Identification of surface-exposed B-cell epitopes on high molecular-weight adhesion proteins of nontypeable Haemophilus influenzae.

ABSTRACT The HMW1- and HMW2-like adhesion proteins of nontypeable Haemophilus influenzae are expressed by 75% of these strains, and antibodies directed against these proteins are protective in animal models of infection. The purpose of the present study was to define the functional activity of human antibodies specific for these proteins in an in vitro complement-dependent opsonophagocytic assay. Human promyelocytic cell line HL-60 served as the source of phagocytic cells, and a commercial preparation of intravenous immunoglobulin (IVIG) served as the source of human antibodies. High-molecular-weight (HMW) proteins were purified from four prototype nontypeable H. influenzae strains and used to prepare solid-phase affinity columns. IVIG was adsorbed on each column to remove strain-specific anti-HMW antibodies and to allow recovery of affinity-purified anti-HMW antibody fractions. Unadsorbed IVIG killed each of the prototype strains at titers of 1:80 to 1:320. HMW-adsorbed sera demonstrated fourfold decreases in opsonophagocytic titer against the homologous strains compared to unadsorbed IVIG. Affinity-purified anti-HMW antibody preparations demonstrated opsonophagocytic titers of 1:20 to 1:80 against the respective homologous strains and opsonophagocytic titers as high as 1:80 against heterologous strains. None of the affinity-purified anti-HMW antibody preparations was opsonophagocytic for a representative nontypeable H. influenzae strain that did not express HMW1- or HMW2-like proteins. These data demonstrate that human antibodies specific for the HMW1/HMW2-like adhesion proteins of nontypeable H. influenzae are opsonophagocytic and that such antibodies recognize epitopes shared by the HMW proteins of unrelated nontypeable H. influenzae strains. These results argue for continued investigation of the HMW1/HMW2-like proteins as potential vaccine candidates for prevention of disease due to nontypeable H. influenzae.

Download Full-text

Identification of New hmwA Alleles from Nontypeable Haemophilus influenzae

Infection and Immunity ◽

10.1128/iai.73.2.1221-1225.2005 ◽

2005 ◽

Vol 73 (2) ◽

pp. 1221-1225 ◽

Cited By ~ 8

Author(s):

I. Zafer Ecevit ◽

Kirk W. McCrea ◽

Carl F. Marrs ◽

Janet R. Gilsdorf

Keyword(s):

Molecular Weight ◽

Epithelial Cells ◽

Haemophilus Influenzae ◽

High Molecular Weight ◽

Nontypeable Haemophilus Influenzae ◽

Dna Variation ◽

High Molecular Weight Proteins ◽

Different Strains ◽

High Degree ◽

New Alleles

ABSTRACT High-molecular-weight proteins of Haemophilus influenzae mediate attachment to epithelial cells. Previous reports describe several allelic versions of hmwA genes that have different adherence properties. Here we report three new alleles of hmwA (hmwA from strain AAr96, hmwA from strain AAr105, and hmwA from strain G822), demonstrating the high degree of DNA variation of these genes among different strains.

Download Full-text