IMMUNOLOGICAL ANALYSIS OF THE PROTECTIVE RESPONSES TO THE CHIMERIC SYNTHETIC PEPTIDE REPRESENTING T-CELL AND B-CELL EPITOPES FROM THE FUSION PROTEIN OF MEASLES-VIRUS

The role of different adjuvant formulations and routes of immunization on the antibody responses and protection induced in mice was determin ed by a synthetic peptide representing T- and B- cell epitopes from th e measles virus (MV) fusion (F) protein (TTB peptide) which has previo usly been shown to induce protective responses against MV encephalitis in mice. When the peptide TTB was administered in Freud's complete ad juvant (FCA), Freud's imcomplete adjuvant (FIA), alum or with IL-2, an ti-peptide antibody responses and anti-MV antibody responses were dete cted. Interestingly, immunization with TTB without adjuvant resulted i n the induction of anti-peptide antibody responses which did not cross react with the MV. The use of FIA as an adjuvant led to a significant ly higher IgG2a antibody response compared with FCA and alum, whereas alum led to a significantly lower IgG3 response. Immunization with TTB in FCA, FIA and alum led to the generation of high affinity antibodie s (with alum generating the highest affinity), whereas immunization of peptide with IL-2 or in PBS resulted in the induction of antibodies o f lower affinity. Only the FCA, FIA and alum formulations led to the i nduction of protective responses in mice against MV-induced encephalit is. When the subcutaneous route (s.c.) of immunization was compared wi th the intraperitoneal route (i.p.), s.c. immunization with the TTB pe ptide led to higher anti-peptide and anti-MV antibody responses and hi gher affinity antibodies compared to those induced following i.p. immu nization. Mice receiving the TTB peptide via the s.c. route had a high er percentage survival after MV challenge than those immunized via the i.p. route. These results show that the nature of the adjuvant used a s well as the route of immunization play an important role in the indu ction of protective anti-TTB peptide antibody responses against MV-ind uced encephalitis in mice.