Figure 1.

Antibody responses to replicating and nonreplicating TI-1, TI-2, and TD viral antigens. C3^−/− (▪, •) and control mice (□, ○) ([C57BL/6 × 129Sv]F1 or C57BL/6) were immunized with (A) 2 × 10⁶ pfu live VSV i.v., (B) 2 × 10⁸ pfu VSV UV-inactivated i.v., (C) 2 × 10⁶ pfu Vacc VSV G, or (D) 10 μg baculovirus VSV G protein i.v. Neutralizing antibody titers were assessed at the time points indicated. In the experiment shown, three out of five C3^−/− mice died between day 8 and 12 after infection with VSV (Table ). Antibody titers in the dying mice were not different from those in surviving mice. After immunization with (E) 200 pfu LCMV-WE or (F) UV-inactivated purified LCMV-WE (∼20 μg protein), LCMV NP–specific antibodies were determined in an ELISA on baculovirus-derived LCMV NP–coated plates. Titers are shown as dilutions leading to OD 405 nm twice over background. (G) C3^−/− and control mice were immunized every other day until day 12 with 2 × 10⁸ pfu UV-inactivated VSV, and neutralizing antibody titers were measured. (H) CR2^−/− and control mice were immunized once with 2 × 10⁸ pfu UV-inactivated VSV, and VSV-IND–neutralizing antibody titers were assessed at the time points indicated. All results (A–H) are given as mean ± SD of three mice per group. Experiments were repeated twice with similar results.