Four E. ruminantium 1H12 open reading frames and their proteins known to protect sheep against heartwater needle challenge were encapsulated into, or adsorbed onto poly (d,l-lactide-co-glycolide) microparticles. Microspheres with smooth surface and smaller than 5 m diameters were produced,
with high adsorption and encapsulation efficiencies. Gel electrophoresis showed that neither encapsulation nor adsorption affected the stability of the DNA or proteins. Cationic microparticles released ∼40% of plasmid DNA on day 1 while PLGA50:50-COOH microparticles co-encapsulating plasmid DNA and polyvinyl alcohol only started to release from days 12-28. Recombinant proteins were released from PLGA 85:15 and homopolymer R 203 S microparticles in a biphasic manner with a high initial burst release (∼45–80%). In contrast, PLGA 50:50 microparticles had low (15–65%) initial burst release followed by (25–80%) release by days (days 28–42). A cocktail of these microparticles could there fore be used as single-dose auto booster vaccine.