Background: High mobility group box 1 (HMGB1) is a highly conserved protein present
in the nuclei and cytoplasm of cells which has an important role as a mediator of inflammation
in the extracellular environment. HMGB1 was identified as an innate adjuvant that induces immune
responses against soluble antigens in vivo.
Objective: Our goal is the generation of recombinant HMGB1-GFP fusion protein in insect cells for
evaluation of immune responses in mouse model.
Method: In the current study, we used a baculovirus
expression system for insect cells that was
based on expression of HMGB1 with target gene (GFP), and purified the recombinant HMGB1-
GFP fusion protein. We then demonstrated whether immunogenicity of GFP changes in the presence
or absence of recombinant HMGB1 acting as an adjuvant in C57BL/6 and BALB/c mice.
Results: Our data showed that HMGB1 had a major influence on antibody immune responses induced
by GFP in both animal models. The groups receiving HMGB1-GFP fusion protein showed
total IgG and IgG2a responses significantly higher than IgG1 in BALB/c mice. Indeed, a mixed
IgG1/IgG2a response was observed with high intensity toward IgG2a. In contrast, C57BL/6 mice
immunized by HMGB1-GFP protein elicited the same levels of IgG1 and IgG2a. However, the
levels of IgG2a and total IgG against the recombinant GFP (rGFP) in C57BL/6 mice were lower
than those in BALB/c mice.
Conclusion: We concluded that fusion of HMGB1 with GFP was immunologically more effective
than GFP alone.