Jw. Stgeme et al., CHARACTERIZATION OF THE GENETIC-LOCUS ENCODING HAEMOPHILUS-INFLUENZAETYPE-B SURFACE FIBRILS, Journal of bacteriology, 178(21), 1996, pp. 6281-6287
Haemophilus influenzae is a common gram-negative pathogen that initiat
es infection by colonizing the upper respiratory tract epithelium. In
previous work, we reported the isolation of a locus involved in expres
sion of short, thin surface fibrils by H. influenzae type b and presen
ted evidence that surface fibrils promote attachment to human epitheli
al cells. In the present study, we determined that the fibril locus is
composed of one long open reading frame, designated hsf, which encode
s a protein (Hsf) with a molecular mass of similar to 240 kDa. The der
ived amino acid sequence of the hsf product demonstrated 81% similarit
y and 72% identity to a recently identified nontypeable H. influence a
dhesin referred to as Hia. In experiments with a panel of eight cultur
ed cell lines, the Hsf and Hia proteins were found to confer the same
binding specificities, suggesting that hsf and hia are alleles of the
same locus. Southern analysis and mutagenesis studies reinforced this
conclusion, Further investigation revealed that an hsf homolog is ubiq
uitous among encapsulated H, influenzae strains and is present in a su
bset of nontypeable Haemophilus strains as well, We speculate that the
hsf gene product plays an important role in the process of respirator
y tract colonization by H. influenzae.