Thymosin α1 (Tα1) and Bursopentin (BP5) are both immunopotentiators. To explore whether the thymosin α1-Bursopentin (rTα1-BP5) is an adjuvant or not, we cloned the gene of Tα1-BP5 and provided evidence that the gene of Tα1-BP5 in a recombinant prokaryotic expression plasmid was successfully expressed in Escherichia coli BL21. To evaluate the immune adjuvant properties of rTα1-BP5, chickens were immunized with rTα1-BP5 combined with H9N2 avian influenza whole-inactivated virus (WIV). The titers of HI antibody, antigen-specific antibodies, Avian influenza virus (AIV)-neutralizing antibodies, levels of Th1-type cytokines (gamma interferon (IFN-γ)) and Th2-type cytokines (interleukin 4 (IL-4)), and lymphocyte proliferation responses were determined. We found that rTα1-BP5 enhanced HI antibody and antigen-specific immunoglobulin G (IgG) antibodies titers, increased the level of AIV-neutralizing antibodies, induced the secretion of Th1- and Th2-type cytokines, and promoted the proliferation of T and B lymphocyte. Furthermore, virus challenge experiments confirmed that rTα1-BP5 contributed to the inhibition replication of the virus (H9N2 AIV (A/chicken/Jiangsu/NJ07/05) from chicken lungs. Altogether, these findings suggest that rTα1-BP5 is a novel adjuvant suitable for H9N2 avian influenza vaccine.
Part of the book: Steps Forwards in Diagnosing and Controlling Influenza