Covalent complexes of antigen and alpha(2)-macroglobulin: evidence for dramatically-increased immunogenicity

A safe. effective, more potent adjuvant than currently available would be b eneficial in developing new therapeutics and diagnostic reagents, We report here a technique for the rapid, efficient incorporation of non-proteolytic antigens into alpha (2)-macroglobulin (alpha M-2; tradename. SynerVax (TM) ), allowing us to covalently couple much larger subunit antigens to alpha M -2 than previously possible. Our goal was to determine if incorporation of HB, the monomeric form of Hepatitis B virus (HBV) surface antigen (HBsAg), into alpha M-2 would result in increased immune reactivity. Earlier attempt s to immunize animals using HB did not generate significant levels of antib odies. Using HB complexes prepared with alpha M-2 we now report dramatic al ly-increased immunogenicity of HB in BALB/c mice, Combining these soluble c omplexes with a depot-generating agent (alum), titers > 1:1,000,000 are obt ained with a single injection. This novel adjuvant technology should provid e a valuable tool for the development of either prophylactic and therapeuti c vaccines, or monoclonal antibodies against hitherto poorly-immunogenic su bunit antigens. (C) 2001 Published by Elsevier Science Ltd.