TABLE 2.

Adoptive transfer of serum, spleen cells, or T-enriched spleen cells^a

Transferred material	Survival (%)	MST (days)	No. of animals (no. of experiments)
Serum	98 ± 2	12 ± 0	27 (3)
Crude spleen cells	6.7 ± 6.7	10.1 ± 1.7	33 (3)
T-enriched spleen cells	0	11.9 ± 1.7	15 (2)

^aMice that were exposed to 1,000 PFU of TBEV while being passively protected by human TBEV Ig and that survived an identical rechallenge were used as donor animals for serum, crude spleen cells, or T-enriched spleen cells. Naive donor mice received either serum (0.2 ml i.v., 2 days and 2 h prior to challenge), crude spleen cells (10⁸ cells i.p., 3 to 6 h prior to challenge), or T-enriched spleen cells (4 × 10⁷ cells i.p., 3 to 6 h prior to challenge) from pools of 6 to 30 donor animals before they were inoculated i.p. with 1,000 PFU of TBEV. The survival of the mice was monitored for 28 days or until no further deaths occurred for a consecutive week. The results presented are the mean (± SEM) survival percentages and the MST (in days) of mice that died. The data presented were collected from two or three independent experiments with the indicated number of animals.