Background: Hepatitis C Virus (HCV) is a major cause of chronic liver disease in the
world. Many studies showed that T-cell responses to HCV Nonstructural Protein 3 (NS3) play an
important role in clearing acute HCV infections, thus NS3 can be considered as a suitable candidate
antigen for development of a HCV therapeutic vaccine.
Objective: We used Hp91 peptide and small heat shock protein 20 as an adjuvant for enhancement
of NS3-specific humoral and cellular immunity in mice.
Method: In this study, various NS3 DNA and protein constructs were generated in eukaryotic and
prokaryotic expression systems, and their potency in eliciting humoral and cellular immune responses
was compared using small Heat shock protein 20 (Hsp20), the High Mobility Group Box 1
protein (HMGB1)-derived peptide (Hp91), and Freund’s adjuvant in a BALB/c mouse model.
Results: Our results indicated that both the Hsp20 conjugated with NS3 protein and Hp91 significantly
enhanced the levels of IgG2a, IgG2b and IFN-γ directed toward Th1 responses compared to
other groups. Moreover, the immunostimulatory properties of Hp91 were significantly higher than
Hsp20 and Freund’s adjuvant in various immunization strategies. Mice immunized by NS3 protein
formulated with Freund’s adjuvant, and also mixed with Hp91 peptide showed higher secretion of
Granzyme B than other groups.
Conclusion: Hp91 peptide could develop NS3-specific B- and T-cell immune responses as a promising
HCV therapeutic vaccine candidate in future.