Viral co-infection does not reduce the efficacy of vaccination against non-typeable Haemophilus influenzae middle ear infection in a rat model

The mucosal vaccination of rodents with killed non-typeable Haemophilus influenzae (NTHi) has been previously shown to enhance live NTHi clearance following middle ear challenge. This study assessed the efficacy of mucosal anti-NTHi vaccination during a concomitant viral infection of the respiratory tract. Animals were mucosally immunised with killed NTHi by intra-Peyer's patch primary inoculation and lung (intratracheal) boost. At the time of both immunisations rats were also infected intra-nasally with Sendai virus. Concomitant Sendai virus infection did not influence the efficacy of anti-NTHi vaccination mediated clearance of NTHi from the middle ear. This would suggest that immunisation strategies to prevent bacterial middle ear infection would be effective despite the presence of concomitant viral agents.