Interactions and Mechanisms of Respiratory Tract Biofilms Involving Streptococcus Pneumoniae and Nontypeable Haemophilus Influenzae

The pathology associated with human respiratory tract bacterial agents that exist as opportunistic commensals in the nasopharynx cause infections. This is particularly true for the middle ear disease otitis media (OM) and exacerbations of chronic obstructive pulmonary disease (COPD). Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are a commonly recurrent combination and the formation of bacterial biofilms by these pathogens in the bronchial airway or middle ear contributes significantly to the chronic nature of these diseases. While S. pneumoniae and NTHi have been extensively studied in mono-culture, our knowledge about how they exist together, either in their free-living (planktonic) form or as a biofilm, or indeed the implication of co-infection is still limited. Several key elements are believed to contribute or are induced: (1) a set of sugar metabolic pathways; (2) surface structures in S. pneumoniae and NTHi when they are able to co-exist equally; (3) epithelial cell contact that dramatically increases the rate of biofilm formation; (4) chemical modifications of NTHi surface structures involved in host cell interactions; and (5) transcription factors that regulate particular surface molecules and the switch to a biofilm state. There appears to be multiple mechanisms involved and that these are active under specific conditions

Mucosal Immunization with the Moraxella Catarrhalis Porin M35 Induces Enhanced Bacterial Clearance from the Lung: A Possible Role for Opsonophagocytosis

Moraxella catarrhalis is a significant cause of respiratory tract infection against which a vaccine is sought. Several outer membrane proteins are currently under investigation as potential vaccine antigens, including the porin M35. We have previously shown that the third external loop of M35 was immunodominant over the remainder of the protein for antibody produced in mice against the refolded recombinant protein. However, as this loop is predicted to fold inside the porin channel we also predicted that it would not be accessible to these antibodies when M35 is expressed on the surface of the bacteria in its native conformation. This study investigated the functional activity of antibodies against M35 and those specific for the loop 3 region of M35 in vitro and in vivo. Antisera from mice immunized with M35 or the loop 3-deletion, M35loop3−, recombinant proteins were not bactericidal but did have enhanced opsonic activity, whereas antibodies raised against the loop 3 peptide were not opsoniszing indicating that the immunodominant loop 3 of M35 was not accessible to antibody as we had previously predicted. Mucosal immunization with M35, M35 that had an antigenically altered loop 3 [M35(ID78)] and M35loop3− enhanced the clearance of M. catarrhalis from the lungs of mice challenged with live M. catarrhalis. The in vivo clearance of bacteria in the mice with the M35-derived protein constructs correlated significantly (p < 0.001) with the opsonic activity assessed an in vitro opsonophagocytosis assay. This study has demonstrated that the immunodominant B-cell epitope to loop 3 of the M. catarrhalis outer membrane protein M35 is not associated with immune protection and that M35-specific antibodies are not bactericidal but are opsoniszing. The opsoniszing activity correlated with in vivo clearance of the bacteria suggesting that opsoniszing antibody may be a good correlate of immune protection

Developmental Profiles of Mucosal Immunity in Pre-school Children

This study investigated the effect of attending pre-school on mucosal immunity. Children 3.5 to 5 years of age who attended pre-school were observed for a 10 month period. Demographic information was collected on previous childcare experiences, the home environment and clinical information relating to the child and the family. A daily illness log was kept for each child. A multivariate longitudinal analysis of the relation between immunoglobulins in saliva and age, gender, childcare experience, pre-school exposure, number of siblings, environmental tobacco smoke (ETS), atopy and hospitalisation was conducted. There was a positive association of higher IgA levels with the winter season and with children being older than 4 years (P < .001), having attended childcare prior to commencing pre-school (P < .05), and having been exposed to ETS at home (P < .05). Lower IgA levels were associated with being atopic (P < .05). Higher IgG levels were associated with exposure to ETS (P < .001), while lower levels were associated to having atopy. Higher IgM levels were associated with previous childcare experience (P < .01) whilst having been hospitalised was associated with having low salivary IgM levels (P < .01). Lagged analyses demonstrated that immunological parameters were affected by the number of respiratory infections in the preceding 2 months

Developmental Profiles of Mucosal Immunity in Pre-school Children

This study investigated the effect of attending pre-school on mucosal immunity. Children 3.5 to 5 years of age who attended pre-school were observed for a 10 month period. Demographic information was collected on previous childcare experiences, the home environment and clinical information relating to the child and the family. A daily illness log was kept for each child. A multivariate longitudinal analysis of the relation between immunoglobulins in saliva and age, gender, childcare experience, pre-school exposure, number of siblings, environmental tobacco smoke (ETS), atopy and hospitalisation was conducted. There was a positive association of higher IgA levels with the winter season and with children being older than 4 years (P < .001), having attended childcare prior to commencing pre-school (P < .05), and having been exposed to ETS at home (P < .05). Lower IgA levels were associated with being atopic (P < .05). Higher IgG levels were associated with exposure to ETS (P < .001), while lower levels were associated to having atopy. Higher IgM levels were associated with previous childcare experience (P < .01) whilst having been hospitalised was associated with having low salivary IgM levels (P < .01). Lagged analyses demonstrated that immunological parameters were affected by the number of respiratory infections in the preceding 2 months

Integration of post-graduate studies with corporately funded biotechnology programs

Post graduate research students need to undertake programs that will develop their potential as a scientist. They need to acquire skills to develop scientific argument, design an experimental approach to test a hypothesis, obtain and analyse data, and effectively communicate their ideas and findings to the scientific community. Many biotechnology-based programs are now funded by industry partnerships and integrating post graduate students into these programs require special considerations

Special edition editorial celebrating 25 years of publication

The conference celebrating 25 years of the journal Vaccine was an event worthy of the significance of the occasion. Held in the beautiful city ofAmsterdam at a magnificent new harborside venue, over 350 delegates enjoyed three days of vibrant presentations, robust discussions and enjoyable networking events. Over 250 papers were presented, with themes that highlighted the breadth, achievements and continuing challenges in the field of Vaccines

Towards a protein vaccine for nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHI), a gram-negative bacterium that is considered an important human pathogen, causes a broad spectrum of disease in both adults and children. An effective vaccine against NTHI would reduce the incidence of disease and reduce the dependency on antibiotic therapies as a means of defense. The results from immunization studies with whole killed-cell formulations of NTHI indicate that it is feasible to protect against NTHI infections by vaccination. The limitation of a whole-cell formulation is the considerable strain-heterogeneity in NTHI strains. Several proteins on the outer membrane appear highly conserved and offer potential as vaccine candidates

The roles of epithelial cell contact, respiratory bacterial interactions and phosphorylcholine in promoting biofilm formation by Streptococcus pneumoniae and nontypeable Haemophilus influenzae

Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) often share a common niche within the nasopharynx, both associated with infections such as bronchitis and otitis media. This study investigated how the association between NTHi and S. pneumoniae and the host affects their propensity to form biofilms. We investigated a selection of bacterial strain and serotype combinations on biofilm formation, and the effect of contact with respiratory epithelial cells. Measurement of biofilm showed that co-infection with NTHi and S. pneumoniae increased biofilm formation following contact with epithelial cells compared to no contact demonstrating the role of epithelial cells in biofilmformation. Additionally, the influence of phosphorylcholine (ChoP) on biofilm production was investigated using the licD mutant strain of NTHi2019 and found that ChoP had a role in mixed biofilm formation but was not the only requirement. The study highlights the complex interactions between microbes and the host epithelium during biofilm production, suggesting the importance of understanding why certain strains and serotypes differentially influence biofilm formation. A key contributor to increased biofilm formation was the upregulation of biofilm formation by epithelial cell factors

Identifying vaccine antigens and assessing delivery systems for the prevention of bacterial infections

Bacterial infections in the respiratory tract and middle ear continue to be a major cause of morbidity and mortality despite the availability of antibiotic therapies. To assist development of vaccines for preventing these infections, animal models have been established in rodents. These models have been used effectively to evaluate different vaccination strategies. Our studies have found that for respiratory tract infections caused by Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHI) and Moraxella catarrhalis, a primary immunisation targeted to the gut-associated lymphoid tissue was extremely effective in enhancing bacterial clearance. For the gram-negative pathogens, NTHI and M. catarrhalis, this mucosal immunisation was significantly more effective than systemic immunisation, however, for S. pneumoniae systemic immunisation was as effective. A strategy using these models has effectively been used to determine the potential of antigens from each of the pathogens to protect against infection. Antigens that demonstrate significant vaccine potential have been used to investigate delivery systems. One of the major challenges that still exists is to find mechanisms that will effectively deliver protein antigens to mucosal surfaces. Several strategies have been investigated and resulted in varying degrees of success

Comparison of mucosal and parenteral immunisation in two animal models of pneumococcal infection: otitis media and acute pneumonia

Bacterial clearance and immune responses in a mouse model of pneumonia and a rat model of otitis media following parenteral or mucosal immunisation in both models were compared. Both the immunisation routes were equally effective in inducing bacterial clearance from the lung, upregulated the recruitment of white cells and lead to an increase in the concentration of TNF-&#0945;, IL-1&#0946; and specific antibody in the bronchoalveolar lavage. Both the routes of immunisation enhanced clearance of bacteria from the middle ear. Parenteral immunisation was most effective overall in enhancing bacterial clearance and recruiting white cells to the middle ear. Both the routes significantly suppressed the levels of TNF-&#0945; in the middle ear lavage. Mucosal immunisation induced a Streptococcus pneumoniae-specific IgA antibody response. Both the animal models gave highly reproducible disease and provided high levels of sensitivity for testing the efficacy of candidate vaccine antigens. Differences observed in the inflammatory responses require further study