Sendai virus-specific binding antibody titers. Sera were collected on day 30 of the experiment.

Titers were measured by reciprocal endpoint dilutions in ELISA assays and the fold change in titers over mock inoculated mouse levels was calculated. Data for airborne transmission corresponds to experiments that had a 7.6-cm separation between donor and recipient mice. Significance was determined using the Student's t-test: * p≤0.03 and ** p = 0.004. No trans. = no transmission, trach. dom. = tracheal dominant infection, rep. diss. = respiratory tract disseminated infection.