Fig 3.

Production of rRABV-ΔM-induced RABV-specific VNAs is delayed in sIgM^−/− mice compared to wild-type controls. Groups of sIgM^−/− or wild-type mice were immunized i.m. with a single dose of 10⁶ FFU of rRABV-ΔM. Blood was collected on the indicated days postimmunization, and VNA titers from pooled sera were determined using the RFFIT. Neutralization titers, defined as the inverse of the highest serum dilution that neutralizes 50% of the challenge virus (challenge virus strain 11), were normalized to international units/ml (IU/ml) using the WHO anti-RABV antibody reference standard. Data represent 2 independent experiments consisting of sera from 3 mice/experiment pooled and then analyzed in duplicate (total n = 6 mice/group). To compare two groups of data for antibody responses, we used an unpaired, two-tailed t test.