Production of glycosylphosphatidylinositol-anchored proteins for vaccines and directed binding of immunoliposomes to specific cell types

• Published in: The journal of venomous animals and toxins including tropical diseases 2020-08, Vol.26, p.e20200032
• Main Authors: Fotoran, Wesley L, Kleiber, Nicole, Müntefering, Thomas, Liebau, Eva, Wunderlich, Gerhard
• Format: Article
• Language: English
• Subjects: Immune targeting; Liposome; Plasmodium; TOXICOLOGY; TROPICAL MEDICINE; Vaccine
• ISSN: 1678-9199; 1678-9199
• DOI: 10.1590/1678-9199-JVATITD-2020-0032

Liposomes are highly useful carriers for delivering drugs or antigens. The association of glycosylphosphatidylinositol (GPI)-anchored proteins to liposomes potentially enhances the immunogenic effect of vaccine antigens by increasing their surface concentration. Furthermore, the introduction of a universal immunoglobulin-binding domain can make liposomes targetable to virtually any desired receptor for which antibodies exist. We developed a system for the production of recombinant proteins with GPI anchors and histidine tags and Strep-tags for simplified purification from cells. This system was applied to i) the green fluorescent protein (GFP) as a reporter, ii) the promising vaccine antigen PfRH5 and iii) a doubled immunoglobulin Fc-binding domain termed ZZ from protein A of . As the GPI-attachment domain, the C-terminus of murine CD14 was used. After the recovery of these three recombinant proteins from Chinese hamster ovary (CHO) cells and association with liposomes, their vaccine potential and ability to target the CD4 receptor on lymphocytes in conditions were tested. Upon immunization in mice, the PfRH5-GPI-loaded liposomes generated antibody titers of 10 to 10 , and showed a 45% inhibitory effect on growth at an IgG concentration of 600 µg/mL in cultures. Using GPI-anchored ZZ to couple anti-CD4 antibodies to liposomes, we created immunoliposomes with a binding efficiency of 75% to CD4 cells in splenocytes and minimal off-target binding. Proteins are very effectively associated with liposomes via a GPI-anchor to form proteoliposome particles and these are useful for a variety of applications including vaccines and antibody-mediated targeting of liposomes. Importantly, the CHO-cell and GPI-tagged produced PfRH5 elicited invasion-blocking antibodies qualitatively comparable to other approaches.