FIG. 1.
Oral immunization with Ad recombinants expressing rabies virus glycoprotein results in rabies virus-specific serum antibodies and protection against rabies virus challenge. (A) Groups of eight ICR or C57BL/6 mice were immunized orally with 2 × 107 (open symbols), 2 × 106 (closed symbols), or 2 × 105 (half-closed symbols) PFU of AdHu5rab.gp (left panels) or AdC68rab.gp (right panels). Mice were bled 21 days later, and sera were tested for antibodies to rabies virus in comparison to sera from naïve mice (X) by an ELISA. Data show means ± standard deviations for pools of sera tested in duplicate. (B) Groups of five ICR mice were immunized either per os (closed squares) or i.m. (open squares) with 107 (left) or 105 (right) PFU of AdHu5rab.gp. Serum antibody titers were tested 4 weeks later. X, sera from naïve ICR mice. (C) The graph shows data generated with sera from groups of eight ICR mice immunized orally with 2 × 104 to 2 × 107 PFU of AdHu5rab.gp (striped bars) or AdC68rab.gp (solid bars). Sera were tested 3 weeks after vaccination for neutralizing antibodies to rabies virus. Data are expressed as international units determined by comparison to a World Health Organization reference serum. Normal mouse sera tested in parallel had titers below 0.5 IU. (D) The graph shows survival of the same groups of mice whose results are shown in Fig. 1C upon intracerebral challenge with 10 mean lethal doses of rabies virus. Striped bars, AdHu5rab.gp; solid bars, AdC68rab.gp. (E) Isotypes of serum antibodies to rabies virus from ICR and C57BL/6 mice immunized orally 3 weeks previously with 2 × 107 PFU of AdHu5rab.gp (striped bars) or AdC68rab.gp (solid bars) or with nothing (speckled bars) were tested by an ELISA. Data show results for pooled sera tested in duplicate at a 1:200 dilution.