Recombinant fusion protein of Heparin-Binding Hemagglutinin Adhesin and Fibronectin Attachment Protein (rHBHA-FAP) of Mycobacterium avium subsp. Paratuberculosis elicits a strong gamma interferon response in peripheral blood mononuclear cell culture

Background: Mycobacterium avium subsp. Paratuberculosis (MAP) is a causative agent of Johne's disease in all ruminants worldwide. Economic problems in dairy cattle and sheep industries, public health concern, persistence of MAP in the environment and lack of effective vaccines mentioned necessity of research about various antigens to introduce as vaccine candidates. Based on MAP pathogenesis, it seems that research about the production of new recombinant proteins to stimulate cell-mediated immunity is helpful. This study describes successful expression and purification of a chimeric fusion protein which consists of Heparin-Binding Hemagglutinin Adhesin (HBHA) and high antigenic region of Fibronectin Attachment Protein (FAP-P). Triggered antigen-specific IFN-γresponse of isolated PBMCs from immunized goats to rHBHA-FAP and all crude proteins of MAP (PPD), was measured by ELISA. Results: Significant increases were observed in the IFN-γproduction level of peripheral blood mononuclear cells (PBMCs) stimulated by constructed chimeric protein from rHBHA-FAP and PPD vaccinated goats. Antigen-specific gamma interferon (IFN-γ) secretion in positive group (immunized by PPD) against rHBHA-FAP and test group (immunized by rHBHA-FAP) against PPD, also statistically insignificant rises between stimulation with rHBHA-FAP and PPD, suggested the potential and specificity of our chimeric protein to stimulate cell mediated immunity against MAP. Conclusions: Collectively, these results demonstrate that rHBHA-FAP elicits a strong IFN-γproduction in PBMC culture. Therefore, further studies of the present product as a candidate vaccine in naturally infected animals should be conducted, to analyze its potential.