Helix pomatia hemocyanin - a novel bio-adjuvant for viral and bacterial antigens

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.

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.

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.