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Background: New generated subunit vaccines are characterized by increased safety and lack of side effects, however they suffer from weak immunogenicity. The adjuvants are substances that have the ability to enhance the magnitude and duration of the immune response and to increase vaccine efficacy, but the different vaccines may require diverse adjuvants. The urgent need of novel adjuvant formulations occurs, thus ensuring protective cellular and humoral responses against infectious pathogens. The hemocyanins, oxygen binding copper proteins in the hemolymph of molluscs and arthropods, are widely used as peptide carriers and vaccine adjuvants., Results: In the present study we promote the hemocyanin isolated from the terrestrial gastropod Helix pomatia (HPH) as bio-adjuvant, combined with standard antigens. The purified HPH combined with influenza virus hemagglutinin intersubunit peptide (IP) or with tetanus toxoid (TT) were used for immunization. Administration of tetanus toxoid combined with HPH in mice resulted in an increased number of anti-TT IgG producing plasmocytes and induced a significant increase of B and T cell proliferation. The level of the anti-TT IgG antibodies in mice sera was comparable to the group administered with TT+Al(OH)3. An immunization of experimental animals with IP combined with H. pomatia hemocyanin led to generation of strong anti-influenza cytotoxic response., Conclusion: The vaccination of mice demonstrates that the HPH is acceptable as a potential bio-adjuvant for subunit vaccines and it could be used as a natural adjuvant or protein carrier., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Killed viral vaccines and bacterial toxoids are weakly immunogenic. Numerous compounds are under evaluation as immunological adjuvants and peptide-carriers to improve the immune response. The hemocyanins, giant extracellular copper proteins in the blood of many mollusks, are widely used as immune stimulants. In the present study we investigated the adjuvant properties of hemocyanins isolated from marine gastropods Rapana thomasiana and Megathura crenulata. An immunization with Influenza vaccine or tetanus toxoid combined with Rapana thomasiana hemocyanin (RtH) and Keyhole limpet hemocyanin (KLH) in mice induced an anti-influenza cytotoxic response lasting at least 5 months and an antibody response to viral proteins. The IgG antibody response to the tetanus toxoid (TT) combined with RtH or KLH was comparable to the response of the toxoid in complete Freund's adjuvant. The results obtained demonstrate that the both hemocyanins are acceptable as potential bio-adjuvants for subunit vaccines., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

We have investigated the non-specific immunostimulatory and specific immunomodulatory effects of hemocyanin from marine gastropod Rapana thomasiana (RtH). The purified RtH, its structural subunits RtH1 and RtH2 and a construct with influenza virus hemagglutinin intersubunit peptide (IP) were used in immunization protocols of Balb/c mice. Antibody formation against RtH, RtH1, RtH2, RtH-IP as well as anti-RtH IgG antibody isotypes were determined by ELISA. The immune homology between both subunits and the whole RtH molecule was investigated by cross-blotting technique. The retaining of the B-cell epitope of IP, coupled to the RtH was recognised by Western blot. The results obtained demonstrate that the immunization with RtH or its subunits in experimental models resulted in strong immune response in vivo. Common epitope of influenza A virus hemagglutinin jointed to RtH results in generation of molecule with increased immunogenicity. Our results are the first demonstration that RtH and/or its subunits could be used in different immunization protocols as an adjuvant or as a protein-carrier.