The potential of retro-inverso peptides as synthetic vaccines.

Retro-inverso (RI) peptides, also called all-D-retro peptides, have been shown to mimic the antigenic and immunogenic properties of L-peptides successfully. RI peptides corresponding to the loop 141-159 of the VP1 protein of foot-and-mouth disease virus (FMDV) have been synthesized and used to immunize rabbits and guinea pigs. These peptides induced longer-lasting and higher antibody titres in immunized animals than did the corresponding L-peptides and the antibodies cross-reacted strongly with virus particles and with L-peptides. Antisera raised to RI peptides had in vitro virus neutralization titres equal to or better than those obtained after immunization with classical FMDV antigens and L-peptides. In view of their increased stability, RI peptides may overcome some of the shortcomings of synthetic viral vaccines based on L-peptides.