Open AccessAntibodies Specific for the Hia Adhesion Proteins of NontypeableHaemophilus influenzaeMediate Opsonophagocytic Activity
Author(s) -
Linda E. Winter,
Stephen J. Barenkamp
Publication year - 2009
Publication title -
clinical and vaccine immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.649
H-Index - 77
eISSN - 1556-6811
pISSN - 1556-679X
DOI - 10.1128/cvi.00090-09
Subject(s) - bacterial adhesin , biology , microbiology and biotechnology , haemophilus influenzae , heterologous , recombinant dna , plasmid , escherichia coli , antibody , gene knockout , epitope , gene , immunology , genetics , antibiotics
The Hia autotransporter proteins are highly immunogenic surface adhesins expressed by nontypeableHaemophilus influenzae (NTHI). The objective of our study was to assess the opsonophagocytic activity of anti-Hia antibodies against homologous and heterologous NTHI. A segment of thehia gene that encodes a surface-exposed portion of theH. influenzae strain 11 Hia protein was cloned into a pGEMEX-2 expression vector.Escherichia coli JM101 was transformed with the resulting pGEMEX-Hia BstEII del recombinant plasmid, and recombinant fusion protein was recovered. An immune serum against recombinant GEMEX-Hia (rGEMEX-Hia)-mediated killing of the homologous NTHI strain 11 at a 1:160 titer and five heterologous Hia-expressing strains at titers of ≥1:40. Immune serum did not mediate killing of two Hia-knockout strains whosehia genes were inactivated but did mediate killing of one knockout strain at a high titer after the strain was transformed with a plasmid containing thehia gene. Immune serum did not mediate killing of HMW1/HMW2-expressing NTHI strains, which do not express the Hia adhesin. However, when two representative HMW1/HMW2-expressing strains were transformed with the plasmid containing thehia gene, they expressed abundant Hia and were susceptible to killing by the immune serum. Immune serum did not mediate killing of HMW1/HMW2-expressing strains transformed with the plasmid without thehia gene. Our results demonstrate that the Hia proteins of NTHI are targets of opsonophagocytic antibodies and that shared epitopes recognized by such antibodies are present on the Hia proteins of unrelated NTHI strains. These data argue for the continued investigation of the Hia proteins as vaccine candidates for the prevention of NTHI disease.