Clonagem de antígenos quiméricos contendo epítopos das glicoproteínas E1 e E2 do envelope do vírus da hepatite C e caracterização de suas propriedades imunogênicas através da imunização com DNA

Abstract

Approximately 130 million people are infected chronically with hepatitis C virus (HCV). The development of vaccines has been hampered by the high genetic variability of the virus as well as by the lack of suitable animal models. In this study, we describe the construction of an artificial antigen based in the nucleotide sequence of the strain JFH1 (genotype 2a) containing segments of the HCV glycoproteins E1 and E2 that have been reported to elicit neutralizing antibodies against HCV. The immunogenicity of the E1E2 antigen was assessed in BALB/c mice by DNA immunization given in three doses (homologous immunization). Also, another group of mice was immunized with two doses of DNA and one additional dose of bacteria-expressed E1E2 protein (heterologous immunization). The sera of immunized mice were tested by ELISA and reacted against the recombinant E1E2 protein as well as four synthetic peptides (I - IV) covering parts of the E1E2 sequence. In addition, the antibodies present in some sera of both immunized groups of mice reacted against viral proteins in Huh7.5 cells producing JFH1 strain HCV in immunofluorescence assay. Moreover, the sera of animals had antibodies with virus-neutralizing capacity as evidenced by a reduction in approximately 40% of viral infection in cell culture. Our results demonstrate the ability of an artificial antigen, administered as DNA vaccine, to elicit specific antibodies with neutralizing capacity against HCV glycoprotein(s). Further investigations are still needed to explore the cellular immune response elicited by this antigen.