Transcription of genes encoding iron and heme acquisition proteins of Haemophilus influenzae during acute otitis media

Paul W. Whitby, Kim Eng Sim, Daniel J. Morton, Janak Patel, Terrenck L. Stull

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Unencapsulated Haemophilus influenzae is the second most common etiologic agent of otitis media in children. H. influenzae requires heme for aerobic growth in vitro and is able to utilize hemoglobin and complexes of heme-hemopexin, heme-albumin, and hemoglobin-haptoglobin and ferritransferrin as sources of iron and heme in vitro. Several of the acquisition mechanisms have been characterized and been shown to be heme repressible in vitro. However, little is known about the expression of heme and/or iron acquisition mechanisms during infections in the middle ear. This study was performed to determine if the genes encoding heme and iron acquisition proteins are transcribed during in vivo growth and to compare these findings with those for samples grown in vitro. Reverse transcriptase PCR (RT-PCR) was used to analyze total RNA fractions derived from in vitro- and in vivo-grown H. influenzae. Genes encoding the transferrin-binding proteins TbpA and TbpB, the 100-kDa hemopexin-binding protein HxuA, and the hemoglobin-binding protein HgpA were transcribed during otitis media. Twelve middle car fluid samples were analyzed by blind RT-PCR to determine the transcriptional status of these genes in H. influenzae during otitis media. Five isolates had transcripts corresponding to tbpA, tbpB, and hxuA. The presence of hgpA transcripts was variable, depending on the presence of hgpA in the genome of the H. influenzae isolate. Samples without H. influenzae gene transcripts contained other etiologic agents commonly causing otitis media. These data demonstrate that H. influenzae iron and/or heme acquisition genes are transcribed during otitis media and suggest that the microenvironment during acute otitis media starves H. influenzae of heme.

Original languageEnglish (US)
Pages (from-to)4696-4700
Number of pages5
JournalInfection and Immunity
Volume65
Issue number11
StatePublished - 1997
Externally publishedYes

Fingerprint

Haemophilus influenzae
Otitis Media
Heme
Iron
Genes
Proteins
Hemopexin
Hemoglobins
Reverse Transcriptase Polymerase Chain Reaction
Transferrin-Binding Protein A
Transferrin-Binding Protein B
Carrier Proteins
Haptoglobins
Middle Ear
Growth
Albumins
In Vitro Techniques
Genome
RNA
Infection

ASJC Scopus subject areas

  • Immunology

Cite this

Whitby, P. W., Sim, K. E., Morton, D. J., Patel, J., & Stull, T. L. (1997). Transcription of genes encoding iron and heme acquisition proteins of Haemophilus influenzae during acute otitis media. Infection and Immunity, 65(11), 4696-4700.

Transcription of genes encoding iron and heme acquisition proteins of Haemophilus influenzae during acute otitis media. / Whitby, Paul W.; Sim, Kim Eng; Morton, Daniel J.; Patel, Janak; Stull, Terrenck L.

In: Infection and Immunity, Vol. 65, No. 11, 1997, p. 4696-4700.

Research output: Contribution to journalArticle

Whitby, PW, Sim, KE, Morton, DJ, Patel, J & Stull, TL 1997, 'Transcription of genes encoding iron and heme acquisition proteins of Haemophilus influenzae during acute otitis media', Infection and Immunity, vol. 65, no. 11, pp. 4696-4700.
Whitby, Paul W. ; Sim, Kim Eng ; Morton, Daniel J. ; Patel, Janak ; Stull, Terrenck L. / Transcription of genes encoding iron and heme acquisition proteins of Haemophilus influenzae during acute otitis media. In: Infection and Immunity. 1997 ; Vol. 65, No. 11. pp. 4696-4700.
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