Structural analysis of P6 from nontypable Haemophilus influenzae suggests that it is not a transmembrane protein

Abstract

The objective of our research was to identify an epitope in the outer membrane protein P6 of nontypable Haemophilus influenzae (NTHi). The long term goal of this research is to develop a protein/peptide vaccine against NTHi, as it is one of the major causes of pneumonia, bronchitis, ear infections, and other illnesses. Recombinant DNA technologies, nuclear magnetic resonance (NMR) spectroscopy and ELISA experiments were utilized to determine that residue 40 is part of the epitope to monoclonal antibody 7F3. This result, in light of structural analysis of the protein, suggests that P6 is not a transmembrane protein. From these findings, we were able to develop a novel hypothesis which describes P6 as an intracellular lipoprotein and raises doubt as to whether P6 can still be considered a viable vaccine candidate. This study was funded by NIH NIDCD RO1 08671 and the Rochester Institute of Technology.