liver were placed directly into 2 ml of isotonic saline with 0.167% gelatin
(gel
saline). The right half of the brain was used for histology and viral antigen
staining as described below. All organs were weighed and stored frozen at 80°C
until determination of virus titers. Organs were homogenized, and virus titers
were determined by plaque assay on L2 cell monolayers