Induction of cytotoxic T-cell responses following oral immunization with synthetic peptides encapsulated in PLG microparticles.

CTL responses play a critical role in clearing viral infections. We have investigated the potential of poly(lactide-co-glycolide) (PLG) microparticles as an oral delivery system for peptides representing CTL epitopes from measles virus nucleoprotein. Oral administration of CTL epitopes encapsulated in 50:50 PLG microparticles, resulted in vivo priming of splenic peptide-specific CTL responses. However, the observed CTL lysis was low and cofeeding of encapsulated peptide with cholera toxin as a mucosal adjuvant did not result in any significant enhancement of the observed CTL responses. The pronounced immunostimulatory effect of microparticles, combined with their excellent tissue compatibility and biodegradability makes them a valuable delivery system for synthetic peptide immunogens. However, further work is needed to improve their efficiency via the oral route.