INTRAVAGINAL IMMUNIZATION IN SHEEP USING A BIOADHESIVE MICROSPHERE ANTIGEN DELIVERY SYSTEM

An enzymatically cleaved glycoprotein fragment (amino acids 28-328: 40 kDa) from influenza virus haemagglutinin (TOPS) was used to assess an intravaginal antigen delivery system, comprising lysophosphatidylchol ine (LPC) and degradable starch microspheres (DSM). Three groups of th ree sheep received intravaginal immunization with TOPS as follows: gro up 2, TOPS in solution; group 3, TOPS and DSM/LPC as a powder formulat ion and group 4, TOPS and LPC in solution. A fourth group, group 1, re ceived intramuscular immunization with TOPS adsorbed to aluminium hydr oxide gel (Alugel). Intravaginal immunizations were repeated on two co nsecutive days. Two weeks later, booster doses of the same formulation s were administered on two consecutive days to each group. Group 1 she ep were boosted with a single injection, 2 weeks after the single prim ary immunization. The serum and vaginal wash IgA and IgG antibody resp onses were compared among the four groups of sheep at days 15, 30 and 45 after the booster immunizations. At day 45, the serum IgG and the v aginal wash IgA antibody responses induced by TOPS and DSM/LPC (group 3), were significantly greater than the responses induced by intravagi nal immunization with TOPS (group 2). However, the highest levels of a ntibodies in serum and vaginal wash samples were induced by intramuscu lar immunization with TOPS and Alugel (group 1). Intravaginal immuniza tion with TOPS and LPC (group 4) did not result in the induction of en hanced levels of antibodies in serum or vaginal wash sa les.