rat blood-passaged BPF isolate of H. influenzae biogroup aegyptius was more virulent than the original strain was. When compared with the original strain, the animal-passaged variant was found to display an altered lipooligosaccharide (LOS) phenotype and to lack pili. To examine the role of LOS phenotype and pili in virulence, we isolated isogenic variants differing in LOS phenotype or expression of pili. The virulence of variants was compared by examining the results of blood cultures obtained 24 h after intraperitoneal inoculation with 105 CFU. Our results indicate that the LOS phenotype is a critical determinant of BPF clone virulence for infant rats. To a lesser extent, the absence of piliation and an undefined additional factor(s) contribute to virulence.

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Insertion sequence IS1016 and absence of Haemophilus capsulation genes in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius

Cited by 23 publications

References 20 publications

Identification and characterization of genomic loci unique to the Brazilian purpuric fever clonal group of H. influenzae biogroup aegyptius: functionality explored using meningococcal homology

Identification and characterization of genomic loci unique to the Brazilian purpuric fever clonal group of H. influenzae biogroup aegyptius: functionality explored using meningococcal homology

hicap:in silicoserotyping of theHaemophilus influenzaecapsule locus

Role of lipooligosaccharide in virulence of the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius for infant rats

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