Biodegradable Polymers Controlled Release Research On Rotavirus

Human Rotavirus(HRV) has played the primary part of acute diarrhea or death in infants from 3 months to 5 years old. It has been estimated that a lot of young children suffered from gastroenteritis and each year about 450,000 children died under the age of 5 worldwide, thanks to group A rotavirus infections. Currently, the commercially available oral rotavirus vaccines attenuated and inactivated exist disadvantages of stability, safety and effectiveness. In this paper, we use different biodegradable polymeric materials to prepare microspheres vaccines of SA11 rotavirus and study result in vitro and in vivo.Firstly, we used the hydrophobic poly(D,L-lactide-co-glycolide)(PLGA) as carrier material to prepare RV-PLGA microspheres. In this study, adding sucrose as stabilizer can improve encapsulation efficiency of antigen in inner aqueous phase and outer aqueous phase during the preparation process. The encapsulation efficiency of antigen can reach 43.41±1.61% and 35.67±1.66% when the ratio of the oil phase and the external aqueous phase is 1/4 and when the concentration of polymer is 160mg/m L. The surface of the microspheres observed is good and smooth by Scanning Electron Microscope(SEM).Secondly, we used the poly-D,L-lactide-poly(ethylene glycol)(PELA) owning hydrophilic groups as carrier material to prepare RV-PELA microspheres. In the study, the morphology of microsphere was observed by SEM. The size distribution of microspheres was determined using laser particle size analyzer and in vitro release and degradation behaviors were measured. The mice were immunized with different doses and the differences in different immunization times were determined with ELISA. The results show that RV-PELA microspheres have smooth appearance, the antigen can produce immune response in mice, and the microspheres can achieve purposes of sustaining antigen release.Finally, the star biodegradable material polylactic acid-4-arm-PEG copolymer(4-arm-PELA) was obtained and prepared RV-4-arm-PELA microspheres. In this study, we primarily report the ring-opening polymerization of Lac-OCA initiated by 4-arm-PEG using DMAP as an initiator and the characterization of the produced polymer. Then using the solvent evaporation method, the rotavirus antigen was encapsulated and obtained the 4-arm star PELA microspheres. The encapsulation efficiency of antigen can reach 43.78±1.35%, without adding any stabilizer. The experiment researches on in vitro release of antigens and in vitro degradation of microspheres prove that the release rate of antigens is slow; burst effect is not obvious and the degradation rate of the material is very slow. This study shows results that the star polymer material as a controlled release of drug is a good choice via immune in mice.