Co-immunization with M-CSFR and mM-CSF DNA vaccines is better than M-CSFR-mM-CSF fusion DNA vaccine.

BACKGROUND AND OBJECTIVES DNA vaccine against macrophage colony-stimulating factor receptor (M-CSFR) has shown both protective and therapeutic effects. In this study, we explore the possibility of using DNA vaccines against both M-CSFR and membrane-bound macrophage colony-stimulating factor (mM-CSF) to achieve better effects. DESIGN AND METHODS Three plasmids were constructed by inserting either extracellular and transmembrane region of mM-CSF (pM), or extracellular region of M-CSFR (pR), or extracellular region of M-CSFR linked with extracellular and transmembrane regions of mM-CSF by a (Gly Gly Ser)2 flexible linker (pF), into pcDNA3.1. A SP2/0 cell line stably expressing pF (SP2/0-F) was established to evaluate humoral and cytotoxic immune responses as well as therapeutic and preventive effects induced by pM, pR, pF or pM+pR vaccination in BALB/c mice. The mechanisms of these vaccinations were also studied by monitoring the release of interleukin (IL)-4 and interferon (IFN)-g by splenocytes upon activation. RESULTS Vaccination against two epitopes had better effects than against a single epitope while vaccination by pM+pR had the greatest effects on inducing humoral and cytotoxic immune responses, prolonging survival of mice challenged with SP2/0-F, and inducing IL-4 and IFN-g release by splenocytes. INTERPRETATION AND CONCLUSIONS Our results suggest that co-immunization of M-CSFR and mM-CSF DNA vaccines is better than M-CSFR-mM-CSF fusion DNA vaccine.