DEVELOP AND RHEOLOGICAL STUDY OF A THERMORESPONSIVE AND MUCOADHESIVE IN SITU GEL BASED ON POLOXAMER 407-CHITOSAN AS VACCINE DELIVERY SYSTEM OF POLYMERIC ANTIGEN BLSOMP31.

ALEJANDRA DIAZ; DANIELA A QUINTEROS; SILVINA GUTIERREZ; SANTIAGO PALMA; ALLEMANDI DA; VANESA ZYLBERMAN; F. A GOLDBAUM; S.M. ESTEIN

Mar del Plata

Congreso; XLVIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE FARMACOLOGÍA EXPERIMENTAL; 2016

Nanomedar -safe-sai-saic

Brucella ovis causes reproductive failure in sheep with significant economic losses. The only available vaccine is an attenuated strain which shows important drawbacks. Consequently, there is a need for developing of safe and efficient vaccines. Previous studies have showed that the polymeric antigen BLSOmp31 emulsified in Incomplete Freund Adjuvant (parenteral route) conferred significant protection against B. ovis in lambs. Immunization with BLSOmp31 by conjunctival route could be efficient for induction of immune response. However, this immunogen needs to be associated to an appropriate delivery system. Our aim was to develop and characterize a thermoresponsive and mucoadhesive in situ gel as vaccine delivery system for BLSOmp31. Poloxamer 407 (16% w/v) was added to an aqueous solution of BLSOmp31. To enhance the mucoadhesive capability of the formulation, chitosan (0.25 % w/v in 0.5% acetic acid solution) was added. All reagents were dispersed at 20ºC and then mixed on a magnetic stirrer (4ºC) until a homogeneous solution was obtained. Rheological studies were performed to determine the sol-gel transition temperature and to evaluate the viscosity at 37°C. Measurements were carried out using an Anton Paar MCR 301 rheometer (from 0 to 50°C). To evaluate the diffusion of BLSOmp31 out of the gel in aqueous media, the formulation was cooled at 37°C in a thermo-controlled water bath. When the temperature inside the tube reached 37°C and gelation occurred, PBS (pH 6.85) was incorporated with mild magnetic stirring. At selected time intervals (0 to 270 min) samples were withdrawn. BLSOmp31 released from the gel was determined by a capture ELISA. This formulation showed a reverse thermogelation in which aqueous solution was free-flowing liquid at room temperature and formed a stable gel at 37ºC. The profile of release BLSOmp31 from P407-Ch gel was slow at the beginning and then it began to increase (50% of BLSOmp31 was released after 210 min). The results indicate that the mixture solution developed presents an appropriate behavior as a thermoresponsive delivery system, a good viscosity and could be able to deliver structurally intact immunogen BLSOmp31.