Lactobacillus plantarum displaying CCL3 chemokine in fusion with HIV-1 Gag derived antigen causes increased recruitment of T cells.
BACKGROUND
Chemokines are attractive candidates for vaccine adjuvants due to their ability to recruit the immune cells. Lactic acid bacteria (LAB)-based delivery vehicles have potential to be used as a cheap and safe option for vaccination. Chemokine produced on the surface of LAB may potentially enhance the immune response to an antigen and this approach can be considered in development of future mucosal vaccines.


RESULTS
We have constructed strains of Lactobacillus plantarum displaying a chemokine on their surface. L. plantarum was genetically engineered to express and anchor to the surface a protein called CCL3Gag. CCL3Gag is a fusion protein comprising of truncated HIV-1 Gag antigen and the murine chemokine CCL3, also known as MIP-1α. Various surface anchoring strategies were explored: (1) a lipobox-based covalent membrane anchor, (2) sortase-mediated covalent cell wall anchoring, (3) LysM-based non-covalent cell wall anchoring, and (4) an N-terminal signal peptide-based transmembrane anchor. Protein production and correct localization were confirmed using Western blotting, flow cytometry and immunofluorescence microscopy. Using a chemotaxis assay, we demonstrated that CCL3Gag-producing L. plantarum strains are able to recruit immune cells in vitro.


CONCLUSIONS
The results show the ability of engineered L. plantarum to produce a functional chemotactic protein immobilized on the bacterial surface. We observed that the activity of surface-displayed CCL3Gag differed depending on the type of anchor used. The chemokine which is a part of the bacteria-based vaccine may increase the recruitment of immune cells and, thereby, enhance the reaction of the immune system to the vaccine.
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway. geir.mathiesen@nmbu.no.
Katarzyna
K
Kuczkowska
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway. geir.mathiesen@nmbu.no.
Geir
G
Mathiesen
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway. geir.mathiesen@nmbu.no.
Vincent G H
VG
Eijsink
Department of Pathology and Centre for Immune Regulation, Oslo University Hospital-Rikshospitalet, and University of Oslo, Oslo, Norway. geir.mathiesen@nmbu.no.
Inger
I
Øynebråten
D002460:Cell Line; D054405:Chemokine CCL3 / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis; D005434:Flow Cytometry; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D048191:Lactiplantibacillus plantarum / Q000254:growth & development / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
D054405:Chemokine CCL3; D011993:Recombinant Fusion Proteins; D014614:Vaccines, Synthetic; D054301:gag Gene Products, Human Immunodeficiency Virus