Comparative studies on immune responses of BALB/c mice immuned with HCV NS3/4A by routes of gene gun bombardment and intramuscular injection

Objective A DNA vaccine expressing HCV NS3/4A was evaluated for inducing immunity in mice.The plasmid was administered via intramuscular injection(IM)and gene gun bombardment(GB).Methods Immunizing the BALB/C mice separately with 2 μg and 10 μg pcDNA3.1-NS3/4A by GB comparing to100 μg by IM for three times at 2 weeks intervals.Collecting the sera of mice and separating the splenocytes separately at 10 d and 20 d after immunization.The antibodies in the sera were assayed with ELISA.IFN-γ,IL-2,IL-4 was detected by ELIspot and CTL assays were performed with the non-radioactive cytotoxicity assay kit.Results The result from ELISA at 10 d after immunization showed that the specific antibody titers with 2 μg and 10 μg by GB were 1∶500 and 1∶1 000 compared to 1∶1 000 by IM.Surprisingly the specific antibody titers by GB were still 1∶500 and 1∶1 000 detected at 20 d,but it decreased to 1∶500 by IM.The result from ELIspot showed that IFN-γ and IL-2 by GB were higher than that by IM(P0.05).IL-4 was not detected remarkedly during all groups.The special cytotoxic effects of immunization with 10 μg and 2 μg by GB were stronger than 100 μg by IM.Conclusion Overall,our results suggest that the celuller and humoral immune response against HCV NS3/4A vaccinated by GB were higher than that by IM.