Epitope-specific immune recognition of the nontypeable Haemophilus influenzae outer membrane protein 26

Immunological characterisation of truncated lipooligosaccharide-outer membrane protein based conjugate vaccine against Moraxella catarrhalis and nontypeable Haemophilus influenzae

Moraxella catarrhalis and nontypeable Haemophilus influenzae are important bacterial causes of otitis media in children and respiratory diseases in adults. Lipooligosaccharide (LOS) from M. catarrhalis and outer membrane protein 26 (OMP26) from NTHi are major surface antigens identified as potential vaccine components against these organisms. We previously constructed M. catarrhalis in which LOS is truncated, but contains a structure common to the three known serotypes of M. catarrhalis. OMP26 is known to enhance clearance of NTHi following vaccination in animal models, so was chosen as the carrier protein. In this study, we conjugated wild-type and truncated M. catarrhalis detoxified-LOS to a recombinant modified OMP26, rOMP26VTAL. Vaccination of mice with these conjugates resulted in a significant increase in anti-LOS and anti-rOMP26VTAL IgG levels. Importantly, mouse antisera showed complement-mediated bactericidal activity against all M. catarrhalis serotype A and B strains and a NTHi strain tested. Serotypes A & B make up more than 90% of isolates. These data suggest that the LOS and OMP based conjugate can be used as vaccine components and require further investigation in animal models.

Panel 6: Vaccines

Objective To review the literature on progress regarding (1) effectiveness of vaccines for prevention of otitis media (OM) and (2) development of vaccine antigens for OM bacterial and viral pathogens. Data Sources PubMed database of the National Library of Science. Review Methods We performed literature searches in PubMed for OM pathogens and candidate vaccine antigens, and we restricted the searches to articles in English that were published between July 2011 and June 2015. Panel members reviewed literature in their area of expertise. Conclusions Pneumococcal conjugate vaccines (PCVs) are somewhat effective for the prevention of pneumococcal OM, recurrent OM, OM visits, and tympanostomy tube insertions. Widespread use of PCVs has been associated with shifts in pneumococcal serotypes and bacterial pathogens associated with OM, diminishing PCV effectiveness against AOM. The 10-valent pneumococcal vaccine containing Haemophilus influenzae protein D (PHiD-CV) is effective for pneumococcal OM, but results from studies describing the potential impact on OM due to H influenzae have been inconsistent. Progress in vaccine development for H influenzae, Moraxella catarrhalis, and OM-associated respiratory viruses has been limited. Additional research is needed to extend vaccine protection to additional pneumococcal serotypes and other otopathogens. There are likely to be licensure challenges for protein-based vaccines, and data on correlates of protection for OM vaccine antigens are urgently needed. Implications for Practice OM continues to be a significant health care burden globally. Prevention is preferable to treatment, and vaccine development remains an important goal. As a polymicrobial disease, OM poses significant but not insurmountable challenges for vaccine development.

Development and antigenic characterization of three recombinant proteins with potential for Glässer's disease prevention

Haemophilus parasuis is the causative agent of Glässer's disease, which causes high morbidity and mortality in piglets, leading to severe economic losses. The lack of a commercial vaccine against a broad spectrum of strains has limited the disease control. H. parasuis outer membrane proteins (OMPs) are potentially essential components for vaccine formulation. In this study, seven putative OMPs were selected from the annotated H. parasuis serovar 5 genome; they were predicted by bioinformatics and annotated as potential virulence-related factors. These proteins were cloned, expressed, and purified as His-tagged proteins. Antigenicity of the candidate proteins was assessed using Western blotting with convalescent sera against H. parasuis serovar 5. The immunogenicity of the seven OMPs was assessed in a guinea pig model. Except VacJ, all the other six recombinant proteins elicited a detectable antibody response. Antisera against four of the selected proteins effectively killed the bacteria in vitro. Three proteins (Omp26, VacJ, and HAPS_0742) were found to confer significant protection against challenge with a lethal dose of H. parasuis in a guinea pig model. The results suggest that these three proteins have a strong potential to be vaccine candidates against Glässer's disease.