From synthetic polyelectrolytes to polymer-subunit vaccines

The results of many years of collaborative research by chemists and immunologists in the area of application of synthetic polyelectrolytes in immunology are reviewed. Linear synthetic polyelectrolytes with diverse structures (which are not structural analogs of biopolymers and, hence, not antigenic because they are unknown to the immune system), when introduced into the organism, noticeably intensify the formation, migration, and dissemination of stem cells, which are precursors of all specialized cells including functional immune cells. In addition, synthetic polyelectrolytes, when introduced in mixtures with typical antigens (proteins, natural microbial poly saccharides, and their synthetic analogs), serve as immunostimulants enhancing immune response by several times. Moreover, individual bacterial or viral antigens, not sufficiently active by themselves, induce specific immune response enhanced by orders of magnitude if chemically bound to synthetic polyelectrolytes. Such conjugates being preliminarily administrated, protect organisms from absolutely mortal doses of the corresponding bacteria or viruses. The nontoxic immunostimulant was developed: the ternary copolymer of 1,4-ethylenepiperazine, 1,4-ethylenepiperazine-N-oxide, and (N-carboxymethylene)-1,4-ethylenepiperazinium bromide (brand name "polyoxidonium"(TM)) permitted for human administration. The conjugate of polyoxidonium with hemagglutinin and neuraminidase, protein subunits of influenza viruses, has appeared as the first non-Pasteurian vaccine, which now is successfully used in Russia (about 50 million immunized people for the last 7 years). The physicochemical mechanisms of the biological effect of these compounds and challenges of the further use of the approach developed are considered in the review.