| Target |
Advantages |
Drawbacks |
Preliminary data |
| Outer Membrane Protein - P1 |
Significant areas of conservation among typeable and nontypeable strains |
Only 1 epitope in common between 28 strains tested |
Rabbit antisera presented bactericidal activity against NTHi [42]. |
| Outer Membrane Protein - P2 |
reveals the presence of both heterogeneous and conserved surface-exposed loops of the P2 molecule among strains
Bactericidal antibodies to P2 are present in normal human sera |
Immunization with P2, did not enhance clearance as much as did immunization with P1 or P6. |
Induce the synthesis of antibodies protective against experimental Hib disease. Immunization with a P2-LOS complex in mice and purified P2 preparation in a rat model showed enhanced pulmonary clearance of a homologous strain of NTHi [22,43,44]. |
| Outer Membrane Protein - P4 |
One surface-exposed epitope was conserved |
Did not presented effective antigenicity |
After in vitro and vivo trials did not demonstrated effective antigenicity [36] |
| Outer Membrane Protein - P6 |
1 surface epitope common to all strains, conserved among encapsulated and nonencapsulated H. influenzaestrains |
Cannot be a transmembrane protein and is not conserved in all NTHi strains [49]. |
Mice and rabbits have been shown to produce bactericidal antibodies after systemic immunization with P6 and recombinant P6 [46-48]. |
| lipooligosaccharide (LOS)-tetanus toxoid (TT) |
Protective against NTHi strains |
Not yet tested in children |
Well tolerated in adults [50] |
| NTHi OMV |
Protective against NTHi strains. Various heterologous antigens in the vesicules |
Not yet tested in humans |
Tests in mice demonstrate a cross-protective immunization [51]. |
