Protection against measles virus-induced encephalitis by antibodies from mice immunized intranasally with a synthetic peptide immunogen.

Balb/c mice were immunized intranasally (i.n.) with a chimeric synthetic peptide containing two copies of a T- and one copy of a B-cell epitope (TTB) from measles virus (MV) fusion protein, plus cholera toxin B (CTB) adjuvant. The antibodies induced cross-reacted with, and neutralized MV and on passive transfer, protected mice against encephalitis induced by neuroadapated MV. Immunization with TTB alone induced antibodies which increased survival but not significantly compared to controls. Furthermore, i.n. immunization with TTB plus CTB induced TTB-specific IgA antibodies in saliva and nasal washes. Co-administration of CTB increased the affinity of antibodies to the B-cell epitope of TTB and caused a relative increase in the level of anti-peptide antibodies of the IgG2a subclass and the overall titre of IgG antibodies. These results indicate the potential of the i.n. route for immunization with synthetic peptide immunogens for induction of both local and systemic anti-peptide antibody responses.