Immunization of woodchucks (Marmota monax) with hepatitis delta virus DNA vaccine

We investigated the DNA immunization approach in order to induce a protecti ve immune response against hepatitis delta virus (HDV) superinfection of ch ronically woodchuck hepatitis virus (WHV) infected woodchucks. The animals were immunized with an expression vector encoding HDAg by gene gun. T cell and humoral immune responses induced by this protocol were determined and c ompared with those induced by HDAg immunization using a CpG oligonucleotide as an adjuvant. After immunization the woodchucks were challenged with 10( 6) genome equivalents of HDV. The protein immunization with HDAg induced go od humoral and T helper cell responses in the woodchucks, but did not prote ct them from HDV superinfection. The, DNA immunized woodchucks were also no t protected from HDV superinfection, however, the course of infection was m odified: HDV viremia occurred later, the typical fluctuation of the HDV RNA titer with several peaks was absent, and antibodies to HDV were not detect able. (C) 2001 Elsevier Science Ltd. All rights reserved.