High Potency of Novel Polymeric Adjuvant in Eliciting of the Immune Response in Mice to Major Antigens of Chlamydia and Yersinia

Abstract

Polyoxidonium (PO) has been recognized as an effective, safe immunomodulator with a marked immuno-stimulating activity suitable for the complex treatment of both acute and chronic infections in humans. The PO contains high-polymeric units of 100 kDa based on both N-oxide 1,4- ethylene piperazine and (N-carboxyethyl-) 1,4 ethylene piperazine bromide. Recently, PO has been licensed for human use in the new Russian trivalent polymeric subunit flu vaccine “Grippol.” This will open a possibility of using the PO for the development of vaccines against other infectious diseases. Here we studied the potency of the PO in eliciting the humoral immune response to specific antigens of Chlamydia spp. (C1 and C2) and Yersinia pestis (Pla, LcrV, and YopM) in comparison with the Freund's complete (FCA) and Titermax (TMC) adjuvants. The Balb/c mice were primed with a single intraperitoneal injection of the 10-20 μg of antigen mixed 1:1 with either adjuvant and boosted 3 times with the same antigen alone. We found at least 8- to 16-fold and 4- to 8-fold increases in IgG titers to Chlamydia and Yersinia antigens, respectively, after injections of the antigens with the PO in relation to the use of the either FCA or TMC. The PO was found to be absolutely safe for animal health, since there were no visible adverse reactions at the inoculation site characteristic of those seen with the other adjuvants, in particular FCA. Thus, the PO could be the adjuvant of choice to elicit a strong immune response to the major antigens of Chlamydia and Yersinia, suggesting the possibility of its use in developing bi- and tri-valent subunit vaccines with enhanced immunity. The exact mechanism of priming the immune response by the PO is under investigation.