FIG. 1.

Viral replication in O. porcinus porcinus ticks following oral exposure. Ticks were exposed by membrane feeding. The inoculum contained MAL or Pr4 diluted in either heparinized pig blood (A) or fetal bovine serum in place of pig blood (B). Immediately postfeeding, a portion of each group was killed by momentary freezing in liquid nitrogen. At the indicated times p.i., individual ticks (n = 4) from each group were ground in cell culture medium and titrations were performed. The values are mean titers ± the standard errors of the means.