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 antib iotic therapies. To assist development of vaccines for preventing these inf ections, animal models have been established in rodents. These models have been used effectively to evaluate different vaccination strategies. Our stu dies have found that for respiratory tract infections caused by Streptococc us pneumoniae, nontypeable Haemophilus influenzae (NTHI) and Moraxella cata rrhalis, a primary immunisation targeted to the gut-associated lymphoid tis sue 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. pn eumoniae systemic immunisation was as effective. A strategy using these mod els has effectively been used to determine the potential of antigens from e ach of the pathogens to protect against infection. Antigens that demonstrat e significant vaccine potential have been used to investigate delivery syst ems. One of the major challenges that still exists is to find mechanisms th at will effectively deliver protein antigens to mucosal surfaces. Several s trategies have been investigated and resulted in varying degrees of success . (C) 2000 Elsevier Science B.V. All rights reserved.