PROTECTION OF MICE FROM BORDETELLA-PERTUSSIS RESPIRATORY-INFECTION USING MICROENCAPSULATED PERTUSSIS FIMBRIAE

Conditions have been established which allow the efficient entrapment of Bordetella pertussis fimbriae in poly(lactide-co-glycolide) microspheres. Fimbriae released from the matrix were found to have retained some degree of conformational structure, as determined by assessing the capacity of fimbrial protein to bind to antibodies mapping to either conformational or denatured structures on the fimbriae. Following a single intraperitoneal injection, equivalent amounts of fimbriae, either encapsulated in microspheres with a mean diameter of 24 mu m and an estimated in vitro protein release rate of approximately 42 days, or conventionally adjuvanted with alhydrogel, elicited vigorous immune responses in mice. The encapsulated fimbriae appear to elicit marginally lower serum antibody levels than those induced by equivalent amounts of alhydrogel adjuvanted fimbriae. Mice immunised with both preparations were, however, protected against intranasal infection with live B. pertussis as evidenced by the significant reduction in levels of bacterial colonisation observed in the lungs and tracheas of immunised animals when compared to the immunologically naive controls.