Pharmacokinetics studies of TS-SAPA deletion proteins. Mice intravenously inoculated with 100 pmoles of the indicated protein, were bled at the indicated days after injection and quantitated for remnant trans-sialidase activity in blood as indicated in the legend to Fig 2. Data are expressed as the mean ± SD (n = 3 animals). TS-3R, TS-8R, and TS-13R proteins contain 3, 8, or 13 SAPA-repetitive units, respectively. One out of two experiments with similar results is shown. Asterisks (*) indicate significant differences (P < .05) to TS-SAPA protein.