Cloning and Sequencing of a Genomic Island Found in the Brazilian Purpuric Fever Clone of Haemophilus influenzae Biogroup Aegyptius

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.

Nucleotide Sequences and Organization of the Genes for Carotovoricin (Ctv) fromErwinia carotovoraIndicate That Ctv Evolved from the Same Ancestor asSalmonella typhiProphage

“…During the preparation of this manuscript, a genetic island containing prophage remnant genes was found in a Brazilian purpuric fever clone of the Haemophilus influenzae biogroup aegyptis. 33) Several hypothetical genes showed the mosaic structure of CtvEr genes and Mu-like prophage genes, and the structure of the entire genomic island showed significant similarity to the prophage in the Salmonella CT18 strain. Although the phage-like or bacteriocin-like biological activity of these genomic island gene products have not been mentioned, wide distribution of the related prophage or prophagelike elements among Erwinia, Haemophilus, Photorhabdus, and Clostridium is probable.…”

Genomic Sequence of an Otitis Media Isolate of Nontypeable Haemophilus influenzae : Comparative Study with H. influenzae Serotype d, Strain KW20

“…Because one of the most useful sets of data in the study of an organism's biology is its genomic sequence, a number of investigations have identified and characterized genes found in H. influenzae type b strains, H. influenzae biogroup Aegyptius strains or in nontypeable strains that are not present in strain Rd (13,17,30,60,64,82,106). Previously we carried out partial analyses and comparisons of the genomes of two NTHi strains, 1885MEE and 86-028NP, that were isolated from the middle ear and nasopharynx, respectively, of children with chronic otitis media (72).…”

The other siblings: Respiratory infections caused by Moraxella catarrhalis and Haemophilus influenzae

“…The plasmid, however, was subsequently found in non-BPF strains and some BPF strains did not contain the plasmid so that the virulence of the organism could not be explained by the BPF strain alone [47]. More recently, a chromosomal genomic island was identified in a Haemophilus influenzae biogroup aegyptius BPF strain 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 [48]. This genetic island could be important in characterizing the differences between BPF and non-BPF strains.…”