Biotechnological Approaches to Fight Pathogens at Mucosal Sites

Most interactions between host and pathogens occur at the host mucos al surfaces. Many pathogens, such as the human immunodeficiency virus (HIV), gain entry via the mucosa while others, including Candida, Streptococcus mutans and Helicobacter pylori , must become established at the mucosa to cause damage to the host. Strategies aimed at controlling pathogens at mucosal surfaces and infectious diseases in general are summarized in Figure 13.1. These include primarily vaccination and the use of antimicrobial chemotherapy, particularly antibiotics, which have both had an enormous impact on infectious disease (Cohen, 2000). Passive immunization has been used less with the advent of vaccines and antibiotics but is of increasing importance for treatment of immunocornpromised patients (Hammarstrom, 1999) whilst the development and use of topical microbicides is regarded as a potentially important means of preventing infection with HIV (Lange et al., 1993). Pathogens at mucosa( sites, however, present particular problems for these measures, e.g. antibiotics can be very effective in clearing systemic infections while being unable to affect mucosal carriage of the pathogen. A limited number of vaccines induce protective mucosal responses and vaccines are not yet available for several microorganisms that infect rnucos al surfaces. These observations, together with concern over the spread of antibiotic resistance (Hawkey, 1998; Irvin and Bautista, 1999), have stimulated investigation of additional antimicrobial strategies as well as refinement of existing approaches.